Phycology doi: 10.3390/phycology4010010
Authors: Elena Bișinicu Laura Boicenco Elena Pantea Florin Timofte Luminița Lazăr Oana Vlas
In order to analyze how environmental factors affect planktonic organisms along the Romanian Black Sea coast, this study created semi-quantitative models of the causal relationships between phytoplankton, zooplankton, and physicochemical parameters by utilizing user-friendly modeling tools. Eleven years of time-series data (March–September 2008–2018) were used to investigate the relationships between phytoplankton, zooplankton, and environmental factors (such as temperature, salinity, and nutrients). Variables such as marine reporting units and phytoplankton species and classes were used to identify developmental patterns, utilizing the Mental Modeler platform to consider interactions between the physicochemical parameters and phytoplankton, phytoplankton and zooplankton, and zooplankton and physicochemical parameters. Although the increase in the overall number of elements and linkages was uncertain in waters with variable salinity compared to marine ones, the semi-quantitative models created for the three marine reporting units along the Romanian Black Sea coast were comparable in terms of complexity. Across the typical and examined types of phytoplankton proliferation (normal, abundant, and blooms), the number of components and connections in the case of phytoplankton blooms substantially decreased as species- and growth-promoting variables increased.
]]>Phycology doi: 10.3390/phycology4010009
Authors: Paul J. Oberholster Yolandi Schoeman Anna-Maria Botha
This review outlines the potential of phycoremediation as a natural, cost-effective solution for domestic wastewater treatment in Africa, particularly focusing on its application in less densely populated and rural areas. The urgency of improving sanitation access, a key objective in both the Millennium Development Goals (2000–2015) and the Sustainable Development Goals (2015–2030), is underscored by the fact that half of Africa’s population suffers from diseases linked to inadequate water and sanitation facilities. South Africa, a focal point of this study, faces significant challenges in wastewater management. These include the limited capacity of wastewater treatment plants to handle the burgeoning wastewater volumes due to population growth, unregulated discharges causing fluctuating pollution levels, and high operational costs leading to improper sludge disposal and odor issues. Compounding these problems are frequent power outages, financial constraints impacting wastewater treatment plant operations and maintenance across Africa, and a lack of skilled personnel to manage these facilities.
]]>Phycology doi: 10.3390/phycology4010008
Authors: Dalila Aldana Arana Tania P. Gil Cortés Víctor Castillo Escalante Rosa E. Rodríguez-Martínez
Macroalgal blooms are increasing globally, with those linked to pelagic Sargassum affecting over 30 nations since 2011. As Sargassum mats traverse the Atlantic Ocean and the Caribbean Sea, they entrap and transport plastic to coastal areas, intensifying pollution in diverse ecosystems. This research assessed microplastics (MPs) within Sargassum fluitans III collected from the northern Mexican Caribbean coast (March 2021 to January 2022). The study employed a hydrogen peroxide protocol for macroalgae pretreatment to optimize MP extraction. All samples analyzed contained MPs at monthly mean concentrations that ranged from 3.5 to 15.3 MPs g−1 DW, with fibers constituting ≥90%. Fiber colors, mainly transparent, blue, and black, exhibited diverse sizes and wear stages. The study underscores the pervasive and consistent presence of MPs in pelagic Sargassum reaching the Mexican Caribbean. Considering the documented Sargassum influxes to this coast in recent years (2789–11,297 tons km−1 yr−1), potential annual MP influxes range from 0.1 × 109 to 17.3 × 109 km−1 yr−1. Efficiently removing beach-cast Sargassum and directing it to landfills could serve as a viable strategy for the simultaneous removal of attached MPs from the ocean and coastal waters, offering a promising mitigation strategy to combat plastic pollution in the examined marine environment.
]]>Phycology doi: 10.3390/phycology4010007
Authors: Ammara Nawaz Pavlína Eliška Šotek Marianna Molnárová
Several types of contaminants are anthropogenically introduced into natural aquatic ecosystems and interact with other chemicals and/or with living organisms. Although metal toxicity alone has been relatively well studied, the toxic metal ion effects in the mixture have been thoroughly studied only during the last decades. This review focuses on the published reciprocal effects of different metals on different species of algae, together with describing their toxic effects on studied parameters. Phytoplankton as a bioindicator can help to estimate the reciprocal metal risk factor. Many methodologies have been developed and explored, such as the biotic ligand model (BLM), concentration addition (CA), independent action (IA), sensitivity distribution of EC50 species sensitivity distribution (SSD curves), and others, to study reciprocal metal toxicity and provide promising results, which are briefly mentioned too. From our review, we can commonly conclude the following: Zn acted antagonistically with most heavy metals (Al, Cu, Cd, and Ni). The Cu interaction with Cd, Fe, and Pb was mostly antagonistic. Cd showed synergistic behaviour with Hg, Cu, Zn, and Pb and antagonistic behaviour with Co and Fe in many cases. Methods and techniques need to be developed and optimised to determine reciprocal metal toxicity so that the ecotoxicological predictions made by using phytoplankton can be more accurate and related to real-time toxic metals risks to the aquatic ecosystem. This is the main objective of ecotoxicological tests for risk assessment. Understanding how metals enter algal cells and organelles can help to solve this challenge and was one of the main parts of the review.
]]>Phycology doi: 10.3390/phycology4010006
Authors: Hideaki Shiraishi Mari Sasase Ayano Sakaida Nakashima
The velocity of the gliding movement of filamentous cyanobacteria on a solid surface usually has a strong temperature dependency, and the higher the temperature, the faster the speed. Former studies on this phenomenon were conducted using filamentous cyanobacteria with straight morphology. We examined the velocity of the gliding movement of Arthrospira platensis NIES-39 along its longitudinal axis to see if the same was true for this cyanobacterium with helicoid trichomes. Experimental results showed little temperature dependency in the velocity in a wide temperature range in this cyanobacterium. However, when we examined the velocity using mutants with straight trichomes, their velocity was strongly affected by temperature, like other formerly analyzed filamentous cyanobacteria. This result indicates that the helicoid morphology of A. platensis trichomes confers temperature compensation to their migration velocity, enabling them to keep a relatively constant velocity under various temperatures. Migration of wild-type trichomes is considerably suppressed compared to the straight-trichome mutants on solid media. The temperature compensation in the locomotion of this organism appears to be established as part of such a suppression. It was also found that the velocity of this cyanobacterium depended on the trichome length when they were atypically short (<250 µm); the shorter the trichomes, the slower the gliding movement tended to be. This result indicates that the coordinated action of a high number of cells constituting the trichome is required for efficient gliding movement.
]]>Phycology doi: 10.3390/phycology4010005
Authors: César Augusto Sodré da Silva Karen Vanessa Marimón Sibaja Sabrina de Ramos Cizilio José Roberto Miranda Júnior Rejane de Castro Santana Marcio Arêdes Martins Maurício de Oliveira Leite Eduardo Basílio de Oliveira Jane Sélia dos Reis Coimbra
The high protein content of several microalgal species makes them attractive and unconventional candidates for use in the food and pharmaceutical industries. Due to the robust cell walls of microalgae, cell rupture is necessary to improve the extraction of intracellular proteins. Thus, choosing a suitable cell-breaking treatment before protein extraction is a vital downstream processing step. Additionally, it is necessary to use an effective technique for monitoring and measuring the impact of rupture treatments on microalgal cell walls. In our study, Tetradesmus obliquus cells were disrupted using three different mechanical rupture methods: high-pressure homogenization (HPH), ultrasound (US), and ball milling (BM). The ruptured biomass cells were counted, and soluble proteins were extracted and quantified. The cell-counting technique did not detect any differences between intact and damaged cells after BM treatment because the dye (erythrosine B) did not permeate the microalgal biomass accurately. The US treatment promoted the highest yield of total protein extraction (19.95%), while the highest yields in the HPH and BM treatments were 15.68% and 14.11%, respectively. Since the cell breakage method affects protein extraction from microalgal biomass, protein release can be used as a central indicator of the degree of cell disruption.
]]>Phycology doi: 10.3390/phycology4010004
Authors: Daniela Gabriel William E. Schmidt Joana Micael Mónica Moura Suzanne Fredericq
Up to the present study, only 8.5% of the 522 macroalgal species reported at the Azores have sequences deposited in GenBank and BOLD public repositories. The sequences of four genetic markers (cox1, rbcL, UPA, tufA) were obtained for recently collected samples from two Azorean islands. DNA barcode-assisted identification was conducted on newly generated and unpublished sequences from public repositories. A literature review of recently published studies, including the molecular identifications of Azorean macroalgae, was also performed. The results confirm the occurrence of 51 species (including subspecific ranks) and provide four new records, namely, three cryptogenic species (Olokunia boudouresquei, Padina gymnospora, and Ulva lacinulata) and one introduced species (Ulva australis). This study contributes 23 DNA barcodes generated for the first time to the Azores, which now has 10.5% of its marine flora represented in public repositories. Additionally, UPA sequences were generated for the first time for the five taxa.
]]>Phycology doi: 10.3390/phycology4010003
Authors: James Smith Amy Pilsbury Vinod Kumar Eleni E. Karamerou Christopher J. Chuck Leopoldo Herrera-Rodriguez Julio V. Suarez Michael J. Allen
Mass Sargassum inundations have created opportunities for readily available biomass to be used as a crop enrichment application. However, the heavy metal contents of Sargassum pose serious concerns for crop administration and subsequent human consumption. Hydrothermal processing can break the feedstock components, allowing heavy metals to be partitioned, through the utilisation of high temperatures and pressures. As a result, seemingly nutrient-rich phases can be produced. Elemental analyses showed that Sargassum-derived fractions contain important macro- and micronutrients for plants, particularly ammonium, orthophosphate, and potassium, making them potential nutrient sources for plant growth. To date, no research has investigated the plant growth potential of hydrothermally processed Sargassum products from a bioavailability or biotoxicity perspective. We seek to determine if the aqueous phase products derived following Sargassum processing by hydrothermal carbonisation and liquefaction are toxic to higher plants, and if they can support plant growth. Aqueous phase products in ≥1% concentrations inhibit root growth and lateral root formation in Arabidopsis plants, likely from the presence of inhibitory compounds. However, aqueous phase products in ≤0.1% concentrations paired with an established nutrient mix may provide improved leaf and root growth. Both HTC and HTL were capable of eliciting improved foliage growth, while only HTC induced improved root growth. Conclusively, aqueous phase products lack nutrient potency to allow high dilutions for fertiliser application on their own and may contain inhibitory compounds that deter plant growth at high concentrations. However, they might have a purpose as an additive extract. The recovery of important elements needed for plant growth draws a promising path for future applications of hydrothermal processing with different feedstocks.
]]>Phycology doi: 10.3390/phycology4010002
Authors: Andrezza Carvalho Ítalo Braga Florencia Chaar Alessandro Pereira Cardozo José María Monserrat Juan Rafael Buitrago Ramírez Wilson Wasielesky Luís H. Poersch
This study focused on evaluating the effect of different concentrations of nutrients and total suspended solids on the removal rate of nutrients and biocompounds from the macroalgae U. lactuca in an integrated system with the shrimp Penaeus vannamei in biofloc. The experiment lasted 45 days and included five treatments with three replicates each, with percentages of 0 (control), 25, 50, 75, and 100% biofloc inoculum (73.3 ± 5.7 and 325.0 ± 21.2 mg L−1 initial nitrate and solids, respectively, in the 100% inoculum), from a shrimp farm, resulting in different concentrations of solids and nutrients. The macroalgae were introduced into 280 L tanks at a density of 0.88 kg m−2, along with 200 shrimp m−3. The algae were separated by a floating structure. Water quality parameters were measured, and the nutrient removal rate was evaluated. The treatment with 75% inoculum showed a removal rate of 55.0 ± 4.0 and 31.0 ± 10.0% of nitrate and phosphate, respectively. There was no difference in macroalgae growth between the treatments; however, macroalgae grown in 75% inoculum had higher protein, chlorophyll-a, and lower ash values compared with the control. The use of macroalgae in integrated production with shrimp under the conditions of the treatment with 75% biofloc inoculum proved to be viable and sustainable.
]]>Phycology doi: 10.3390/phycology4010001
Authors: Sachin G. Rathod Satej Bhushan Vaibhav A. Mantri
Plant hormones and pheromones are natural compounds involved in the growth, development, and reproductive processes. There is a plethora of studies on hormones and pheromones in terrestrial plants, but such investigations are few in the phycological literature. There are striking similarities between the chemical diversity, biosynthetic processes, roles, and actions of hormones and pheromones in both higher angiospermic plants and algae. However, there are substantial knowledge gaps in understanding the genes responsible for hormone biosynthesis and regulation in algae. Efforts have focused on identifying the genes and proteins involved in these processes, shedding light on lateral gene transfer and evolutionary outcomes. This comprehensive review contributes to benchmarking data and essential biotechnological tools, particularly for the aquaculture industry where seaweed is economically crucial. Advanced techniques in plant hormones and pheromones can revolutionize commercial aquaculture by using synthetic analogs to enhance growth, yield, and reproductive control, thereby addressing seasonal limitations and enabling sustainable seedling production. To the best of our knowledge, this is the first comprehensive review that focuses on biosynthetic pathways and modes of action (of five plant hormones and five pheromones), roles (of 11 hormones and 29 pheromones), and extraction protocols (of four hormones and six pheromones) reported in the phycological domain.
]]>Phycology doi: 10.3390/phycology3040034
Authors: Stefan Sebök Martina Strittmatter Claire M. M. Gachon Dieter Hanelt
Within the last decade, the red alga P. palmata gained increasing interest as a food additive in Europe. Traditionally, P. palmata is harvested from wild stocks, but higher biomass demands request a shift towards industrial cultivation of this species. Using a land-based tumble culture approach, we have successfully grown P. palmata via vegetative propagation over a 2-year period. One year after the initial setup, phenotypic changes represented in the formation of randomly shaped, mostly circular galls and homogeneous greenish–white spots with significantly reduced photosynthetic activity were observed on the algal thalli. With progressing time, galls increased into large flat or sunken structures, whereas the tissue in the center of the greenish–white spots weakened. In later stages, the weakened tissue is disrupted, forming holes in the thallus. In this study, we present observations, microscopy analysis, PAM results, and biotechnological approaches to describe a possible infection of P. palmata. Test results showed that light quantity might be the most important factor for the propagation behavior of the infection, whereas the pH level might be secondary, and the nutrient level and biomass density might be of minor relevance. Similarly, changes in light quality could also influence the occurrence of pathological changes in P. palmata.
]]>Phycology doi: 10.3390/phycology3040033
Authors: Abraham O. James Abayomi O. Bankole Caroline M. E. Pompei Gustavo A. S. A. Dantas Graziele Ruas Gustavo H. R. Silva
Increasing the volume of untreated and inadequately treated municipal wastewater undermines the circular economy potential of wastewater resources, particularly in low-income regions. This present study focused on and evaluated the performance of native microalgae-activated sludge (MAS) growth for tertiary treatment of anaerobically digested wastewater from an up-flow anaerobic sludge blanket (UASB) in an outdoor lab-scale photobioreactor (2.2 L). Three conditions with distinct MAS inoculum concentrations alongside three controls were operated in batch mode for 5 days hydraulic retention time (HRT) at 11.5:12.5 photo-hours. The MAS inoculum concentration influenced the treatment outcome. The best performance was observed when the MAS concentration was 0.10/0.20 g L−1, and the cell density was 1.60 × 107 cells mL−1, total biomass productivity of 0.10 g TSS L−1 d−1, total phosphorus uptake of 85.1%, and total nitrogen uptake of 66.1%. Logarithmic removal (Log-Re) of bacterial pathogens (water quality indicators) showed Log-Re 3.4 for total coliforms (1.37 × 102 CFU 100 mL−1) and 4.7 for Escherichia coli (0.00 × 100 CFU 100 mL−1). The results revealed optimum remediation performance and nutrient recovery potential with appropriate inoculum concentration, in admiration to advancing the science of circular economy.
]]>Phycology doi: 10.3390/phycology3040032
Authors: Jonas Kollmen Judith Stiefelmaier Ramtin Mofrad Dorina Strieth
Cyanobacteria are promising organisms for the sustainable production of various biotechnological interesting products. Due to their energy production via photosynthesis, the cultivation of cyanobacteria expands the CO2 cycle. Most cyanobacteria form biofilms on surfaces in their natural environment by surrounding the cells with a self-produced matrix of extracellular polymeric substances (EPS) that hold the cells together. These special growth properties need special reactors for cultivation. By immobilizing cyanobacteria on carriers, systems currently established in industry could also be used for biofilm formers. Various artificial carriers for immobilized growth of cyanobacteria and microalgae have already been described in the literature. However, the use of waste materials or natural biodegradable carriers would be more sustainable and is, therefore, the focus of this study. Dried Luffa cylindrica, zeolite, and corn stalks were investigated for their use as carriers for cyanobacteria. L. cylindrica was shown to be an excellent natural carrier for (i) Anabaena cylindrica, (ii) Nostoc muscorum 1453-12a, and (iii) Nostoc muscorum 1453-12b. Higher or at least similar growth rates were achieved when cyanobacteria were cultivated with L. cylindrica compared to submerged cultivation. Additionally, the production of EPS and C-phycocyanin was increased at least 1.4 fold in all strains by culturing on L. cylindrica. The improved growth could be explained on the one hand by the high surface area of L. cylindrica and its properties, and, on the other hand, by the release of growth-promoting nutrients from L. cylindrica to the medium.
]]>Phycology doi: 10.3390/phycology3040031
Authors: Mahshid Sedghi John Fagan Soheil Sedghi Frithjof C. Küpper Ricardo Amils
Symbiotic microalgal–bacterial biofilms can be very attractive for potato wastewater treatment. Microalgae remove nitrogen and phosphorus and simultaneously produce the oxygen that is required for the aerobic, heterotrophic degradation of organic pollutants. In this study, symbiotic microalgal–bacterial biofilms were grown in flow cells with ammonium and phosphate, and with acetate as a simulated biodegradable organic pollutant. The symbiotic biofilms removed acetate without an external oxygen or carbon dioxide supply, but ammonium and phosphate could not be completely removed. The biofilm was shown to have a considerable heterotrophic denitrification capacity. The symbiotic relationship between microalgae and aerobic heterotrophs was proven by subsequently removing light and acetate. In both cases, this resulted in the cessation of the symbiosis and in increasing effluent concentrations of both acetate and the nutrients ammonium and phosphate.
]]>Phycology doi: 10.3390/phycology3040030
Authors: Julianna T. Arita Lowell Andrew R. Iporac Natalie K. Bally Mutue T. Fujii Ligia Collado-Vides
Since 2011, the Caribbean and Gulf of Mexico coasts have been receiving massive influxes of holopelagic sargasso algae composed of Sargassum natans and Sargassum fluitans. This phenomenon has been causing several negative local impacts, such as ecological disturbances and socioeconomic and health concerns of communities in impacted areas. This work aimed to assess the status of scientific knowledge related to pelagic sargasso, including trends, emphases, and gaps. A literature review was conducted on publications and reports from 2011 to 2022, of which 251 articles were collected based on an inclusion–exclusion criteria. Aspects of each article were quantified, including location, description of sargasso, the type of study, and research theme. A region-wide research emphasis on ecology, remote sensing, and valorization was observed. Areas first affected by the inundations composed a higher percentage of sargasso studies than other locations, and the distribution of studies varied among subregions. Topics requiring further investigation include sargasso’s growth and mortality rates and drivers, taxonomic and physiologic differences among morphotypes, and real-time forecasting resolution at local scales both on and offshore. This research emphasized efforts from the scientific community on research and mitigation initiatives.
]]>Phycology doi: 10.3390/phycology3040029
Authors: Yanara Alessandra Santana Moura Ariadne Tennyle Vieira De Souza Páblo Eugênio Da Costa e Silva Marllyn Marques Da Silva Ana Lúcia Figueiredo Porto Raquel Pedrosa Bezerra
Thrombosis is characterized by the pathological formation of fibrin clots within a blood vessel, leading to the obstruction of blood flow. Fibrinolytic enzymes from microorganisms have been shown to be more efficient and safer in dissolving clots. Then, this study aimed to evaluate the cell growth and fibrinolytic enzyme production of Tetradesmus obliquus under different cultivation conditions. T. obliquus grew under autotrophic and mixotrophic conditions using different concentrations of corn steep liquor (0.25 ≤ CSL ≤ 4.00%). The cells were concentrated and lysed via two different methods (sonication or homogenization) to trigger the release of the enzyme. It was precipitated via acetone or ammonium sulfate additions and purified using ion exchange chromatography. The highest biomass productivity (Px = 130 ± 12.8 mg∙L−1day−1), specific growth rate (µmax = 0.17 ± 0.00 day−1), and fibrinolytic activity (391 ± 40.0 U∙mg−1) was achieved on a mixotrophic cultivation at a 0.25% CSL concentration. The results showed that the homogenizing method had better performance in the release of enzyme, and the precipitation with acetone obtained the highest fibrinolytic activity (567 ± 49.3 U∙mg−1). The purified enzyme showed a specific activity of 1221 ± 31 U∙mg−1 and a molecular mass of 97 kDa. So, the fibrinolytic enzyme from T. obliquus had higher activity when compared to the other fibrinolytic enzymes, being a potential source for the development of therapeutic agents in thrombosis treatment. Additional studies are needed to investigate the biochemical properties and biological profile of this enzyme.
]]>Phycology doi: 10.3390/phycology3040028
Authors: T. T. Yen Le Alina Becker Jana Kleinschmidt Ntambwe Albert Serge Mayombo Luan Farias Sára Beszteri Bánk Beszteri
Salinization and warming are of increasing concern for freshwater ecosystems. Interactive effects of stressors are often studied in bifactorial, two-level experimental setups. The shape of environmental reaction norms and the position of the “control” conditions along them, however, can influence the sign and magnitude of individual responses as well as interactive effects. We empirically model binary-stressor effects in the form of three-dimensional reaction norm surfaces. We monitored the growth of clonal cultures of six freshwater diatoms, Cymbella cf. incurvata, Nitzschia linearis, Cyclotella meneghiniana, Melosira varians, Ulnaria acus, and Navicula gregaria at various temperature (up to 28 °C) and salinity (until the growth ceased) shock treatments. Fitting a broad range of models and comparing them using the Akaike information criterion revealed a large heterogeneity of effects. A bell-shaped curve was often observed in the response of the diatoms to temperature changes, while their growth tended to decrease with increasing electrical conductivity. C. meneghiniana was more tolerant to temperature, whilst C. incurvata and C. meneghiniana were the most sensitive to salinity changes. Empirical modelling revealed interactive effects of temperature and salinity on the slope and the breadth of response curves. Contrasting types of interactions indicates uncertainties in the estimation by empirical modelling.
]]>Phycology doi: 10.3390/phycology3040027
Authors: Eduardo Gabriel Torres-Conde Brigitta I. van Tussenbroek Rosa E. Rodríguez-Martínez Beatriz Martínez-Daranas
Since 2011, the distribution, abundance, and composition of holopelagic Sargassum spp. (sargasso) have changed by the emergence of the Great Atlantic Sargasso Belt (GASB) in the northern tropical Atlantic. We expected that the north of the Cuban coast would receive sargasso from both the original Sargasso Sea and the GASB. We systematically monitored six beaches on the NW coast of Cuba to assess changes in sargasso composition from June 2019 to June 2021. During landing months, mean Sargasso wet biomass was at 1.54 kg/m2 (SE: 0.7), which was considerably lower than the sargasso on the Atlantic coasts directly impacted by GASB. Eleven out of 13 landings occurred in the autumn-winter seasons 2019–2020 and 2020–2021, with a dominance of S. natans I (accounting for 41–63% of total biomass), followed by S. fluitans III (25–36%) and S. natans VIII (12–31%). This composition is similar to those observed on the Sargasso Sea. During this season, dominant winds (≥14 km/h) came from northern (N), eastern (E), and east-northeastern (ENE) directions. In May and August 2020 (spring-summer season), S. fluitans III dominated (52–56%), followed by S. natans VIII (33–43%) and S. natans I (5–12%). This composition is similar to those observed on GASB-impacted Atlantic coasts in the spring-summer seasons (April to September). During this season, dominant winds (≥20 km/h) came from eastern (E) and east-northeastern (ENE) directions. Thus, the NW Cuba’s morphotype composition suggests that landings have different origin sources depending on season and specific meteorological and oceanographic conditions.
]]>Phycology doi: 10.3390/phycology3030026
Authors: Ryuya Yamamoto Koki Takizawa Yoshikatsu Miyabe Martin Alain Mune Mune Hideki Kishimura Yuya Kumagai
Mycosporine-like amino acids (MAAs) are natural UV-absorbing compounds found in microalgae and macroalgae. The content of MAAs in algae varies with the seasons and environmental factors. Red alga dulse in Usujiri (Hokkaido, Japan) is an underutilized resource. Therefore, we investigated the amount of MAAs in Usujiri dulse in 2022 to clarify the suitable months for MAA extraction. In addition, we also evaluated the extraction method focusing on the extraction volume. MAAs were prepared via the 20 volumes of 25% ethanol extraction method and detected via HPLC. The results showed that the amount of MAAs on 25 March 2022 showed the highest value (40.4 μmol/g DW) among the samples from 24 January to 13 May. The tendency of suitable samples for MAA preparation corresponded to the term from mid-February to early April, which was the same as the previous three years. Although the surveys from 2019–2021 were performed by using the successive water–methanol method, it was found that the improved method also reflected the monthly variation in MAAs. The extraction of MAAs was performed via 20 or 40 volumes of 25% ethanol at 4 °C for 24 h. The amount of MAAs with 40 volumes of 25% ethanol extraction increased 1.3-fold compared to that with 20 volumes of 25% ethanol extraction. These data are useful information for valuable compound extraction from Usujiri dulse.
]]>Phycology doi: 10.3390/phycology3030025
Authors: Roland O. Ofori
The harmful impacts of the ongoing Sargassum invasions in the Atlantic Ocean include fish kills, skin and eye irritation, beach fouling, and declines in fisheries and tourism in West Africa and the Americas. This study was conducted to address important gaps in the non-market valuation literature and support the design of effective adaptation policies to reduce the harmful impacts of algal blooms. Contingent valuation survey data and linear mixed-effects regression models were utilized to estimate the drivers of willingness to pay (WTP) and willingness to contribute time (WTCT) for the management of invasive Sargassum seaweeds in Ghana. The study revealed that income, education, family size, years of residence, sex, attitudes, and political affiliation are significant drivers of WTP, while distance to the beach, occupation, house ownership, attitudes, and political affiliation are also significant predictors of WTCT. Hence, only attitudes about invasive seaweeds and political affiliation influence both WTP and WTCT. The findings suggest that for developing countries to generate enough funding and adequate economic support for coastal resource conservation, they should design local resource protection programs that give residents the option to contribute both time and money.
]]>Phycology doi: 10.3390/phycology3030024
Authors: Natalya Mineeva Ivan Semadeni
Using the fluorescent method in the modification of Krasnoyarsk State University, we studied the development (as chlorophyll content, ∑CHL) and photosynthetic activity of phytoplankton in seven large flat reservoirs of the Volga River cascade (Russia) in August 2015–2017. In the period of the maximal warming of water, average ∑CHL varied in limits of 19.4–33.7 μg L−1 in the Upper Volga, 8.5–27.8 μg L−1 in the Middle Volga, and 5.2–11.3 μg L−1 in the Lower Volga. The photosynthetic activity coefficient (PhAC) varied mostly in limits of 0.12–0.59, with an average of 0.22–0.38 and only in 2017 decreased to minimal < 0.10 and average < 0.20. The average PhAC values show the normal physiological state of the phytoplankton of the Upper Volga during all periods of observation, with an occasional decrease in PhAC in the Middle Volga and low photosynthetic activity in the Lower Volga. A decrease in the average ∑Chl and PhAC in 2017 was under cyclonic windy weather with a large amount of precipitation, low solar radiation, and large volume of flow. A trend towards a decrease in ∑CHL, like a decrease in PhAC from the Upper Volga to the Lower Volga, is explained by an increase in the flow rate and volume of runoff downstream of the Volga River.
]]>Phycology doi: 10.3390/phycology3030023
Authors: Laura Teuma Emanuel Sanz-Luque Benoit Guieysse Maxence Plouviez
Anthropogenic activities cause the introduction of nitrogen (N) into aquatic environments where these N inputs drive the biological synthesis of nitrous oxide (N2O), a potent and ozone-depleting greenhouse gas. To assess the significance of N2O emissions to climate change, the Intergovernmental Panel on Climate Change (IPCC) estimates indirect N2O emissions from rivers, lakes, and estuaries by multiplying the amounts of N received by these ecosystems with specific emission factors. Interestingly, the IPCC recently increased the N2O emission factor associated with wastewater discharge into “nutrient-impacted (eutrophic) aquatic receiving environments” nearly four times based on experimental evidence of high N2O emissions from N-receiving eutrophic ecosystems. As microalgae can produce N2O, these organisms may contribute to the N2O emissions frequently reported in eutrophic aquatic bodies. If that is the case, estimating N2O emissions solely based on nitrogen inputs to water bodies might lead to inaccurate N2O budgeting as microalgae growth is often limited by phosphorus in these environments. Establishing the significance of microalgal N2O synthesis in eutrophic environments is, therefore, critical and may lead to considerable changes on how to budget and mitigate N2O emissions and eutrophication.
]]>Phycology doi: 10.3390/phycology3030022
Authors: Elena Nevrova
The key role of benthic diatoms in coastal ecosystems highlights the relevance of studying their biodiversity and developing integrated biodiversity conservation measures. Benthic diatom richness in the northern part of the Black Sea was estimated based on both published data and our own data. The checklist of benthic diatoms includes 1100 species and intraspecific taxa, 953 species, 149 genera, 61 families, 32 orders, and 3 classes of Bacillariophyta. More than 280 species and intraspecific taxa, as well as 8 genera new to the diatom flora of the Black Sea and 7 species new to science, were revealed. An interregional analysis of the diversity of benthic Bacillariophyta along the coasts of Bulgaria, Romania, and Crimea, as well as the northwestern and northeastern parts of the Black Sea shelf, was carried out using the Taxonomic Distinctness Indices (TaxDI). The lowest TaxDI value for Crimea was closest to the average value expected for the Black Sea diatom flora, indicating a large proportion of polyspecies branches in the taxocene structure, which resulted in the maximum species richness (species/genus = 7) and led to a decrease in the vertical evenness of hierarchical tree. On the contrary, the highest TaxDI value was detected off the Romanian coast, which was caused by the significant proportion of mono- and oligospecies branches and minimal species saturation in the taxocene structure (species/genus = 4). We also identified some species with a high taxonomic exclusivity rank. If these species disappear, the entire architectonics of the Black Sea hierarchical tree of Bacillariophyta may be significantly altered. Such region-specific species are given the highest protection priority since they have great importance for gene pool conservation.
]]>Phycology doi: 10.3390/phycology3020021
Authors: Graziella Silva Keilla Cerqueira Jacqueline Rodrigues Karollyna Silva Diego Coelho Roberto Souza
Microalgae have a high growth rate, high CO2 absorption capacity, and high content of chlorophyll, proteins, vitamins, mineral salts, carbohydrates, antioxidant substances, and fatty acids. In recent years, Chlorella vulgaris has been widely used as a feedstock for producing third-generation biofuels, such as bioethanol. Thus, this work aims to develop a strategy to increase the production scale of the microalgae Chlorella vulgaris grown in distilled reused water, supplemented with a modified BG-11 medium, to use biomass in the production of bioethanol. The total cultivation of 72 L presented a concentration of 0.415 g·L−1·d−1, with 61.32 g of final biomass. To improve carbohydrate extraction, the biomass was pre-treated with sulfuric acid at different concentrations (1.5% and 3% v/v). The hydrolyzed solution was supplemented with YPD (yeast extract peptone dextrose) medium and inoculated with Saccharomyces cerevisae yeast, initiating fermentation. In each sample, the Brix degree, cell concentration, reducing sugar concentration, and alcohol content were analyzed. The sample pre-treated with sulfuric acid 1.5% v/v was the one that presented the best result, with alcohol content after distillation of 68 °GL (Gay-Lussac). It appears that the cultivation of the microalgae Chlorella vulgaris in scale-up, with reused water, has high potential in the production of third-generation biofuel.
]]>Phycology doi: 10.3390/phycology3020020
Authors: Lorena María Durán-Riveroll Oscar E. Juárez Yuri B. Okolodkov Ana Luisa Mejía-Camacho Fabiola Ramírez-Corona Dania Casanova-Gracia María del Carmen Osorio-Ramírez Victor A. Cervantes-Urieta Allan D. Cembella
The genus Amphidinium Clap. & J. Lachm. comprises a high diversity of planktonic and benthic (epiphytic and sand-dwelling) dinoflagellates from marine and freshwater ecosystems. High morphological plasticity and vaguely defined genus characteristics (e.g., a small epicone size) have complicated the clear delineation of species boundaries. Although six Amphidinium morphospecies have been reported from Mexican coastal waters, species identifications are uncertain and not generally supported by molecular phylogenetic data. In this study, seven isolates of Amphidinium from diverse benthic coastal locations on the NE Pacific, Gulf of California, and southern Gulf of Mexico were subjected to critical morphological analysis using photonic and scanning electron microscopy. The phylogenetic reconstruction was based on nuclear-encoded, partial large-subunit (LSU) rDNA and internal transcribed spacer I and II (ITS1 and ITS2) sequences. The revised phylogenetic analysis was consistent with the traditional subdivision of the genus Amphidinium into two sister groups: Herdmanii and Operculatum clades. This study provided the first confirmed records of A. theodorei and A. massartii from coastal waters of Mexico. The molecular phylogenetic evidence indicated that the morphologically described A. cf. carterae from Baja California was in fact more closely allied with A. eilatiensis sequences. A few Amphidinium species are known to form toxigenic (i.e., fish-killing) harmful algal blooms worldwide, and therefore knowledge on species diversity and biogeography is critical in developing effective strategies for evaluating the potential emerging threat in Mexican coastal waters.
]]>Phycology doi: 10.3390/phycology3020019
Authors: Sydney Brown Kalina M. Manoylov
Streams play vital roles in surrounding communities and provide essential ecosystem services. The protection of streams is important, they are legally protected under the Clean Water Act, and they can be monitored through the continuous analyses of biological data, such as algal or other aquatic communities. The goals of this study were to analyze the long-term recovery of Tobler Creek, a recovering agricultural stream on the site of a National Historic Landmark, and yield comparisons to a local low-impact stream, Murder Creek, located within the Oconee National Forest. In 2011, Tobler Creek exceeded reference criteria values for total phosphorus (TP) but met the nitrate nitrogen criteria. With an 11-year recovery period, Tobler Creek met both nutrient reference criteria. In 2022, periphyton samples were collected according to standard protocols, confirming that diatoms are the dominant algal group in the community. With recovery, Tobler Creek showed an increase in diatom species richness (χ2 = 116.11, df = 5, p < 0.01) but this was significantly lower than the values documented in Murder Creek. The multi-metric index (MMI), calculated using diatom community analysis to estimate ecological health, indicated that Tobler Creek experienced degradation from 2011 to 2022 (χ2 = 55.97, df = 5, p < 0.05) and is below the regional 25th percentile. The percentage of sediment-tolerant taxa (surirelloid, naviculoid, and nitzschoid) was significantly higher in Tobler Creek in 2022 (χ2 = 500.96, df = 5, p < 0.01) compared to Murder Creek in 2022 (t = −4.67, df = 10, p < 0.01). Despite a reduction in nutrients given the 42-year recovery period, the diatom community in Tobler Creek was significantly different than other regional protected streams. Ecological degradation of the habitat was likely driven by sedimentation due to run-off in the recovering agriculture stream. These findings highlight the importance of protecting water quality, as the recovery of nutrients can be a decades-long process overlayed with many potentially new stressors influencing aquatic organisms.
]]>Phycology doi: 10.3390/phycology3020018
Authors: Andrezza Carvalho Léa Carolina de Oliveira Costa Mariana Holanda Mayra Gonçalves Jorge Santos César S. B. Costa Gamze Turan Luís H. Poersch
The constant production of solids in intensive shrimp and tilapia culture can affect the performance of macroalgae when cultivated in an integrated system, and little is known about culture structures that enhance the performance of macroalgae in biofloc systems. The objective of this work was to evaluate different depths of culture structure for the macroalgae Ulva lactuca in an integrated system with Litopenaeus vannamei and Oreochromis niloticus in a biofloc system. The experiment lasted 70 days, with six systems composed of: a 16 m3 shrimp tank, a 3 m3 tilapia tank, and a 3 m3 macroalgae tank, with water recirculation between tanks. Two treatments were carried out, shallow float, with a structural depth of 10 cm, and bottom float, where the depth was kept at 30 cm from the surface. The shallow float resulted in a growth rate of up to 0.95 ± 0.54% day−1, with biomass loss only at the end of the culture due to the high density of macroalgae, decreasing temperature, and increasing solids concentration. The bottom float had biomass loss throughout the culture cycle. The integrated culture of shrimp, fish, and macroalgae is feasible with the use of shallow floats within 10 cm from the surface.
]]>Phycology doi: 10.3390/phycology3020017
Authors: Juan Alfredo Gómez-Figueroa Jaime Rendón-von Osten Carlos Antonio Poot-Delgado Ricardo Dzul-Caamal Yuri B. Okolodkov
To describe the seasonal response of the major phytoplankton groups to environmental variables along the Campeche coast, southeastern Gulf of Mexico, seven shallow-water (ca. 1 m) stations were monitored from January 2019 to January 2020. Orthophosphate, ammonium, nitrite, nitrate and silicate were measured. Several tests, including ANOVA, the Kolmogorov–Smirnov test, Tukey TSD, Bartlett’s test and canonical correspondence analysis (CCA), were applied. The physicochemical variables (temperature, salinity and pH) recorded are typical for the central coast of Campeche. Seasonal characteristics are affected by the shallowness of the study area. The variation of inorganic nutrient concentrations is likely to be related to specific polluting activities. While the abundance of phytoplankton presented a minimum value of 4.1 × 104 cells L−1 in March, the maximum value of 8.8 × 106 cells L−1 occurred in May; the general average was 5.3 × 105 cells L−1. Based on CCA, the correlation between major phytoplankton groups and physical–chemical variables was high (r ≈ 0.8), indicating a significant relationship. The CCA graphs separated the samples of diatoms by higher values of pH and silicate and separated the samples of cyanobacteria with high values of temperature (>30 °C) from the samples with dinoflagellates and nanoflagellates. Nanoflagellates were abundant in the samples with high values of ammonium and phosphate.
]]>Phycology doi: 10.3390/phycology3020016
Authors: Luiza Araujo-Motta Cicero Alves-Lima Leonardo Zambotti-Vilella Pio Colepicolo
We report here the effects of cadmium on the metabolome of the macroalga Gracilaria caudata. The IC50 of 3 mg/L (12 µM) was obtained after 48 hrs exposure and induced lower photosynthesis efficiency. Threshold concentrations determined by the Brazilian Environmental Council (CONAMA) in marine waters (0.04 mg/L) and effluent discharge (0.2 mg/L) were also tested, and the latter changed photosynthetic efficiency similarly to IC50. A total of 43 metabolites were identified, including monosaccharides, carboxylic acids, and amino acids. By an unsupervised PCA, we identified significative alterations in the metabolome by the IC50. An OPLS-DA analysis showed that Cd2+ exposure caused the variation of 20 metabolites, mainly glyoxylate-related, ascorbate, floridoside and proline. Five metabolic pathways altered by Cd2+ showed an accumulation of amino acids, carbon metabolism intermediates and antioxidant responses to Cd2+. We recommend a review of the toxicity parameters and methods that guide environmental policies on cadmium levels in Brazilian marine waters.
]]>Phycology doi: 10.3390/phycology3020015
Authors: Agatha Miralha Silvia M. Nascimento Raquel A. F. Neves
Benthic dinoflagellates of the Coolia genus have been associated with cytotoxicity and lethal and sublethal effects on marine species. This study aimed to assess the harmful effects of C. cf. canariensis phylogroup II (PII) and C. malayensis strains through bioassays. Experimental exposures (24, 48, and 72 h) of Artemia salina nauplii to Coolia species (330–54,531 cells mL−1) were performed independently. When a concentration-dependent response was achieved, additional experiments were carried out to evaluate the cell-free medium toxicity. The two Coolia species were harmful to Artemia nauplii, inducing significant mortality and sublethal responses. Coolia cf. canariensis PII was the most toxic species, inducing significant lethality at lower concentrations and shorter exposure times, followed by C. malayensis. Only the survival curves achieved after 24 and 48 h of exposure to C. cf. canariensis PII fitted to a concentration–response curve with valid LC50s of 18,064 and 19,968 cells mL−1, respectively. Moreover, extracellular compounds (i.e., culture filtrates) of C. cf. canariensis PII induced significant mortality to nauplii after 48 and 72 h. The toxicity of C. cf. canariensis PII was demonstrated for the first time using bioassays, and it was surprisingly higher than that of the C. malayensis strain, which was previously demonstrated to induce biological activity at the cellular and subcellular levels. Our findings highlight the harmful and lethal effects induced by Coolia cells and the importance of bioassays for toxicity assessments.
]]>Phycology doi: 10.3390/phycology3010014
Authors: Mariana de Sousa Santos Hempel Pio Colepicolo Leonardo Zambotti-Villela
With the growth in the number of people searching for ways to improve personal care, the consumer finds the solution in cosmetic products. However, this demand is currently made concomitantly with the demand for products of natural origin, including seaweed. Algae, in their composition, are full of bioactive compounds with several applications. Therefore, their insertion in cosmetics is evidenced in the high number of scientific studies, which makes this natural resource potentially useful for the cosmetic industry. From this, a review was conducted with the aim of highlighting some of these active compounds and the latent applicability and versatility of others. In addition, the best way to add to the production of these substances while staying in alignment with green consumption, the design of biorefineries, and the promising production of macroalgae on a large scale using green technologies was sought.
]]>Phycology doi: 10.3390/phycology3010013
Authors: Douaa Salim Josephine Al-Alam Othmane Merah Asma Chbani Pascale de Caro
Penicillium digitatum causes severe damage to postharvest and stored citrus fruits, making it necessary to seek acceptable solutions limiting environmental and sanitary impacts. The seaweed liquid extracts (SLEs) obtained from the green macroalgae Ulva lactuca have previously shown anti-fungal activities towards postharvest green mold due to P. digitatum. Moreover, treatment with aqueous and ethanolic extracts had an influence on disease incidence and lesion severity on wounded oranges “Valentia late”. Therefore, we studied the abilities of the U. lactuca extracts and chlorophyll a (as a standard) to activate defense mechanisms in oranges. The analyses showed modifications in the protein concentrations and activities of β-1,3-glucanase and peroxidase in orange tissues, with a maximum activity level reached at 72 h after treatments. It appears that the SLEs were able to fight P. digitatum infections in the absence of direct contact with the pathogen, reflecting that the induction of host resistance is also a probable mode of action. Ulva lactuca fractions are rich in chlorophyll a, polyphenols, organic acids and ulvans, which might be the key molecules involved in the defense mechanism of oranges’ albedo. The use of these natural substances could be an alternative way to control postharvest citrus rot.
]]>Phycology doi: 10.3390/phycology3010012
Authors: Ângelo Almeida João Cotas Leonel Pereira Paula Carvalho
One of the biggest global challenges in the mining industry is managing the risks associated with contamination by potentially toxic elements (PTEs) resulting from their activity. The oxidation of sulfides is the main cause of polluted mine drainage through the leaching of PTEs from mine waste and mine galleries to the water systems. Mine drainage can be highly acidic and often has a high concentration of PTEs, particularly arsenic, one of the environment’s most toxic elements. PTEs endanger the ecosystem’s equilibrium and raise worries about human and animal health. Some species of algae which can be naturally present in mine drainage waters, such as Spirogyra sp. And Chlorella sp., have a high capacity for absorbing PTEs from wastewater and may thrive in harsh environments. As a result, algal-based systems in bioremediation were studied and carefully analyzed, since their capacity to remove heavy metals and hazardous contaminants from polluted mine water have already been shown in previous studies. Biofuels derived from microalgal biomasses are a viable alternative to fossil fuels that can lead to a circular bioeconomy. This study reviews and analyses Chlorophyta-based bioremediation systems with application to mine waters focusing on Spirogyra sp. and Chlorella sp., since they are naturally present in mine drainage and can serve as a study model to better understand their application in bioremediation.
]]>Phycology doi: 10.3390/phycology3010011
Authors: Silvana Raquel Halac Ana Laura Ruibal-Conti Luciana del Valle Mengo Florencia Ullmer Aldana Cativa Raquel Bazan Maria Ines Rodriguez
The eutrophication of aquatic systems is a problem related to the contribution of excess nutrients—phosphorus (P) and nitrogen (N)—to water bodies, which produces an increase in cyanobacterial blooms. Under eutrophic conditions, P and N concentrations are sufficient for cyanobacteria growth, and some micronutrients are considered to become limiting for population growth. This work aimed to assess the effect of iron on cyanobacteria growth and the content of MCs in natural populations of Microcystis spp. Microcosm setting experiments were carried out with natural samples collected during two bloom events of Microcystis spp., kept under controlled light, temperature and pH conditions. The first bloom sample was exposed to different iron concentrations (400, 700 and 1100 µg Fe·L−1) to determine the optimum concentration for growth. The second was exposed to different iron addition modes (one: T1P, and two pulses: T2P) to imitate the iron increase produced by the downward migration of Microcystis spp. colonies. Our results show that iron is a growth-promoting factor and that its optimal range of concentrations for the growth of Microcystis spp. under the experimental setting conditions is between 700 and 1100 µg Fe·L−1. On the other hand, growth rates were not significantly different between T1P and T2P; thus, different addition modes did not have an effect on growth. Regarding microcystin content, the MC quota in natural populations of Microcystis spp. did not show a clear relationship with the iron supply. This work contributes to the understanding of the underlying factors affecting cyanobacteria bloom formation and the production of MCs, which in turn would impact the development of management strategies to control cyanobacteria blooms.
]]>Phycology doi: 10.3390/phycology3010010
Authors: Timothy Omara Christine Betty Nagawa Christine Kyarimpa Stefan Böhmdorfer Thomas Rosenau Solomon Omwoma Lugasi Henry Matovu Silver Odongo Patrick Ssebugere
Advected cyanobacteria, algal blooms and cyanotoxins have been increasingly detected in freshwater ecosystems. This review gives an insight into the present state of knowledge on the taxonomy, dynamics, toxic effects, human and ecological health implications of cyanobacteria, algal blooms and cyanotoxins in the East African Community lakes. The major toxigenic microalgae in East African lakes include Microcystis, Arthrospira, Dolichospermum, Planktolyngbya and Anabaenopsis species. Anatoxin-a, homoanatoxin-a, microcystins (MCs), cylindrospermopsin and nodularin have been quantified in water from below method detection limits to 81 µg L−1, with peak concentrations characteristically reported for the wet season. In whole fish, gut, liver and muscles, MCs have been found at concentrations of 2.4 to 1479.24 μg kg−1, which can pose human health risks to a daily consumer. While there have been no reported cases of cyanotoxin-related poisoning in humans, MCs and anatoxin-a (up to 0.0514 μg kg−1) have been identified as the proximal cause of indiscriminate fish kills and epornitic mortality of algivorous Phoeniconaias minor (lesser flamingos). With the unequivocal increase in climate change and variability, algal blooms and cyanotoxins will increase in frequency and severity, and this will necessitate swift action towards the mitigation of nutrient-rich pollutants loading into lakes in the region.
]]>Phycology doi: 10.3390/phycology3010009
Authors: Edén Magaña-Gallegos Eva Villegas-Muñoz Evelyn Raquel Salas-Acosta M. Guadalupe Barba-Santos Rodolfo Silva Brigitta I. van Tussenbroek
Holopelagic Sargassum species have bloomed recurrently in the northern tropical Atlantic since 2011, causing socioeconomic and environmental problems. Little is known about their basic biology and responses to the abiotic environment. The aim of this study was to determine how temperature affects the growth rates of the genotypes S. fluitans III, S. natans I, and S. natans VIII that predominate in these blooms. The growth rates were evaluated in specially designed ex situ systems between 22 and 31 °C, which corresponds with the natural temperature range of these seaweeds in the northern tropical Atlantic. All the genotypes had decreased growth rates at 31 °C, and they varied in their response to temperature, with S. fluitans III presenting a maximal rate of 0.096 doublings· day−1 (doubling its weight in 10.5 d) at 28 °C and S. natans VIII a minimal rate of 0.045 doublings· day−1 (doubling its weight in 22.2 d) at 31 °C. In addition, the response to the temperature varied depending on the time of the year. Understanding the role of temperature in the growth of holopelagic Sargassum genotypes, amongst other factors influencing their physiology (such as nutrients, salinity tolerance, or light, including their interactions), could help to understand the dynamics of the recent blooms in the tropical North Atlantic.
]]>Phycology doi: 10.3390/phycology3010008
Authors: Ryuya Yamamoto Martin Alain Mune Mune Yoshikatsu Miyabe Hideki Kishimura Yuya Kumagai
Mycosporine-like amino acids (MAAs) are natural ultraviolet-absorbing compounds found in microalgae and macroalgae. MAA content changes seasonally and in response to environmental factors. We previously investigated MAAs from the red alga dulse (Devaleraea inkyuleei, formerly Palmaria palmata in Japan) in Usujiri, Hokkaido, Japan, from 2019 to 2020. At that time, some factors affecting MAA content were still unclear. In this study, we investigated MAA variation during the period from January to June 2021, and evaluated new methods of MAA extraction from dulse. We recorded a maximum MAA extraction yield (7.03 µmol/g dry weight) on 25 March 2021. Over the course of our three years of investigations from 2019 to 2021, we found that dulse was most suitable for MAA preparation from the middle of February to late April. In the later work reported in this paper, we improved our extraction method by using a lower-risk organic solvent (ethanol) rather than methanol. In addition, we evaluated MAA extraction using different levels of ethanol concentration (25, 50, and 99%) and different extraction times (2, 6, and 24 h). We found that extraction with 25% ethanol for 24 h increased MAA content by a factor of 3.2, compared with our previous extraction method. In summary, we determined the most suitable sampling period for Usujiri dulse, to extract the highest content of MAAs. We also improved the effectiveness of the extraction process.
]]>Phycology doi: 10.3390/phycology3010007
Authors: Dilantha Gunawardana Sashika Abeysiri Pathmalal Manage
In a paradigm shift in plastic wastes due to the COVID-19 pandemic, wetlands such as mangroves are threatened by a new form of pollution, plastics, on top of the eutrophication of estuarine waters due to nitrogen and phosphorus wastes/effluents that lead to cyanobacterial proliferation. Both plastic and nutrient pollution lead to prosperity of cyanotoxin-producing cyanobacteria that flourish in both and disperse leading to the detriment of fauna and flora in the mangrove ecosystem due to resulting toxicities. Although cyanotoxins are still a relatively poorly studied phenomenon in mangroves, their presence does create a focus of attention due to biofilm formation and the resultant flotation and sinking properties that are linked to cyanobacterial mats on plastic debris. Sri Lanka, being the first country in the world to conserve all its mangrove wetlands, does have a responsibility to prevent the invasion of plastics to this protected ecosystem, and binding with the Ramsar Convention, precluding plastic waste and their concomitant footprint, is a task at hand to the relative authorities. The path ahead mandates that we study the properties of plastics for cyanobacterial proliferation, biofilm formation, the fates of such plastics (flotation, dispersal and sinking), the cyanotoxin production changes that are attributed—or linked—to plastic pollution and the resultant impacts on mangrove ecosystems. Cyanotoxins are long-lived, and it is paramount that we find the necessary mechanisms to eliminate or curtail their production in mangrove ecosystems while establishing surveillance and monitoring of both the producers and the harmful agents. Cyanobacteria although vehicles for nitrogen fixation and replenishing of nutrients to an N-depleted ecosystem such as the mangroves, could lead to enhancements in cyanotoxins production. However, this phenomenon remains ambiguous and poorly studied in applied phycology in relation to mangroves. “New normal” plastics are lodged mostly on the surfaces of bark, prop roots, and pneumatophores, which are the localities where the highest level of new nitrogen is fixed, and this may lead to the proliferation of N-fixing, cyanotoxin-producing cyanobacteria, which may have repercussions on both flora and fauna of mangroves. Therefore, it is crucial that we monitor plastic pollution and find mechanisms for sanitizing plastics-imprinted mangroves to lessen the harmful footprint resulting from plastic overload.
]]>Phycology doi: 10.3390/phycology3010006
Authors: Jonás Adrián Tardivo Kubis Francisco Rodríguez Araceli E. Rossignoli Pilar Riobó Eugenia A. Sar Inés Sunesen
In the framework of a monitoring program of harmful microalgae from the marine coastal waters of the Buenos Aires Province, seven strains were isolated and characterized by morphological and molecular analysis (LSU rDNA partial sequencing, D1–D3 regions). Established strains belonged to Alexandrium catenella, Protoceratium reticulatum and Pseudo-nitzschia multiseries. The toxinological profile of the target strains were determined by UHPLC-FLD equipment for paralytic shellfish toxins (PSTs) and LC-MS/MS for lipophilic (LSTs) and amnesic toxins (ASTs). The toxin profile varied in the four strains of A. catenella, the predominant compounds were gonyautoxins (GTXs) GTX2,3 and GTX1,4 for strains LPCc001 and LPCc004, and N-sulfocarbamoyl toxins (Cs) C1,2 and GTX1,4 for strains LPCc002 and LPCc008. The obtained cellular toxicity values were moderate-to-high (12.38–46.40 pg saxitoxin equiv. cell−1). The toxin profile of P. reticulatum was dominated by yessotoxins (YTXs) (up to 94.40 pg cell−1) accompanied by homo-yessotoxin (Homo-YTX) traces. In P. multiseries, the toxin profiles were dominated by domoic acid (DA) (1.62 pg cell−1 and 1.09 pg cell−1) and secondarily by Isomer A (Iso-A), Epi-domoic acid (Epi-DA), Isomer-E (Iso-E) and Isomer-D (Iso-D). This study provides detailed information about representative HAB species in the area, useful for resource management, risk evaluation and related research on toxic dinoflagellates and diatoms.
]]>Phycology doi: 10.3390/phycology3010005
Authors: Tomasa Cuellar-Martinez Lourdes Morquecho Rosalba Alonso-Rodríguez Ana Carolina Ruiz-Fernández Joan-Albert Sanchez-Cabeza
The production of cysts by dinoflagellates can be part of the life cycle of some species, improving their survival under adverse environmental conditions; cyst germination may explain the recurrence of algal blooms in some cases. In order to evaluate the germination rates of Pyrodinium bahamense, its cysts were retrieved from surface sediments collected in San José Lagoon, SW Gulf of California, and germination assays were carried out through the cysts incubation under two contrasting light and nutrient concentration conditions. Also, to evaluate cysts viability, we isolated P. bahamense cysts and other dinoflagellate species from different depth layers of a 210Pb-dated sediment core (~100 years) to examine their germination for 20 days. Germination rates were higher under light (28–56%) than in darkness (23–34%); there were indications that the nutrient-enriched media was more effective in promoting germination than seawater. Furthermore, germination was observed in cysts isolated from all selected core depths, even those corresponding to ~100 years. These results demonstrate that cysts remain viable for long periods, and P. bahamense cysts germinate in any light and nutrient conditions. The results of this research provide relevant information to understand its physiology and complex population dynamics. This species should be closely monitored in the area in the context of climate change, as current natural conditions are likely to change.
]]>Phycology doi: 10.3390/phycology3010004
Authors: Fernando Pagels A. Catarina Guedes António A. Vicente Vitor Vasconcelos
As a producer of pigments with known bioactive potential, cyanobacteria are a great source of active ingredients for cosmetics (i.e., carotenoids and phycobiliproteins). Multiple phases in the cyanobacteria-based bioprocess led to the obtention of these compounds. The marine Cyanobium sp. LEGE 06113 has been proposed as a promising source for pigments for cosmetic uses, and it has been optimized in the past few years in terms of production, extraction, and application of pigment extracts. This report aims at providing an overview of the cyanobacteria-based bioprocess, regarding optimization strategies, consolidating into a proposed bioprocess for this cyanobacterium. The optimization of Cyanobium sp. included strategies regarding its production (culture medium, light, temperature, pH and salinity) and extraction (successive solvent extraction and ohmic heating). After the optimization, the two pigment-rich extracts (carotenoids and phycobiliproteins) were assessed in terms of their cosmetic potential and compatibility as an ingredient. Finally, aiming a scale-up proposal, life cycle assessment (LCA) was used as tool for a sustainable process. Ultimately, the proposed process gives the possibility to obtain two stable cosmetic ingredients from the same biomass and applied as anti-agent agents, especially due to their high anti-hyaluronidase capacity. Moreover, there remain challenges and information regarding novel cosmetic ingredient regulations were also discussed.
]]>Phycology doi: 10.3390/phycology3010003
Authors: Helen Rosenkranz Martyn G. Kelly Alexandre M. Anesio Marian L. Yallop
Phytobenthos, major primary producers in freshwater, may be periodically exposed to herbicides through runoff, spray drift, and leaching, but experimental work on their response to herbicides is limited. Outdoor flumes were used to measure the recovery of intact phytobenthic biofilms, following a short-term pulse to a glyphosate-based herbicide (GBH) and chlorotoluron (CLT), singly or as a mixture (GBHC). Two days following the removal of the herbicides, significant declines in biomass and rates of areal gross maximum photosynthesis were recorded in GBH and GBHC-treated flumes. Herbicide pulses negatively impacted the biomass of phytobenthos, measured as chlorophyll a, which in turn may have alleviated resource limitation, evidenced by significant increases in biomass-specific rates of gross maximum photosynthesis. After 4.5 days, biomass concentrations were similar in controls and treatments, indicating biofilm recovery in the GBH and GBHC biofilms, though the proportion of green algae relative to diatoms was significantly higher in GBH and GBHC-impacted biofilms. Significant increases were recorded in the Trophic Diatom Index (TDI), indicating benthic diatom development along different trajectories, following the herbicide pulse. Collectively, these results indicate greater insights into herbicide impacts on phytobenthos may be gained by working with the whole phytobenthic community.
]]>Phycology doi: 10.3390/phycology3010002
Authors: Oana Alina Marin Valentina Coatu Elena Stoica
Macroalgal cultures are currently of great interest worldwide. Although along the Romanian Black Sea coast, there is no tradition in this sense, currently, a major interest in developing this direction exists, taking into consideration that the overexploitation of wild seaweed resources involves the disturbance of the marine environment, with implications that can sometimes be irreversible. Porphyra and Pyropia species (also known as nori algae) are considered the world’s most valuable mariculture algal products due to their high nutritional value and multiple active principles, considered unique representatives of marine algae. Considering these aspects, attention was focused on the only nori species from the Romanian Black Sea coast, namely, Pyropia leucosticta. The species was cultivated in controlled laboratory conditions for 5.5 months by manipulating its reproductive elements. The aim was to establish a simple, low-cost method by avoiding the complicated conchocelis phase of the species; therefore, reproduction and further species development were achieved by collecting the released neutral spores and isolating them in culture vessels, ensuring, at the same time, proper nutrient conditions, using sterile enriched seawater and mimicking ambient conditions. At the end of the experiment, specimens of almost 80−90 mm were obtained, making this method suitable for obtaining ex situ P. leucosticta blades on the Romanian Black Sea shore.
]]>Phycology doi: 10.3390/phycology3010001
Authors: Yoran Le Strat Thierry Tonon Catherine Leblanc Agnès Groisillier
Macroalgae (seaweeds) are key primary producers in marine coastal habitats and largely contribute to global ocean carbon fluxes. They also represent attractive renewable feedstock for the production of biofuels, food, feed, and bioactive. Brown algae are seaweeds that produce alginates and fucose containing sulfated polysaccharides in their cell wall and laminarin and mannitol for carbon storage. The availability of genomes of the kelp Saccharina japonica and of the filamentous Ectocarpus sp. paved the way for the biochemical characterization of recombinant enzymes involved in their polysaccharide and carbohydrates synthesis, including, notably, mannitol. Brown algal mannitol biosynthesis starts with the conversion of fructose-6-phospate into mannitol-1-phosphate (mannitol-1P), and this intermediate is hydrolysed by a haloacid dehalogenase phosphatase (M1Pase) to produce mannitol. We report here the biochemical characterization of a second M1Pase in Ectocarpus sp. (EsM1Pase1). Both Ectocarpus M1Pases were redox-sensitive enzymes, with EsM1Pase1 active only in presence of the reducing agent. Such catalytic properties have not been observed for any M1Pases yet. EsM1Pases were specific to mannitol-1-P, in contrast to S. japonica M1Pases that could act on other phosphorylated sugars. Finally, brown algal M1Pases formed two well-supported clades, with possible distinct subcellular localization and physiological role(s) under diverse environmental conditions and/or life cycle stages.
]]>Phycology doi: 10.3390/phycology2040023
Authors: Madalena Mendes Diana Pacheco João Cotas Kiril Bahcevandziev Leonel Pereira
Estuarine eutrophication due to the nutrient run-off from the agricultural fields encourages the establishment of several opportunistic seaweeds. These fast-growing seaweeds, considered an untapped resource, with a circular economy approach, can be employed as soil plant fertilizer. In agriculture, there is a global trend toward shifting from chemical-based conventional farming to sustainable agriculture. In this context, this study aimed to understand the biostimulant potential of the aqueous extracts from seaweeds harvested in Mondego estuary located on the Atlantic coast of Portugal, namely Ulva lactuca (Sea lettuce), Fucus ceranoides (Estuary Wrack) and Gracilaria gracilis (Slender Wart Weed), in kale (Brassica oleracea L.) seed germination and seedling development. The results showed that Gracilaria gracilis extract enhanced kale seed germination, presenting a higher seedlings weight (0.076 ± 0.004 g) and length (15.48 ± 0.59 cm), when compared with seedlings obtained in distilled water used as a control (weight = 0.059 ± 0.002 g; length = 13.10 ± 0.54 cm). Fucus ceranoides showed the lowest influence on seedling development (weight = 0.062 ± 0.002 g; length = 12.97 ± 0.59 cm). However, these results demonstrated that seaweed aqueous extracts can indeed enhance seed germination and seedling development.
]]>Phycology doi: 10.3390/phycology2040022
Authors: Agneta Persson Barry C. Smith
This quantitative dinoflagellate cyst study reveals an enormous difference in survival rates in oxygenated versus anoxic sediments. Replicate samples of concentrated natural dinoflagellate cysts with the same initial species composition (1.4 × 104 resting cysts·cm−3 sediment, 61% filled with live-appearing contents) were placed in bags of 20 µm plankton screen. Replicate bags containing 10.0 cm−3 concentrated cyst samples were placed on the seafloor in different environments in Long Island Sound, USA (anoxic and oxygenated), as well as refrigerated in test tubes in the laboratory. Three sets of 15 bags were placed in each environment. Once every year for four consecutive years, three bags were recovered from each set, and the contents were analyzed by cyst counting and germination experiments. An enormous difference in preservation potential between samples in oxygenated versus anoxic environments was revealed. The number of dinoflagellate cysts decreased abruptly within the first year in the oxygen-rich environment; living cysts became very rare (only 5% remained) and also empty walls of cysts disappeared (20% of total cysts remained). In anoxic sediment samples, living cysts also decreased significantly with time, but less quickly. After 1 year, 35% of the living cysts in the anoxic environment and 70% of the living cysts refrigerated in test tubes remained intact. After 4 years, 21% of the cysts with contents in the anoxic environment remained, and 31% in test tubes. The empty cyst walls remained intact for a longer time under anoxic conditions, especially of species known to fossilize well. Germination experiments showed that cysts with live-appearing contents were likely alive, because species with identifiable live-appearing cysts were also identified as vegetative cells in corresponding slurry cultures. The cyst assemblage was dominated by Protoperidinaceae, Dipolopsalidaceae, and Gonyaulacaceae. Of special interest is the ichthyotoxic Margalefodinium polykrikoides, the bloom-forming Peridinium quinquecorne, which has an undescribed resting cyst, and a previously undescribed Krypoperidinium species. The results show greater preservation of dinoflagellate cysts in “dead-zone sea bottoms” and may also provide an answer to the question of the absence of cyst beds in an area despite observed sedimentation of dense blooms.
]]>Phycology doi: 10.3390/phycology2040021
Authors: Fernando Pagels Ana Arias Adriana Guerreiro A. Catarina Guedes Maria Teresa Moreira
Seaweeds represent a diverse and valuable source of cosmetic compounds such as vitamins, minerals, trace elements, amino acids, antioxidants, etc., with moisturizing, anti-inflammatory, and regenerative effects. The so-called “blue cosmetics” represent a line of products related to the use of natural active ingredients and an important market share in major international cosmetic brands. To be recognised as environmentally sustainable, it is essential to ensure that algae-derived products comply with environmentally sound harvesting, production, and extraction practices. In this work, Life Cycle Assessment (LCA) methodology was used to carry out an environmental impact assessment of the processing of the brown algae extract from Fucus vesiculosus and its comparative profile with the most used antioxidants in cosmetics: vitamin C and green tea extracts. Considering an equivalent formulation in antioxidant content, the results showed that seaweed has the lowest environmental load while green tea extracts have the highest environmental impact. Furthermore, to further reduce emissions from seaweed processing, the use of renewable energy sources and the valorisation of biomass residues as fertilisers in a circular economy approach are proposed.
]]>Phycology doi: 10.3390/phycology2040020
Authors: Kenichi Furuhashi Akinari Magota Yifan Liu Fumio Hasegawa Shigeru Okada Yutaka Kaizu Kenji Imou
Botryococcus braunii is a green microalga that is attracting attention as an alternative aviation fuel owing to its hydrocarbon production. In this study, we investigated two approaches to reducing the energy required by pretreatment for hydrocarbon recovery by solvent extraction. Saltwater culture has been reported previously only for the B race of Botryococcus braunii; it improved hydrocarbon recovery from the A race too. We developed a hot water rinsing method that reduced the temperature requirement from the 85 °C which was previously reported for the B race. As the salt concentration in the medium increased, the colony sheath that covered the entire colony surface of the Yamanaka strain (race A) became thinner and the hydrocarbon recovery increased. Saltwater culture can be applied to race A without any energy input. Hydrocarbon recovery from the Showa strain (race B) exceeded 90% after nine rinses with 70 °C hot water while maintaining this temperature. Thus, both pretreatments lowered the treatment temperature by at least 15 °C compared to previously reported methods. Both treatments improved hydrocarbon recovery by thinning the colony sheaths.
]]>Phycology doi: 10.3390/phycology2030019
Authors: Zivan Gojkovic Aleksandra Skrobonja Christiane Funk Ines Garbayo Carlos Vílchez
Methylmercury (MeHg) is the most important and the most abundant organic Hg pollutant in the aquatic ecosystem that can affect human health through biomagnification. It is the most toxic organic Hg form, which occurs naturally and by human-induced contamination in water and is further biomagnified in the aquatic food web. MeHg is the only Hg form that accumulates in living organisms and is able to cross the blood–brain barrier, presenting an enormous health risk. Anthropogenic activity increases eutrophication of coastal waters worldwide, which promotes algae blooms. Microalgae, as primary producers, are especially sensitive to MeHg exposure in water and are an important entrance point for MeHg into the aquatic food web. MeHg assimilated by microalgae is further transferred to fish, wildlife and, eventually, humans as final consumers. MeHg biomagnifies and bioaccumulates in living organisms and has serious negative health effects on humans, especially newborns and children. Knowledge of the microalgae–MeHg interaction at the bottom of the food web provides key insights into the control and prevention of MeHg exposure in humans and wildlife. This review aims to summarize recent findings in the literature on the microalgae–MeHg interaction, which can be used to predict MeHg transfer and toxicity in the aquatic food web.
]]>Phycology doi: 10.3390/phycology2030018
Authors: Priscila Torres Fungyi Chow Deborah Yara Alves Cursino dos Santos
Extracts that were obtained with solvents of increasing polarity (hexane, dichloromethane, methanol, 80% methanol, and water) from the red macroalga Gracilaria domingensis were evaluated by reducing power with ferric reduction antioxidant power (FRAP) and Folin–Ciocalteu (FC) assays, lipid peroxidation inhibition by β-carotene-linoleic acid assay, and metal chelating ability based on the iron-ferrozine system. The highest antioxidant capacity was reported for the hexane (Hx) extract by the FRAP, metal chelating, and lipid peroxidation inhibition assays. An activity-guided fractionation of the Hx extract was carried out for the identification of its active constituents. The primary components were the most active antioxidant compounds. Despite the high antioxidant activities, the Hx extract was not active in the FC assay. In this assay, the activities were found in the methanol (M) and 80% methanol (80M) extracts. The FC assay is commonly used to measure the total phenolic compounds. However, no phenolic compounds were detected by GC-MS and HPLC analyses in the M and 80M extracts. Thus, non-phenolic components influenced the FC assay. The M and 80M extracts showed high content of mycosporine-like amino acids (MAAs). A fraction contained two MAAs (porphyra-334 and shinorine) (156 mg GAE·g−1) showed a similar performance to the values that were found for well-known antioxidants (BHT = 156 mg GAE·g−1 and Trolox = 166 mg GAE·g−1) and 30 times higher than those of the original extracts (~5 mg GAE·g−1) in the FC assay. Thus, MAAs contribute to the antioxidant activities that were observed in the FC assay within the studied samples. Together, these results advance our understanding of the antioxidant properties of algal extracts.
]]>Phycology doi: 10.3390/phycology2030017
Authors: Ricardo Rogers Paranhos Mauro Vilar Luísa Hoffmann Thayane Bottaro Rosane Silva Renato C. Pereira Sandra M. F. O. Azevedo
Findings about CO2 dynamics in the Earth’s ancestral atmosphere have suggested much higher concentrations in past eras. Along this line, cyanobacteria are an early evolved photosynthetic group that is suggested to have experienced both high and low CO2 availability since their Precambrian origin, and therefore, it is reasonable to assume that these microbes have the potential to cope with these scenarios by rapidly adjusting to various carbon dioxide levels. Thus, in this work, we performed a short-term (72-h) investigation of the physiological parameters (cell growth, photosynthesis and saxitoxin production) of toxic and nontoxic strains of the cyanobacterium Raphidiopsis raciborskii challenged by an extremely high pCO2 (40,000 ppm). Additionally, the transcriptomic profile (regarding the carbon concentrating mechanism and photosynthesis) of selected toxic and nontoxic strains is also presented. We found that short-term exposure to extremely elevated CO2 concentrations did not affect R. raciborskii physiology regardless of toxin production. However, transcripts related to bicarbonate transporters and the RuBisCO enzyme indicated the upregulation of CCM and downregulation of the Calvin cycle, respectively. According to our findings, at least at the initial growth phase, R. raciborskii was able to cope with a very high CO2 level, which shed light on the understanding that this species might have the potential to cope with carbon dioxide in water above the predicted levels.
]]>Phycology doi: 10.3390/phycology2030016
Authors: Emanga Alobwede Anne Cotton Jonathan R. Leake Jagroop Pandhal
Global estimates show that less than half the nitrogen fertiliser inputs to agricultural soil are taken up by crops. The remaining inorganic nutrients follow several pathways, with run off into nearby waterbodies being particularly problematic, contributing to the formation of algal blooms. A proposed solution is to recover the algae biomass from receiving waterbodies and apply it back to the land to replenish soil nutrients and enable a reduction in the need for inorganic fertilizers. A 15N tracer study was performed under greenhouse conditions, where labelled algal N (55.75% atom% 15N) was added to soil at 15.8 mg N/500 g soil) to assess the fate of nitrogen derived from a common unicellular green alga, Chlorella vulgaris, into soil and wheat nitrogen pools, with an assessment of the impact on soil bacterial communities. The soil retained a higher amount of algal nitrogen (10.3%) compared to the wheat shoot (0.7%) after 30 days, corresponding to the results of the 16S rDNA sequencing, which demonstrated that the algal biomass increased microbial diversity after 30 days and changed the relative abundance of microbial taxa putatively involved in facilitating the breakdown of organic residues. These findings provide useful insights into the application of algae biomass to agricultural soils to influence nitrogen fertilization and improve soil health through the increase in soil microbial diversity.
]]>Phycology doi: 10.3390/phycology2030015
Authors: Larissa de Oliveira Magalhães Fabio Nunes de Mello Flavia Vischi Winck
Microalgae biomass is considered a promising alternative feedstock for biodiesel production due to its high productivity of neutral lipids, especially under abiotic stress conditions. Among the unicellular microalgae that show this characteristic, Chlamydomonas reinhardtii appears as one of the most important model species with increased lipid production under abiotic stress conditions. In this study, we show that C. reinhardtii cells cultivated under mixotrophic condition supplemented with 0.1 M of NaCl rapidly raise their intracellular amount of neutral lipids without a reduction in their cellular growth rate, representing a promising condition for biomass production toward bioenergy applications. The nuclear proteome of these cells was investigated, and we identified 323 proteins with an enrichment of almost 60% of nuclear proteins in the total dataset. We found 61 proteins differentially regulated upon salt treatment, including proteins annotated in functional categories related to translation and nucleosome assembly functions. Additionally, we identified transcription factor proteins (TFs) and analyzed their likely transcription factor-binding regulatory elements, identifying target genes related to lipid metabolism and kinase functions, indicating possible regulatory pathways of lipid biosynthesis. Together, these data can help understand regulatory nuclear mechanisms, leading to an increase in lipids in the first 24 h of salt stress.
]]>Phycology doi: 10.3390/phycology2030014
Authors: Judith Rosellón-Druker Edith Calixto-Pérez Elva Escobar-Briones Jaime González-Cano Luis Masiá-Nebot Fernando Córdova-Tapia
This study collates and reviews the state of the art in the phenomenon of atypical pelagic Sargassum influxes in the coastline of the Mexican Caribbean, focusing on projects, studies and initiatives that have been conducted in the country for a decade. We integrated multisectoral and multidisciplinary knowledge and identified gaps and strengths in current knowledge. Initiatives and projects conducted in Mexico are numerous, diverse and valuable. However, interdisciplinary and transdisciplinary research and interinstitutional coordinated actions in the medium- and long-term are still lacking. Because of this, there is an imbalance of actions in different knowledge areas that prevents this phenomenon from being addressed in a comprehensive way. Furthermore, the funding opportunities for Sargassum research projects and other initiatives seem to respond to the events of massive influxes, without continuity or long-term planning. Attention is mainly focused on urban and touristic areas, so impacts to rural or uninhabited zones are unknown. This review represents a stepping-stone towards an integrated multisectoral effort to shift the perspective from Sargassum being a “national problem” to a “national resource,” considering and fully understanding the ecological importance of this macroalgae as a floating ecosystem and its potential as an economic resource once it massively arrives in Mexican coastal areas.
]]>Phycology doi: 10.3390/phycology2020013
Authors: Kushagra Tewari
The occurrence of harmful algal blooms (HABs) in coastal and inland waters has a significant impact on societies. This complex biogeophysical phenomenon becomes further complicated due to the impact of climate change. This review summarizes the research performed in recent years in the direction of climate change on three lake parameters, viz. lake temperature, precipitation, runoff, and lake ice, which impacts the lake ecology and, in turn, impacts the HABs. The present paper also reviews the research work related to the relationship between climate change and HABs. The purpose of this study is to provide the researchers with the opportunity to understand the current research in the direction of climate change and HABs so they can contribute effectively to one of the most important phenomena that will severely impact water quality in the future warmer climate, in coastal as well as inland water bodies. Furthermore, this work aims to discuss how HABs will change in the future warmer climate.
]]>Phycology doi: 10.3390/phycology2020012
Authors: Punniamoorthy Thiviya Ashoka Gamage Nalin Suranjith Gama-Arachchige Othmane Merah Terrence Madhujith
Protein is one of the major macronutrients essential in human nutrition. Protein sources especially animal sourced proteins are expensive, thus much work has been carried out to explore alternative protein sources. Seaweeds, or macroalgae, are emerging as one of the alternative protein sources. They are rich in protein with an excellent amino acid profile comparable to the other conventional protein sources. Seaweed protein contains bioactive components, such as free amino acids, peptides, lectins, and phycobiliproteins, including phycoerythrin and phycocyanin, among others. Seaweed proteins have been proved for their antihypertensive, antidiabetic, antioxidant, anti-inflammatory, antitumoral, antiviral, antimicrobial, and many other beneficial functional properties. Therefore, seaweed proteins can be a natural alternative source for functional food development. This paper discusses the compositional and nutritional aspects of seaweed protein, protein extraction techniques, functional properties of various seaweed proteins, as well as their safety for new product development and functional food applications.
]]>Phycology doi: 10.3390/phycology2010011
Authors: Thierry Tonon Carla Botelho Machado Mona Webber Deanna Webber James Smith Amy Pilsbury Félix Cicéron Leopoldo Herrera-Rodriguez Eduardo Mora Jimenez Julio V. Suarez Michael Ahearn Frederick Gonzalez Michael J. Allen
Massive and recurrent strandings of pelagic Sargassum biomass have become the new norm in the Caribbean and the Western Africa since 2011, and there is no sign of this abating. These Sargassum events have negative environmental, socioeconomic and health impacts in the affected countries. In the meantime, various processing techniques and applications have been suggested for valorisation of this biomass. However, variability in quantity, quality and location creates substantial uncertainty for the development of reliable and robust industrial processes. As part of ongoing efforts to better characterise seasonal and geographical variations in the biochemical and elemental composition of the pelagic Sargassum biomass across the Caribbean, we analysed samples from Mexico, Jamaica and the Dominican Republic harvested during summer 2020 and winter 2021. Different degrees of variation were observed in the contents of ash, metals and metalloids, vitamins, fatty acids, amino acids and biogenic amines, and monosaccharides. Our results indicate that biomass is of highly variable quality depending on season and location. In this context, we suggest that biorefinery approaches geared towards controlled metal removal and focused on the extraction and purification of amino acids, fatty acids and vitamins should be prioritised to assess the potential valorisation of pelagic Sargassum biomass into standardised and high-value outputs.
]]>Phycology doi: 10.3390/phycology2010010
Authors: Haresh S. Kalasariya Leonel Pereira Nikunj B. Patel
Cosmetics are broadly used by people to protect the skin from external environmental stresses and for beauty purposes globally. A recent trend towards cosmetics with natural formulations has emerged. The cosmetic industry uses the term ‘cosmeceutical’ to refer to a cosmetic formula that has drug-like applicative advantages. Recently, macroalgae have received increased attention as natural ingredients for cosmeceutical applications. Many marine algae are rich in biologically active components that have been reported to exhibit strong benefits to the skin, mainly for photoprotection, skin whitening, moisturization, anti-aging, anti-wrinkle, antioxidants, and antimicrobial uses. The present review provides a detailed study of the literature on the cosmetic potentials of marine algae-derived polysaccharides, peptides and amino acids, pigments, phenolic components, and fatty acids. We provide an overview of different types of macroalgae with their biologically active constituents and potential cosmetic benefits. In addition, the bioactive molecules of cosmetic products containing marine macroalgae as well as their mechanisms of action are briefly discussed.
]]>Phycology doi: 10.3390/phycology2010009
Authors: Hanan Al-Adilah Martin C. Feiters Lucy J. Carpenter Puja Kumari Carl J. Carrano Dhia Al-Bader Frithjof C. Küpper
Many marine algae are strong accumulators of halogens. Commercial iodine production started by burning seaweeds in the 19th century. The high iodine content of certain seaweeds has potential pharmaceutical and nutritional applications. While the metabolism of iodine in brown algae is linked to oxidative metabolism, with iodide serving the function of an inorganic antioxidant protecting the cell and thallus surface against reactive oxygen species with implications for atmospheric and marine chemistry, rather little is known about the regulation and homoeostasis of other halogens in seaweeds in general and the ecological and biological role of marine algal halogenated metabolites (except for organohalogen secondary metabolites). The present review covers these areas, including the significance of seaweed-derived halogens and of halogens in general in the context of human diet and physiology. Furthermore, the understanding of interactions between halogenated compound production by algae and the environment, including anthropogenic impacts, effects on the ozone layer and global climate change, is reviewed together with the production of halogenated natural products by seaweeds and the potential of seaweeds as bioindicators for halogen radionuclides.
]]>Phycology doi: 10.3390/phycology2010008
Authors: Rashed Farzanah Mathias Clausen Eva Arnspang Jens Schmidt Juan-Rodrigo Bastidas-Oyanedel
Food resources are limited in arid countries such as the United Arab Emirates (UAE); the salinity of the groundwater, together with a lack of natural fresh water sources and arable land, force the country to import most of its food. However, seaweed could play an important role in providing a locally available food resource, as it does not require fresh water and arable land to grow. The traditional use of several seaweed species as food sources has been documented in Asia and the Americas, where their nutritional composition has been well reported. Although the UAE’s aquatic environment is quite harsh due to high water salinity (over 40 g/L) and high surface water temperatures (over 35 °C), its native seaweed species could play a role as a food source in this arid region, thereby bolstering the country’s level of food security. To evaluate its potential in this context, fresh samples of the native Ulva intestinalis seaweed were collected in the shallow waters of Abu Dhabi Emirate, UAE. These samples were calculated to contain 34.38 ± 0.24 kcal, with a biomass composition of 5.185 ± 0.04% carbohydrate, 3.32 ± 0.14% protein, and 0.04 ± 0.01% fat (by dry matter). Of all the minerals present in the biomass, potassium had the highest concentration (7947 ± 319.5 ppm), followed by magnesium (3075.9 ± 1357 ppm) and sodium (756.3 ± 478 ppm). The water-soluble vitamins B1, B2, B3, B6, and C were below the detection limit in the samples. The rich concentration of essential minerals such as potassium, magnesium, iron and zinc in Ulva intestinalis makes it a promising novel food source. To the best of our knowledge, this is the first experimental study to examine the feasibility of using seaweed that is native to the UAE as a nutritional and sustainable food source in order to address the challenge of food security currently being faced by the country.
]]>Phycology doi: 10.3390/phycology2010007
Authors: Anh Tu Van Karin Glaser
Desiccation and high salinity are two abiotic stressors that are related in terms of their effect on water homeostasis within cells. The success of certain aeroterrestrial microalgae is influenced by their ability to cope with desiccation, and in some cases, high salinity. The microalgae of the Stichococcus clade are ubiquitous in terrestrial habitats and are known to withstand desiccation and salinity stress by accumulating secondary metabolites. Nevertheless, it remains unclear if those two related stressors have a synergistic effect. Hence, we studied the effect of salinity on desiccation on various representative taxa within the Stichococcus clade. The results showed that in contrast to other Stichococcus taxa, Pseudostichococcus was able to recover fully after desiccation, with and without salinity stress. This observation was connected to elevated proline production under salinity stress and higher proline:sorbitol ratio in Pseudostichococcus to the other strains tested. In the other taxa, increasing salinity reduced their ability to withstand desiccation. This might have severe effects on microalgae in (semi)arid regions, where salinization of soils is an increasing threat also for agriculture. The results encourage further research to be done on the possible applications of this genus in salinity bioremediation, as it seems to be comparable to other halotolerant green algae used for this purpose.
]]>Phycology doi: 10.3390/phycology2010006
Authors: Boer Bao Skye R. Thomas-Hall Peer M. Schenk
Microalgae contain high-value biochemical compounds including fatty acids (FA), protein and carotenoids, and are promising bioresources to enhance nutrition of food and animal feed. Important requirements for commercial strains are rapid growth and high productivities of desirable compounds. As these traits are believed to be found in aquatic environments with fluctuating conditions, we collected microalgae from marine and freshwater environments that are subjected to eutrophication and/or tidal fluctuations. Using this directed approach, 40 monoalgal cultures were isolated and 25 identified through 18S rDNA sequencing and morphological characterization. Based on their high growth rates (0.28–0.60 day−1) and biomass productivities (0.25–0.44 g L−1 day−1) in commercial fertilizer under standardized conditions, six new strains were selected. Scenedesmus sp. GW63 produced quality FA-rich biomass with high omega-3 polyunsaturated FA (28.5% of total FA (TFA)) contents, especially α-linolenic acid (ALA; 20.0% of TFA) with a very low n-6/n-3 ratio (0.4), and high FA productivity (32.6 mg L−1 day−1). A high protein productivity (34.5 mg L−1 day−1) made Desmodesmus sp. UQL1_26 (33.4% of dry weight (DW)) attractive as potential protein-rich feed and nutrition supplement. Monoraphidium convolutum GW5 displayed valuable carotenoid production (0.8% DW) with high carotenoid accumulation capability (0.8 mg L−1 day−1). This research provides a pathway for fast-tracking the selection of high-performing local microalgae from different environments for nutraceuticals, functional foods and animal feed applications.
]]>Phycology doi: 10.3390/phycology2010005
Authors: Ainoa Morillas-España Silvia Villaró Martina Ciardi Gabriel Acién Tomás Lafarga
The microalga S. almeriensis was produced in spring and summer using 80 m2 raceway reactors located inside a greenhouse in Almería, Spain. This microalga was selected because it is a fast-growing and robust strain with potential applications in the production of functional foods and feeds or as a high-value agricultural biostimulant. Overall, the biomass productivity obtained in summer was 24.9 ± 0.9 g·m−2·day−1. This value was higher than that obtained in spring, with an average value of 21.4 ± 1.3 g·m−2·day−1 (p < 0.05). The Fv/Fm value of the cultures at the stationary phase was comparable and around 0.6, which is the optimum of this strain. No major differences in the macromolecular composition of the biomass were observed between seasons, with an average protein, lipid, ash, and carbohydrate content of 37.9, 4.6, 10.8, and 46.7%, respectively. The data reported herein were used to validate a previously described model. The differences between the experimental and the predicted biomass productivities were below 5% in spring and 8% in summer, although a larger dataset is needed to validate the model. Overall, results supported the robustness of the selected strain and its utilisation in different industrial sectors.
]]>Phycology doi: 10.3390/phycology2010004
Authors: Sirius Pui-Kam Tse Ka-Fu Yung Pak-Yeung Lo Cheok-Kei Lam Tsz-Wang Chu Wing-Tak Wong Samuel Chun-Lap Lo
Occurrence of large-scale harmful algal blooms (HABs) in our reservoirs and water bodies threaten both quality of our drinking water and economy of aquaculture immensely. Hence, rapid removal of HAB biomass during and after a bloom is crucial in protecting the quality of our drinking water and preserve our water resources. We reported here a rapidly deployable algae cleaning system based on a high-capacity high-throughput (HCHT) spiral blade continuous centrifuge connected with inlet and effluent water tanks and a series of feed-in and feed-out pumps as well as piping, all fitted into a standard 20 feet metal shipping container. The system separates algal biomass from algae-laden water with a maximum flow rate of 4000 L/h and a centrifugal force of 4500× g. Cells collected by the system are still intact due to the low centrifugal force used. We showed that after HCHT centrifugation, cellular contents of HAB biomass were not found in the effluent water, and hence, could be discharged directly back to the water body. Furthermore, the addition of flocculants and chemicals prior to the separation process is not required. The system could operate continuously with proper programmed procedures. Taken overall, this system offered a much better alternative than the traditional flocculation- and sonication-based methods of HAB removal in a freshwater environment. This deployable system is the first of its kind being built and had been field-tested successfully.
]]>Phycology doi: 10.3390/phycology2010003
Authors: Toshiki Uji Shinnosuke Ueda Hiroyuki Mizuta
Extracellular matrix (ECM) proteins play crucial roles in the regulation of cell proliferation and differentiation. We identified homologous genes encoding ECM proteins that are known to associate with integrins in animal cells in red macroalga Neopyropia yezoensis. Four genes encoding spondin domain-containing proteins (NySPLs) and eight genes encoding fasciclin domain-containing proteins (NyFALs) from N. yezoensis were selected for bioinformatics and expression analysis in order to obtain insights into the roles of ECM proteins for the life cycle. NySPLs had eight β-strands with two contiguous α-helices, which were similar to those of the F-spondin domain of animals. NyFALs had conserved H1 and H2 motifs and a YH motif between the H1 and H2 regions. Quantitative reverse transcription polymerase chain reaction showed that NySPL1–3 and NyFAL8 transcripts were highly accumulated in mature gametophytes that formed the spermatia. Furthermore, expressions of all NySPLs were upregulated in response to the ethylene precursor 1-aminocylopropane-1-carboxylic acid that induces gametogenesis. NyFAL1, 4 were highly expressed in sporophytes, whereas NyFAL2, 3, 5, 6, and 7 were overexpressed in gametophytes, especially at the vegetative stage. These findings facilitate future research on ECM architecture in the unique life cycles of red macroalgae.
]]>Phycology doi: 10.3390/phycology2010002
Authors: So Hyun (Sophia) Ahn Patricia M. Glibert
Karenia mikimotoi is a toxic bloom-forming dinoflagellate that sometimes co-blooms with Karenia brevis in the Gulf of Mexico, especially on the West Florida Shelf where strong vertical temperature gradients and rapid changes in nitrogen (N) can be found. Here, the short-term interactions of temperature, N form, and availability on photosynthesis–irradiance responses were examined using rapid light curves and PAM fluorometry in order to understand their interactions, and how they may affect photosynthetic yields. Cultures of K. mikimotoi were enriched with either nitrate (NO3−), ammonium (NH4+), or urea with varying amounts (1, 5, 10, 20, 50 µM-N) and then incubated at temperatures of 15, 20, 25, 30 °C for 1 h. At 15–25 °C, fluorescence parameters (Fv/Fm, rETR) when averaged for all N treatments were comparable. Within a given light intensity, increasing all forms of N concentrations generally led to higher photosynthetic yields. Cells appeared to dynamically balance the “push” due to photon flux pressure and reductant generation, with consumption in overall metabolism (“pull” due to demand). However, at 30 °C, all fluorescence parameters declined precipitously, but differential responses were observed depending on N form. Cells enriched with urea at 30 °C showed a smaller decline in fluorescence parameters than cells treated with NO3− or NH4+, implying that urea might induce a photoprotective mechanism by increasing metabolic “pull”.
]]>Phycology doi: 10.3390/phycology2010001
Authors: Marta V. Freitas Diana Pacheco João Cotas Teresa Mouga Clélia Afonso Leonel Pereira
Algae taxa are notably diverse regarding pigment diversity and composition, red seaweeds (Rhodophyta) being a valuable source of phycobiliproteins (phycoerythrins, phycocyanin, and allophycocyanin), carotenes (carotenoids and xanthophylls), and chlorophyll a. These pigments have a considerable biotechnological potential, which has been translated into several registered patents and commercial applications. However, challenges remain regarding the optimization and subsequent scale-up of extraction and purification methodologies, especially when considering the quality and quantity needs, from an industrial and commercial point of view. This review aims to provide the state-of-the-art information on each of the aforementioned groups of pigments that can be found within Rhodophyta. An outline of the chemical biodiversity within pigment groups, current extraction and purification methodologies and challenges, and an overview of commercially available products and registered patents, will be provided. Thus, the current biotechnological applications of red seaweeds pigments will be highlighted, from a sustainable and economical perspective, as well as their integration in the Blue Economy.
]]>Phycology doi: 10.3390/phycology1020011
Authors: Birthe Vejby Nielsen John James Milledge Heidi Hertler Supattra Maneein Md Mahmud Al Farid Debbie Bartlett
The Turks and Caicos Islands (TCI) have been affected by sargassum inundations, with impacts on the economy and environment. Sargassum removal can be costly, but sargassum use and valorisation may generate income and offset environmental damage. A significant barrier to the valorisation of sargassum is insufficient knowledge of its chemical makeup, as well as its seasonal variation and decay after stranding. The chemical characterisation of mixed sargassum and its constituent species and morphotypes (S. natans I, S.natans VIII and S. fluitans) collected from TCI between September 2020 and May 2021 and changes in the composition of sargassum decaying (over 147 days) were studied. High ash (24.61–51.10% dry weight (DW)) and arsenic (49–217 mg kg−1) could severely hamper the use of this seaweed for food or feed purposes. Although there was some reduction in arsenic levels in decaying sargassum, levels remained high (>49 mg kg−1). Biomethane production by anaerobic digestion (AD) is a potential option. Nevertheless, the exploitation of sargassum for biogas, either fresh or as it decays on the beach, is challenging due to low methane yields (<42% of theoretical potential). Pre-treatment or co-digestion with other waste may be options to improve yield. The metal sorption ability of sargassum, which can be problematic, makes biosorption of pollutants an option for further research.
]]>Phycology doi: 10.3390/phycology1020010
Authors: Yoichi Sato Tomonari Hirano Hiroyuki Ichida Nobuhisa Fukunishi Tomoko Abe Shigeyuki Kawano
The Sanriku district is one of the largest Undaria pinnatifida (Wakame) cultivation areas in Japan. However, the production has steadily declined in recent years due to the high retirement rate among fishers. Extending the cultivation period is a potential way to improve productivity by decentralizing the workforce through the production process. We aimed to investigate the phenotypic differentiation between regional strains of U. pinnatifida collected from Matsushima Bay (MAT) and Hirota Bay (HRT) in the Sanriku district through a cultivation trial to verify the application for the purpose of extending the cultivation period. The growth of MAT was better than that of HRT when the cultivation started earlier (i.e., 9 and 19 October 2014); in contrast, HRT outperformed MAT when the cultivation started later (6 November and 12 December 2014). The yield of MAT reached over the standard amount in the Sanriku district in February. On the other hand, the yield of HRT reached over this value in April. Furthermore, the photosynthetic performance and nutrient uptake rates differed between MAT and HRT, indicating that the differences may result in maturation characteristics. According to these results, the combined use of MAT and HRT would be a valuable strategy by which to extend the cultivation period.
]]>Phycology doi: 10.3390/phycology1020009
Authors: Yuki Nishida Yoshikatsu Miyabe Hideki Kishimura Yuya Kumagai
Mycosporine-like amino acids (MAAs) are the natural ultraviolet (UV)-absorbing compounds from micro- and macro-algae. The MAAs in algae change with the environmental conditions and seasons. We previously determined an efficient extraction method of MAAs from red alga dulse in Usujiri (Hokkaido, Japan) and revealed monthly variation of MAA in 2019. Dulse samples in 2019 for MAA preparation were suitable from late February to April. In this study, to confirm the suitable timings to extract MAAs from Usujiri dulse, we also investigated the monthly (from January to May) variation of MAA content in 2020. There were the most MAAs in the sample on 18 March (6.696 µmol g−1 dry weight) among the samples from January to May 2020. From two years of investigation, we deduce that samples of Usujiri dulse from late February to early April were suitable for MAA preparation. The UV stability of the two major purified MAAs in Usujiri dulse—palythine and porphyra-334—was tested. The two MAAs and 2-hydroxy-4-methoxybenzophenone were stable for up to 12 h under a 312 nm lamp at 200 µW cm−2, but 2-ethylhexyl-4-methoxycinnamate formed a cis/trans-mixture in a short time. The data in this study show the suitable sampling period for Usujiri dulse and the possible application for UV protection from food and cosmetics.
]]>Phycology doi: 10.3390/phycology1020008
Authors: Marcin Dębowski Marcin Zieliński Izabela Świca Joanna Kazimierowicz
Algae biomass is perceived as a prospective source of many types of biofuels, including biogas and biomethane produced in the anaerobic digestion process, ethanol from alcoholic fermentation, biodiesel synthesized from lipid reserve substances, and biohydrogen generated in photobiological transformations. Environmental and economic analyses as well as technological considerations indicate that methane fermentation integrated with bio-oil recovery is one of the most justified directions of energy use of microalgae biomass for energy purposes. A promising direction in the development of bioenergy systems based on the use of microalgae is their integration with waste and pollution neutralization technologies. The use of wastewater, another liquid waste, or flue gases can reduce the costs of biofuel production while having a measurable environmental effect.
]]>Phycology doi: 10.3390/phycology1020007
Authors: Debbie Bartlett Franziska Elmer
Since 2011, holopelagic Sargassum fluitans and natans have been arriving en masse to the wider Caribbean region and West Africa, impacting near-shore habitats and coastal communities. We examined the impacts of the Sargassum influx on tourism-related businesses through face-to-face interviews and focus groups and on near-shore seagrass beds through in-water surveys in the Turks and Caicos Islands (TCI). Substantial accumulations of sargassum were found on the beaches of South Caicos and Middle Creek Cay in 2018 and 2019, including a Sargassum brown tide in 2018. A variety of different approaches to removing sargassum from the beaches were mentioned and a desire from local businesses as well as local authorities to find a sustainable, cost-effective solution to what is viewed by many as a serious problem. The brown tide and sargassum accumulating as a layer on the benthos inside the seagrass beds caused significant loss of Thalassia testudinum. Halodule wrightii, macroalgae and sand plains were found in the areas lost by T. testudinum. This finding suggests that, if a cost-effective end use for sargassum could be identified, harvesting material in inshore waters rather than when it has arrived on the beach would have dual benefits.
]]>Phycology doi: 10.3390/phycology1020006
Authors: Joël Fleurence
Algae have been used in agriculture as fertilizers for a long time. Recently, they have also been applied to crops as biostimulants that target plant growth promotion and tolerance to biotic (herbivores, fungi, bacteria, viruses) or abiotic stresses. In addition, algae contain bioactive compounds that have been shown to maintain the health of domestic animals or aquaculture species. This opinion piece highlights different aspects of the present use of algae in agriculture and animal production and their future perspectives.
]]>Phycology doi: 10.3390/phycology1010005
Authors: Peer M. Schenk
I often like to tell my students: “It does not matter what the question is, “algae” is the answer [...]
]]>Phycology doi: 10.3390/phycology1010004
Authors: Luke A. Gray Andres G. Bisonó León Folkers E. Rojas Samuel S. Veroneau Alexander H. Slocum
Sargassum spp. blooms exacerbated by climate change and agricultural runoff are inundating Caribbean beaches, emitting toxic fumes and greenhouse gases through decomposition. This hurts tourism, artisanal fishing, shore-based industry, human health, standards-of-living, coastal ecology, and the global climate. Barriers, collection machinery, and Sargassum valorization have been unable to provide sufficient, sustainable, or widespread relief. This article presents a total Sargassum management system that is effective, low-impact, and economically scalable across the Caribbean. Littoral Collection Modules (LCMs), attached to artisanal fishing boats, collect Sargassum in nets which are brought to a barge. When full, the barge is towed to the deep ocean where Sargassum is pumped to ~150–200 m depth, whereafter it continues sinking (Sargassum Ocean Sequestration of Carbon; “SOS Carbon”). Costing and negative emissions calculations for this system show cleanup costs <$1/m3 and emissions reduction potential up to 1.356 → 3.029 tCO2e/dmt Sargassum. COVID-19 decimated Caribbean tourism, adding to the pressures of indebtedness and natural disasters facing the region. The “SOS Carbon strategy” could help the Caribbean “build back better” by establishing a negative emissions industry that builds resilience against Sargassum and flight shame (“flygskam”). Employing fishermen to operate LCMs achieves socioeconomic goals while increasing Sargassum cleanup and avoiding landfilling achieves sustainable development goals.
]]>Phycology doi: 10.3390/phycology1010003
Authors: Hazel A. Oxenford Shelly-Ann Cox Brigitta I. van Tussenbroek Anne Desrochers
Over the last decade, the Caribbean has seen massive, episodic influxes of pelagic sargassum negatively impacting coastal ecosystems, people’s livelihoods and climate-sensitive sectors. Addressing this issue solely as a hazard has proven extremely costly and attention is slowly turning towards the potential opportunities for sargassum reuse and valorization. However, turning the ‘sargassum crisis into gold’ is not easy. In this study we use a multi-method approach to learn from sargassum stakeholders (researchers, entrepreneurs and established businesses) across the Caribbean about the constraints and challenges they are facing. These can be grouped into five broad categories: (1) unpredictable supply of sargassum; (2) issues related with the chemical composition of the seaweed; (3) harvest, transport and storage; (4) governance; and (5) funding. Specific issues and potential solutions associated with each of these categories are reviewed in detail and recommended actions are mapped to five entry points along a generalized value chain to demonstrate how these actions can contribute to the development of sustainable sargassum value chains that promote economic opportunities and could help alleviate impacts of massive influxes. This paper offers guidance to policy makers and funding agencies on existing gaps and challenges that need to be addressed in order to scale-up successful and sustainable solutions to the sargassum crisis.
]]>Phycology doi: 10.3390/phycology1010002
Authors: Koji Mikami Takaharu Matsumura Yuji Yamamoto
Gametophyte-to-sporophyte transition in the haploid-diploid life cycle depends on fertilization of male and female gametes. We describe here a mutant of the marine red seaweed Neopyropia yezoensis, designated akasusabi (aks), where the gametophyte-to-sporophyte transition occurs independently of fertilization. Although conchocelis filaments were produced from carpospores, severe defects in the maturation of carposporangia via mitosis to generate conchospores were observed. In the aks mutant, however, somatic cells of gametophytic thalli were able to produce conchocelis filaments without fertilization. Thus, apogamy occurs in aks. In addition, aks was highly sensitive to wounding that promotes both asexual and apogamous reproductive responses by producing spores, which develop either into blades or conchocelis filaments, indicating that aks responds to wounding by enhanced reproduction. These findings indicated that the aks mutation enables the transformation of vegetative cells to carpospores to produce sporophytes by apogamy and wound-inducible life cycle trade-off, stimulating a reset of the timing of reproduction during the life cycle. Therefore, AKS is involved in regulations of the gametophyte-to-sporophyte transition and asexual spore production in N. yezoensis.
]]>Phycology doi: 10.3390/phycology1010001
Authors: Roger J.H. Herbert Jay Willis John Baugh
On dynamic coastlines, populations of protected algal species with poor dispersal might be especially vulnerable to infrequent recruitment events and local extinction. As a model, we here consider the dispersal of the alga Padina pavonica from the largest remaining and physically isolated enclaves on the south coast of England. A bio-physical model was used to investigate the likely importance of local propagule dispersal in maintaining populations. Dispersal kernels that simulate the position of propagules at different time steps over 5 days were examined from five release sites. Exceptionally steep declines in model propagule density were observed over the first few hours from release, yet over the first day, 75–85% of model propagules remained close to their source but had not reached other enclaves. After five days, the dispersal from source populations ranged from 0 to 50 km, with only ~5% remaining within the source 1 km2 area. Although distances of modelled propagule dispersal might be adequate for maintaining a regional population network, vegetative perrenation also appears to be important for persistence of P. pavonica. For rare and protected species on isolated and energetic coastlines, local conservation efforts, rather than a reliance on a wider meta-population network, remain very important to ensure long-term protection and survival.
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