Sargassum Golden Tides, a Global Problem

A topical collection in Phycology (ISSN 2673-9410).

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Editors


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Guest Editor
Faculty of Engineering and Science, Algae Biotechnology Research Group, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
Interests: algae; seaweed; sargassum, biofuel; biogas; biorefinery; anaerobic digestion; nutraceuticals; pharmaceuticals; energy balance; ensilage; food technology; wastewater
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Centre for Resource Management and Environmental Studies, Cave Hill Campus, University of the West Indies, Bridgetown BB11000, Barbados
Interests: interest in the valorisation of pelagic Sargassum and related challenges; particular interest in Sargassum-derived products for agriculture, environmental restoration, sustainable building materials and bioplastics in the wider Caribbean context; other research interests include monitoring of pollutants in the environment, including pesticides and heavy metals

Topical Collection Information

Dear Colleagues,

Beach and coastline inundations by Sargassum blooms have been called the single greatest threat to tourism and fisheries in the Caribbean. The impact of Sargassum is not only economic but has implications for the environment and health of coastal ecosystems and communities. Golden tides of Sargassum are also causing major problems in other areas of the world, such as the Mexican and West Africa coasts. This recurrent challenge is the focus of increasing research and innovations.

This Special Issue will emphasise the various impacts and potential uses of Sargassum. Submissions from research groups worldwide are requested. Also, papers from the conference “Sargassum Golden Tides, a global problem” will be published in this issue. Scientific articles on the composition; potential uses (biofuels, fertiliser, feed, food industry, biochemical, pharmaceutical, cosmetics, activated carbon and others); environmental, socio-economical and health impacts; monitoring; inundation prediction; and case studies are welcomed. Publications from multidisciplinary groups are especially encouraged.

Dr. John James Milledge
Dr. Anne Desrochers
Guest Editors

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Keywords

  • Sargassum
  • S. natans
  • S. fluitans
  • golden tide

Published Papers (14 papers)

2024

Jump to: 2023, 2022, 2021

20 pages, 2991 KiB  
Article
Morphological and Molecular Characters Differentiate Common Morphotypes of Atlantic Holopelagic Sargassum
by Amy N. S. Siuda, Aurélie Blanfuné, Skye Dibner, Marc Verlaque, Charles-François Boudouresque, Solène Connan, Deborah S. Goodwin, Valérie Stiger-Pouvreau, Frédérique Viard, Florence Rousseau, Valérie Michotey, Jeffrey M. Schell, Thomas Changeaux, Didier Aurelle and Thierry Thibaut
Phycology 2024, 4(2), 256-275; https://doi.org/10.3390/phycology4020014 - 7 May 2024
Viewed by 732
Abstract
Since 2011, massive new strandings of holopelagic Sargassum have been reported on the coasts of the Caribbean, northern Brazil, Guiana, and West Africa, causing severe economic and ecological damage. Three common morphotypes (S. fluitans III, S. natans I, and S. natans VIII) [...] Read more.
Since 2011, massive new strandings of holopelagic Sargassum have been reported on the coasts of the Caribbean, northern Brazil, Guiana, and West Africa, causing severe economic and ecological damage. Three common morphotypes (S. fluitans III, S. natans I, and S. natans VIII) were identified as responsible for these catastrophic events, with dominance shifts between them over time. However, the taxonomic status of these holopelagic Sargassum morphotypes remains unclear. Using an integrative taxonomy framework, combining a morphological study and molecular analyses, this study aimed to clarify their taxonomic status. Morphological analyses of 54 characters revealed no intermediate form between the three morphotypes, with the overall shape, nature of the axis, and size and shape of blades and vesicles being the most discriminating. An analysis of mitochondrial (IGS, cox2, cox3, mt16S rRNA, and nad6) and plastid (rbcL) markers confirmed the genetic divergence among the three morphotypes, with a lower level of divergence between the two S. natans morphotypes. Without additional molecular characterization, these morphotypes cannot be classified as three distinct species. However, due to their distinct morphological characteristics and sympatry within drifting aggregations, a revision of holopelagic species names is proposed, with Sargassum fluitans var. fluitans (for S. fluitans III), Sargassum natans var. natans (for S. natans I), and S. natans var. wingei (for S. natans VIII). This revision provides necessary clarity on the species involved in inundations of the tropical Atlantic. Full article
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21 pages, 2727 KiB  
Article
Comprehensive Analysis of Biomass, Nutrient, and Heavy Metal Contributions of Pelagic Sargassum Species (Phaeophyceae) Inundations in South Florida
by Danielle C. Hatt, Natalie K. Bally, Lowell Andrew R. Iporac, Samantha Olszak, Justin E. Campbell and Ligia Collado-Vides
Phycology 2024, 4(2), 235-255; https://doi.org/10.3390/phycology4020013 - 20 Apr 2024
Viewed by 625
Abstract
Pelagic Sargassum landings (hereby referred to as sargasso) increased dramatically in 2011 throughout the equatorial tropical Atlantic due to the formation of the Great Atlantic Sargassum Belt (GASB). Despite increasing reports, understanding of local abundances and vegetative characteristics, especially in South Florida, remains [...] Read more.
Pelagic Sargassum landings (hereby referred to as sargasso) increased dramatically in 2011 throughout the equatorial tropical Atlantic due to the formation of the Great Atlantic Sargassum Belt (GASB). Despite increasing reports, understanding of local abundances and vegetative characteristics, especially in South Florida, remains limited. From 2018 to 2021, sargasso was collected at two South Florida beaches, with additional sampling at a third beach to assess nutrient and heavy metal concentrations. Biomass landings varied greatly, with S. fluitans III predominant during the “peak season” (May to July) and S. natans I predominant in the “off season”, while S. natans VIII was consistently least abundant. This suggests that South Florida may receive sargasso from the Sargasso Sea during the low season and from the GASB during the peak sargasso season. Across all three morphotypes, mean nitrogen (N) and phosphorus (P) contents were 0.97% and 0.04% (dry weight), respectively. Out of the 16 heavy metals detected, our values were similar to those reported across the Caribbean. Arsenic was the most prevalent heavy metal, with sargasso containing epibionts having higher arsenic concentrations. These results provide comprehensive information to better understand the characteristics and potential origin of sargasso landings in South Florida. Full article
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23 pages, 2382 KiB  
Article
Global Chemical Characterization of Sargassum spp. Seaweeds from Different Locations on Caribbean Islands: A Screening of Organic Compounds and Heavy Metals Contents
by Jérôme Bauta, Elliot Calbrix, Sophie Capblancq, Christine Cecutti, Jérôme Peydecastaing, Christine Delgado Raynaud, Antoine Rouilly, Valérie Simon, Guadalupe Vaca-Medina, Virginie Vandenbossche, Emeline Vedrenne and Pascale De Caro
Phycology 2024, 4(2), 190-212; https://doi.org/10.3390/phycology4020011 - 13 Apr 2024
Viewed by 1104
Abstract
Large-scale strandings of Sargassum spp. seaweeds occur annually on the beaches of the Caribbean islands and cause major environmental, health, and economic problems. In order to support an approach of valorisation of algae, an exhaustive characterisation of the composition of these seaweeds has [...] Read more.
Large-scale strandings of Sargassum spp. seaweeds occur annually on the beaches of the Caribbean islands and cause major environmental, health, and economic problems. In order to support an approach of valorisation of algae, an exhaustive characterisation of the composition of these seaweeds has been performed by analysing the contents in alginates, structural carbohydrates (fucans and glucans), minerals, proteins, lipids, mannitol, polyphenols, and heavy metals. Nine batches were collected at different harvesting sites over the years 2021 and 2022, to estimate the spatial and temporal variation in Sargassum composition. A batch of floats was harvested and analysed to estimate the differences in composition between floats and whole algae. Samples collected during the same year (floats or entire plant, freshly collected or stored) showed no significant differences in composition. However, slight differences were observed between batches collected in the two years. Some samples showed significant amounts of heavy metals, especially arsenic. A detailed structural carbohydrates analysis was carried out and discussed with literature data. As the nitrogen content of algae is an interesting parameter for food or agronomic uses, protein analysis enabled us to calculate a new nitrogen–protein conversion factor, specific to these algae species. Full article
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14 pages, 3622 KiB  
Article
Pelagic Sargassum as a Potential Vector for Microplastics into Coastal Ecosystems
by Dalila Aldana Arana, Tania P. Gil Cortés, Víctor Castillo Escalante and Rosa E. Rodríguez-Martínez
Phycology 2024, 4(1), 139-152; https://doi.org/10.3390/phycology4010008 - 23 Feb 2024
Cited by 1 | Viewed by 1770
Abstract
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 [...] Read more.
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. Full article
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12 pages, 3692 KiB  
Article
Accessing the Efficacy of Sargassum-Based Aqueous Phase Products Derived from Hydrothermal Carbonisation and Hydrothermal Liquefaction on Plant Growth
by James Smith, Amy Pilsbury, Vinod Kumar, Eleni E. Karamerou, Christopher J. Chuck, Leopoldo Herrera-Rodriguez, Julio V. Suarez and Michael J. Allen
Phycology 2024, 4(1), 53-64; https://doi.org/10.3390/phycology4010003 - 18 Jan 2024
Viewed by 1150
Abstract
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 [...] Read more.
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. Full article
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2023

Jump to: 2024, 2022, 2021

12 pages, 2338 KiB  
Article
Integrative Literature Analysis of Holopelagic Sargassum (Sargasso) in the Western Atlantic (2011–2022): Status, Trends, and Gaps
by Julianna T. Arita, Lowell Andrew R. Iporac, Natalie K. Bally, Mutue T. Fujii and Ligia Collado-Vides
Phycology 2023, 3(4), 447-458; https://doi.org/10.3390/phycology3040030 - 9 Oct 2023
Viewed by 1203
Abstract
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 [...] Read more.
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. Full article
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8 pages, 1244 KiB  
Communication
Temporal Changes in the Composition of Beached Holopelagic Sargassum spp. along the Northwestern Coast of Cuba
by Eduardo Gabriel Torres-Conde, Brigitta I. van Tussenbroek, Rosa E. Rodríguez-Martínez and Beatriz Martínez-Daranas
Phycology 2023, 3(4), 405-412; https://doi.org/10.3390/phycology3040027 - 22 Sep 2023
Cited by 3 | Viewed by 1208
Abstract
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 [...] Read more.
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. Full article
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9 pages, 1185 KiB  
Communication
The Effect of Temperature on the Growth of Holopelagic Sargassum Species
by Edén Magaña-Gallegos, Eva Villegas-Muñoz, Evelyn Raquel Salas-Acosta, M. Guadalupe Barba-Santos, Rodolfo Silva and Brigitta I. van Tussenbroek
Phycology 2023, 3(1), 138-146; https://doi.org/10.3390/phycology3010009 - 9 Feb 2023
Cited by 10 | Viewed by 4080
Abstract
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 [...] Read more.
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. Full article
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2022

Jump to: 2024, 2023, 2021

26 pages, 3927 KiB  
Article
A Review of a Decade of Local Projects, Studies and Initiatives of Atypical Influxes of Pelagic Sargassum on Mexican Caribbean Coasts
by Judith Rosellón-Druker, Edith Calixto-Pérez, Elva Escobar-Briones, Jaime González-Cano, Luis Masiá-Nebot and Fernando Córdova-Tapia
Phycology 2022, 2(3), 254-279; https://doi.org/10.3390/phycology2030014 - 30 Jun 2022
Cited by 11 | Viewed by 4171
Abstract
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 [...] Read more.
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. Full article
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12 pages, 893 KiB  
Article
Biochemical and Elemental Composition of Pelagic Sargassum Biomass Harvested across the Caribbean
by 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 and Michael J. Allen
Phycology 2022, 2(1), 204-215; https://doi.org/10.3390/phycology2010011 - 11 Mar 2022
Cited by 15 | Viewed by 4154
Abstract
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 [...] Read more.
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. Full article
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2021

Jump to: 2024, 2023, 2022

20 pages, 6211 KiB  
Article
Chemical Characterisation of Sargassum Inundation from the Turks and Caicos: Seasonal and Post Stranding Changes
by Birthe Vejby Nielsen, John James Milledge, Heidi Hertler, Supattra Maneein, Md Mahmud Al Farid and Debbie Bartlett
Phycology 2021, 1(2), 143-162; https://doi.org/10.3390/phycology1020011 - 13 Dec 2021
Cited by 14 | Viewed by 5473
Abstract
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 [...] Read more.
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. Full article
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22 pages, 1854 KiB  
Article
The Impact of Sargassum Inundations on the Turks and Caicos Islands
by Debbie Bartlett and Franziska Elmer
Phycology 2021, 1(2), 83-104; https://doi.org/10.3390/phycology1020007 - 2 Nov 2021
Cited by 16 | Viewed by 4492
Abstract
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 [...] Read more.
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. Full article
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27 pages, 6562 KiB  
Article
Caribbean-Wide, Negative Emissions Solution to Sargassum spp. Low-Cost Collection Device and Sustainable Disposal Method
by Luke A. Gray, Andres G. Bisonó León, Folkers E. Rojas, Samuel S. Veroneau and Alexander H. Slocum
Phycology 2021, 1(1), 49-75; https://doi.org/10.3390/phycology1010004 - 12 Aug 2021
Cited by 13 | Viewed by 7440
Abstract
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 [...] Read more.
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. Full article
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22 pages, 535 KiB  
Article
Challenges of Turning the Sargassum Crisis into Gold: Current Constraints and Implications for the Caribbean
by Hazel A. Oxenford, Shelly-Ann Cox, Brigitta I. van Tussenbroek and Anne Desrochers
Phycology 2021, 1(1), 27-48; https://doi.org/10.3390/phycology1010003 - 5 Aug 2021
Cited by 44 | Viewed by 10573
Abstract
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 [...] Read more.
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. Full article
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