Aquatic Environment Research for Sustainable Development

Satellite ocean color and sea surface temperature (SST) observations from 2012 to 2021 and sea surface salinity (SSS) measurements from the Soil Moisture Active Passive (SMAP) mission from 2015 to 2021 are used to characterize and quantify the seasonal and interannual variability in the physical, optical, and biological sea surface features in the Costa Rica Thermal Dome (CRTD) region. High-resolution climatology and the seasonal variability in SST, SSS, and ocean color properties are produced. Chlorophyll-a (Chl-a) concentration, SST, and SSS show these three properties are linked with similar spatial patterns and seasonal variations, i.e., elevated Chl-a concentrations, match the depressed SST and increased SSS and vice versa. This reflects that the physical driving force is the same for these three ocean properties and implies that nutrient supply associated with the physical processes is the major driver for the seasonal biological variability. The interannual changes in Chl-a, SST, and SSS also show that these three ocean properties are consistent among themselves. The positive (negative) Chl-a anomaly generally occurs with negative (positive) SST anomaly and enhanced (reduced) SSS. The in situ measurements evidently show that the subsurface ocean dynamics in the upper 100 m controls the sea surface variability for Chl-a, SST, and SSS. We report that no significant enhancement of Chl-a is observed in the CRTD region during the central Pacific (CP)-type 2020–2021 La Niña event, while Chl-a changes are significant in the other three of four ENSO events between 2012 and 2021. Furthermore, the difference in Chl-a variability driven by the CP-type ENSO and eastern Pacific (EP)-type ENSO is further discussed. Full article

Despite the limited coverage of coral reefs in the world’s oceans, they play a crucial role in global marine biodiversity and providing essential ecosystem services. This study explores the influence of chlorophyll-a (Chl-a) concentration in the water column on the estimation of bottom reflectance (r_b) in coral reefs monitored by the Allen Coral Atlas coral reef monitoring system, using satellite imagery from a Sentinel-2 MSI sensor. We conducted a comprehensive analysis, considering Chl-a global distribution and variability, and its combined effect with water column depth over r_b calculation. Our results demonstrated that the impact of Chl-a on r_b estimation becomes significant when the water column depth exceeds 3 m. While suggesting the optionality of using regional Chl-a values, our study highlights potential overestimations of Chl-a in optically complex environments, such as along the Brazilian coast. This research contributes to refining coral reef monitoring systems and underscores the importance of accurate Chl-a assessments for robust environmental evaluations. Full article

Small wetlands provide crucial ecosystem services but are facing widespread loss and degradation. At present, small wetland complexes provide an alternative avenue for conservation; we used a dataset to illustrate how zeta diversity can be assessed in a small wetland complex. The small wetland complex studied consisted of nine hydrologically connected ponds, and all the ponds were connected by narrow ditches. Data collected included the composition of both zooplankton and phytoplankton communities, water physicochemical parameters, and hydrological connectivity. Two ways in which connectivity affects biodiversity, dispersal filtration (path distance-controlled biological diffusion) and environmental filtration (environment-selected species), were quantified. As a result, (1) 46 zooplankton and 119 phytoplankton species were identified, with species richness distribution significantly affected by water properties (explained variances of 68% and 39%, respectively), reflecting significant environmental filtration, and (2) both zooplankton and phytoplankton showed zeta diversity distance decay (p < 0.001), reflecting significant dispersal filtration, and (3) relatively rare species dominated community turnover, in which environmental filtration was far stronger than dispersal filtration. Overall, the small wetland complex in this study was characterized by hydrological connectivity, which not only allowed moderate biological connectivity but also promoted the coexistence of diverse habitats and communities. We emphasize the applicability of zeta diversity for assessing small wetland complexes, further demonstrating the value of small wetland complexes in promoting biodiversity such as species richness and species turnover. Full article

Urban streams and rivers often experience high levels of pollution from anthropogenic sources. Litter and plastic debris are of particular concern because they negatively impact ecosystem health, increase the risk of flooding, and limit human recreational opportunities. In the City of Knoxville, Tennessee, several urban streams are posted as impaired, with health and use advisories in place. Despite remediation efforts from local governance and charitable initiatives, urban stream pollution remains a pervasive issue in Knoxville. To support and inform local remediation actions and sustainable policy-making, this study seeks to model the relationship between meteorological and hydrological variables and anthropogenic debris pollution in three of Knoxville’s urban creeks. The study uses an innovative approach that includes the use of data from a local stream cleanup initiative. The results, which identify a number of significant relationships, are discussed as they relate to the locally specific context. The implications for local remediation actions and policy-making are discussed. Also, the limitations and directions for future study are presented. Full article

Seaports are gateways that connect a nation to the world economy. With trade by sea increasing due to globalization, the need for the improvement and development of seaports cannot be overlooked. While the development of ports is considered essential for the economic growth and prosperity of a nation, they also result in environmental deterioration that can hurt the future of humanity. The factors that cause such deterioration are many and have been discussed and studied in some detail over the years. Of these, however, studies associated with the environmental impacts of seaports emanating from the oceanfront are limited. It is with this understanding that the current work discusses the physical and biological impacts that occur due to the oceanic environment in seaports, the existing policy provisions, and the possible ways ahead to reduce environmental deterioration and allow their sustainable operation, by means of reviewing published works. Full article

Powerplants frequently use river water for cooling, subsequently discharging warm effluent. Some of these plants can cycle on and off rapidly based on electricity demand, resulting in dramatic temperature fluctuations in the receiving waters. To understand the impacts on resident fish populations in the Upper Mississippi River, we (i) assessed the effects of rapid water cooling on three native fish species; (ii) investigated whether smallmouth bass (Micropterus dolomieu) behavior favored movement into thermal plumes when given a choice of cooler or ambient water; and (iii) tracked native M. dolomieu with acoustic tags and recorded core body temperature during the thermal cycling process of a steam electric powerplant. In cold shock experiments, mortality was associated with rapid temperature declines and dependent on the final (cold) holding temperature. The species or developmental stage of the tested organism did not affect survival. When given a choice between warm and ambient waters, M. dolomieu exhibited little inclination to acclimate to the warmer water and instead “self-regulated” by moving in and out of the warm water plume. This finding was supported by telemetry data on M. dolomieu. The core temperature of the fish never increased more than 2 °C above the ambient (upstream) Mississippi River temperature, even during warm effluent discharge. Full article

The establishment of managerial approaches for the sustainable use of fishery resources depends on a critical understanding of the stock status. The Monte Carlo catch maximum sustainable yield (CMSY) method and a Bayesian state–space implementation of the Schaefer model (BSM) are recent, but widely used, stock assessment methods for data-limited situations. Here, CMSY and BSM were used to evaluate the state and exploitation level of the seabream population. Collections of catch and effort data from 1988 to 2021, pertaining to time series, were obtained from the Fishery Statistics Book published by the Ministry of Agriculture, Fisheries and Water Resources of Oman. The CMSY and BSM results were similar, indicating that the seabream stock of Oman was overfished, as B/B_MSY = 0.96 (<1) and F/F_MSY = 1.25 (>1). The probability that the stock was being overfished and undergoing overfishing in 2021 was 53%, while the probability that the stock was healthy (high biomass and low fishing pressure) was only 16.2%, when the target should be higher than 75%. The conclusions are of a preliminary nature owing to the utilization of comparatively new methodologies employed to generate them, which commonly validate the condition and utilization of the populations under investigation. Our research suggests that the seabream population in Oman is overfished, and reducing fishing activity is necessary to restore its abundance. Full article

Biofloc technology (BFT) culture systems based on low salinity can meet the needs of shrimp growth and environmental protection, thus having potential application. To evaluate the effects of BFT on water quality, the microbial community, growth, digestive enzyme activity, and antioxidant and immune status of Litopenaeus vannamei under low salinity conditions, a four-week experiment was conducted in a BFT culture system (C/N ratio of 12: 1) with three salinity conditions: 5.0‰ (S5 group), 10.0‰ (S10 group), and 15.0‰. The results showed that water quality parameters were all within the range suitable for the culture of L. vannamei. There were no significant differences in growth parameters such as final weight or specific growth rate. Muscle moisture, crude protein, and crude lipid contents of L. vannamei did not differ among groups (p > 0.05). In addition, intestinal amylase and trypsin activities in the S5 group significantly increased (p < 0.05). In the S15 group, the superoxide dismutase activity and total antioxidant capacity in the serum and hepatopancreas of L. vannamei, as well as serum catalase, acid phosphatase, and alkaline phosphatase activities, markedly increased (p < 0.05). The microbial diversity (Shannon and Simpson indices) and richness (Chao1 and ACE indices) were higher in the S5 group than in the S15 group. Our findings indicated that although the shrimp in BFT systems with a salinity of 5‰ had lower antioxidant and immune levels, the digestive enzyme activity as well as the gut microbial diversity and richness improved compared to other groups, suggesting the possibility of culturing L. vannamei in low-saline areas with BFT systems. Full article

Eutrophication-resistant phytoplankton communities in freshwater ecosystems have a novel lipid potential to contribute to the development of tropical regions. The question that arises due to the unsustainability of their eutrophicated waters is how the recognition of the lipids of the resident phytoplankton progresses. Our aim was to provide an overview of the pico-, nano- and micro-cellular lipids of phytoplankton with a focus on eutrophic tropical freshwater ecosystems. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework, global and Latin American publications were retrieved based on search equations and specific questions. In total, 490 studies were reviewed. The inclusion criteria, in order, were (1) peer-reviewed articles, (2) articles investigating phytoplankton strains or communities from any aquatic environment, (3) articles on freshwater ecosystems, and (4) research in tropical climates. The contribution of freshwater phytoplankton was high and discontinuous, with a representation of 63% in the 21st century. Freshwater themes were resolved in the ecological context with phytoplankton or algae keywords, while microalgae were targeted using resource use keywords. On the tropical scale, technological themes on lipid microalgae were related to fatty acids, biofuels, biodiesel, antioxidants, and recombinant DNA. It is concluded that studies of the lipid composition of phytoplankton communities are delayed in the case of eutrophic tropical freshwater ecosystems. Full article

Landscape ecological risk is considered the basis for regional ecosystem management decisions. Thus, it is essential to understand the spatial and temporal evolutionary patterns and drivers of landscape ecological risk. However, existing studies lack exploration of the long-term time series and driving mechanisms of landscape ecological risk. Based on multi-type remote sensing data, this study assesses landscape pattern changes and ecological risk in the Three Gorges Reservoir Area from 1990 to 2020 and ranks the driving factors using a geographical detector. We then introduce the geographically weighted regression model to explore the local spatial contributions of driving factors. Our results show: (1) From 1990 to 2020, the agricultural land decreased, while forest and construction land expanded in the Three Gorges Reservoir Area. The overall landscape pattern shifted toward aggregation. (2) The landscape ecological risk exhibited a decreasing trend. The areas with relatively high landscape ecological risk were primarily concentrated in the main urban area in the western region of the Three Gorges Reservoir Area and along the Yangtze River, with apparent spatial aggregation. (3) Social and natural factors affected landscape ecological risk. The main driving factors were human interference, annual average temperature, population density, and annual precipitation; interactions occurred between the drivers. (4) The influence of driving factors on landscape ecological risk showed spatial heterogeneity. Spatially, the influence of social factors (human interference and population density) on landscape ecological risk was primarily positively correlated. Meanwhile, the natural factors’ (annual average temperature and annual precipitation) influence on landscape ecological risk varied widely in spatial distribution, and the driving mechanisms were more complex. This study provides a scientific basis and reference for landscape ecological risk management, land use policy formulation, and optimization of ecological security patterns. Full article

This overview presents the different water masses present in the various primary and secondary marine regions of the Mediterranean Sea and Black Sea, providing information on their main physical characteristics (i.e., temperature, salinity, density), the water depths at which they have been observed and the processes involved in their formation. There is a characteristic difference in the overall hydrology of the Mediterranean Sea compared to the Black Sea, in terms of the number and characteristics of water masses and their formation processes, although they form a single (integrated) marine system. This difference is explained by the limited communication between the two seas through the Sea of Marmara and its straits (the Dardanelles and Bosporus) and by the fact that the Mediterranean Sea is a condensation basin while the Black Sea is a dilution basin; therefore, the deficit of water in the former is compensated by the inflow of Atlantic waters, while the surplus in the latter outflows to the Aegean Sea. In total, 21 different water masses have been identified in the Mediterranean Sea (excluding the Straits of Gibraltar and the Sea of Marmara) compared to the 5 water masses identified in the Black Sea (excluding the Sea of Azov). This large number of water masses is attributed to coastal morphology (i.e., presence of straits) and submarine relief (i.e., deep basin separated by shallow sills) and different formation processes. Full article

Meromictic lakes of the marine coast, quite widely distributed in the northern hemisphere, are the result of climate changes and glacier retreat. The bottom sediments of these lakes serve as a geological chronicle of the history of marine basin’s development with the geochemical occurrence forms of elements indicate various processes of their accumulation. This paper presents research results concerning the occurrence of forms of heavy metals in lake sediments along the coast of the White Sea. These results are based on a sequential seven step leaching procedure, followed by ICP-MS analysis and subsequent statistical data processing. To determine differences among the examined geochemical parameters, Pearson’s correlation analysis and Ward’s cluster analysis were utilized. The total content of Cr, Mn, Fe, Co, Ni, Zn, V, and Pb in the sediments did not exhibit significant differences based on their degree of isolation from the sea. The major contribution to deposition of these metals in sediments of the meromictic lakes studied is the residual form, encompassing the mineral matrix of the sediment. At the same time, the elevation of mobile forms for all the metals examined corresponds to an increase in the isolation of lakes from the White Sea. In the meromictic lake sediments, concentrations of Cu, Mo, and U demonstrated significant increases in forms tightly bound to organic matter, while Cd exhibited an association with Fe-Mn oxyhydroxides. Notably, a significant difference in the occurrence forms of Cu, Cd, Mo, and U was evident in the reduced sediments of meromictic lakes when compared to those of open sea bays. The meromictic lakes along the White Sea coast, positioned at various stages of isolation, hold promise for investigating the migration of metals in response to environmental changes. Full article

The hydrodynamics and sediment transport at the microtidal harbour of La Spezia Arsenale (Liguria, Italy) were studied through a numerical approach, with the objective of providing useful information for: (1) the understanding of the hydro-morphodynamics of microtidal harbour settings and (2) the operation management and planning for the Arsenale, the pivotal harbour for the Italian Navy. Three different scenarios were used to parametrically gain knowledge on the role of extreme (100-year return period) meteomarine forcing. FUNWAVE and Delft3D were used to simulate, respectively, the wave propagation from the open sea toward the Arsenale and the influence of two freshwater streams on the basin circulation. The first scenario was aimed at understanding the effect of wind waves and swell on the basin dynamics; the second scenario was set up to inspect the role of the rivers’ discharges on the Arsenale hydro-morphodynamics; the third scenario combined all of the above forcings. All the simulations also included the tidal forcing and were run under two different wind directions. We found that the hydrodynamics inside the Arsenale were mainly influenced by the tide and the wind; the former caused the water to enter/exit the basin during the flood/ebb phases, respectively, and the latter influenced the circulation cell, whose sense of rotation depended on the wind direction. In addition, the discharge of the Lagora stream, debouching into the sea close to the Arsenale entrance, partially entered the basin and created an eddy whenever its direction was opposite to that of the wind-forced circulation cell, while the Caporacca stream, flowing directly into the Arsenale, mainly fed the dominant circulation without altering it. On the other hand, the morphodynamics were strongly affected by the rivers’ discharges, which were solely responsible for the supply of sediment to the basin. Also, the major influence on the sediment transport was exerted by the rivers and the wind forcing. Small sedimentation rates were observed in the Arsenale close to the rivers’ mouths, particularly after the occurrence of the rivers’ discharges, while no siltation due to waves took place. This study evaluated for the first time the influence of freshwater streams flowing nearby/into the Arsenale, representative of semi-enclosed microtidal ports located in the vicinity of rivers. It was found that the contribution of the rivers to the hydro-morphodynamics of the Arsenale cannot be neglected; indeed, it represents one of the main forcings of the harbour dynamics and should, therefore, be considered from a management viewpoint. Full article

Coastal inundation has recently started to require significant attention worldwide. The increasing frequency and intensity of extreme events (sea storms, tsunami waves) are highly stressing coastal environments by endangering a large number of residential areas, ecosystems, and tourist facilities, and also leading to potential environmental risks. Predicting such events and the generated coastal flooding is thus of paramount importance and can be accomplished by exploiting the potential of different tools. An example is the combination of remote sensors, like marine radars, with numerical models. Specifically, while instruments like X-band radars are able to precisely reconstruct both wave field and bathymetry up to some kilometers off the coast, wave-resolving Boussinesq-type models can reproduce the wave propagation in the nearshore area and the consequent coastal flooding. Hence, starting from baseline simulations of wave propagation and the conversion of water elevation results into radar images, the present work illustrates the reconstruction of coastal data (wave field and seabed depth) using a specifically suited data processing method, named the “Local Method”, and the use of such coastal data to run numerical simulations of coastal inundation in different scenarios. Such scenarios were built using two different European beaches, i.e., Senigallia (Italy) and Oostende (Belgium), and three different directional spreading values to evaluate the performances in cases of either long- or short-crested waves. Both baseline and inundation simulations were run using the FUNWAVE-TVD solver. The overall validation of the methodology, in terms of maximum inundation, shows its good performance, especially in cases of short-crested wind waves. Furthermore, the application on Oostende Beach demonstrates that the present methodology might work using only open-access tools, providing an easy investigation of coastal inundation and potential low-cost integration into early warning systems. Full article

To ensure the sustainability of the marine environment, it is crucial to understand the intricate relationship between environmental factors and marine biota. Human activities have been recognized as significant contributors to profound changes in marine ecology. However, these observable alterations often represent a cumulative effect that intertwines with less apparent natural influences. This research delved into the relationships between environmental factors and marine life in the waters adjacent to Nanwan Bay, Kenting, Taiwan. Specifically, it examined the linear relationships and the degree of changes between environmental factors and marine life. To achieve these objectives, factor analysis was employed to uncover potential latent variables that could impact marine organisms, with these variables named based on previous studies and related literature. The findings led to the development of a structural equation model (SEM) to represent the marine ecology of Nanwan Bay. The results accentuated the significant influence of primary productivity and nutrient levels on the assemblage of marine life. The application of SEM methodology sheds more light on the degree of impact natural and anthropogenic interference have on marine ecosystems. Full article

Water can act as a vector for several microbes with significant pathogenic potential for both humans and animals. Waterborne infections are a critical public health concern as they cause more than 3.4 million deaths annually. Total and thermotolerant coliforms and intestinal enterococci have traditionally been used to assess the quality and suitability of drinking water. The aim of this study was to evaluate the microbiological quality of groundwater from six sub-basins located in the upper Choluteca River basin in Honduras and to determine the E. coli phylogroups isolated in these samples. Our findings show high rates of fecal contamination, which suggests that the groundwater in the basin is unsafe for human consumption. Phylogroups B1 and D were the most frequent among 99 E. coli isolates, while C and F were the least frequent phylogroups. Measures must be taken to raise awareness about sanitation and good practices for the management of household waste as well as the waste generated by agro-industrial activity and livestock. Full article

Water pollution is a serious problem in China and abroad. Revealing the source types and their spatio-temporal characteristics is the premise of effective watershed management and pollution prevention. Since the national control unit can better match the administrative division, it was useful for the manager to control water pollution. Taking the Fenhe River Basin as the research area, a SWAT model based on the national control unit was established in this study to reveal the current situation of water quantity and quality. Then, in combination with the differential evolution algorithm, the dynamic water environment capacities of each control unit were further discussed. The results showed that the flow upstream was lower, only 7.62–8.40 m³/s, but flow in the midstream and downstream increased to 17.58 m³/s and 18.32 m³/s. Additionally, the flow in tributaries was generally lower than that in the main stream, the flow in unit 6 and unit 11 were only 0.23 m³/s and 0.62 m³/s. The water quality upstream could meet the water quality requirements of drinking water sources, but the pollution in the midstream was the most serious after passing through Taiyuan City, the concentration of NH₃-N and TP reached to 6.75 mg/L and 0.41 mg/L. The results of water environmental capacity showed that the residual capacity of ammonia nitrogen (NH₃-N) and total phosphorus (TP) in the main stream were positive, indicating that the Fenhe River Basin can accommodate the current pollution load in general, but there was an obvious difference in different months of the year. Especially in the wet season, the non-point source (NPS) pollution problem in the midstream and downstream was more prominent, resulting in a high-capacity consumption rate. It showed that in Taiyuan, Jinzhong, and Linfen Yuncheng in Shanxi Province, should be wary of non-point source pollution. In addition, the water environmental capacity of different units also varied greatly. The capacity consumption of the Taiyuan Section in the midstream was the highest, which mainly occurred in the wet season. The negative values of the residual capacity of NH₃-N and TP reached the highest, −131.3 tons/month and −12.1 tons/month. Moreover, the capacity consumption downstream also reached 21–40% of the whole year in the wet season. In addition to the impact of NPS pollution in the wet season, due to the impact of point source pollution, units 8, 9, and 10 downstream had high negative residual capacity in the dry season, especially in January and February. The construction of a SWAT model based on control units and the further analysis of dynamic water environment capacity could provide technical support for Fenhe River Basin management to realize accurate pollution control. Full article