Search

Global climate change has generated an increasing number of environmental problems, especially in Mediterranean coastal areas, such as the Po Delta (PD), where shellfish production has undergone an overall decline because of strong environmental changes. The present study is centred on assessing the fundamental ecological aspects in one of the most crucial European shellfish production lagoons, Sacca degli Scardovari (SC), addressing phytoplankton community parameters directly affecting shellfish production, namely, chemotaxonomic composition, size fractions, and total biomass, in relation to the physicochemical properties of the water column and mussel filtering activity. Our findings suggest that the phytoplankton community structure, its role within the lagoon food web and its production cycles depend on two distinct allogenic inputs, which shape the community differently and exert substantial control on shellfish production. At the same time, the suspended mussel biomass strongly controls the phytoplankton size composition, as their growth is largely supported by nanophytoplankton. As the Po River collects the drainage waters of the Italian side of the entire Alpine Arch, the phytoplankton dynamics reported here represent a useful baseline for further addressing issues of climatic changes affecting lagoon ecology. We believe that our study presents an innovative tool for the planning and management of interventions aimed at enhancing national mussel production without neglecting aspects of environmental protection or the integrity of the coastal system, with significant scientific implications. [ABSTRACT FROM AUTHOR]

Estimations of ecosystem metabolism have rarely been used to quantify productivity in structural reductionist approaches for the description of phytoplankton composition. However, estimations of ecosystem metabolism could contribute to a better understanding of the relationship between phytoplankton composition and ecosystem functioning. To examine this, we investigated the community structure of phytoplankton in a set of Mediterranean coastal lagoons (natural and artificial) during a hydrological cycle to identify the most important environmental variables determining phytoplankton species composition. The focus of the study was on the quantification of productivity-related variables using estimations of ecosystem metabolism, such as different proxies for the estimation of the production-to-biomass ratio and of the relative importance of K- and r-strategies, which are commonly used conceptually but not quantified. Our results demonstrated differences in phytoplankton composition between seasons, due to the dominant hydrological pattern of flooding confinement in the salt marsh, and between lagoons that were caused by different levels of nutrient availability. Moreover, there was a notable decrease in the production/biomass ratio and a prevalence of K-strategists with seasonal succession, as predicted by Margalef's mandala. Thus, the results showed that estimations of ecosystem metabolism are useful for the higher frequency quantification of important ecological variables, and contribute to a better understanding of planktonic assemblages, and physical and chemical changes, in these fluctuating ecosystems. [ABSTRACT FROM AUTHOR]

Although the effect of salinity on phytoplankton community structure has been studied in many coastal lagoons at different times, it has not been studied simultaneously in different lagoons that are not on the same delta but are geographically close to each other. In the present study, the effect of temporal and spatial changes in salinity on the phytoplankton biovolume, species richness, diversity, and species composition was investigated seasonally in 2020 and 2021 in 6 coastal lagoons of Marmara Basin (Türkiye). In more saline lagoons, phytoplankton biovolume, species richness, diversity, and the total number of species were lower. In lagoons which salinity values were approximate, the species composition was similar. Although the salinity in the lagoons did not show significant change seasonally, biovolume values were lower in Mert lagoon in the fall of 2020 when the salinity values were higher compared to the spring of 2021. Moreover, the considerable decrease in salinity shifted the dominant species structure from high salinity optima species to low salinity optima species in this lagoon. Other effective parameters in the seasonal distribution of dominant species were detected as temperature, dissolved oxygen, alkalinity, and nitrate nitrogen. [ABSTRACT FROM AUTHOR]

Ecological disturbances such as fish kills can negatively impact ecosystem processes in coastal lagoons. To gain an understanding of factors causing fish kills, we examined conditions associated with a summertime fish kill in a northeastern Pacific coastal lagoon (Rodeo Lagoon, CA, USA). Examination of available data indicated the fish kill was likely caused by hypoxia involving the following etiology: (1) strong onshore winds (up to 12 m/s) mixed a stratified water column, (2) water column mixing transported nutrients from near the bed into the photic zone, (3) increased nutrient concentrations in the photic zone (> 200%) together with high solar irradiance fueled a phytoplankton bloom, (4) death and decomposition of phytoplankton (72% decrease in abundance) contributed to biological oxygen demand that led to (5) hypoxic conditions (as low as 0.6 mg/L) that caused the fish kill. The event resulted in the death of an estimated 3677 Tidewater Goby (Eucyclogobius newberryi), a species listed as endangered under the US Endangered Species Act, and numerous (but not enumerated) Threespine Stickleback (Gasterosteus aculeatus), unidentified sculpins (Cottidae), and macroinvertebrates (primarily Amphipoda). The processes contributing to the event are likely re-occurring phenomena responsible for observed periodic fish kills. Coastal lagoons with limited freshwater inflows and connection to the Pacific Ocean may retain nutrients and be susceptible to similar events. [ABSTRACT FROM AUTHOR]

The proposed study is focused on an ecological analysis of Latvian coastal lagoons, emphasizing their unique but vulnerable nature. Coastal lagoons are recognized as fragile ecosystems of significant ecological, social, and economic value, as recognized by the European Directive 92/43/EEC (Habitats Directive). Despite their protected status, the existence of these ecosystems can be threatened by morphological, hydrological, and anthropogenic changes. The uniqueness of these ecosystems can be determined by the large number of influencing factors and their dynamics. They are affected by seawater, their level of fluctuation, wind exposure, overgrowing with macrophytes, freshwater sources, and water flow generated streams affecting sediment transport and accumulation. All the influencing factors determine a highly trophic ecosystem, which in the studied lagoons is rated as medium to poor ecological status, which confirms the above-mentioned vulnerability and fragility. The aim of this study was to analyze two lagoons in the coastal area of the Baltic Sea in the Riga Gulf, by characterizing, for the first time, their current conditions and ecological parameters because understanding such ecosystems is only partial. The physicochemical composition of lagoon sediments and water shows the impact of seawater by increased electrical conductivity and the concentration of SO42− and Cl− in water, while the presence of detritus in sediments is almost non-existent; thus, the content of organic matter is low with relatively variable pH. The results show that the diversity of studied benthic macroinvertebrates, macrophytes, zooplankton, and even phytoplankton species is low, but there is higher diversity in lagoons and their parts with regular water exchange with the sea. The study provides valuable insight into the ecological dynamics of coastal lagoons in Latvia, shedding light on their current conditions, anthropogenic impact, and the need for sustainable management measures.

The proposed study is focused on an ecological analysis of Latvian coastal lagoons, emphasizing their unique but vulnerable nature. Coastal lagoons are recognized as fragile ecosystems of significant ecological, social, and economic value, as recognized by the European Directive 92/43/EEC (Habitats Directive). Despite their protected status, the existence of these ecosystems can be threatened by morphological, hydrological, and anthropogenic changes. The uniqueness of these ecosystems can be determined by the large number of influencing factors and their dynamics. They are affected by seawater, their level of fluctuation, wind exposure, overgrowing with macrophytes, freshwater sources, and water flow generated streams affecting sediment transport and accumulation. All the influencing factors determine a highly trophic ecosystem, which in the studied lagoons is rated as medium to poor ecological status, which confirms the above-mentioned vulnerability and fragility. The aim of this study was to analyze two lagoons in the coastal area of the Baltic Sea in the Riga Gulf, by characterizing, for the first time, their current conditions and ecological parameters because understanding such ecosystems is only partial. The physicochemical composition of lagoon sediments and water shows the impact of seawater by increased electrical conductivity and the concentration of SO42− and Cl− in water, while the presence of detritus in sediments is almost non-existent; thus, the content of organic matter is low with relatively variable pH. The results show that the diversity of studied benthic macroinvertebrates, macrophytes, zooplankton, and even phytoplankton species is low, but there is higher diversity in lagoons and their parts with regular water exchange with the sea. The study provides valuable insight into the ecological dynamics of coastal lagoons in Latvia, shedding light on their current conditions, anthropogenic impact, and the need for sustainable management measures. [ABSTRACT FROM AUTHOR]

Raygoza-Alcantar, L.N.; Vázquez, G., and Rodríguez-Zaragoza, F.A., 2024. Spatiotemporal relationship between diatom diversity and environmental gradients at La Mancha coastal lagoon (Veracruz, Mexico). Journal of Coastal Research, 40(2), 366–381. Charlotte (North Carolina), ISSN 0749-0208. This study analyzed the composition and distribution of diatoms in the La Mancha tropical coastal lagoon, Veracruz, Mexico, under different environmental conditions. Water samples were collected from the surface and bottom of the lagoon at five sites during the "nortes" (cold winter fronts), dry, and rainy seasons. The physical and chemical variables of the lagoon water were also analyzed. Diatom taxa were identified and quantified. Sixty-five taxa were determined and classified according to functional groups. Sites 1 and 2 were considered potential sources of nutrients and folin phenol active substances (FPAS). In addition, two horizontal gradients were observed. The first concerned nutrient concentration, which increased in the area of the mouth of the Caño Grande River and decreased towards the bar. The second was a salinity gradient characterized by high values in the area of the bar and decreasing values towards the river mouth. Diatom richness and diversity were higher in the areas influenced by the opening of the bar and the Caño Grande River discharges in the "nortes" season. Diatom composition varied across seasons, sites, and depth levels; functional groups only varied between sites (p ≤ 0.05). A redundancy analysis recorded the species that responded to the salinity and temperature gradients, including Paralia sulcata, Odontella spp., and Grammatophora oceanica. The species that responded to high nutrient concentrations, total phosphorus, and transparency were Aulacoseira granulata, Stephanocyclus meneghinianus, Ulnaria ulna, Gyrosigma acuminatum, Navicula subrhynchocephala, and Amphipleura pellucida in different seasons in the area close to the river mouth and mangrove swamp. The correlation between diatom density and FPAS indicates that Psammodictyon constrictum and Amphiprora pseudoduplex have optimal growth when the FPAS concentration increases. [ABSTRACT FROM AUTHOR]

While the role that groundwater discharge plays in supporting primary production in coastal ecosystems is well recognized, there is still limited evidence on its impacts higher up the food chain. In this study, we investigate the role of groundwater discharge in supplying nitrogen and carbon to the Mediterranean mussels (Mytilus galloprovincialis) in the Salses-Leucate lagoon (France). Nitrogen (δ15N) and carbon (δ13C) isotope values in the mantle and gill tissues of Mediterranean mussels are used to trace nitrogen and carbon sources at groundwater-exposed sites and a control site. Our results show similar isotope values for mantle and gill tissues, likely due to relatively stable environmental conditions in the study sites and to the biochemical composition of tissues. Diet shift, fractionation, and the physiological function of tissues could also explain this observation. δ15N values in mussel tissues increase overall in winter at both the groundwater-influenced sites (4.9 to 7.8‰) and the control site (3.4 to 8.5‰) in comparison with those in autumn (3.5 to 7.4‰ at the groundwater-influenced sites and 4.5 to 6.9‰ at the control site), likely due to reduced food supply and slower metabolism in winter, resulting in 15N enrichment. In contrast, mussel δ13C values decrease in winter at the groundwater-influenced sites (− 23.4 to − 21.6‰) and the control site (− 22.0 to − 19.0‰), suggesting input from 13C-depleted sources originating from groundwater input. The comparison of the isotopic values of mussel tissues and potential food sources indicates that the main diet of M. galloprovincialis in the Salses-Leucate lagoon is a mixture of groundwater particulate organic matter (POM), lagoon POM, and marine POM (POM as a proxy of phytoplankton). Depleted δ13C values in mussel tissues, particularly at groundwater-exposed sites, provide evidence of uptake of groundwater-derived nutrients. The ecological benefit of groundwater input on filter feeders results from local increases in food availability (mainly phytoplankton), supported by groundwater-derived nitrogen and carbon. In summary, this study shows the combined (a) indirect effect of groundwater discharge on mussel growth via uptake of their food, phytoplankton, and (b) the likely direct feeding of groundwater POM by M. galloprovincialis. It thus shows the important ecological implication of groundwater inputs in coastal lagoon food webs. [ABSTRACT FROM AUTHOR]

Introduction: Successful management and mitigation of harmful algal blooms (HABs) requires an in-depth understanding of the physiology and nutrient utilization of the organisms responsible. We explored the preference of various nitrogen (N) and phosphorus (P) substrates by two novel groups of HAB-forming phytoplankton originating from the Indian River Lagoon (IRL), Florida: 1) a consortium of picocyanobacteria (Crocosphaera sp. and 'Synechococcus' sp.) and 2) ananochlorophyte (Picochlorum sp.). Methods: Short-term kinetic uptake experiments tested algal use and affinity for inorganic and organic N substrates (ammonium (NH4 +), nitrate (NO3 -), urea, and an amino acid (AA) mixture) through 15N and 13C isotope tracing into biomass. Results: Picocyanobacteria exhibited Michaelis-Menten type uptake for the AA mixture only, while nanochlorophytes reached saturation for NH4 +, the AA mixture, and urea at or below 25 µM-N. Both picocyanobacteria and nanochlorophyte cultures had highest affinity (Vmax/Ks) for NH4 + followed by the AA mixture and urea. Neither culture showed significant uptake of isotopically-labeled nitrate. Disappearance of glucose-6-phosphate (G6P) added to culture medium suggesting use of organic P by both cultures was confirmed by detection of alkaline phosphatase activity and the tracing of 13CG6P into biomass. Discussion: Together, our results suggest that these HAB-forming phytoplankton groups are able to use a variety of N and P sources including organic forms, and prefer reduced forms of N. These traits are likely favorable under conditions found in the IRL during periods of significant competition for low concentrations of inorganic nutrients. Bloom-forming phytoplankton are therefore able to subsist on organic or recycled forms of N and P that typically dominate the IRL nutrient pools. [ABSTRACT FROM AUTHOR]

Estuarine systems, being situated at the interface between land and marine environments, are important sites for nitrate (NO3–) retention and processing due to large inputs, long retention time, and high biogeochemical activity. However, it remains uncertain how pelagic and benthic processes control NO3– cycling and how these differ between contrasting seasons. In this study, we measured pelagic and benthic assimilatory and dissimilatory NO3– processes in a large lagoon (Curonian Lagoon, SE Baltic Sea) to understand changes in NO3– cycling in relation to variation in riverine inputs and shifts in phytoplankton community composition. We show that in spring, benthic dissimilatory and assimilatory NO3– processes were important, while in summer, pelagic assimilatory processes dominated. During spring, diatom blooms promote greater delivery of nitrogen (N) and labile organic matter to the benthos resulting in greater denitrification in the sediments and a net flux of NO3– from the water column to the sediments. In summer, phytoplankton blooms dominated by buoyant cyanobacteria exhibited high rates of assimilatory uptake and greater particulate organic N export to the sea, but low rates of sediment–water exchange. Cyanobacteria blooms were associated with higher absolute rates of NO3– uptake, as well as higher mass-specific rates compared to spring. Given the low dissolved inorganic N in summer, high uptake indicates that the pelagic community possessed a nutritional strategy to efficiently utilize multiple N forms. Overall, our findings show that the seasonal succession from diatom to cyanobacteria-dominated communities is associated with a shift from strong benthic-pelagic coupling to predominantly pelagic-based N cycling. [ABSTRACT FROM AUTHOR]

Phytoplankton are dominant primary producers and key indicators in aquatic ecosystems. Understanding the controlling factors on the structure of phytoplankton assemblages is fundamental, but particularly challenging at the land–ocean interface. To identify the patterns and predictors of phytoplankton assemblage structure in the Ria Formosa coastal lagoon (south Portugal), this study combined phytoplankton abundance along a transect between the discharge point of a wastewater treatment plant and a lagoon inlet, over two years, with physico-chemical, hydrographic, and meteo-oceanographic variables. Our study identified 147 operational taxonomic units (OTUs), and planktonic diatoms (60–74%) and cryptophyceans (17–25%) dominated the phytoplankton in terms of abundance. Despite strong lagoon hydrodynamics, and the lack of spatial differences in the phytoplankton abundance and most diversity metrics, the multivariate analysis revealed differences in the assemblage structure between stations (p < 0.001) and seasons (p < 0.01). Indicator analysis identified cryptophyceans as lagoon generalists, and 11 station-specific specialist OTUs, including Kryptoperidinium foliaceum and Oscillatoriales (innermost stations) and potentially toxigenic species (Pseudo-nitzschia and Dinophysis; outer lagoon station, p < 0.05). Water temperature, pH, and nutrients emerged as the variables that best explained the changes in the phytoplankton assemblage structure (p < 0.001). Our findings provide insight into the relevance of local anthropogenic and natural forcings on the phytoplankton assemblage structure and can be used to support the management of RF and other coastal lagoons. [ABSTRACT FROM AUTHOR]

Mediterranean coastal lagoons are affected by multiple threats (demographic pressures, eutrophication, climate change) expected to increase in the future and impact the ecosystem services provided. Conservation norms and scientific studies usually focus on large lagoons (> 0.5 km2) due to their economic importance, while they ignore smaller lagoons. These are poorly understood and often unprotected, despite their prevalence within the Mediterranean region and their importance. Qualitative and quantitative characterisation of small lagoons, in terms of functioning and sensitivity to global and local changes, are needed to develop appropriate management strategies. For this purpose, this work provides the first inventory of all Corsican lagoons and has investigated three of them of small size (Arasu, Santa Giulia, Balistra), characterised by contrasting anthropogenic contexts (highly modified/disturbed, medium disturbance, quasi-pristine). At the regional level, 91 of the 95 lagoons identified are < 0.5 km2, making Corsica a good example for the study of small Mediterranean lagoons. The three case studies showed differences in their seasonal biogeochemical cycles and phytoplankton communities (biomass, diversity, photosynthetic efficiency). Arasu and Santa Giulia lagoons showed an increase in watershed urbanisation (+ 12% and + 6% in 30 years), high phytoplankton biomass, low diversity and blooms of potentially harmful dinoflagellates. Conversely, Balistra lagoon showed a good status overall, but some anthropogenic pollution sources within its watershed. This study demonstrates the importance of small lagoons at regional and Mediterranean scale, and provides knowledge on studied local sites but also potential applications elsewhere. The importance of an integrated approach considering lagoons within their adjacent connected systems (watershed and sea) and anthropogenic contexts is highlighted. [ABSTRACT FROM AUTHOR]

Mediterranean coastal lagoons are particularly vulnerable to increasing direct anthropogenic threats and climate change. Understanding their potential responses to global and local changes is essential to develop management strategies adapted to these ecosystems. Salinity is a fundamental structuring factor for phytoplankton communities; however, its role under climate change is understudied. We hypothesized that salinity variations imposed by climate change and/or management actions could disturb Mediterranean lagoons' phytoplankton communities. To test our hypothesis, we performed two 5-day microcosm experiments in which natural phytoplankton assemblages from the Santa Giulia lagoon (Corsica Island) were subjected to three increasing (53–63–73) and decreasing (33–26–20) levels of salinity, to mimic strong evaporation and flash flooding, respectively. Results indicate that over-salinization inhibited growth and modified the assemblages' composition. Freshening, on the contrary, showed feeble effects, mainly boosting microphytoplankton abundance and depleting diversity at lowest salinity. In both experiments and under freshening in particular, initially rare species emerged, while photosynthetic activity was degraded by salinity increase only. We demonstrated that phytoplankton communities' structure and metabolism are strongly altered by the predicted implications of climate change. Such impacts have to be considered for future management of coastal lagoons (control of sea exchanges and watershed fluxes). This work constitutes a priority step towards the proactive adapted management and conservation of such as-yet-neglected ecosystems in the context of climate change. [ABSTRACT FROM AUTHOR]

In a saline semi-isolated lagoon on Cape Zeleny (White Sea), the annual dynamics of the vertical hydrological structure and the seasonal dynamics of phytoplankton were traced. Species composition, vertical distribution, abundance, nutrition type, and biomass were analyzed. In total, 293 species and supraspecific taxa of algae and cyanobacteria were found. Most of the identified species are marine, and 38 species are freshwater. Taxonomic composition changed in the lagoon throughout the year. Dinoflagellates dominated in winter and early June; unidentified cocci and flagellates in July; diatoms, dinoflagellates, and unidentified cells in August; dinoflagellates in September; and unidentified cocci and flagellates in October–November. The abundance of algae also changed in the lagoon throughout the year. The integrated biomass in the water column varied from 0.01 g C/m2 in January to 0.78 g C/m2 in early September. According to the environmental parameters, the water column of the lagoon was subdivided into several zones with different environmental conditions and corresponding phytoplankton communities. The similarity between the communities of different horizons was 32–46% in summer and 7% in winter. The chemocline layer was the most populous. It contained a maximum of phytoplankton biomass, 1–2 orders of magnitude higher than that in the overlying horizons. Despite the connection to the sea, the phytoplankton structure in the surface water layer in the lagoon and in the sea differed significantly in composition, quantitative parameters, and seasonal dynamics. The similarity between the communities never exceeded 50%. In terms of biomass dynamics, the lagoon lagged behind the sea until mid-summer, but, starting from August, it outnumbered it, and the phytoplankton development in the lagoon lasted longer, until late autumn. According to sequential tests DistLM, the phytoplankton structure and dynamics in the lagoon and in the sea were related to the daylength, water salinity, oxygen content, and pH by 24.5%. At the same time, the PhP structure did not depend on water temperature, underwater illuminance, or depth. Oxygen content and pH were defined by PhP activity. Salinity serves as a vector of the vertical sequence of ecological niches. The day length seems to be the crucial factor of the seasonal PhP dynamics in the semi-isolated coastal stratified lakes and lagoons. [ABSTRACT FROM AUTHOR]

The Ria Formosa coastal lagoon is a highly productive shallow ecosystem in southern Portugal, subjected to nutrient inputs from anthropogenic and natural sources. Nutrients are major abiotic drivers of phytoplankton in this system, but their effects on phytoplankton assemblages and the occurrence of nutrient limitation are still poorly understood. The main goal of this study was, thus, to evaluate the occurrence, type, and effects of nutrient limitation on phytoplankton community and specific functional groups in the Ria Formosa coastal lagoon. We conducted nutrient enrichment experiments with factorial additions of nitrogen (N) and phosphorus (P) using natural phytoplankton assemblages from distinct locations in the Ria Formosa, throughout a yearly cycle. Phytoplankton composition and abundance were evaluated using inverted and epifluorescence microscopies, and spectrophotometric methods were used for biomass. Limitation was defined as higher phytoplankton growth following enrichment with a particular nutrient in relation to the non-enriched control. The most common type of phytoplankton limitation was simultaneous co-limitation by N and P; diatoms, as r-strategists, were the most frequently limited group. Single N and P limitation, and serial P limitation were also observed, as well as negative responses to nutrient enrichment. Group-specific responses to nutrient enrichment were not reflected in the relative abundance of phytoplankton groups within the whole assemblage, due to the numerical dominance of pico-sized groups (cyanobacteria and eukaryotic picophytoplankton). Ambient nutrient ratios and concentrations did not predict phytoplankton nutrient limitation, given the different nutrient utilisation traits among phytoplankton functional groups. Therefore, nutrient ratios should not be used as indicators of nutrient limitation in eutrophication assessment. [ABSTRACT FROM AUTHOR]

Coastal lagoons are unique ecosystems in terms of their phytoplankton community structure, due to their unstable environment in terms of biological, chemical, and physical conditions as a result of flooding and seasonality. Seasonal and spatial variations in phytoplankton are controlled by various biotic and abiotic factors. In this study, temporal and spatial changes in the phytoplankton biovolume, species richness, diversity, and Reynolds functional groups (FGs) with the effect of different environmental variables were investigated seasonally in 2020 and 2021 for seven coastal lagoons of Kızılırmak Delta (Samsun, Türkiye). Phytoplankton biovolume and species richness were lower in more saline lagoons. Moreover, their species composition was significantly different compared to lagoons with lower salinity. Phytoplankton biovolume, species richness, and diversity were generally recorded lower in spring periods. During the studied periods, 14 FGs (C, D, J, Lo, M, MP, P, S1, S2, SN, W1, W2, X1, and X2) were prominent in the total biovolume. Three FGs (C, P, and SN) were only found as dominant in Karaboğaz, Gıcı, and Cernek lagoons, and their distributions were affected by pH, nitrate–nitrogen, and low light availability (high Zmix/Zeu). Due to the seasonality and hydrology, environmental parameters and dominant FGs were generally segregated into flooding (spring), drying (summer), and transition (fall) periods. [ABSTRACT FROM AUTHOR]

The water quality of tile Indian River Lagoon has experienced a significant decline in recent years due to harmful algal blooms. The Florida Institute of Technology's Living Docks restoration program has sought to improve water quality by deploying oyster mats on dock pilings throughout the lagoon. As a whole, the communities that settle on oyster mats have improved local water quality on a small scale throughout the lagoon. However, contributions by individual species which make up these mat communities are unknown. This study examines the capabilities of SO, ela p/icam, a sea squirt commonly found on the oyster mats, in removing harmful algal bloom species from the lagoon. The purpose of the study was to l) determine i falgal and bacterial composition varies between S. plicata and the surrounding water column and 2) if so, examine spatial and temporal differences in algal and bacterial composition between S. plicata and the surrounding water column. Gut content of S. plicata was quantified in phytoplankton density by species, and presence of bacterial species. Gut data was compared to open water data to examine the possibility of S. plicata having a selective diet. Two locations were each sampled at two timepoints, and data was compared within and between locations to identify spatial and temporal patterns. [ABSTRACT FROM AUTHOR]

The Aquatina Lagoon (Southern Adriatic Sea, Mediterranean Ecoregion) is a transitional water ecosystem with great ecological and socio-economic interest. Anthropogenic activities around the lagoon (e.g., agriculture and tourism) and hydrology can affect the environmental quality and biodiversity of the lagoon. Herein, the dynamics and diversity of phytoplankton communities were studied before and after the opening of a new canal connecting the lagoon with the sea, by using different approaches based on an evaluation of the size and structure of the phytoplankton as well as the taxonomic analyses. The lagoon depicted time-related fluctuations in chemical-physical parameters. The phytoplankton trend was characterized by an increase in abundance and biomass in summer, when pico-sized autotrophs dominated. Generally, nano-sized phytoflagellates dominated the community, while micro-sized dinoflagellates and diatoms were less abundant. An increase in the phytoplankton taxa number was observed throughout the years. All the analyzed parameters were generally relatively homogeneous before the opening of the channel, while some quantitative differences among stations were observed in the second sampling period. Considering the statistical evidence, both environmental and biological parameters were affected by the "dilution" effect exerted by marine water inputs. This research supports the evidence that phytoplankton is a good indicator of the environmental status, and the obtained results contribute to the implementation of management strategies for the conservation of transitional water ecosystems. [ABSTRACT FROM AUTHOR]

In January 2013, tropical cyclone Oswald caused widespread flooding in the North-East coast of Australia, and large and highly episodic inputs into Princess Charlotte Bay (PCB, northern Great Barrier Reef). Freshwater outflows from the Normanby and Kennedy rivers, the two main rivers draining the adjacent catchments, resulted in drastic changes in physical, biogeochemical and optical properties within PCB. On 31 January, 2 days after the peak riverine discharge from the Normanby river, nutrients and dissolved organic matter contents peaked under the influence of large outflows from the Kennedy river into the western section of the bay (5.8 μM for dissolved inorganic nitrogen, 6.9 g m−3 for dissolved organic carbon and 6.1 m−1 for the colored dissolved organic matter absorption coefficient at 412 nm). In the eastern section of the bay, the situation appeared more 'mixed', with a suspended solids concentration reaching 23.1 g m−3 close to the Normanby river mouth. The main phytoplankton bloom occurred in the transition zone between the Kennedy and Normanby flood plumes, and was dominated by diatoms with a chlorophyll a concentration reaching 14.6 mg m−3. This study highlights the need to better describe the critical spatial and temporal scales of variability of key biogeochemical and optical properties after a major flood event. The data collected is key to improve the accuracy of ocean color remote sensing algorithms and regional biogeochemical budgets following highly episodic inputs. [ABSTRACT FROM AUTHOR]

The predator-prey relationship is generally size-specific in the pelagic food webs. Phytoplankton cell size structure can provide information on the successive levels of consumers and therefore on the energy that can flow towards the top consumers. This work focuses on phytoplankton cell size structure in a coastal lagoon (Cabras Lagoon, Italy) considered one of the most important for fishing productivity in the Mediterranean. The inter-annual and seasonal dynamics of picophytoplankton (Pico, cell size <3 µm) and Utermöhl Fraction of Phytoplankton (UFP, cell size >3 µm) were considered during almost three years in relation to the temporal dynamics of selected environmental variables and zooplankton. Small-sized cells with a mean linear cell size <10 µm and a mean cell volume <103 µm3 mainly represented UFP along the entire study period. This size class contributed the most to total phytoplankton biomass (up to 86%) and density (up to 99%) during the first part of the investigation period. A compositional change was detected: smaller species of Chlorophyceae, Bacillariophyceae, filamentous Cyanophyceae, and autotrophic nanoflagellates thrived in the second part of the study, replacing larger Mediophyceae that dominated UFP at the beginning. Picocyanobacteria rich in phycocyanin were the dominant taxa of Pico along the entire investigation period and this size class contributed the most to total phytoplankton biomass (up to 30%) and density (up to 96%) at the end of the study. The observed shift towards different and even smaller UFP and Pico in the second part of the study was most probably due to complex interactions between top-down and bottom-up effects. Indeed, an increased temperature, a decreased salinity and decreased concentrations of nutrients (mainly ammonium and orthophosphate), as well as an increased grazing pressure of rotifers on the larger Mediophyceae were simultaneous with the changes detected in phytoplankton. The obtained results highlight a longer planktonic trophic web in Cabras Lagoon that includes small phytoplankton at the base, ciliates, rotifers, and copepods. This suggests low energy availability for planktivorous fish, with possible future relevant consequences for fishing activities in this coastal lagoon. [ABSTRACT FROM AUTHOR]

Coastal lagoons are among the most productive ecosystems in the world, and they provide a wide range of ecosystem services and resources. In the Ria Formosa (southern Portugal), phytoplankton production has rarely been addressed. The main goal of this study is thus to evaluate the variability of phytoplankton production and photosynthetic characteristics over the seasonal cycle and in different locations (landward, urban, intermediate, and seaward boundaries) of the Ria Formosa coastal lagoon, subjected to distinct natural and anthropogenic stressors. Primary production was evaluated using the 14C incorporation technique, and photosynthetic parameters were estimated by fitting photosynthesis-irradiance curves. Primary production showed significant seasonal variations, with higher values in the summer associated with lower euphotic depths, higher water temperatures, and higher nutrient concentrations. No spatial differences were found for primary production or photosynthetic parameters. Primary production values were lower than previous estimates, which reflects an improvement in water quality in the Ria Formosa, but values are higher than primary production estimates for other temperate coastal ecosystems, which reflects the highly productive nature of this coastal lagoon. [ABSTRACT FROM AUTHOR]

Coastal lagoons are biodiversity hotspots that support neighboring ecosystems and various services. They can exhibit distinct biophysical characteristics compared to the adjacent open sea and act paradoxically as autonomous ecosystems. Using remotely sensed observations and state‐of‐the‐art numerical simulations, the role of water column hydrodynamics in shaping the seasonal succession of phytoplankton biomass was investigated for a non‐estuarine coastal lagoon situated in the northeastern Red Sea. Observations reveal that seasonal phytoplankton blooms inside the lagoon occur during a distinctively different period compared to the adjacent open sea. We provide evidence that this striking difference is due to the contrasting hydrodynamic conditions between inside and outside the lagoon, through their effects on stratification that regulate nutrient availability and hence favorable conditions to sustain rapid phytoplankton growth. The proposed mechanism may offer new insights into understanding the biophysical dynamics of non‐estuarine coastal lagoons in other tropical regions of the global oceans. [ABSTRACT FROM AUTHOR]

Climate change impacts the coastal lagoons and can affect various species reproductive cycles, feeding habits, and survival. Due to natural factors, the ecosystem habitat at Pulicat Lagoon on the east coast of India is under severe stress. This study assesses the ecosystem using a numerical model and field-collected physical, chemical, biological, and meteorological data for 2018 and 2019. A coupled hydro-ecological model was used to analyze circulation features, biological and chemical interactions, and transformation processes. The study indicates that high abnormalities in the lagoon ecosystem are caused by less exchange of fresh/coastal water from river sources and sea mouths due to less rainfall during the study period. The model output depicts the salinity variation from 15 to 58 PSU in different seasons of 2018 and 2019. Furthermore, high concentrations of Chl-a ranged from 50 μg/L to 95 μg/L during the monsoon and post-monsoon seasons, triggering phytoplankton C (70–350 mg/m3) and zooplankton C (9–43 mg/m3) at the Lagoon, resulting in an algal bloom. The monsoonal shift of Chlorophyte (9.52%–9.68%), Cyanobacteria (13.22%–14.95%), Diatoms (66.08%–63.87%), and Dinoflagellates (11.18%–11.51%) is observed in the biological field, with Diatom showing the highest abundance (65%). As a result, appropriate scenario-based model studies were conducted to conserve and strengthen the ecosystem during such extreme events. The model studies suggest that widening the lagoon inlet (800m) with a depth of 5 m (3 km length) increases the optimal tidal exchange to the ecosystem. The model output demonstrates the optimal exchange that normalizes the salinity from 12 to 34 PSU from the inner Lagoon to the mouth region. This study will support environmental authorities in conserving the ecosystem through proper management adaptations. • A coupled hydro-ecological model was used to analyse circulation features and biological and chemical interactions. • Observations reveal tidal variability of 0.8–1m, maximum current magnitude of 48cm/s at the southern mouth, and significant suspended and alongshore transport. • Tidal flux inside the lagoon from the mouth region spreads around 8 km, and river inflow water sources sustain the water balance during the monsoon. • Larger proportional shift/changes in phytoplankton species such as Ditylum sol, Diplonesis, Triporas furca, Surirella sp. with seasonal flow. • An optimized solution to mitigate and restore the ecosystem from extreme events by widening the lagoon inlet to 800m width and 5m depth, spanning a length of 1.8 km has been arrived at using scenario studies. This intervention aims to enhance tidal flux and exchange within the ecosystem. [ABSTRACT FROM AUTHOR]

Detailed seasonal analyses of phytoplankton assemblages' composition were performed on long-term datasets (20 years) of two oligotrophic Mediterranean lagoons (Diana and Urbino), in order to test if phytoplankton community and bloom events patterns rely on a seasonal basis. Our results highlight a similar phytoplankton composition between the lagoons, but different patterns in terms of phytoplankton abundances, of timing, magnitude and occurrence of Taxonomic Units, and of bloom events occurrence. Dominant diatoms group showed a seasonal repartition, with highest contribution of Skeletonema sp. during winter and spring, some other groups emerging in warmer seasons (e.g. Chaetoceros spp.), or not showing marked seasonality (e.g. Pseudo-nitzschia spp.). Dinoflagellates' abundances were higher during autumn, besides exhibiting punctual proliferations over the year. Salinity was the strongest environmental parameter in controlling Diana lagoon phytoplankton community, while Urbino community was mostly controlled by turbidity. A worrying evolution of the toxic diatom Pseudo-nitzschia spp., linked to salinity and temperature changes, was detected in both lagoons. We further demonstrated changes in the phytoplankton community are ongoing in these lagoons, despite their contrasting human pressure contexts, indicating that serious impacts on phytoplankton dynamics and blooms triggering in Mediterranean lagoons shall be foreseen within the current and forecasted climate change scenarios. [ABSTRACT FROM AUTHOR]

This study aimed to test the effects of rainfall-driven nutrient loading on the microphytoplankton dynamics in the shallow water at Trou aux Biches lagoon on the northwest coast of Mauritius. Changes in density, diversity and estimated productivity of microphytoplankton were monitored in three zones—coast, lagoon and reef—during two rainfall periods of 4 and 3 days' duration, respectively, in March–April 2017. The average nutrient loading from terrestrial runoff was 15.5% and the salinity decreased by 2.5%. Following the two rainfall events, a 3-fold increase in total microphytoplankton density (TMPD), with a dominance of diatoms, was noted within a week at the coast and lagoon, while it remained relatively unchanged at the reef. These changes in microphytoplankton densities were concomitant with adequate levels of silicate (>2 µM) and high nitrate:silicate ratios (2.84–6.93). During this study, the numbers of genera of diatoms, dinoflagellates and cyanobacteria observed were 28, 12 and 3, respectively. The Shannon–Wiener, equitability and evenness indices showed high diversity values for diatoms and cyanobacteria prior to the rainfall events and for dinoflagellates after the events. The chlorophyll a content, relative electron transport rate, and estimated productivity of microphytoplankton increased during and after the rainy periods. TMPD and chlorophyll a were correlated significantly and positively with nutrients, salinity and temperature. Toxic algal species such as the dinoflagellates Alexandrium, Dinophysis and Tripos were recorded, although not in bloom densities. These findings indicate that rainfall-driven nutrient loading led to an increase in microphytoplankton density and estimated productivity, and a change in its diversity. [ABSTRACT FROM AUTHOR]

The coronavirus (COVID-19) pandemic is the defining health crisis of our time. It has led to lockdowns of major cities and curbed industrial, commercial and vehicular activities. Lagos is the commercial and industrial hub of Nigeria and has the Lagos lagoon as the sink for the flow of wastes streams from all these activities. Here we examine the water chemistry features and photosynthetic pigment parameters before the lockdown, during the lockdown and around the ease of the lockdown. Results show that parameters such as Dissolved Oxygen, Chlorophyll a and b, pH, Total Suspended Solids, Zinc, Copper, Lead, Chromium and Manganese increased considerably during the lockdown. On the other hand, parameters such as Conductivity, Total Dissolved Solids, Salinity, Acidity, Alkalinity, Total Hardness, Chloride, Sulphate, Phosphate, Calcium, Magnesium, Dissolved Inorganic Phosphate, Sodium and Chlorophyll c values reduced in the same period. In all, trends signify cleaner and clearer waters of the Lagos lagoon and these positive effects lingered during the ease of the lockdown period characterized by the cessation of major industrial and vehicular activities. During the lockdown, there were improved water quality conditions as well as primary production. The effects of seasonal variation in water chemistry factors including salinity were also noted. [ABSTRACT FROM AUTHOR]

The abundances of 17 cytometric groups encompassing four groups of bacteria, three groups of cyanobacteria, six groups of eukaryotic picophytoplankton (<2–3 µm), and four groups of small eukaryotic nanophytoplankton (between 3 and 6 µm) were studied in the Thau Lagoon across different seasonal conditions. Among them, the growth (µ) and mortality rates due to grazing (g) of 12 groups of bacteria, cyanobacteria, and eukaryotic pico- and nanophytoplankton were simultaneously studied in the Thau Lagoon via four dilution experiments across different seasonal conditions. The abundances of heterotrophic flagellates and ciliates and their potential predators were studied and linked to prey mortality. Bacteria were more active than phytoplankton and displayed the highest growth and grazing mortality rates. Most studied groups had g:µ ratios > 1, suggesting that predators efficiently grazed and transferred these preys. Surprisingly, the observed variations in predator abundance across seasons did not necessarily correspond with changes in grazing pressure. The significant positive relationship found between water temperature and bacterial grazing mortality rates and the reverse trend observed for larger eukaryotic prey suggested that warmer water increases small prokaryote transfer to higher trophic levels but disadvantages larger eukaryotic prey transfer. [ABSTRACT FROM AUTHOR]

Copyright of Egyptian Journal of Botany is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The 2011-2012 data on the hydrochemical mode ofthe transboundary River Viliya (Neris) and two of its tributaries in the territory of the Republic of Belarus and on structure of the phytoplankton community therein are presented. High phytoplankton biomass was determined in the summer period. For the first time, the presence of microcystin synthase genes (meyE) was detected in the River Viliya (Neris), and four variants of microcystins were determined employing the MALDI-TOF method. Similarities in the species composition (including toxic species) of cyanobacteria from the River Viliya (Neris) and from the Curonian Lagoon of the Baltic Sea were noted. It can be assumed that the phytoplankton community structure of rivers can influence algal community formation in the downstream areas as well as in the coastal estuarine lagoons that eventually receive water from these rivers. [ABSTRACT FROM AUTHOR]

Phytoplankton structure and patterns are key components to forecast the net result of the gain and loss process that outline the resilience of the lagoon ecosystem. In order to understand the phytoplankton community structure and its relationship with the environmental variables in the shallow hypersaline Pulicat lagoon, east coast of India, observations were carried out during August 2018–January 2019 covering the three seasons: premonsoon (PrM), monsoon (M), and postmonsoon (PoM). The salinity of the lagoon varied with a minimum of 12.1 for the M and a maximum of 81.65 during the PoM. The clustering analysis performed on the phytoplankton abundance data separated the lagoon into three sectors: north sector (NS), central sector (CS), and south sector (SS). A total of 59 taxa/morphotypes from four taxonomic classes (Bacillariophyceae, Chlorophyceae, Cyanophyceae, and Dinophyceae) were recorded during the study period. The class Bacillariophyceae was dominant in the lagoon both spatially and temporally by 44.06% with Chaetoceros borealis as dominant species. Presence of characteristic species like Dunaliella sp. was observed in the higher salinity, whereas Pediastrum duplex and Scenedesmus sp. were dominant in the freshwater influx areas. The individual-based functional approach allowed grouping these taxa into 11 functional entities based on the derived 4 functional trait values (cell size, trophic regime, mobility, and coloniality). Formation of algal blooms of Protoperidinium sp. (3.3×105ind L−1) and Odentella sp. (2.8×105ind L−1) was observed in the SS during PoM as a result of reduced water exchange in the lagoon. During the same period, toxin-producing strains like Anabaena sp. and Nostoc sp. of Cyanophyceae were also recorded. Correlating the three sectors of the lake (NS, CS, and SS), it is observed that the physical, chemical, and biological properties of the lake varied continuously depending on the season and freshwater availability. Seasonal nutrient stoichiometry played a significant role in regulating the community structure and distribution pattern of phytoplankton communities of the lagoon. [ABSTRACT FROM AUTHOR]

This study aimed to characterize their Spatio-temporal distribution of hydrological variables and plankton during neap tides in Bahía Magdalena, a subtropical lagoon south of the California Current. We compare data from surface and bottom waters of stations located inside the lagoon with those near the bay's mouth and between surface and bottom. The availability of nutrients and the chlorophyll-a are associated primarily with the intense upwelling activity in spring. Due to direct marine influence, this relationship was more significant at the inlet than inside the lagoon, especially at the bottom. During the intense upwellings marine influence is maintained even during neap tides. The wind probably causes the homogeneous distribution in most variables within the bay's surface; this may also contribute to the re-suspension of nutrients due to vertical water column mixing. Abiotic variables were not linearly related with zooplankton biovolume and the density of diatoms and dinoflagellates. Phytoplankton was composed mainly by the micro fraction and diatoms during spring and nanoplankton in the warmest season of the year; however, the strong upwellings at the spring's end caused a HAB composed for diatoms. Chlorophyll-a concentration and diatoms were more abundant inside the lagoon and could explain the lower nutrient concentration of that zone. Zooplankton biovolume seasonality differed from other years, with higher values during winter and a significant decreasing trend throughout the year, resulting from the phytoplankton variability. Upwelling and wind variability explains the high biological productivity observed over most of the year. [ABSTRACT FROM AUTHOR]

In this work, the experiments related to seasonal variations of phytoplankton composition and heavy metal contamination along with some water quality parameters were carried out throughout the channel, serving as a waterway between Lake Küçükçekmece and the Sea of Marmara. Considered as a Class B wetland, the lake has been stayed within the metropolitan area of Istanbul overtime. The samples from the surface water were taken monthly by using Nansen bottles at 5 sampling sites through the period of March-November. After experimental procedures, a total of 46 taxa were recorded belonging to Bacillariophyta (20), Charophyta (4), Chlorophyta (6), Cryptophyta (1), Cyanobacteria (4), Euglenozoa (3), and Miozoa (8) divisions. The phytoplankton densities were found to be varied from 76 individual cm-3 to 3,283 individual cm-3 throughout the channel and the variation for chlorophyll-a contents was between 0.99-55.32 mg m-3. From our results, the heavy metal and nutrient concentrations were found to be as: 0.78-1.55 mg L-1 for Al, 4.28-13.88 mg L-1 for B, 1,201-1,693 mg L-1 for Ca, 45.20-120.40 µg L-1 for Cd, 432.40-1,398.40 µg L-1 for Cr, 232.00-1,043.00 µg L-1 for Cu, 663.40-2,315.60 µg L-1 for Fe, 626.20-1,435.20 mg L-1 for K, 738.00-1,113.00 mg L-1 for Mg, 1,882-6,084 mg L-1 for Na, 30.00-317.80 µg L-1 for Ni, 17.40-158.00 µg L-1 for Pb, and 440.20-1,186.20 µg L-1 for Zn. According to the data obtained in this study, the area where research conducted was determined as having eutrophic characteristics. [ABSTRACT FROM AUTHOR]

Microphytoplankton and environmental parameters were monitored and analyzed bimonthly (twice a month) over an annual cycle (June 2011 to May 2012) at six stations in Oualidia lagoon. The present study is conducted to assess the relationship between physicochemical parameters and microphytoplankton assemblages, which can serve as a method to assess the quality of paralic ecosystem. The assessment results revealed a seasonal variation of nutrients concentrations. Spatial variation of temperature, salinity and concentration of dissolved oxygen was noticed. Two microphytoplankton classes were dominant: Bacillariophyceae and Dinophyceae. The phytoplankton diversity and abundance were characterized by a pronounced seasonal pattern. Canonical correspondence analysis between environmental variables and dominant taxa of phytoplankton indicated the tidal influence on microphytoplankton distribution in Oualidia lagoon. Concentrations of nitrite, salinity, pH and temperature showed a positive correlation with dinoflagellates and diatoms indicating their importance in microphytoplankton growth and sustenance. Concentrations of orthophosphates developed negative correlation with microphytoplankton. Finally, fifteen taxa were identified that may present a risk of inducing harmful blooms (Pseudo-nitzschiasp., Dinophysisacuminata, D. acuta, D. caudata, D. fortii. D. sacculus, Phalacromarotundatum, Gonyaulaxpolygramma, Lingulodiniumpolyedra, Ostreopsissp., Pelagodiniumsp., Gyrodiniumspirale, Heterocapsasp., Prorocentrumcordatum and P. micans). [ABSTRACT FROM AUTHOR]

A microscopic study of microplankton in two coastal lagoons in the Florida Keys coincidently, and unexpectedly, revealed the widespread presence of high concentrations of polystyrene microplastic particles. The polystyrene particles were first observed in the second year of a 2-year study of phytoplankton communities, with peak densities in the spring/summer of 2019 at all ten sampling sites in the two lagoons. Polystyrene particle densities reached levels up to 76,000 L−1. The particles ranged in size from 33 to 190 µm, similar to the size range of microplanktonic algae (20–200 µm). Over the period of peak polystyrene densities, average particle densities were similar to average densities of microplanktonic algae cells. The latter observation highlights the potential significance of the microplastic particles for the ecology of the pristine waters of the Florida Keys, if they persist. [ABSTRACT FROM AUTHOR]

Atanasovsko Lake is a coastal lagoon used for salt extraction for many years. Its salinity varies within a wide range (from 6.3 to > 72‰). Despite these extreme conditions, phytoplankton blooms are often observed. Therefore, our aim was to study the key abiotic drivers and ecological optimum of the picoplankton in a 5-year period (2013-2017). The taxonomic composition, long-term dynamics and abiotic drivers of the autotrophic picoplankton (APP) has been investigated in North Saltern of the coastal lagoon in Atanasovsko Lake. The APP species were identified by using a polyphasic approach based on molecular and phylogenetic analyses of 16S/18S rDNA in combination with cytomorphological and ecological characterization. Picochlorum oklahomense (Trebouxiophyceae, Chlorophyta) and marine Synechococcus sp. (Synechococcales, Cyanobacteria) were the dominant genotypes within the APP. The relative biovolume of the APP to the total phytoplankton biovolume was strongly variable (from 36 to 99%) as the salinity and temperature were found to be the main abiotic drivers of its dynamics. Salinity between 30-59‰ and mid-summer temperature above 24°С provide an ecological optimum for the APP development at a relative biovolume of 93%. This is the first record of Picochlorum оklahomense/Synechococcus sp. assemblage within the APP composition of a European coastal lagoon. [ABSTRACT FROM AUTHOR]

Agriculture within the Great Barrier Reef catchment area has contributed to pesticide contamination of adjacent freshwater ecosystems that flow into the Great Barrier Reef World Heritage Area. A novel multispecies toxicity test was used to assess the toxicity of diuron and hexazinone, 2 herbicides commonly detected within the Great Barrier Reef catchment area, to a community of 3 tropical freshwater microalgae: Monoraphidium arcuatum, Nannochloropsis‐like sp., and Pediastrum duplex. Diuron was the most toxic herbicide, with 10% inhibition concentration (IC10) values of 4.3, 7.1, and 29 µg/L for P. duplex, M. arcuatum, and Nannochloropsis‐like sp., respectively, followed by hexazinone, with IC10 values of 15, 18, and 450 µg/L, respectively Toxicity testing on 2 commercial formulations (Barrage, 13.2% hexazinone and 48.6% diuron; Diurex, 90% diuron) showed that additives in the commercial formulations did not significantly increase the toxicity of diuron. Direct toxicity assessments were carried out on water samples from the herbicide‐contaminated Sandy Creek, which discharges to the Great Barrier Reef lagoon, and a clean reference site, Tully Gorge in the Tully River. Toxicity was observed in several Sandy Creek samples. Artificial herbicide mixtures were assessed in synthetic soft water and natural freshwaters, with toxic responses being observed at environmentally relevant concentrations. The present study successfully applied a novel multispecies tropical microalgal toxicity test, indicating that it is an effective tool for the assessment of herbicide toxicity in both natural and synthetic freshwaters. Environ Toxicol Chem 2021;40:473–486. © 2020 SETAC [ABSTRACT FROM AUTHOR]

Two sediment cores were collected from two sites in Nagatsura-Ura Lagoon, the mouth of which was destroyed in the 2011 Tohoku-oki tsunami. Although sediment conditions differed widely between the central and inner parts of the lagoon, we could identify traces of the 2011 Tohoku-oki tsunami at both, and those of earlier tsunamis in the inner part of the lagoon. Chlorophyll a maxima were observed at core depths between 62 and 72 cm in the central part of the lagoon. We inferred that this horizon correlated with the 2011 Tohoku-oki tsunami deposit. In the inner part of the lagoon, the horizon at core depths of 116—142 cm could be aged to the 1400s, and is thus thought to have been formed as a consequence of the Kyotoku earthquake of 1454. The dinoflagellate Alexandrium spp. accounted for ~ 22.6% of the total read numbers of phytoplankton from next generation sequencing. Diatoms made up the second largest group of phytoplankton, with Chaetoceros spp. representing ~ 10.5% of the total. The vertical profiles of dinoflagellate and diatom compositions showed little change. Although traces of tsunamis were observed in cores from the lagoon, and in nearby closed bays, we believe that the microbial composition has changed only slightly in the lagoon due to poor seawater exchange through the closed lagoon mouth. [ABSTRACT FROM AUTHOR]

Integrated multi-trophic aquaculture (IMTA) is a way to help preserve the environment while maintaining a good level of total production. An ecologically semi-intensive pond system was designed in which a polyculture fishpond was associated with a lagoon planted with macrophytes to bioremediate the water. The properties of this "semi-intensive coupled" system (SIC) were compared to those of semi-intensive (SI) and extensive (E) systems, each of which was contained in a single fishpond with the same fish polyculture (common carp (Cyprinus carpio), roach (Rutilus rutilus), and perch (Perca fluviatilis)) as SIC. E differed in that it had half the initial density of fish, and the fish were not fed. Fish growth performances, water quality (chemical and biological indicators), chlorophyll concentrations, and invertebrate production were measured. The systems were compared based on fish production performances and physicochemical and biological characteristics, and were then described using principal component analysis (PCA). Carp and roach in the two fed systems had higher growth performances than those in E. Compared to SI, the planted lagoon in SIC, induced a decrease of 15% in fish growth performances and of 83% in total chlorophyll concentration (a proxy for phytoplankton) but improved water quality (−34%, −60% and −80%, for the concentrations of total nitrogen, total phosphorus, and blue green algae (for micro-algae in class Cyanophyceae), respectively). According to the PCA, SIC clearly differed from SI in benthic macro-invertebrate production and concentrations of total nitrogen, total phosphorus, and brown algae (for micro-algae in class Dinophyceae or a branch of Bacillariophyta) in the water. SIC differed from E in oxygen parameters (dissolved and saturation), estimated annual zooplankton production, and pH. In conclusion, the properties of a lagoon reveal perspectives for environmentally friendly practices, while using biodiversity and secondary production in order to enhance fish production. [ABSTRACT FROM AUTHOR]

The physico-chemical parameters, plankton and macro-benthic invertebrates of the Lagos Lagoon (Badore, Ajah), Lagos State, Nigeria were studied between February and July 2018 at four sampling stations in a disparate range of human activities and impact. The result of phytoplankton analysis indicated a total of 56 genera with 40 genera within Bacillariophyta, accounting for 72% of the abundance. Zooplankton comprised 26 genera with 82% of the abundance of crustacea. The benthic macroinvertebrates were composed of mollusca, arthropoda and annelida. Results also indicated that the main drivers affecting the abundance and distribution of planktonic and benthic invertebrates were water temperature, pH, TDS and EC. The monthly variations of physicochemical parameters in the Lagoon could be the result of human activities associated with transportation, fishing and domestic sewage disposal from the surrounding settlements. Therefore, it is necessary that relevant authorities keep in check some of these activities around the Lagoon as well as educate the population on the necessity for the conservation of these water resources. [ABSTRACT FROM AUTHOR]

Research on the impact of heavy metals and their accumulation in ecosystem elements of Lake Burullus is still scarce. Therefore, this study focuses on the relationship between the levels of heavy metals in the lake water, plankton communities and Nile tilapia (Oreochromis niloticus). The mean annual concentrations of Fe, Zn, Cu, Mn, Pb and Cd in water and fish samples were 527.8, 366.7, 162.6, 137.3, 119.8 and 3.6 μg l−1, and 70.8, 43.6, 8.05, 1.2, 0.14 and 0.045 μg g−1 dry weight (d.w.), respectively. The study demonstrated the relationship between the accumulation of metals in fish muscles and their levels in the lake water (p < 0.05; r = 0.7–0.9), with the metal content in O. niloticus muscles being mostly below the permissible limits. The obtained results showed that the levels of the metals in the lake water are not correlated with phytoplankton and zooplankton, and their groups, except copper and zinc, are negatively correlated with phytoplankton (r = −0.45 and −0.58, respectively). The study concluded that the concentrations of the analyzed metals in Lake Burullus did not reach the effective levels that would have a significant impact on the distribution of phytoplankton and zooplankton, or a hazardous effect on O. niloticus and its safety for human consumption. [ABSTRACT FROM AUTHOR]

The impact of environmental variables and processes of nutrient enrichment on phytoplankton community at Epe lagoon was studied for 18 months (November 2012–April 2014). Two cyanobacterial bloom incidences were observed in the two dry seasons during this period. Rainfall pattern regulated nitrogen limitation which triggered cyanobacterial bloom development and influenced the bloom duration. Nutrient-laden influx from agricultural practices accounted for the increase in nitrate, phosphate and the relatively low silicate. Hypoxic conditions during the two bloom episodes reflected the vulnerability of this lagoon ecosystem. The cyanobacterial blooms were dominated by potentially toxic species; Anabaena circinalis, A. flos-aquae, A. limnetica and A. spiroides. A comparison of ambient nutrient ratios with the Redfield ratio (N/P/Si = 16:1:16) showed clear temporal variations that coincided with phytoplankton dynamics and the bloom regime. Low N/P ratios were recorded during the first 8 months, and there was a shift to higher ratios during the subsequent 8 months, followed by low N/P ratios in the last 2 months. Higher silicate values coincided with decreased cyanobacterial biomass, cyanobacteria bloom collapse and proliferation of diatoms during the first annual cycle. Cyanobacterial abundance exceeded the alert level 1 and almost reached alert level 2 which call for continuous environmental monitoring and management of coastal waters. [ABSTRACT FROM AUTHOR]

Concentrations of phaeopigments (Pha) and chlorophyll a (Chl) were determined in surface waters from a temperate lagoon during six sampling campaigns at high and at low tide. In order to develop models for phaeopigment concentration in water, it was necessary to replace Chl with photosynthetic pigment concentration (Pt = Pha+Chl) as one of the explanatory variables. Under first approximation, food availability and water temperature (T) could be considered as independent variables. The concentrations of Pha were then determined following seasonal change of response curves of the consumer community on T. However, multiple regression models with Pt, T and, eventually, salinity as explanatory variables were better able to depict Pha. All equations, developed with Pt, were also solved using Chl as an input variable. Although part of the performance was lost, such back‐transformed models can be used at low/medium T and moderate to high concentrations of Chl. The developed equations about middle to long‐term variations of Pha could be applied to study the biogeochemistry of contaminants related to Pha and to evaluate the dependence on temperature of phytoplankton utilization by consumers. Practitioner points: Phaeopigment concentration depicted by chlorophyll (Chl), temperature (T), and salinity.Better results obtained at low to medium T and moderate to high Chl concentration.Multiple regression (MR) better for extrapolation than model (S) with variable separation.Thermal response of consumer community in mesotrophic lagoon studied using model S. [ABSTRACT FROM AUTHOR]

The city of Cartagena, Colombia, was founded in 1533, making it the fifth oldest, continuously inhabitated colonial city in South America. Today, Cartagena is the fifth largest city in Colombia, with ~ 1.2 million inhabitants. Las Quintas Lagoon lies near the center of Cartagena and is connected hydrologically to the Bay of Cartagena and Las Virgenes Lagoon via channels. The sediments of Las Quintas Lagoon thus offer a unique opportunity to explore the environmental history of one of the oldest cities in South America. We analysed a 210Pb- and 14C-dated sediment core from Las Quintas Lagoon to investigate the environmental effects of long-term urban development in this tropical, estuarine setting. The sediment core from Las Quintas Lagoon displays evidence of change in the depositional environment during the last few centuries. Principal Component Analysis indicated relatively stable conditions in Las Quintas Lagoon from the begining of the record (about 1300 CE) until ca. 1900 CE, when the ongoing eutrophication began. PC1 shows statistical significance and was dominated by geochemical indicators, whereas PC2 correlated with pollen spectra. Upcore decreases in TOC/TN values, together with increases in TOC, TN and δ15N values, indicate greater autochthonous (i.e. phytoplankton) production and eutrophication. Lack of statistical significance of PC2 points to low variability among pollen spectra, and hence vegetation, through time. Diatom assemblages in the Las Quintas Lagoon sediment record display two shifts during the last 100 years, ca. 1940 and 2000, which also reflect progressive eutrophication of the system. [ABSTRACT FROM AUTHOR]

Variations in phytoplankton species abundance and composition are regulated by changes in physico-chemical factors. A study of biodiversity and successional sequences was carried out monthly from November 2012 to April 2014 to determine the environmental factors controlling phytoplankton assemblages in Epe Lagoon, Lagos, Nigeria. Surface water and phytoplankton samples were collected from 12 stations within the lagoon. Physico-chemical analyses and phytoplankton biodiversity were carried out using American Public Health Association (APHA) protocols and light microscopy, respectively. A canonical correspondence analysis and the Pearson correlation coefficient (r) were used to determine the relationship between physico-chemical parameters and different phytoplankton divisions identified within the lagoon. Five phytoplankton divisions (Bacillariophyta, Chlorophyta, Cyanobacteria, Euglenophyta and Pyrrophyta) were represented within the lagoon. Higher phytoplankton biomass was recorded in the dry season (November to April) than in the wet season (May to October). Centric diatoms (Aulacoseira granulata var. angustissima O. Mull and Melosira granulata (Ehr.) Ralfs) dominated the phytoplankton spectrum throughout the study period, except in June and July 2013, when Mougeotia sp. was dominant. Rainfall distribution patterns primarily determined the physico-chemical environment, whereas salinity, calcium ions, hydrocarbons (oil and grease), conductivity, total dissolved solids (TDS), turbidity and silicate were the major factors controlling phytoplankton dynamics during the study period. [ABSTRACT FROM AUTHOR]

Abstract Stable isotopic compositions (δ13C and δ15N) and C/N ratios of suspended particulate organic matter (POM) and surface sediment organic matter (SOM) in the Asia's largest lagoon (Chilika, India) were analyzed to identify spatial and seasonal variabilities in sources of organic matter. The variability of POM composition (δ13C: −23.5‰ to −27.9‰, δ15N: 2.1‰ to 7.5‰, C/N: 9.5 ± 0.9) collected during monsoon, a period of highest river discharge, suggests dominant input of terrestrial organic matter, whereas wintertime POM (δ13C: −22.3‰ to −27.7‰, δ15N: −0.2‰ to 4.8‰, C/N: 9.1 ± 1.0) exhibits a mixed source of agricultural runoff, and lagoon phytoplankton and cyanobacteria. The composition of POM collected during summer/dry season (δ13C: −21.2‰ to −26.2‰, δ15N: 2.0‰ to 6.0‰, C/N: 8.9 ± 1.1) indicates enhanced lagoon phytoplankton and bacterial productivity. Spatial variability of POM isotopic composition clearly shows more contribution of terrestrial sources in the northern sector- influenced by perennial Mahanadi River distributaries- compared to the central and southern sectors. The isotopic compositions (δ13C: −20.9‰ to −22.9‰, δ15N: 1.9‰ to 6.6‰) and C/N ratios (10.1 ± 1.3) of SOM indicate major contribution from terrestrial and macrophyte sources and minor contribution from phytoplankton and/or cyanobacteria. The northern sector is also heavily influenced by urban/industrial wastewater input, whereas the outer channel with higher salinity remains dominated by marine organic matter. Western part of the central sector is significantly influenced by untreated domestic sewage discharged from nearby townships and villages, which endangers the lagoon ecosystem. Highlights • First detailed spatio-seasonal variability of organic matter sources in Chilika lagoon is presented. • Monsoon season particulate organic matter (POM) is mainly of terrestrial origin. • Mixed sources (terrestrial and phytoplankton) contribute to winter and summer POM. • Sediment organic matter is dominated by terrestrial and macrophyte sources. • Western part of central sector and northern sector have anthropogenic input. [ABSTRACT FROM AUTHOR]

Diversity and productivity of primary producers are known to be influenced simultaneously by resource availability and resource ratio, but the relative importance of these two factors differed among studies and so far only entire phytoplankton communities were investigated which might ignore specific nutrient requirements and stoichiometric plasticity of different functional groups. We measured nutrient availability (DIN, total N [TN], total P [TP]), nutrient imbalance (TN:TP, DIN:TP, N:Pseston), species richness, and abundance of the whole phytoplankton community, as well as those specific for cyanobacteria, diatoms, and dinoflagellates in Cau Hai lagoon in Vietnam. We determined the correlation among these variables, using structural equation modeling. The models applied to the whole phytoplankton community indicated that the nutrient availability (particularly TP and DIN) drove variation in phytoplankton abundance and richness, and that abundance also depended on species richness. The models applied to different functional groups differed considerably from the entire community and among each other, and only a part of the models was significant. The relationship between nutrient availability (mainly TP) and abundance was driven by cyanobacteria, and the relationship between nutrient imbalance (only with N:Pseston) and species richness was driven by diatoms. Remarkably, the positive relationship between species richness and abundance, as consistently observed for the whole phytoplankton community, was only observed for one of the three functional groups (diatoms), indicating that resource complementarity occurs particularly among species of different functional groups. Our results emphasized that nutrient availability (TP and to a lesser extent DIN) as well as nutrient imbalance (albeit only with N:Pseston as proxy) were driving factors for the phytoplankton community in the Cau Hai lagoon and hence alterations in both of these factors leading to a shift in phytoplankton species composition and productivity. [ABSTRACT FROM AUTHOR]

Abstract Short-term bioassays were conducted in Biguglia lagoon (Corsica) to study the physiological and behavioral responses of phytoplankton to N- and P-availability. Natural communities were collected in two stations representative of the two sub-basins, at three periods with contrasting environmental characteristics to address the impact of seasonal variability. These samples were separately enriched with a full N and P enrichment, and with enrichments minus N or minus P. Phytoplankton size structuration, diversity, and growth of the total phytoplankton, the micro-, nano- and ultraphytoplankton were evaluated using spectrofluorimetry, and optical microscopy. Results showed that the communities were fueled by NO 3 − in the wet periods (autumn and spring) and NH 4 + in summer. The phytoplankton communities displayed highest cell size in autumn, with high abundances of nanoflagellates, and smallest cell size in summer with a large dominance of phycocyanin-rich picocyanobacteria. Blooms of dinoflagellates also occurred during the wet periods, coinciding with high N:P ratios. The full enrichment has not stimulated phytoplankton growth in autumn, suggesting the importance of other controlling factors such as light, a possible NH 4 + inhibition or the use of mixotrophic abilities. In spring, communities have displayed single P-limitation in the northern basin and different N and P co-limitations in the southern basin. In summer, the full enrichment consistently stimulated the growth of all cell sizes. The communities showed high N and P co-limitations, which is consistent with growing observations in aquatic ecosystems, and reflects the different functional responses of phytoplankton communities to the nutrient availability. Graphical abstract Chlosrophyll a (Chl a) concentration, DIN:DIP ratio, main taxa/morphotypes, response to the full nutrient enrichment, and N- and/or P-limitation during the three bioassay periods in the two stations representatives of the Northern and the Southern basins of Biguglia lagoon. Image 1 Highlights • Freshwater inputs from the watershed strongly influenced the phytoplankton of Biguglia lagoon. • Nanoflagellates dominated phytoplankton communities in autumn and spring with high N:P ratios. • Phycocyanin-rich picocyanobacteria bloomed in the sampling in September with low N:P ratios. • Phytoplankton showed differential responses to nutrient enrichments and induced limitations. • Phytoplankton was generally co-limited by N and P, with exceptions depending on seasons. [ABSTRACT FROM AUTHOR]

Albufera of Valencia shallow lagoon experiences water clarification about once a year. This study aimed to observe the timing of water clarity events and to detect the associated flow during these periods. Spatial variation in chlorophyll a along the Albufera was observed using remote sensing images. Due to the lagoon's spatial complexity and the varying water qualities flowing in from more than 60 tributaries, remote sensing was the only approach that could obtain images simultaneously covering the entire lagoon. The data were used to explore the evolution, duration and intensity of the clear-water phase, and the lagoon's subsequent re-eutrophication. The duration and intensity of the clear-water phase varied across the lagoon, but complete water quality renovation occurred in 1 week. Our analysis demonstrates that rapid flushing could remediate the lagoon eutrophication. [ABSTRACT FROM AUTHOR]

Abstract Foz do Almargem and Salgados are two small, intermittently closed and open lakes and lagoons (ICOLLs) located in the Portuguese southern coast, both remaining isolated from the sea throughout great part of the year. Based on environmental and biotic parameters, the first lagoon was classified as mesotrophic, with a greater marine influence, while the second one was classified as hypereutrophic. The plankton relations and seasonal variation were examined in both lagoons aiming at understanding the biological patterns here present and relating them with the environmental conditions, as well as inferring possible top-down or bottom-up control in the communities, determining also in which alternative trophic state they are: a clean water lagoon, with submerged macrophyte vegetation; or a turbid water lagoon, with only phytoplankton as primary producer. The plankton community greatly differs in the two lagoons. Salgados lagoon presented extremely high concentrations of phytoplankton, which form blooms throughout the year, mostly composed by potential harmful organisms. This lagoon also had very high densities of zooplankton. Phytoplankton and zooplankton density was always lower in Foz do Almargem. Rotifera, Ostracoda and Cladocera dominated the Zooplankton community in Salgados. In Foz do Almargem, Rotifera also dominates, together with other groups, such as annelids, crustaceans and mollusks larvae, which denotes a stronger marine influence. In both lagoons, organisms with body size inferior to 100 μm mainly composed the zooplankton. In Salgados lagoon, excess nutrient load induced a high density of phytoplankton, which is utilized by a high density of zooplankton, following a bottom-up control model. The lagoon clearly showed a permanent turbid-water alternative state due to excess nutrients. On Foz do Almargem, the frequent openings of the inlet throughout the wet season caused strong physical disturbance, which prevented the development of a stable planktonic community. Highlights • Foz do Almargem and Salgados are two ICOLLs that remain isolated from the sea part of the year. • The first lagoon is mesotrophic, while the other is hypereutrophic. • Salgados is in a permanent turbid state, with characteristics of bottom-up control. • In Almargem, the frequent openings of the inlet cause strong physical disturbance. • These disturbances prevent the development of a stable planktonic community. [ABSTRACT FROM AUTHOR]

Copyright of Revista Biociências is the property of Revista Biociencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)