Spatio-temporal composition of aquatic birds communityin Juluapan Lagoon, Colima, Mexican Central Pacific / Composición espacio-temporal de las aves acuáticas en la laguna Juluapan, Colima, en el Pacífico Central Mexicano

Abstract Introduction: Aquatic birds (AB) are usually associated with wetlands, which provide refuge, food, and/or nesting sites for resident and migratory species. Despite their ecological importance, there is little knowledge on AB in some tropical environments, such as those found on the Colima coast. Objective: To investigate the spatial and temporal composition of the AB community in Juluapan Lagoon, Colima, Central Mexican Pacific. Methods: Monthly counts were conducted between June 2017 and May 2018 during low-tide conditions to record habitat use by AB. Species richness and bird counts were obtained to compare sampling areas; mean richness and number of individuals were compared between seasons. Results: We detected 53 species and 5 750 individuals. The highest species richness and relative abundance values were obtained in winter at the lagoon area farthest from the connection with the marine system, where anthropogenic activity is lower. Diversity was greater in zones 2 and 3 in spring, summer, and fall. Muddy flats were the most used environment, and the most frequent activity was resting. Nesting activity was only recorded in the middle of the lagoon at the mangrove during spring. "Shorebirds" and "waders" were the most dominant groups in the bird community of the Juluapan lagoon. Conclusions: This coastal wetland is a site of great biological importance for aquatic birds; thus, conservation measures should be implemented, and there should be a continuous study of the effects of anthropogenic pressure.

Resumen Introducción: Las aves acuáticas (AA) son usualmente relacionadas a los humedales debido a que éstos funcionan como sitios de refugio, alimentación y anidación de diferentes especies residentes y migratorias. Sin embargo, el conocimiento sobre las aves acuáticas en algunos humedales es nulo. Objetivo: Investigar la composición espacio-temporal de la comunidad de AA en la laguna Juluapan, Colima, en el Pacífico Central Mexicano. Métodos: Entre junio de 2017 y mayo de 2018 se llevaron a cabo conteos mensuales en condiciones de marea baja para registrar el uso de hábitat de las AA. Se obtuvieron valores de riqueza de especies y número de individuos para realizar comparaciones entre zonas de muestreo, así como el promedio del número de especies y número de individuos para comparaciones entre temporadas. Resultados: Se registraron un total de 53 especies y 5 750 individuos. Los valores de riqueza de especies y densidad de individuos fueron más altos durante invierno, en la zona más alejada al ambiente marino, donde la actividad antropogénica es menor. La diversidad tuvo valores más altos en la zona 2 y 3, durante primavera, verano y otoño. El ambiente más explotado por las aves fueron las planicies lodosas; y el descanso fue la actividad más frecuente. Asimismo, la actividad de anidación sólo se registró en el manglar de la zona media durante primavera. Las "aves playeras" y "aves zancudas" fueron los grupos más predominantes en la comunidad de aves de la laguna Juluapan. Conclusiones: Este humedal costero es un sitio de gran importancia biológica para aves acuáticas, por lo que resulta necesario la implementación de medidas de conservación, así como el estudio de los efectos por la presión antropogénica.

Environmental assessment of toxic heavy metals in bottom sediments of the Sharm Obhur, Jeddah, Saudi Arabia.

The concentrations, spatial distributions, pollution level, and health risks of heavy metals in sediments of the Sharm Obhur, Northern Jeddah, Saudi Arabia were evaluated. Average concentrations were found to be: Cr > Zn > Ni > Cu > As>Pb with the highest concentrations found near the head of the sharm, and decreasing towards the mouth. Environmental indices, together with the statistical analyses, showed that the sharm experiences a low to moderate degree of pollution. Sampling sites with heavy metal contamination are concentrated near the head and the southern coast of the sharm, where intensive human activities associated with a boat dock, construction, and recreation are common. The mean carcinogenic risk (CR) values of As, Cr and Ni are at permissible level suggesting unlikely adverse impacts of heavy metals on human health. Despite acceptable CR values; however, serious non-carcinogenic and carcinogenic health threats from metals may yet be an issue particularly for sensitive populations such as children.

Genome sequences of Vibrio diabolicus and Algoriphagus sp. isolated from the San Elijo coastal lagoons in San Diego.

We report two draft genome sequences related to the genera Vibrio and Algoriphagus, isolated from water samples at the San Elijo Lagoon Ecological Reserve, which is one of the largest remaining coastal wetlands in San Diego, California. The initial whole genome-based comparison illustrates the uniqueness of these species.

Ecotoxicological and health risks associated with sediment-bound polycyclic aromatic hydrocarbons in peri-urban closed and open coastal lagoons.

Coastal urbanisation has ramifications for the sustainable development of developing nations. There are often unquantified ecological and health risks associated with urbanisation. Sixteen polycyclic aromatic hydrocarbons (PAHs) were analysed in surface sediment from three peri-urban coastal lagoons in southern Ghana. We found significant spatial variations of sediment PAHs. These variations were attributed to physiography of the lagoons and diverse anthropogenic activities surrounding them. Total PAHs ranged from 20.81 to 24,801.38 µg/kg (dry weight), underscoring a low to very high pollution level. Diagnostic ratios revealed both pyrogenic and petrogenic origins. Over 50 % of individual PAHs were of moderate ecological risk to benthic organisms, and cancer risk to humans was above the World Health Organisation's recommended safety limit (1 × 10-6). These ecological and health risks should be wake-up call for a more integrated urban planning approach to coastal urbanisation as coastal communities largely depend on natural ecosystems for food and livelihood opportunities.

Ciliate diversity in rodrigo de freitas lagoon (Rio de Janeiro, Brazil) from an integrative standpoint.

The Rodrigo de Freitas Lagoon is a highly eutrophic lacustrine system and has one of the longest histories of exploration and anthropic alteration in Brazil. Despite its relevance, limited studies explored the diversity of micro-eukaryotes in the lagoon. Ciliates (Alveolata, Ciliophora) are overlooked in environmental microbiology, especially in tropical and subtropical ecosystems, resulting in limited knowledge about their diversity and functional relevance in South American habitats, particularly in coastal lagoons. To fill this gap, here we investigated the diversity of ciliates in a brackish coastal lagoon in an urban area of Rio de Janeiro, Brazil, applying and comparing the performance of morphological and metabarcoding approaches. The metabarcoding analysis, based on high-throughput sequencing of the hipervariable region V4 of the 18S rRNA genes detected 37 molecular operational taxonomic units (MOTUs) assigned to Ciliophora, representing only about a half (56.9%) of the diversity detected by microscopy, which counted 65 ciliate morphotypes. The most representative classes in both approaches were Spirotrichea and Oligohymenophorea. The metabarcoding analysis revealed that 35.3% of the ciliate MOTUs had less than 97% similarity to available sequences in the NCBI database, indicating that more than one-third of these MOTUs potentially represents still not represented or undescribed ciliate species in current databases. Our findings indicate that metabarcoding techniques can significantly enhance the comprehension of ciliate diversity in tropical environments, but the scarcity of reference sequences of brackish ciliates in molecular databases represents a challenge to the taxonomic assignment of the MOTUs. This study provides new insights into the diversity of ciliates in a threatened coastal lagoon, revealing a vast array of still unknown and rare ciliate taxonomic units in tropical environments.

Trace metal level variation under strong wind conditions and sediment resuspension in the waters of a coastal lagoon highly impacted by mining activities.

The levels of metals in the waters of the Mar Menor lagoon are higher in the southern than in the northern zone both in the dissolved (As: 1.78 µg L-1 north vs 1.86 µg L-1 south; Cd: 0.020 µg L-1 vs 0.055 µg L-1; Pb: 0. 686 µg L-1 vs 2.714 µg L-1; Zn: 3.06 µg L-1 vs 10.2 µg L-1) as in the particulate fraction (As: 13.6 µg g-1 north vs 27.3 µg g-1 south; Cd: 0.510 µg g-1 vs 2.11 µg g-1; Pb: 146 µg g-1 vs 575 µg g-1; Zn: 266 µg g-1 vs 729 µg g-1). This difference is associated to the influence of historical and recent inputs from the Sierra Minera Cartagena -La Unión located south of the lagoon. Strong winds cause sediment resuspension in this shallow lagoon, increasing metal levels in the dissolved (twofold) and especially in the particulate fraction (threefold) because the resuspended sediments are rich in metals. Distribution among dissolved and particulate fraction is determined by the chemistry of each element and salinity. This increase causes the levels to reach limits very close to those established by the Water Framework Directive, especially in the case of lead, whose annual average level of 1.23 µg L-1 is very close to the 1.3 µg L-1 established in the Directive. Therefore, slight change in environmental variables could make Pb levels to exceed legal limits. Future work should focus on investigating how unique environmental events, enhanced by global change, affect metal cycles in highly anthropised coastal areas.

Do feeding responses of a non-native bivalve outperform the native one in a coastal lagoon? A possible explanation for the invasion success of the dark false mussel Mytilopsis leucophaeata.

The present study aimed to evaluate and compare feeding responses of the non-native and native bivalves, the dark false mussel Mytilopsis leucophaeata and the scorched mussel Brachidontes darwinianus, respectively, by offering different concentrations of seston from the coastal lagoon where these species coexist after dark false mussel introduction (Rodrigo de Freitas Lagoon, Rio de Janeiro-Brazil). For this purpose, independent laboratory experiments were carried out under five concentrations of seston to test the differences in clearance and ingestion rates of bivalves as a function of increasing concentrations of suspended particulate matter (SPM) on seston. In addition, from the integrated analysis of data obtained in experiments, it can be inferred about the efficiency levels of these species to remove SPM from seston and their effects on water turbidity and nutrient concentrations (total carbon, nitrogen, and phosphorus). Our hypothesis was that the non-native bivalve is more efficient to clear and ingest SPM from seston compared to the native one, which may lead to competitive advantages to the successful invasion of M. leucophaeata in coastal lagoons. Native species did not show a significant difference in clearance and ingestion rates with increasing concentrations of seston. Whereas the non-native bivalve showed a slight tendency to increase its clearance and ingestion rates with the increase in seston concentrations, evidencing its plasticity to adjust its feeding responses. The native bivalve was significantly more efficient to clear and ingest SPM at the lower seston concentration (i.e., close to natural concentrations found in the lagoon) compared to the non-native bivalve, which, on the other hand, showed a significant increase in its ingestion rates at the higher concentration tested (140 mg SPM L-1). Thus, the present results did not suggest food competition between the non-native M. leucophaeata and the native B. darwinianus in the introduced system. However, M. leucophaeata increased its feeding response with experimental increment in seston concentration, which suggests species ability to benefit from conditions of increased inputs of organic matter and higher primary production that could mediate its establishment in introduced systems.

Linking centennial scale anthropogenic changes and sedimentary records as lessons for urban coastal management.

Coastal eutrophication and urban flooding are increasingly important components of global change. Although increased seawater renewal by barrier openings and channelizing are common mitigation measures in coastal lagoons worldwide, their effects on these ecosystems are not fully understood. Here, we evaluated the relationships between human interventions in the watershed, artificial connections to the sea, and the sediment burial rates in an urban coastal lagoon (Maricá lagoon, Southeastern Brazil). Sediment accretion along with nutrient and carbon burial rates were determined in two sediment cores representing the past ∼120 years (210Pb dating) and associated with anthropogenic changes as indicated by historical records and geoinformation analyses. Lagoon infilling and eutrophication, expressed by the average sediment accretion, TP, TN, and OC burial rates, respectively, increased ∼9-18, 13-15, 11-14 and 11-12-fold from the earliest (<1950) to the most recent (2000-2017) period. These multi-proxy records confirm mechanistic links between deforestation, urbanization, and untreated sewage discharges. In addition, our findings reveal artificial connections to the sea may contribute to lagoonal eutrophication and infilling, particularly when not integrated with sewage treatment and forest conservation or reforestation in the watershed. Therefore, increased seawater renewal by physical interventions commonly considered as mitigation measures may in contrast cause severe degradation in coastal lagoons, causing harmful consequences that should be not neglected when implementing management practices.

Long-term sediment records reveal over three thousand years of heavy metal inputs in the Mar Menor coastal lagoon (SE Spain).

The Mar Menor lagoon combined high biological production and environmental quality, making it an important economic engine. However, the pressure of human activities put its ecological integrity at risk, the oldest environmental impact being mining activity recorded since Roman times, about 3500 years ago, reaching its maximum intensity in the 20th century, contributing heavy metals to the lagoon sediments for almost 30 centuries. This work reviews the spatiotemporal evolution of the main heavy metals in this coastal lagoon using data from 272 surface sediment samples obtained during the last 40 years and two deep cores covering the total history of the lagoon (c. 6500 yrs BP), so as their incidence in the lagoon trophic web. The observed patterns in sedimentation, sediment characteristics and heavy metal content respond to the complex interaction, sometimes synergistic and sometimes opposing, between climatic conditions, biological production and human activities, with mining being mainly responsible for Pb, Zn and Cd inputs and port activities for Cu. High Fe/Al, Ti/Al and Zr/Al ratios identify periods of mining activity, while periods of arid climatic conditions and deforestation that increase erosion processes in the drainage basin and silt concentration in the lagoon sediments are determined by high Zr/Rb and, to a lesser extent, Zr/Al and Si/Al ratios. After the cessation of direct discharges into the lagoon in the 1950s, the recent evolution of heavy metals concentration and its spatial redistribution would be determined by hydrographic and biogeochemical processes, solubility of different elements, and coastal works in harbours and on beaches. The bioconcentration factor decreases along the trophic levels of the food web, suggesting that the lagoon ecosystem provides an important service by retaining heavy metals in the sediment, largely preventing their bioavailability, but actions involving resuspension or changes in sediment conditions would pose a risk to organisms.

Pluvial flood adaptation using nature-based solutions: An integrated biophysical-economic assessment.

Globally, flood events are considered the costliest natural hazard. Changes in precipitation patterns and large areas of impervious surfaces in urban environments are increasing the sensitivity of these systems to runoff production. At the same time, projected global sea-level rise may further increase the frequency of compound flooding due to simultaneous storm surge, sea-level rise and pluvial runoff that cause vast socio-economic and ecological impacts to coastal cities. In this context, over the last decade, the role of Nature-Based Solutions (NBS) has been recognised to support climate change adaptation by addressing ideas of multi-functionality, non-linearity and heterogeneity in urban design. Thus, increasing awareness about NBS benefits increases the willingness to accept these solutions. However, empirical evidence of NBS effectiveness at the urban catchment scale is still subject to debate. This study develops a spatial biophysical-economic framework that allows for the integrated assessment of NBS flood risk mitigation impacts, costs and benefits in the face of climate change, combining the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, benefit transfer methods and Geographic Information System (GIS) tools. Specifically, the InVEST Urban Flood Risk Mitigation model was used to assess the biophysical impacts of NBS on urban pluvial flood risk, benefit-transfer methods were used to evaluate the economic implications of such solutions, and GIS was used to integrate and map biophysical impacts and economic implications. For the case of the coastal lagoon city of Aveiro (Portugal), NBS scenarios of green roofs and bioswales under current and future climate conditions were assessed. The main findings of this study show that green roofs scenarios would save 32 % of the flood damages to buildings and infrastructures every year, while bioswales help save only 0.1 %. Moreover, green roofs implementation provides larger benefits in the future climate scenario (representative concentration pathway - RCP - 4.5). The findings confirm the extent to which knowledge on NBS benefits and costs is partial and uncertain, thus requiring constant progress through biophysical-economic assessment to support an evolutive decision making process in climate adaptation planning.

Eutrophication assessment and environmental management perspectives of Tóbari: an arid subtropical coastal lagoon of the Gulf of California.

Coastal lagoons are vulnerable to eutrophication processes. In this study, we evaluate the eutrophication process in the restricted, arid subtropical Tóbari coastal lagoon, located in the eastern coast of the Gulf of California, where the main source of nutrient inputs and other pollutants is agricultural wastewater from the Yaqui Valley. The Assessment of Estuarine Trophic Status (ASSETS) model and the Trophic State Index (TRIX) were used to evaluate eutrophication. Overall, ASSETS showed that the Tóbari lagoon has a moderate eutrophication process, with seasonal symptoms of hypoxia, increased phytoplankton biomass, dominance of macroalgae (indicative of nutrient enrichment), and blooms development of potentially harmful algae species. The TRIX showed that the lagoon is mesotrophic most of the year. Challenges of environmental management detected correspond to reducing the input of nutrients and others contaminants from anthropic sources: agriculture, shrimp farming, livestock, and urban zones.

One-year variation in quantity and properties of microplastics in mussels (Mytilus galloprovincialis) and cockles (Cerastoderma edule) from Aveiro lagoon.

As filter feeders, marine bivalves inhabiting estuarine and coastal areas are directly exposed to microplastics (MPs) in water. To assess whether MPs number, and their shape, size, colour, and polymer type present in mussels (Mytilus galloprovincialis) and cockles (Cerastoderma edule) varied over one year, bivalves were collected over the year of 2019 in the lower part of the coastal Aveiro lagoon, Portugal. After extraction from the bivalve's whole-body soft tissues, a subset of the visually inspected particles was randomly separated for identification using the Fourier-transform mid-infrared (FT-MIR) spectroscopy. A fraction of the inspected particles, 26-32% of particles >100 µm, and 59-100% of smaller ones were confirmed as MPs. Concentrations varied within the intervals of 0.77-4.3 items g-1 in mussels and 0.83-5.1 items g-1 in cockles, with the lowest values observed in January. In winter, the accumulation of large-sized fibers was composed of a mixture of plastic types, which contrasted against the most abundant MPs in summer consisting mainly of polyethylene of diverse size classes and shapes. Temperature decrease registered in winter might have triggered a lower filtration rate, resulting in lower MPs concentrations in the whole-soft body tissues of organisms. Different properties of MPs found in bivalves between January-February and August-September appear to reflect changes in the characteristics of MPs available in the Aveiro lagoon.

Characteristics and fluxes of plastic debris based on socio-economic data for Patos Lagoon-a choked coastal Lagoon in South Brazil.

Patos Lagoon, located in southern Brazil, is the world's largest choked coastal lagoon. Studies have revealed that plastic pollution affects lagoons; however, to date, they have only focused on a few limited regions of the lagoon. Top-down quantification methods based on socio-economic data from 2010 to 2017 were used to measure the amount of plastic reaching Patos Lagoon, thus broadening the perspective of plastic pollution in this area. According to the findings, Patos Lagoon's hydrographic regions produced an average of 4.54 Mton of plastic during the studied period. 1.86 Mton was consumed on average. High- and low-density polyethylene (HDPE and LDPE, respectively), polypropylene (PP), and polyvinyl chloride (PVC) were the main resins produced. Food-related activities were the largest consumer of plastic (17.98%), indicating a higher amount of single-use plastics being used in the basin. The preforms for plastic bottles, bags, and packaging were the most commonly manufactured plastic utensils. An estimated 8 to 14% of all plastics used to end up as mismanaged waste in the Patos Lagoon hydrographic basin. This resulted in 1.73 and 10.72 Kton, or 0.5 and 3.2 g/per person/per day, of plastic waste flowing into the waters of Patos Lagoon throughout the study period. These findings can help focus on management efforts by providing managers and policymakers with information for better plastic pollution mitigation in this environment.

The presence of COVID-19 face masks in the largest hypersaline lagoon of South America is predicted by urbanization level.

The inadequate disposal of face masks has caused a widespread presence of COVID-19 litter in the environment. We monitored 10 beach arcs along approximately 15 km of the largest hypersaline lagoon of South America looking for face masks during the lockdown (2021) and in the "new normal" (2022) period. Our working hypothesis is that the probability of finding face masks increases with higher urbanization levels, which was estimated by the Human Modification Metric. Approximately 3 × 10-3 face masks m-2 were found on nine of 10 beaches (90 %) during the lockdown. However, this reduced to 1 × 10-4 face masks m-2 found in eight beaches (80 %) after the lockdown. The probability of finding a face mask was significantly higher as urbanization increased (z = 2.799; p = 0.005). This situation imposes the need for a better waste management and environmental education actions, targeting the reduction of direct littering on coastal ecosystem.

Phthalates contamination in the coastal and marine sediments of Rio de Janeiro, Brazil.

Coastal and marine environments have been strongly influenced by anthropogenic activities, which may lead to high concentrations of different pollutants in sediments. Our study aimed to assess sediment contamination by polycyclic aromatic hydrocarbons (PAHs), phthalates (PAEs) and bisphenol A (BPA) in nine coastal and marine environments at Rio de Janeiro-Brazil. Physical and chemical water variables, grain-size parameters, moisture, and organic-matter content in sediments were assessed by sampling station. Multivariate analysis evidenced environmental differences between coastal lagoon and oceanic beaches, mostly influenced by marine waters. Differences among bay's beaches were mostly evidenced by sediment characteristics. PAHs and BPA were not detected in samples. For the first time, PAEs were found in sediments at Rio de Janeiro coast (South Atlantic). DEHP was detected in all coastal and marine environments, DBP was found in coastal lagoon and three marine environments. DnOP and DINP were solely found in the coastal lagoon.

Contamination assessment and spatial distribution of heavy metals in the Sefidrud Delta coastal lagoons, Caspian Sea, N Iran.

Three coastal lagoons on the Sefidrud Delta, Caspian Sea, were investigated to evaluate heavy metal pollution in sediments. Amirkola Lagoon is located in the eastern part of the delta (abandoned delta lobe) and is aged more than 500 years, whereas Kiashahr and Zibakenar lagoons are in the western or active part delta lobe and formed in the last decades. One hundred six sediment samples and three sediment cores were taken from studied lagoons. The samples were analyzed by ICP-OES. Geo-accumulation index (Igeo), contamination factor (CF), degree of contamination (Cdeg), pollution load index (PLI), and Potential ecological risk index (RI) were employed to determine heavy metal pollution for Co, Cr, Cu, Ni, Pb, V and Zn. Nonparametric statistical analysis (Two-step cluster analysis, analysis of variance, and T-test technique) was used to discriminate the pollution sources. Based on contamination indices, the Kiashahr and Zibakenar lagoons show significant to moderate contamination with Co, Cu, Pb, Zn, and V, whereas the Amirkola Lagoon samples show the lowest metal contamination. PLI values demonstrated metal contamination in the Kiashahr and Zibakenar lagoons but no contamination in the Amirkola Lagoon. Although there was a notable rise in RI values from Amirkola to two other lagoons, all indicated low ecological risk. Statistical methods designated the unique interpretation of contaminant sources. Although the same geogenic origin of sediments in the Sefidrud Delta and lagoons deposits, Co, Zn, and Pb show anthropogenic sources in the newly-formed Kiashahr and Zibakenar lagoons.

The fate of antibiotic resistance genes in the coastal lagoon with multiple functional zones.

Coastal lagoons provide many important services to human society, but their year-round use for aquaculture introduces large amounts of sewage. The contamination of antibiotic resistance genes (ARGs) is therefore of great concern. In this study, 50 ARGs subtypes, two integrase genes (intl1, intl2), and 16S rRNA genes were detected by high-throughput quantitative PCR, and standard curves of all target genes were prepared for quantification. The occurrence and distribution of ARGs in a typical coastal lagoon (XinCun lagoon, China) were comprehensively explored. We detected 44 and 38 subtypes of ARGs in the water and sediment, respectively, and discuss the various factors influencing the fate of ARGs in the coastal lagoon. Macrolides-lincosamides-streptogramins B was the primary ARG type, and macB was the predominant subtype. Antibiotic efflux and antibiotic inactivation were the main ARG resistance mechanisms. The XinCun lagoon was divided into eight functional zones. The ARGs showed a distinct spatial distribution owing to the influence of microbial biomass and anthropogenic activity in different functional zones. Fishing rafts, abandoned fish ponds, the town sewage zone, and mangrove wetlands provided a large quantity of ARGs to the XinCun lagoon. Nutrients and heavy metals also significantly correlated with the fate of the ARGs, especially NO2--N and Cu, which cannot be ignored. It is noteworthy that lagoon-barrier systems coupled with persistent pollutant inputs result in coastal lagoons acting as a "buffer pool" for ARGs, which can then accumulate and threaten the offshore environment.

Tracking of sea level impact on Caspian Ramsar sites and potential restoration of the Gorgan Bay on the southeast Caspian coast.

The situation of Ramsar sites along the Caspian Sea coast has deteriorated over the past decades, and this is more noticeable in the narrow coastal strip of the south Caspian Sea. In this study we investigate how the Caspian Sea level changes affect the coastal Ramsar sites. Particularly, we focus on the Gorgan Bay in the southeast corner of the Caspian Sea, which is experiencing extensive water level decline, even desiccation. We used satellite images from three periods corresponding to periods of two sea level falls and one sea level rise, in order to decipher spatio-temporal changes of the wetlands. We conducted field campaign in the Gorgan Bay for sampling and measurement of physical, chemical and biological parameters. We simulated water circulation for the past, current and future conditions of the Gorgan Bay, which is essential to sustain better water exchange between the Bay and the Caspian Sea. We applied dust simulation in the case of a total desiccation of the Gorgan Bay. The result shows that the total area of the Caspian coastal Ramsar sites during the two periods of the sea level fall is almost the same; however, the aerial changes in the southern wetlands are more visible. Nutrient and plankton analysis of the Gorgan Bay display mainly mesotrophic conditions, in some areas close to eutrophic ones. The average current velocity in the main inlet is 2.5 cms-1. Dust simulation indicates that in case of the Gorgan Bay desiccation, it will become a dust source for the surrounding area up to 60 km. Simulation of the water circulation with dredging of inlets (future scenario), indicates that the water exchange velocity doubles compared to the current scenario. A recommended inlet maintenance would accelerate water circulation and reduce residence time, which will lead to better trophy and prevent bay desiccation.

Seasonal and Spatial Variability of Phytoplankton Primary Production in a Shallow Temperate Coastal Lagoon (Ria Formosa, Portugal).

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.

The relict population of Pinna nobilis in the Mar Menor is facing an uncertain future.

Pinna nobilis is undergoing one of the most dramatic events suffered by an endangered species. An emerging disease has relegated its populations to coastal lagoons or estuaries with salinities beyond the 36.5-39.7 psu range. The Mar Menor is one of two such locations on the Spanish coastline. Poor environmental conditions and eutrophication and anoxia events, that became critical in 2016, 2019 and 2021, have reduced its population in >99 %. In this work, the spatial distribution of the species within the lagoon and the factors determining its survival along the successive crises of eutrophication are studied using a two-stage (presence/absence estimation and density modelling) Species Distribution Model. A potential area of 200.97 ha and an average density of 1.05 ind.100 m2 is estimated for 2020. The viability of the Mar Menor population depends on management actions designed both for the species and to improve the lagoon environmental state.