Influence of environmental patterns on the population structure and secondary production of the fiddler crab Uca maracoani (Latreille) in the Amazon mangroves.

Uca maracoani is a fiddler crab found in estuaries along the western Atlantic coast, with a notable preference for euhaline environments. This study aimed to analyze the population structure and dynamics of this species in an estuary on the North Coast of Brazil, specifically in an area of the upper estuary where seasonal rainfall fluctuations result in significant changes in salinity. Monthly crab samples were taken from December 2013 to November 2015, together with measurements of environmental variables, such as water and climate parameters. The population maintains a balanced sex ratio; however, males are generally larger, with lower mortality rates and longer lifespans than females. Reproduction is continuous but mainly takes place in the dry season when salinity levels are higher (above 12‰). Higher crab densities have been observed during the rainy season when, despite lower salinity levels (below 10‰), the conditions for survival (food availability and milder climate) seem to be more favorable. The estimated average annual biomass and production for the population were 2.62 g AFDM m-2 and 5.43 g AFDM m-2 year-1, respectively, characterized by a high turnover rate (P/B = 2.10 year-1). Our results suggest that U. maracoani has thriving populations in the Amazon coast's mangroves, benefiting from the vast muddy intertidal zone and the high organic content delivered by the estuaries.

Trace metal partitioning in the parnaíba delta in dry season, equatorial coast of Brazil.

Trace metal concentrations in the particulate fractions (MP), dissolved fractions (MD) and sediments (MS), such as Ba, Cu, Co, Cr, Pb, Ni and Zn, were determined during the dry season of the largest open sea delta of Americas, the Parnaíba River Delta (Brazil). This study aimed to comprehend the distribution, dynamic changes of metal speciation and environmental quality index of trace metals in the particulate fractions and subsurface sediments in scenario of major marine influence over the delta. The trace metals bound to suspended particulate material (SPM) from weathering the drainage basin exhibited a removal trend under increases in salinity and pH. Desorption influenced the partitioning of BaMP, ZnMP, NiMP, CoMP, CuMP, and the adsorption and precipitation of PbMP and CrMP to the surface sediments. The organic matter contents in the sediments acts as an important geochemical carrier of these contaminants, and the dissolved organic carbon influences the binding of PbMD in the subsurface waters. The geoaccumulation index (Igeo) plays a crucial role in revealing potential contamination with ZnMP contents and weak association to this fraction. These results make possible the assessment of ecological risk by metal contamination and global pollution mitigation in coastal tidal estuaries under intensive physical mixing along the equatorial coast.

Larval fish assemblages in selected Brazilian estuaries: Species-environment relationships under different anthropogenic influences.

We investigate the effects of spatial changes in environmental conditions and anthropogenic influences on larval fish communities in two tropical estuaries with varying levels of human impact. Our findings revealed a distinct structure of larval fish assemblages between the two estuaries located in northeastern Brazil, and we observed that eutrophication, characterized by high concentrations of nutrients, had adverse effects on the abundance and richness of larval fish assemblages. Additionally, we observed that a decrease in rainfall had an impact on larval fish assemblages, particularly during the dry season, when intermittent upstream rivers lead to changes in salinity and species composition within the estuaries. This study contributed to evaluating the community descriptors of two tropical estuaries under different levels of human influence, providing insights into the vulnerability of larval fish assemblages to climate change, specifically in relation to human influences and hypersalinity and the effects of marinization in shallow tropical estuaries in this region.

Long-term trends in juvenile Mugil liza abundance in relation to selected environmental and fisheries influences in southern Brazil.

Overfishing constitutes a major threat affecting marine fish population worldwide, including mullet species that have been exploited by fisheries during the reproductive migration in temperate and tropical latitudes for millennia. In the present study, we investigated the relationship of fishing intensity of mullet Mugil liza during its reproductive migration and the abundance of their juveniles in an essential nursery ground for the species in the southwest Atlantic Ocean. To carry out this analysis, we used a 23-year standardized long-term time series (1997-2019) of monthly abundance of M. liza juveniles, local/regional (water temperature, salinity, water transparency and river discharge) and global (ENSO) environmental factors, along with compilations of fishing landing data for the species. Generalized Additive Models (GAM) revealed the negative effect of fishing adult populations on the abundance of juveniles when they reach the marine surf-zone and after recruiting into the estuary. Our results reinforce the importance of adequate conservation and fishery regulation policies to prevent the species' stock from collapsing.

Intraspecific variation in reproductive traits and embryo elemental composition of the crab Hemigrapsus crenulatus (Milne Edwards, 1837) across fluctuating coastal environments along Chilean coasts.

The estuarine crab Hemigrapsus crenulatus has a wide distribution range along the coast of the South Pacific Ocean (from 20 °S to 53 S°). This decapod is abundant in these coastal and estuarine habitats and plays a key ecological role as prey of the snook fish (Eleginops maclovinus) and kelp gull (Larus dominicanus). Its diet consists of detritus, dead fish, and crustaceans, and the macroalgae Ulva sp. In response to contrasting environmental conditions and anthropogenic impacts along the Chilean coast, H. crenulatus may present intraspecific variations in its reproductive traits and changes in the elemental composition of its embryos, directly affecting its biological fitness. Along the Chilean coast, female individuals were collected during late spring 2019 and early summer 2020 (from November 2019 to February 2020) in six areas of Chile (north: Tongoy (30°S); south-central: Lenga (36°S), Tubul (37°S); south austral: Calbuco (41°S), Castro (42°S), Quellón (43°S). The environmental conditions (i.e. sea surface temperature, precipitation and chlorophyll α) present during each sampling event were also recorded. We evaluated the reproductive parameters of females (fecundity, reproductive output (RO)) as well as their body size (carapace width and dry weight), volume, water content, dry weight, elemental composition (carbon, hydrogen, nitrogen: CHN), and finally the energy content of their embryos. Our results indicated that the environmental conditions of the sea water temperature, precipitation (proxy of water salinity) and chlorophyll α (proxy of food availability) have direct effects on the reproductive parameters of females and the characteristics of their embryos. We observed a low fecundity and high RO in Calbuco and Quellón, where precipitation was high (i.e. diluted salinity) and temperatures and productivity was low. For embryo traits, the highest values of volume and water content were observed in female crabs from the estuarine areas (i.e. Tongoy, Lenga, Tubul), values much higher than those found in the internal sea of Chile (i.e. Calbuco, Castro, Quellón). For the elemental composition, we observed high nitrogen levels and a low C:N proportion in embryos from female crabs from Lenga (a nitrogen enriched area). Fluctuating environmental variables among localities proved to modulate intraspecific variations in females and embryos of H. crenulatus, revealing different reproductive strategies, particularly in the quality and energy investment per embryo, which subsequently influenced successful embryogenesis and larval survival.

Environmental heterogeneity of a tropical river-to-sea continuum and its relationship with structure and phytoplankton dynamics - Lençóis Maranhenses National Park.

ß-diversity and functional traits of phytoplankton indicators associated with environmental heterogeneity were investigated as environmental quality descriptors in coastal (CS), estuarine (ES), and limnetic (LS) sectors in a tropical river-to-sea ecosystem. Results showed that environmental heterogeneity was marked by spatial differences, contributing to biological heterogeneity. Sporadic and recurrent blooms were associated with environmental spatiotemporal variations and reflected a reduction in ES α-diversity. Salinity acted as an environmental filter that governed the structure and dynamics of the community. The spatial heterogeneity and high turnover of phytoplankton resulted in reliable bioindicators selection. Colonial, bloom-forming and harmful species were associated with highly suspended particulate matter (SPM) because these species are better adapted to these conditions. Species small in size were associated with high concentrations of silicate and chlorophyll-a in the ES because of the occurrence of diatom recurrent blooms. Most flagellates indicators genera have bloom-forming potential. Integrating morphofunctional with taxonomic approaches enabled detailed observations of environmental filters, supporting the selection of priority species and areas for introducing biodiversity monitoring programs and conservation in tropical ecosystems.

Behavioural and physiological responses to salinization and air exposure during the ontogeny of a freshwater South American snail.

Salinization is of global concern, threatening freshwater biodiversity. Salinity tolerance is highly variable and therefore needs to be evaluated on a species-specific basis. An estuarine population of Chilina dombeiana, a freshwater gastropod endemic to Chile and classified as vulnerable, has been recently found in the Biobío River's mouth, suggesting some degree of tolerance to brackish waters. This study evaluated the survival, behaviour (medium preference) and physiology of C. dombeiana when exposed to salinities higher than freshwater, thus elucidating the potential mechanisms used to survive salinization. Chilina dombeiana belongs to the Pulmonate group;, so we evaluated oxygen uptake in air and water, aiming to evaluate emersion as a potential avoidance response to a progressive salinity increase. Complete embryo development was observed for salinities ≤ 16 PSU (practical salinity units) but hatching rates above 50% were only achieved in freshwater (0 PSU). It was also found that salinity had stage-specific effects during embryonic development. In adults, acute exposure to brackish water (12 PSU) caused a decrease in oxygen consumption (compared to freshwater), in the ammonium excretion rates and in the percentage of muscular water content. Although C. dombeiana was able to take up oxygen in both mediums, survival in air decreased over time (days), which correlates with the behavioural preference to remain submerged, even at elevated salinities. Considering the survival of adults and embryos decreased as salinity increased and the lack of an avoidance behaviour or a physiological ability to maintain homeostasis at salinities higher than freshwater, our results suggest this snail could be adversely affected by salinization in the long term. Furthermore, given the ability of C. dombeiana to uptake oxygen in both mediums, it should be considered as a facultative air breather snail, rather than a strictly aquatic species.

Food safety concerns on polycyclic aromatic hydrocarbon contamination in fish products from estuarine bays throughout the American continent.

Estuarine environments are highly productive ecosystems exhibiting high fish biodiversity and richness. Estuarine bays yield significant fisheries catches, making them the target of extractive activities by both artisanal and industrial fisheries. These areas, however, are highly vulnerable to chemical contamination, such as polycyclic aromatic hydrocarbons (PAH) associated with oil spills and other anthropogenic activities, which can jeopardize animal health and consumer welfare. In this context, this systematic review aimed to evaluate PAH levels detected in seafood from estuarine bays throughout the entire American continent and assess potential human health risks. The PICO methodology was applied, and 27 experimental papers were evaluated. The findings indicate that naphthalene and pyrene are routinely detected at high concentrations in several species, such as white mullet and catfish, and that biliary metabolites concentrations tend to be higher than tissue levels. Although the effects of PAH on animal health are well defined due to several decades of assessments, food safety evaluations are still not routine, evidencing a significant knowledge gap and the need for legislative measures based on toxicological data.

Methods for a composite ecological suitability measure to inform cumulative restoration assessments in Gulf of Mexico estuaries.

Ecosystem management requires a systematic, holistic approach that considers ecological and social outcomes. Effective restoration practices promote a balance of ecological and social goals by addressing ecological integrity, efficiently maximizing benefits while minimizing investment, and encompassing collaborative stakeholder engagement. Socio-ecological assessments can inform adaptive management and be utilized to prioritize restoration activities and monitor restoration effectiveness. In estuarine systems, socio-ecological assessments should evaluate the ability of habitats to support both ecologically and locally important species. The composite measure presented utilizes a combination of ecological and social measures to characterize ecological suitability for individual and multiple Gulf of Mexico estuarine species. The ecological suitability value (ES) for a given spatial unit is based on a suite of biophysical measures of the quality and extent of suitable habitat for each species, the species' trophic importance in a food web context, and the importance of each species in relation to stakeholder values and benefits. ES values for individual spatial units can be aggregated to estimate the distribution of ecological suitability at the estuarine scale. The ES values are calculated using examples for each step in the process. The information provided by ecological suitability characterizations can support restoration prioritization decisions for Gulf of Mexico estuaries and can provide a baseline measure to gauge restoration effectiveness over time to inform cumulative restoration assessments.

Mercury methylation upon coastal sediment resuspension: a worst-case approach under dark conditions.

Mercury behavior upon resuspension of sediments from two impacted areas of Guanabara Bay was evaluated to assess worst-case methylmercury (MeHg) responses, under dark experimental conditions to prevent demethylation by photolysis. Study areas include the Rio de Janeiro Harbor (RJH) and the chlor-alkali plant-affected Meriti River (MR) estuary. Total mercury (THg) and MeHg concentrations were determined along 24-h experiments of sediment resuspension in the bay water in dark conditions. Fine-grained Meriti River (MR) estuary sediments had 8 times higher MeHg initial concentrations than sandy Rio de Janeiro Harbor (RJH) sediments (3.4 ± 0.29 vs. 0.41 ± 0.1 ng g-1, respectively). Though THg contents were uncorrelated with resuspension time, statistically significant correlations of MeHg (rs = 0.78) and %MeHg in relation to THg (rs = 0.86) with resuspension time were observed for RJH sediments, indicating net methylation only for this study site. These positive correlation trends correspond to a 2.8 times MeHg concentration increase (ΔMeHg = 0.75 ng g-1) and 4.4 times increase in %MeHg (Δ%MeHg = 1.0%), after 24 h of resuspension. This suggests that assessments of factors affecting the MeHg spatial-temporal variability and associated toxicity risks can be limited in some sites if concentration changes due to sediment resuspension-redeposition processes are not considered. Therefore, the inclusion of MeHg evaluation before and after sediment resuspension events is recommendable for the improvement of dredging licensing and monitoring activities.

Citizen science as a tool for understanding the silent dispersion of toadfish Opsanus beta (Goode and Bean, 1880).

Citizen science is an excellent tool in studies of the spatial distribution of non-native species. In Brazil, Opsanus beta has recently been introduced. Studies indicate the occurrence of this species in five estuaries off the Brazilian coast (Guanabara Bay, Sepetiba Bay, Santos Bay, Paranaguá Estuarine Complex and Guaratuba Bay). The present study aims to understand the dispersion of this species on the Brazilian coast through citizen science. Between January and May 2021, information about O. beta was weekly posted in 32 recreational fishing Facebook groups. Sixty-five fishers reported catches of O. beta in estuaries (Guanabara Bay, Sepetiba Bay, Santos Bay and Paranaguá Estuarine Complex). In addition, there were reports from other shallow areas outside adjacent estuaries (Bertioga and Peruíbe, in Sao Paulo State) and the first occurrence record for Laguna (Santa Catarina State), a southern estuarine zone (28° 29' 45″ S to 48° 45' 36″ W). In four estuaries along the Brazilian coast where O. beta was recorded, there are internal ports that trade with countries from the Gulf of Mexico and Caribbean Sea (species original range), indicating ballast water as a possible introduction route. In Laguna, the introduction may have occurred by maritime cabotage services. The reproductive capacity, the aquarists' interest, the absence of introduction policies aimed at this species and the cabotage fleet transportation may be factors that help further extend the dispersal of O. beta on the Brazilian coast.

Genotoxicity assessment in two Amazonian estuaries using the Plagioscion squamosissimus as a biomonitor.

Genotoxicity studies in coastal ecosystems have been a priority in Environmental Risk Assessment (ERA). This research aimed to study the genotoxicity by the micronucleus test and comet assay in two Brazilian Amazon estuaries (anthropized and control) using Plagioscion squamosissimus as a biomonitor. Blood samples were collected from 54 specimens. No significant genotoxic effects were detected in the cells analyzed, although the highest occurrence (MN and DNA damages) was observed in anthropized site. The percentage of genomic damage differed between the sites studied, being always higher in anthropizes site as well. Of the nucleoids analyzed in this site, on average, 28 ± 14.42% of the cells were classified in the highest damage class. The fish analyzed in the present study are direct influenced of xenobiont agents capable of producing damage to the genetic material of aquatic organisms in both sites and, consequently, may bring consequences still little reported in studies of morphophysiological alterations in humans.

Microplastics in rivers and coastal waters of the province of Esmeraldas, Ecuador.

This study represents the first assessment of microplastic (MP) contamination in the coastal area of the Esmeraldas Province, Ecuador. MPs were quantified in 14 coastal waters in beaches with different urbanization level and in 10 rivers. The most abundant MP types were transparent fibres, brown fragments, grey fragments, transparent fragments, and black fragments, which together represented 84% of the total count. Coastal waters presented significantly higher quantities of MP than rivers. No difference in microplastic abundance was detected between beaches with higher and lower urban occupation, nor between beaches facing North or West. Our results indicate that MP contamination is widespread, and most likely transported from multiple sources. Our results can serve as a baseline for future MP monitoring in the area.

Hábitos alimentarios de tres especies de peces lenguados (Pleuronectiformes: Achiridae) en la Bahía de Buenaventura, Pacífico Colombiano / Feeding habits of three species of sole fish (Pleuronectiformes: Achiridae) in Buenaventura Bay, Colombian Pacific

Resumen Introducción: La dinámica de las condiciones ambientales influencia la variación del alimento disponible para los organismos estuarinos, afectando el consumo de alimento de los organismos bentónicos como los lenguados, esenciales para establecer y monitorear la calidad ambiental en estos ecosistemas. Objetivo: Determinar los hábitos tróficos de tres especies de la familia Achiridae en la Bahía de Buenaventura, Pacífico colombiano. Métodos: Los peces se recolectaron por medio de pesca de arrastre artesanal. Así mismo, en laboratorio se determinó la dieta de cada una de las especies y se calcularon diferentes índices tróficos, registrando diferencias en los hábitos alimentarios entre estas especies. Resultados: Se recolectó un total de 159 peces del género Achirus, siendo la especie más abundante Achirus klunzingeri (98), luego Achirus mazatlanus (44) y finalmente Achirus scutum (17). La dieta de A. scutum se basó en detritos, la de A. mazatlanus en detritos y peces y la de A. klunzingeri en crustáceos y peces. Los individuos de A. klunzingeri presentaron diferencias en su dieta entre la zona interna y externa del estuario, en la zona interna los peces fueron la presa principal y en la zona externa fueron los crustáceos. Las especies A. klunzingeri y A. mazatlanus presentaron ingesta de microplásticos, principalmente fibras alargadas e incoloras presentes en individuos de todas las tallas. La dinámica de los hábitos tróficos de A. klunzingeri, se relacionaron con algunas variables ambientales, como temperatura, trasparencia y oxígeno disuelto. Por ejemplo, estas tres variables presentaron correlaciones negativas con el ítem peces, y positivas para la categoría crustáceos. Conclusión: Se evidenció que estas especies son generalistas y que las condiciones ambientales no solo influenciaron la dinámica del consumo alimentario, sino que también, determinaron la presencia de los microplásticos.

Abstract Introduction: The dynamic of the environmental conditions influences the availability of the food resources for the estuarine organisms, affecting the food consumption of the benthic organism such as the soles, which are essential for establishing and monitoring the environmental quality of these ecosystems. Objective: To determine the trophic habits of three species of the Achiridae family in Buenaventura Bay, Colombian Pacific. Methods: Fish were captured using artisanal trawling. Then, the diet of each species was determined and different trophic indexes were calculated registering differences in alimentary habits among species. Results: It was collected a total of 159 fishes of the genus Achirus, being the most abundant Achirus klunzingeri (98), then Achirus mazatlanus (44) and finally Achirus scutum (17). The diet of A. scutum was based on detritus, the diet of A. mazatlanus was mainly detritus and fish whereas the diet of A. klunzingeri presented a dynamic pattern based mainly on crustaceans and fish. The individuals of Achirus klunzingeri presented differences in the diet between the internal and external area of the estuary, in the internal zone the fish were the main prey while in the external zone were the crustaceans. The species A. klunzingeri and A. mazatlanus presented ingestion of microplastics, mainly elongated and colorless fibers which were present in individuals of all sizes. The dynamic of the trophic habits of A. klunzingeri was related to the environmental variables such as temperature, transparency and dissolved oxygen. For example, these three variables presented negative correlations with the item fishes, and positive for the crustacean category. Conclusions: Despite the generalist nature of the studied species, the environmental conditions, not only influenced the food consumption dynamic, but also determined the presence of microplastics.

EFECTO DEL pH EN LAS TASAS DE BIOACUMULACIÓN DE METALES PESADOS EN LA MACROALGA Bostrychia calliptera (Rhodomelaceae, Ceramiales) / Effect of pH on the bioacumulation rates of heavy metals in macroalgae Bostrychia calliptera (Rhodomelaceae, Ceramiales)

RESUMEN Uno de los factores que más influye en las características químicas de un metal en solución es el nivel de acidez. El pH, por lo tanto, afecta la reactividad del ion y por ende su interacción con los puntos de unión de la pared celular de la planta. Este estudio evaluó el efecto del pH en la capacidad de bioacumulación de metales pesados en el alga roja Bostrychia calliptera (Rhodophyta, Rhodomelaceae). Se sometieron talos del alga a diferentes concentraciones de mercurio (Hg) y Plomo (Pb), desde 0,1 hasta 10 mg/L para Hg y desde 0,1 hasta 15 mg/L para Pb, durante periodos exposición de 0, 12, 24 y 96 horas, bajo diferentes niveles de pH. Las concentraciones de metal acumulado se determinaron por espectrofotometría de absorción atómica. Las mayores tasas de acumulación se encontraron en el alga expuesta a pH 8 (tanto para Hg como para Pb), el cual es un nivel de pH muy cercano al medido en el área de muestreo. La concentración de metal en el alga se incrementó de manera lineal hasta las 48 h de exposición, tiempo en el que se evidenció una mayor eficiencia de acumulación durante el primer intervalo del periodo del bioensayo. El presente estudio permitió identificar el uso potencial del alga B. calliptera como especie bioindicadora de metales pesados en ambientes estuarinos.

ABSTRACT One of the factors with a bigger influence on the chemical characteristics of metal in solution is the level of acidity. Solution pH affects the cell wall metal-binding sites and the metal ion chemistry in water. This study evaluated the effect of pH on the bioaccumulation capacity in the red algae B. calliptera (Rhodophyta, Rhodomelaceae) exposed to different pH ranges. Algae thalli were subjected to different concentrations ofmercury (Hg) and Lead (Pb), at concentrations from 0.1 to 10 mg/L for Hg and from 0.1 to 15 mg/L for Pb, respectively, during the following exposure times: 0, 12, 24 and 96 hours for each ion. Metal concentrations were determined by atomic absorption spectrophotometry according to standard APHA methods. The highest accumulation rates were found when the algae were exposed to pH 8 (for both Hg and Pb), which is a level very close to that measured in the study area. The metal concentration in the algae increased linearly until 48 hrs, a time where a greater accumulation efficiency was evident. The present study allowed to identify the potential use of the alga B. calliptera as a bioindicator species for heavy metals in estuarine environments.

In vivo experimental study to investigate cytogenotoxicity of a contaminated estuary from Southeastern Brazilian Coast.

The aim of this study was to evaluate cytogenotoxicity in mammalian cells induced by ingestion of superficial water from SESS. For this purpose, surface water was collected from two points of SESS: São Vicente Channel (SVC) and Piaçaguera Channel (PIC). Four groups (n = 5) of adult male Wistar (8 weeks old) received for 5 days: (a) filtered tap water (water control), (b) tap water with 2.4% of NaCl (saline control), (c) estuarine water from PIC and (d) estuarine water from SVC. Results demonstrated that Ki67 immunoexpression was higher in hepatocytes exposed to both sampling site, while caspase-3 demonstrated downregulation in rat liver exposed to estuarine water. There was also significant increase in micronuclei frequency in bone marrow cells and hepatocytes, and DNA damage in blood and liver of rats exposed to estuarine water from SVC and PIC. In summary, studies with complex mixtures, such as contaminated estuarine water are important since this work confirmed by experiments using in vivo mammalian cells of rats that SESS water are genotoxic, mutagenic and cytotoxic, denoting concern for environmental health.

Oil spills: The invisible impact on the base of tropical marine food webs.

The Brazilian oil spill, from August 2019 to January 2020, was considered the most extensive accident in tropical oceans. We estimated the concentration of oil droplets that may be available for ingestion by microzooplankton. The collection was carried out in three areas: estuarine plume, bay and reef (Tamandaré, Pernambuco coast). We highlight the contribution of coral larvae in the reef region, surpassing the copepods, evidencing a spawning event. Oil droplets were recorded in all the sampled areas, with a high numerical abundance in the plume. Traces of oil ingestion by Brachyura zoea and Calanoida, Paracalanidae and Oithonidae copepods were observed, suggesting that these groups might have an important role in the degradation and final destination of oil dispersed after spills. The vulnerability of the larval phases of crabs and reef-building corals has been hypothesized, suggesting that the negative effects of oil on zooplankton can affect the recruitment of benthic invertebrates.

Different trophodynamics between two proximate estuaries with differing degrees of pollution.

Mangroves are complex ecosystems with widely varying abiotic factors such as salinity, pH, redox potential, substratum particle size, dissolved organic matter and xenobiotic concentrations, and a high biodiversity. This paper presents the trophodynamic pathways of accumulation and transfer of metals and metalloids (B, Al, V, Cr, Mn, Fe, Ni, Cu, Zn, Ag, As, Se, Rb, Sr, Pb and Hg), in three trophic chains (plant-crab-fish, plankton-shrimp-fish and plankton-oyster) of similar food webs, corresponding to two mangrove estuaries (Santa Cruz and Vitória Bay, separated by 70 km) in the Espírito Santo State (Brazil). Although the trophic transfer patterns are affected by physical variables, metal and metalloids were found in all trophic levels. We observed similar trophodynamics between both estuaries with some elements, but unequal transfer patterns in other cases, thus questioning the effectiveness of 15N to determine the food chain when the aquatic biota is affected by anthropogenic contaminants. Thus, in the Santa Cruz estuary, most metals were biomagnified through the food web. Conversely, Vitória Bay presented mostly biodilution, suggesting that metal/metalloid transference patterns in mangrove ecosystems may be affected by different anthropogenic contamination inputs. These results indicate the importance of knowing the complete food web when evaluating the trophic transfer of elements, including an evaluation of the differential impact of pollution on diverse components of the food chain.

Behavioral aspects of waterbirds / Aspectos comportamentais de aves aquáticas

Abstract Estuaries are used by waterbirds as foraging, resting and nesting sites, serving also as shelter for migratory birds. The dynamics of this avifauna in an aquatic environment may be associated with the differences of time of day, tide height, temperature, wind speed and use of the site by different species. This study had the objective of evaluating behavioral aspects of aquatic birds, relating the influence of environmental variables with their activities. Bird counts were performed at the mouth of two important rivers of the state of Santa Catarina, Brazil, during two-hour intervals throughout the day in monthly samplings between June (2015) and May (2016). A total of 44 species were recorded, ten of which were migratory. The most recorded behaviors were foraging and resting. The Kruskal-Wallis analysis indicated no significant difference in behavior between the sampling intervals. The Bray-Curtis similarity test resulted in three groups: 1) - species that foraged most of the time; 2) - species that rested most of the time; and 3) - same time in both activities. The Indicator Species Analysis showed that 17 species were associated with only one microhabitat and 15 species with more than one. The Canonical Correlation Analysis indicated that only tide height, temperature and rainfall variables were correlated with the behaviors performed and only the resting activity was positively correlated with all variables. This may be associated with thermoregulation and the ability of some species to stay in midlitoral at high tide. The results demonstrate that different waterbird species used the studied areas in different ways. Thus, the heterogeneity of microhabitats in an aquatic environment of extreme importance for the coexistence and maintenance of the diversity of waterbirds.

Resumo Estuários são utilizados por aves aquáticas como locais de forrageio, descanso e nidificação, servindo, também, como pontos de parada para aves migratórias. A dinâmica dessa avifauna em um ambiente pode estar associada a diferenças entre horários do dia, altura da maré, temperatura, velocidade do vento e uso do local. Esse trabalho teve o objetivo de avaliar aspectos comportamentais de aves aquáticas, relacionando a influência de variáveis ambientais com suas atividades. Amostragens mensais foram realizadas na foz de dois importantes rios do Estado de Santa Catarina, Brasil, entre junho de 2015 e maio de 2016, em intervalos de duas horas no decorrer do dia. Um total de 44 espécies foram registradas, dez das quais foram migratórias. Os comportamentos mais observados foram forrageio e descanso. A análise de Kruskall-Wallis não indicou diferenças significativas no comportamento entre os horários de amostragem. O teste de similaridade Bray-Curtis resultou em três agrupamentos: 1) - espécies que forragearam na maior parte do tempo; 2) - espécies que descansaram na maior parte do tempo; e 3) - mesma quantidade de tempo em ambas atividades. A Análise de Espécies Indicadoras mostrou que 17 espécies estiveram associadas com apenas um microhabitat e 15 espécies com mais de um. A Análise de Correlação Canônica indicou que apenas as variáveis maré, temperatura e precipitação foram significativamente correlacionadas com os comportamentos demonstrados e apenas a atividade de descanso foi positivamente correlacionada com as todas as variáveis. Isso pode estar associado com a termorregulação e com a habilidade de algumas espécies de permanecer no mediolitoral durante a maré cheia. Os resultados demonstram que diferentes espécies de aves aquáticas utilizaram as áreas estudadas de diferentes maneiras. Assim, a heterogeneidade de microhabitats em um ambiente aquático é de extrema importância para a coexistência e a manutenção da diversidade de aves.