Reconnoitre on ichthyofauna of Mahanadi River of India: shifting diversity down the river continuum and linking ecological traits with patterns in biodiversity.

Anthropogenic alterations have paramount impacts on the alpha and beta diversity of aquatic resources, and fishes are predominantly susceptible to such impacts. Mahanadi River, one of the major peninsular rivers of India, has abundant fish resources, which play a significant role in supporting the fishers' livelihoods. The exploratory study in the river conducted for three consecutive years recorded 148 species under 53 families. Cyprinids dominated the fish diversity with 41 species, followed by Bagrids (9) and Sciaenids (7). One hundred-one species under 29 families were reported from the freshwater stretch. With a total of 111 species reported under 48 families, the estuarine and tidal freshwater stretch was more speciose, due to marine migrant species which advent the estuarine and tidal freshwaters stretch for breeding and feeding purposes. Tikarpara, a conserved site within a sanctuary, was the most species-diverse as well as a species-even site. The study also recorded the extension of the distributional range of 3 fish species and also 4 exotic species from the river. The seasonal variations in diversity indicated that the deviations were not prominent in freshwater sites, whereas in tidal brackish water sites, species richness was relatively higher in post-monsoon, and species evenness was higher during monsoon. Taxonomic distinctness test showed that the average taxonomic distinctness was high for tidal estuarine locations as they harbour taxonomically distant fishes. The hierarchical clustering of sites showed the inordinate effect of river gradient and fragmentation on the fish community structure. Analyzing the key drivers of the assemblage structure of the entire river, salinity was the major deterministic factor, and within the freshwater stretch, the major influences were depth, transparency, and specific conductivity. The study concluded that, despite all of its ecological stresses, Mahanadi still supports rich fish diversity, yet there is a notable shift in the fish community structure. There is a need for integrating molecular and morphological tools for the taxonomic revision of many genera and species for proper in situ and ex situ conservation measures and to formulate future biodiversity management plans addressing to reduce the impacts of the ecological threats.

Impact of forest disturbance on microarthropod communities depends on underlying ecological gradients and species traits.

Windstorms and salvage logging lead to huge soil disturbance in alpine spruce forests, potentially affecting soil-living arthropods. However, the impacts of forest loss and possible interactions with underlying ecological gradients on soil microarthropod communities remain little known, especially across different environmental conditions. Here we used DNA metabarcoding approach to study wind-induced disturbances on forest communities of springtails and soil mites. In particular, we aimed to test the effect of forest soil disturbance on the abundance, richness, species composition, and functional guilds of microarthropods. We sampled 29 pairs of windfall-forest sites across gradients of elevation, precipitation, aspect and slope, 2 years after a massive windstorm, named Vaia, which hit North-Eastern Italy in October 2018. Our results showed that wind-induced disturbances led to detrimental impacts on soil-living communities. Abundance of microarthropods decreased in windfalls, but with interacting effects with precipitation gradients. Operative Taxonomic Units (OTU) richness strongly decreased in post-disturbance sites, particularly affecting plant-feeder trophic guilds. Furthermore, species composition analyses revealed that communities occurring in post-disturbance sites were different to those in undisturbed forests (i.e., stands without wind damage). However, variables at different spatial scales played different roles depending on the considered taxon. Our study contributes to shed light on the impacts on important, but often neglected arthropod communities after windstorm in spruce forests. Effects of forest disturbance are often mediated by underlying large scale ecological gradients, such as precipitation and topography. Massive impacts of stronger and more frequent windstorms are expected to hit forests in the future; given the response we recorded, mediated by environmental features, forest managers need to take site-specific conservation measures.

Ambient and substrate energy influence decomposer diversity differentially across trophic levels.

The species-energy hypothesis predicts increasing biodiversity with increasing energy in ecosystems. Proxies for energy availability are often grouped into ambient energy (i.e., solar radiation) and substrate energy (i.e., non-structural carbohydrates or nutritional content). The relative importance of substrate energy is thought to decrease with increasing trophic level from primary consumers to predators, with reciprocal effects of ambient energy. Yet, empirical tests are lacking. We compiled data on 332,557 deadwood-inhabiting beetles of 901 species reared from wood of 49 tree species across Europe. Using host-phylogeny-controlled models, we show that the relative importance of substrate energy versus ambient energy decreases with increasing trophic levels: the diversity of zoophagous and mycetophagous beetles was determined by ambient energy, while non-structural carbohydrate content in woody tissues determined that of xylophagous beetles. Our study thus overall supports the species-energy hypothesis and specifies that the relative importance of ambient temperature increases with increasing trophic level with opposite effects for substrate energy.

Not only climate: The importance of biotic interactions in shaping species distributions at macro scales.

Abiotic factors are usually considered key drivers of species distribution at macro scales, while biotic interactions are mostly used at local scales. A few studies have explored the role of biotic interactions at macro scales, but all considered a limited number of species and obligate interactions. We examine the role of biotic interactions in large-scale SDMs by testing two main hypotheses: (1) biotic factors in SDMs can have an important role at continental scale; (2) the inclusion of biotic factors in large-scale SDMs is important also for generalist species. We used a maximum entropy algorithm to model the distribution of 177 bat species in Africa calibrating two SDMs for each species: one considering only abiotic variables (noBIO-SDMs) and the other (BIO-SDMs) including also biotic variables (trophic resource richness). We focused the interpretation of our results on variable importance and response curves. For each species, we also compared the potential distribution measuring the percentage of change between the two models in each pixel of the study area. All models gave AUC >0.7, with values on average higher in BIO-SDMs compared to noBIO-SDMs. Trophic resources showed an importance overall higher level than all abiotic predictors in most of the species (~68%), including generalist species. Response curves were highly interpretable in all models, confirming the ecological reliability of our models. Model comparison between the two models showed a change in potential distribution for more than 80% of the species, particularly in tropical forests and shrublands. Our results highlight the importance of considering biotic interactions in SDMs at macro scales. We demonstrated that a generic biotic proxy can be important for modeling species distribution when species-specific data are not available, but we envision that a multi-scale analysis combined with a better knowledge of the species might provide a better understanding of the role of biotic interactions.

Occurrence, bioconcentration, and human health risks of pharmaceuticals in biota in the Sea of Marmara, Türkiye.

The presence, bioconcentration, and health risk via seafood consumption of 11 pharmaceutical compounds belonging to different therapeutic groups (anti-inflammatory, antiepileptic, lipid regulators, and hormones) were investigated in the muscle tissues of fish and the meat of shrimp in the Sea of Marmara. Six biota species (Merlangius merlangus, Trachurus meditterraneus, Serranus hepatus, Pomatomus saltatrix, Parapenaeus longirostris, Spratus sprattus) were collected from the five stations in October and April 2019. Ultrasonic extraction method followed by solid phase extraction was used for extraction of pharmaceutical compounds from biota samples and then analyzed using high-performance liquid chromatography. Of the 11 compounds, 10 were detected in biota species. Ibuprofen was the most frequently detected pharmaceutical in the biota tissues at high concentrations (<3.0-1225 ng/g, dw). The other widely detected compounds were fenoprofen (<3.6-323 ng/g, dw), gemfibrozil (<3.2-480 ng/g, dw), 17α-ethynylestradiol (<2.0-462 ng/g, dw), and carbamazepine (<7.6-222 ng/g, dw). The bioconcentration factors of the selected pharmaceuticals calculated in various aquatic organisms ranged from 9 to 2324 L/kg. The estimated daily intakes of anti-inflammatories, antiepileptics, lipid regulators, and hormones via seafood consumption were 0.37-568, 1.1-324, 8.5-197, 3-340 ng/kg bw. Day, respectively. Based on hazard quotients, estrone, 17ß-estradiol, and 17α-ethynylestradiol may pose a health risk to humans through the consumption of this seafood.

Delineating the food web structure in an Indian estuary during tropical winter employing stable isotope signatures and mixing model.

The food and feeding links and sources in an impacted tropical estuary situated along India's western coast, the Ulhas River Estuary (URE) was analyzed employing the stable carbon and nitrogen isotopic signatures (δ13C and δ15N). Three basal carbon sources, such as mangrove leaves, particulate organic matter (phytoplankton), and detritus, were analyzed together with eight consumer groups from various trophic guilds. The δ13C varied from - 19.67 to - 24.61‰, whereas δ15N ranged from 6.31 to 15.39‰ from the primary consumer to the top predator species. The stable isotope mixing model developed for URE revealed a phytoplankton based pelagic food chain and detritus based benthic food chain in URE. The fairly larger value of SEA (Standard Ellipse Area) in the URE suggest a much broader food web structure and high trophic diversity in the ecosystem. Higher influence of detritus on the assimilated diet of majority of consumers and evidences of nitrogen enrichment in the basal sources such as detritus and particulate organic matter by anthropogenic activities in URE point towards nitrogen pollution and subsequent trophic disturbance in this tropical estuarine ecosystem.

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Collembola are among the most abundant and integral group in soil decomposers. They channel C and nutrients from basic food resources to higher trophic levels, and therefore play an irreplaceable role in the underground food web. Collembola community would be altered dramatically by increasing N and P deposition. However, we still know little about how Collembola respond to N and P inputs, which will largely retard our steps to understand the ecological functions of collembolans, material circulation and energy flow of the underground food web, and even C cycling in terrestrial ecosystem. The different classification rules for Collembola functional groups have led to poor comparability of research results in the literature. This review proposed three taxonomic criteria of Collembola and four common research means on trophic relationships, summarized the mechanisms underlying the responses of Collembola to N and P addition alone and coadded. Overall, Collembola generally shows a negative response to N addition namely community density decreases, while a positive response to P addition in most ecosystems. The situation was more complicated under the combined N and P application. In the future, the research of Collembola response to N and P deposition should focus on the scientific taxa of Collembola functional groups, improving the research methods of trophic structure of Collembola, and the mechanism underlying the impacts of N and P interaction on Collembola community.

Micronucleus and different nuclear abnormalities in wild birds in the Cerrado, Brazil.

Free-living birds play an important role as bioindicators in natural environments. In this study, we used the micronucleus test and nuclear erythrocyte abnormalities to investigate the difference in the genotoxic damage frequency between animals in agricultural areas (soybean planting) in relation to the conserved area. It was also discussed the bird's eating habits, which are important for ecotoxicological analysis. The results point to a difference between the insectivorous, granivorous, and omnivorous guilds. The omnivore Gnorimopsar chopi was the species that most exhibited micronucleus frequency in the protected area. In the agricultural area, the animals did not differ in the genotoxic damage frequency. In the comparison between common species in both environments, G. chopi from the agricultural area showed a micronuclei frequency almost three times higher in relation to specimens collected in the conserved area. Based on these results, this study adds to the efforts of using the micronucleus test as a simple and accessible tool for biomonitoring the wild fauna. It can be concluded that the passerine, G. chopi, due to its higher genotoxic damage frequency may be a strong candidate to indicate environmental health.

Functional diversity loss and change in nocturnal behavior of mammals under anthropogenic disturbance.

In the Anthropocene, understanding the impacts of anthropogenic influence on biodiversity and behavior of vulnerable wildlife communities is increasingly relevant to effective conservation. However, comparative studies aimed at disentangling the concurrent effect of different types of human disturbance on multifaceted biodiversity and on activity patterns of mammals are surprisingly rare. We applied a multiregion community model to separately estimate the effects of cumulative human modification (e.g., settlement, agriculture, and transportation) and human presence (aggregated presence of dogs, people, and livestock) on species richness and functional composition of medium- and large-bodied mammals based on camera trap data collected across 45 subtropical montane forests. We divided the detected mammal species into three trophic guilds-carnivores, herbivores, and omnivores-and assessed the nocturnal shifts of each guild in response to anthropogenic activities. Overall, species richness tended to increase (ß coefficient = 0.954) as human modification increased but richness decreased as human presence increased (ß = -1.054). Human modification was associated with significantly lower functional diversity (mean nearest taxon distance [MNTD], ß = -0.134; standardized effect sizes of MNTD, ß = -0.397), community average body mass (ß = -0.240), and proportion of carnivores (ß = -0.580). Human presence was associated with a strongly reduced proportion of herbivores (ß = -0.522), whereas proportion of omnivores significantly increased as human presence (ß = 0.378) and habitat modification (ß = 0.419) increased. In terms of activity patterns, omnivores (ß = 12.103) and carnivores (ß = 9.368) became more nocturnal in response to human modification. Our results suggest that human modification and human presence have differing effects on mammals and demonstrate that anthropogenic disturbances can lead to drastic loss of functional diversity and result in a shift to nocturnal behavior of mammals. Conservation planning should consider concurrent effects of different types of human disturbance on species richness, functional diversity, and behavior of wildlife communities.

Pérdidas en la Diversidad Funcional y Cambios en el Comportamiento Nocturno de los Mamíferos bajo la Perturbación Antropogénica Resumen En el Antropoceno, el conocimiento sobre la influencia antropogénica sobre la biodiversidad y el comportamiento de las comunidades vulnerables de fauna es cada vez más relevante para la conservación efectiva. Sin embargo, sorprende que los estudios comparativos dirigidos a desentrañar el efecto concurrente de los diferentes tipos de perturbación humana sobre la biodiversidad multifacética y sobre los patrones de actividad de los mamíferos son escasos. Aplicamos un modelo de comunidad multirregional para estimar de manera separada los efectos de la modificación humana (p. ej.: establecimientos, agricultura, transporte) y la presencia humana (presencia agregada de perros, gente y ganado) acumuladas sobre la riqueza de especies y la composición funcional de los mamíferos de tamaño mediano y grande con base en datos de fototrampas recolectados en 45 bosques montanos subtropicales. Dividimos las especies de mamíferos detectadas en tres gremios tróficos: carnívoros, herbívoros y omnívoros, y analizamos los cambios nocturnos de cada gremio como respuesta a las actividades antropogénicas. En general, la riqueza de especies tuvo una tendencia al incremento (coeficiente ß = 0.954) conforme aumentaron las modificaciones humanas, pero la riqueza disminuyó conforme incrementó la presencia humana (ß = −1.054). Las modificaciones humanas estuvieron asociadas con una diversidad funcional (distancia promedio al taxón más cercano [DPTC], ß = −0.134; tamaños del efecto estandarizado de la DPTC, ß = −0.397), masa corporal promedio de la comunidad (ß = −0.240) y proporción de carnívoros (ß = −0.580) significativamente más bajas. La presencia humana estuvo asociada con una proporción gravemente reducida de herbívoros (ß = −0.522), mientras que la proporción de omnívoros incrementó significativamente conforme aumentaron la presencia humana (ß = 0.378) y la modificación del hábitat (ß = 0.419). En cuanto a los patrones de actividad, los omnívoros (ß = 12.103) y los carnívoros (ß = 9.368) se volvieron más nocturnos como respuesta a las modificaciones humanas. Nuestros resultados sugieren que las modificaciones humanas y la presencia de personas tienen efectos diferentes sobre los mamíferos y demuestran que las perturbaciones antropogénicas pueden llevar a pérdidas drásticas de la diversidad funcional y resultar en un cambio hacia el comportamiento nocturno en los mamíferos. La planeación de la conservación debería considerar los efectos concurrentes de los diferentes tipos de perturbaciones humanas sobre la riqueza de especies, la diversidad funcional y el comportamiento de las comunidades faunísticas.

Mollusk death assemblages in 210Pb-dated marine sediment cores reveal recent biotic changes in the Gulf of Guanahacabibes, NW Cuba.

We investigated stratigraphic changes in mollusk death assemblages and geochemistry in sediment cores from four seagrass beds and one unvegetated site in the Gulf of Guanahacabibes (GG), NW Cuba. There was a transition from mangrove to seagrass beds, associated with sea level rise ∼6000 years ago. Sediment accumulation rates during the last century showed a general rise, but increased sharply after ∼1980, likely because of human activities. The GG displayed overall high mollusk γ-diversity, and our estimate of 189 species is biased toward the low end. High ß-diversity was driven by inter-site differences in grain size, vegetation cover, and nutrient input. Spatial heterogeneity within the basin influenced downcore abundance and diversity metrics, highlighting the influence of local drivers. Herbivorous gastropods dominated in seagrass beds and suspension feeder bivalves were dominant on sandy bottom. In the top parts of cores, species richness declined at two sites that were subject to high, human-mediated bulk sedimentation rates and eutrophication. Conservation measures are needed to preserve this hotspot of marine diversity.

Classification method for quantification of waterbird nutrient cycling guilds.

This classification method for quantification of waterbird nutrient cycling guilds focuses on the location of feeding habitats and the quantitative role of waterbirds in the nutrient and energy flow for inland aquatic ecosystems. The classification is a complex integration of the taxonomic, trophic, feeding and daily habitat use patterns based on most relevant previous studies and reference data in relation with the ecology and nutrient cycling of waterbirds: A) Net-importer guild: includes species which feed mostly outside inland waters in the terrestrial ecosystems and wetlands, but use water bodies as gathering and roosting sites (geese, cranes). B) Importer-exporter guild: includes species which feed both outside and in of inland waters and wetlands (dabbling ducks and gulls). C) Net-exporter guild: includes species which feed mostly on inland waters and wetlands (diving ducks, grebes, cormorants, small herons, most shorebirds). Conclusion of main findings that method can significantly contribute to the better understanding how waterbirds can effect the environment and the guilds as ecological indicators quantify their ecosystem functions, services.•Net-importer guild includes species which feed mostly outside the inland waters•Importer-exporter guild includes species which feed both in- and outside inland waters•Net-exporter guild includes species which feed mostly inside the inland waters.

Diet composition of abundant fish species in the shallow waters of the Todos os Santos Bay, Bahia, Brazil

Coastal habitats have great ecological importance with estuarine environments providing feeding sites for many fish species, especially during juvenile life stages. This study investigates the diet composition and trophic guild organization of the common and abundant ichthyofauna in shallow areas of the Todos os Santos Bay (TSB), Bahia, Brazil, and their relationships with environmental parameters. Six fish sampling campaigns were carried out in the shallow zones (infralittoral) of the Paraguaçu River estuary which encompasses the inner and outer (marine exposure) reaches of theTSB. The stomach contents of 1231 individualsbelonging to common and abundant species were examined. A total of 32 food items were identifiedand fish were into four trophic guilds: detritivores, zoobenthivores I, zoobenthivores II, and zooplanktivores. The relationship between the guilds and environmental parameters showed that zoobenthivores II and zooplanktivores guilds had a positive relationship with salinity and pH, explaining 86% of data variability, though only the salinity variable was significant. This study provides basic information about the diet composition of common and abundant species in the TSBand their organization into trophic guilds. In addition, demonstrates that shallow waters fish across all guilds have broadly similar diets, comprising food items that are usually associated with bottom waters.

Hydropower affects fish trophic structure both downstream of the dam and upstream of the reservoir

Dams often cause drastic changes in freshwater environments and can compromise the quality and availability of food resources in rivers. This study aims to analyze the influence of a dam on the trophic structure of fish assemblages in lotic areas located both upstream and downstream of the Irapé Hydroelectric Power Plant. Fish sampling occurred before (2003 to 2005) and after (2011 to 2017) the impoundment, which began in 2006. The trophic structure and species composition before dam construction were similar upstream of the reservoir and downstream of the dam. After the building of the dam, both aspects of the assemblages changed along the lotic stretches - the upstream incurred an increase in biomass of detritivores and a decrease of piscivores and omnivores, while downstream went exactly the opposite, causing a differentiation between the two assemblages. Because lotic areas upstream of reservoirs are also impacted by river damming, efforts for impact mitigation should also focus on these areas.(AU)

Barragens causam mudanças drásticas em ambientes de água doce e podem comprometer a qualidade e a disponibilidade de recursos alimentares nos rios. Este estudo teve como objetivo analisar a influência de uma barragem na estrutura trófica da assembleia de peixes em áreas lóticas localizadas a montante e a jusante da usina hidrelétrica de Irapé. A amostragem de peixes ocorreu antes (2003 a 2005) e após (2011 a 2017) o fechamento das comportas, iniciado em 2006. A estrutura trófica e a composição das espécies antes da construção da barragem eram semelhantes a montante do reservatório e a jusante da barragem. Após a construção da barragem, ambos os aspectos das assembleias mudaram ao longo dos trechos lóticos - a montante ocorreu um aumento na biomassa de detritívoros e diminuição de piscívoros e onívoros, enquanto a jusante ocorreu exatamente o oposto, causando uma diferenciação entre as duas assembleias. Como as áreas lóticas a montante dos reservatórios também são impactadas por barramentos, esforços para mitigação de impactos também devem se concentrar nessas áreas.(AU)

Land-use change affects size spectra, energy flux and ecosystem functions in litter and soil invertebrates.

In Focus: Potapov, A. M., Klarner, B., Sandmann, D., Widyastuti, R. and Scheu, S. (2019). Linking size spectrum, energy flux and trophic multifunctionality in soil food webs of tropical land-use systems. Journal of Animal Ecology, 88, 1845-1859. https://doi.org/10.1111/1365-2656.13027 Potapov et al. (2019) advance our understanding of the various levels of the consequences of human impact on ecosystems. They examine the communities of litter and soil invertebrates in four different forests (from rainforest to oil palm plantations). Data on abundance, body masses and trophic guild in litter and soil invertebrates are expanded to a study towards biodiversity, biomass, energy flux and ecosystem functions. Their results show that size spectra are affected differently for decomposers, herbivores, omnivores and predators. Most of these groups decrease in abundance with increasing land use, and only large decomposers increase strongly. Moreover, creating trophic-group food webs for litter and soil invertebrates of each forest demonstrates the changes in energy flux and ecosystem functions. With their study, Potapov et al. (2019) present new insights into ecosystem functions and the sensitivity of communities to changes in land use.

Digging mammal reintroductions reduce termite biomass and alter assemblage composition along an aridity gradient.

Invasions can trigger cascades in ecological communities by altering species interactions. Following the introduction of cats and foxes into Australia, one tenth of Australia's terrestrial mammal species became extinct, due to predation, while many continue to decline. The broader consequences for Australian ecosystems are poorly understood. Soil-dwelling invertebrates are likely to be affected by the loss of fossorial native mammals, which are predators and disturbance agents. Using reintroductions as a model for ecosystems prior to species loss, we tested the hypothesis that mammal reintroduction leads to reduced vegetation cover and altered termite assemblages, including declines in abundance and biomass and changed species composition. We hypothesised that the magnitude of mammal reintroduction effects would diminish with increasing aridity, which affects resource availability. We compared six paired sites inside and outside three reintroduction sanctuaries across an aridity gradient. We sampled termite assemblages using soil trenches and measured habitat availability. Reintroductions were associated with increased bare ground and reduced vegetation, compared with controls. Aridity also had an underlying influence on vegetation cover by limiting water availability. Termite abundance and biomass were lower where mammals were reintroduced and the magnitude of this effect decreased with increasing aridity. Termite abundance was highest under wood, and soil-nesting wood-feeders were most affected inside sanctuaries. Ecological cascades resulting from exotic predator invasions are thus likely to have increased termite biomass and altered termite assemblages, but impacts may be lower in less-productive habitats. Our findings have implications for reserve carrying capacities and understanding of assemblage reconstruction following ecological cascades.

Fish assemblage structure and spatial gradients of diversity in a large tropical reservoir, Panchet in the Ganges basin, India.

Fish assemblage structure in Panchet, a large tropical reservoir along river Damodar, major tributary of river Ganga in India, was studied along the spatial gradient of the impoundment. Fish samples were collected bimonthly from October 2014 to September 2016. Fish community structure in terms of species composition, relative abundance, and trophic and conservation status was recorded. Spatial fish diversity was analyzed from riverine, transitional, and lacustrine zones. Sixty-two fish species were recorded wherein the family Cyprinidae dominated in number of species (26) followed by Bagridae (5). Shannon diversity index, evenness index, and species richness did not reveal significant variation (p > 0.05) across different zones. Relative abundance of individuals and species richness were maximum in the transitional zone and minimum in the lacustrine zone. Multi-dimensional scaling of fish assemblage revealed similar pattern in the riverine and transitional zones. Trophic guild of fishes indicated dominance of carnivorous species followed by planktivores. Conservation status (IUCN 2017.3) showed 4 fish species in Near Threatened category. The study suggests conservation of fish habitats to maintain diversity and sustained production. The baseline information generated in the study will be beneficial for monitoring the alteration in fish assemblage, conservation of fish diversity, and management planning.

Effect of environment on spatio-temporal structuring of fish assemblages in a monsoon-influenced tropical estuary.

This study analyzes the trophic structure of fish assemblages in a well-mixed tropical estuary, Zuari, located in southwest coast of India. A total of 224 fish species were collected between September 2013 and August 2016 from 324 sampling events from 9 sampling stations using surface and bottom set gillnets. The sampling events were designed to cover three major seasons such as the pre-monsoon, monsoon, and post-monsoon. For each sampling event, abiotic variables such as temperature, salinity, dissolved oxygen, and transparency of the water were recorded. The data obtained for abundance of fish species was subjected to cluster analysis and non-metric multidimensional scaling. The results defined six spatio-temporally varying groups (clusters) within Zuari estuary. Canonical correspondence analysis demonstrated that temperature, salinity, dissolved oxygen, and transparency were important in determining the fish assemblages in Zuari. The estuarine resident species were abundant in the inner zone (riverine side) of the estuary, where the salinity and temperature recorded lower dimensions compared to middle and outer zones (marine side). However, the inner shallow zone of the estuary was not a preferred habitat for the migrating marine species. Majority of the fish species preferred middle and outer zones and post-monsoon and pre-monsoon seasons for inhabiting the estuary. The present study furnishes a reference data for the spatio-temporal dynamics of fish assemblages in tropical monsoonal estuaries.

First account of plastic pollution impacting freshwater fishes in the Amazon: Ingestion of plastic debris by piranhas and other serrasalmids with diverse feeding habits.

Reported here is the first evidence of plastic ingestion by freshwater fishes in the Amazon. Plastic bags, bottles, fishing gear, and other products are entering Amazonian water bodies and degrade into meso- and micro-plastic particles that may be ingested, either directly or indirectly via food chains, by fishes. Examination of stomach contents from 172 specimens of 16 serrasalmid species from lower Xingu River Basin revealed consumption of plastic particles by fishes in each of three trophic guilds (herbivores, omnivores, carnivores). Overall, about one quarter of specimens and 80% of species analyzed had ingested plastic particles ranging from 1 to 15 mm in length. Fourier transform infrared spectroscopy indicated 12 polymer types, including 27% identified as polyethylene, 13% polyvinyl chloride, 13% polyamide, 13% polypropylene, 7% poly(methyl methacrylate), 7% rayon, 7% polyethylene terephtalate, and 13% a blend of polyamide and polyethylene terephtalate. Dimensions of ingested plastic particles varied among trophic guilds, even though the frequency and mass of ingested particles were not significantly different among fishes with different feeding habits.

Breath rate of passerines across an urbanization gradient supports the pace-of-life hypothesis and suggests diet-mediated responses to handling stress.

The pace-of-life hypothesis predicts no impact of urbanization on stress responses. Accordingly, several studies have been inconsistent in showing differences in breath rate (BR), a proxy of acute stress responses to handling in passerines, between rural and urban areas. However, this evidence is limited to a single bird species and a limited geographic region (SW Europe). No study addressed whether this pattern is also apparent in other species or regions, such as in tropical environments, or whether it is dependent on the level of diet specialization, given that diet restriction and change influence stress responses. Here, we tested whether there were differences in BR between habitats and diet groups using eight highly diverse passerine assemblages experiencing different levels of anthropogenic disturbance (i.e., natural, rural, and urban locations) in SW China. We predicted that insectivores and herbivores (frugivores, nectarivores, and seed-eating species) would show higher BR than omnivores. We also predicted no differences in BR among habitat types. BR was a moderately repeatable trait, which showed a negative relationship with body mass and a positive relationship with the time of the day. We also recorded a relatively strong phylogenetic bias in the expression of this trait. Confirming our predictions, our results showed no differences in BR among natural, rural, and urban locations. Similarly, within species, there were no differences in BR between rural and urban locations. However, we also found that herbivores showed higher BR than omnivores. Overall, our results provide support to the pace-of-life hypothesis, but suggest acute stress responses can be diet-mediated, which may help to explain the marked decline of specialized trophic guilds around the world in response to anthropogenic disturbance.

Metal concentrations and risk assessment in water, sediment and economic fish species with various habitat preferences and trophic guilds from Lake Caizi, Southeast China.

Despite the potential emissions of heavy metal pollution in Lake Caizi due to extensive agriculture, urban growth and fishing activities, the risk posed by metal concentrations to aquatic environments and human populations has not yet been studied. In this study we compared the concentrations of Hg, As, Pb, Cd, Cr, Cu and Zn in water, sediment, and economic fish species with different habitat preferences and trophic guilds across important fishery areas in Lake Caizi, located on the northern shore of the Yangtze River, Southeast China. The concentrations of Cr in water were found approximately 6 times higher than the safety thresholds established by international legislation. Cr, Zn, As and Cd concentrations in sediments surpassed the background values for Yangtze River basin in Anhui Province. However, all the studied fish species in Lake Caizi had metal concentrations lower than legislation thresholds established by China and international organizations. Heavy metal concentrations were found to be significantly higher in demersal (inhabiting near the sediments) and piscivorous (possessing higher trophic level) fishes than in pelagic/benthopelagic (inhabiting the upper and lower water column) and herbivorous/planktivorous (possessing lower trophic level) fishes. Our finding demonstrated that the metal concentrations in fishes are simultaneously influenced by the habitat and bio-accumulation through the food chain. According to target hazard quotient (THQ) calculations for heavy metal contents in the muscles of fish species, all the determined heavy metals gave THQ values lower than 1, suggesting the inexistence of health risks from the intake of fishes from Lake Caizi.