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International audience; While many efforts have been devoted to understand variations in food web structure among terrestrial and aquatic ecosystems, the environmental factors influencing food web structure at large spatial scales remain hardly explored. Here, we compiled biodiversity inventories to infer food web structure of 67 French lakes using an allometric niche-based model and tested how environmental variables (temperature, productivity, and habitat) influence them. By applying a multivariate analysis on 20 metrics of food web topology, we found that food web structural variations are represented by two distinct complementary and independent structural descriptors. The first is related to the overall trophic diversity, whereas the second is related to the vertical structure. Interestingly, the trophic diversity descriptor was mostly explained by habitat size (26.7% of total deviance explained) and habitat complexity (20.1%) followed by productivity (dissolved organic carbon: 16.4%; nitrate: 9.1%) and thermal variations (10.7%). Regarding the vertical structure descriptor, it was mostly explained by water thermal seasonality (39.0% of total deviance explained) and habitat depth (31.9%) followed by habitat complexity (8.5%) and size (5.5%) as well as annual mean temperature (5.6%). Overall, we found that temperature, productivity, and habitat characteristics collectively shape lake food web structure. We also found that intermediate levels of productivity, high levels of temperature (mean and seasonality), as well as large habitats are associated with the largest and most complex food webs. Our findings, therefore, highlight the importance of focusing on these three components especially in the context of global change, as significant structural changes in aquatic food webs could be expected under increased temperature, pollution, and habitat alterations.

Urban black blooms that are primarily caused by organic carbon are deleterious environmental problems. However, detailed studies on the microbial characteristics that form urban black blooms are lacking. In this study, we observed the composition, diversity, and function of bacterial community in the overlying water and sediments during the occurrence and remediation of urban black blooms using high-throughput 16S rRNA gene amplicon sequencing analysis. First, we found that pivotal consortia in the overlying water increased significantly during the formation of black blooms, including the genera Acidovorax, Brevundimonas, Pusillimonas, and Burkholderiales involved in the degradation of refractory organics, as well as the genera Desulfovibrio, Dechloromonas, and Rhizobium related to the production of black and odorous substances. An RDA analysis revealed that chemical oxygen demand, dissolved oxygen, and oxidation reduction potential were related to the changes in microbial community composition. Furthermore, aeration was found to accelerate the removal of ammonia nitrogen and enhance the function of microbial community by stimulating the growth of order Planktomycetes during the remediation of black blooms, but aeration substantially damaged the microbial diversity and richness. Therefore, the health of the aquatic ecosystem should be comprehensively considered when aeration is applied to restore polluted waterbodies. Notably, we observed a large number of pathogenic bacteria in urban black blooms, which emphasizes the importance of treating domestic sewage so that it is harmless. Together, these findings provide new insights and a basis to prevent and manage urban black blooms.

International audience; Aquatic plants are crucial for the proper functioning of aquatic environments. So far, mixotrophy, widespread in aquatic microbial communities and in certain terrestrial plants, has been studied rarely in aquatic plants other than carnivorous ones. New evidence, particularly in Lemna and other close genera, suggests that mixotrophy is much more widespread than previously thought. Three processes could be involved, namely biotrophic associations, capture of prey (e.g., in carnivorous plants), and absorbotrophy (uptake of dissolved organic carbon). The latter process seems to be the most probable hypothesis in regard to the physiology of aquatic plants, but further research at both organism and cellular levels is needed to understand and clarify the processes involved and their importance. This opinion opens a new window of opportunity in aquatic ecology, with possible unsuspected applications in water management.

Climate warming is expected to alter the distribution, abundance, and impact of non-native species in aquatic ecosystems. In laboratory experiments, we measured the maximum feeding rate and critical thermal maximum (CTmax) of an invasive Eurasian fish, the round goby (Neogobius melanostomus), acclimated to a range of temperatures (18–28 °C) reflecting current and projected future thermal conditions for the nearshore Great Lakes. Fish were collected from four distinct populations along a latitudinal gradient from the western basin of Lake Erie to Hamilton Harbour (Lake Ontario) and the upper St. Lawrence River. Thermal tolerance increased with acclimation temperature for populations in Lakes Erie and Ontario. However, the St. Lawrence River populations had lower acclimation capacity and exhibited an unexpected decline in CTmax at the highest acclimation temperature. Maximum feeding rates peaked at 18–24 °C and declined with temperatures above 24 °C. Northern populations in the basin appear poorly adapted to elevated temperatures such that their performance and impact could be reduced by climate warming. Thermal response data from latitudinally distributed populations are needed to inform invasive species risk assessment.

According to the temperature-size rule, warming of aquatic ecosystems is generally predicted to increase individual growth rates but reduce asymptotic body sizes of ectotherms. However, we lack a comprehensive understanding of how growth and key processes affecting it, such as consumption and metabolism, depend on both temperature and body mass within species. This limits our ability to inform growth models, link experimental data to observed growth patterns, and advance mechanistic food web models. To examine the combined effects of body size and temperature on individual growth, as well as the link between maximum consumption, metabolism and body growth, we conducted a systematic review and compiled experimental data on fishes from 59 studies that combined body mass and temperature treatments. By fitting hierarchical models accounting for variation between species, we estimated how these three processes scale jointly with temperature and body mass within species. We found that whole-organism maximum consumption increases more slowly with body mass than metabolism, and is unimodal over the full temperature range, which leads to the prediction that optimum growth temperatures decline with body size. Using an independent dataset, we confirmed this negative relationship between optimum growth temperature and size within fish species. Small individuals may therefore exhibit increased growth with initial warming, whereas larger conspecifics could be the first to experience negative impacts of warming on growth. These findings help advance mechanistic models of individual growth and food web dynamics and improve our understanding of how climate warming affects the growth and size structure of aquatic ectotherms. Significance statement Predicting organism responses to a warming climate requires understanding how physiological processes such as feeding, metabolism, and growth depend on body size and temperature. Common growth models predict declining optimum growth temperatures with body size if energetic costs (metabolism) increase faster than gains (feeding) with body size. However, the generality of these features has not been evaluated at the within-species level. By collating data on fish through a systematic literature review, we find support for both declining net energy gain and declining optimum growth temperatures with body size. This implies large individuals within populations may be the first to suffer poor growth due to warming, with consequences for fisheries yield and food web structure in warmer climates.

Biological invasions are a major driver of biodiversity loss and socioeconomic burden globally. As invasion rates accelerate worldwide, understanding past invasion dynamics is essential to inform predictions of future invaders and impacts. Owing to a high diversity of pathways and current biosecurity gaps, aquatic systems near urban centres are especially susceptible to alien species establishments. Here, we compiled and compared alien species lists for three different aquatic recipient regions spanning the North Atlantic: Chesapeake Bay, Great Lakes-St. Lawrence River and North and Baltic Seas. Each system is a major trade centre, with a history of invasions, and characterised by a strong natural salinity gradient. Our goal was to compare the alien species across systems, to test for similarities in the taxonomic composition and geographic origin as well as species overlap among the three regions. We selected specific macroinvertebrate, algae and fish taxa for analysis, to control for uneven taxonomic and biogeographic resolution across regions. Cumulatively, we identified 326 individual alien species established in these aquatic systems, with the North and Baltic Seas most invaded overall (163), followed by Great Lakes-St. Lawrence River (84) and Chesapeake Bay (79). Most invasions were from Ponto-Caspian, Eurasian, Northwest Pacific, Northwest Atlantic and North American origins, and mostly comprised Arthropoda, Chordata, Mollusca and Annelida. However, origins and taxonomies differed significantly among destinations, with Ponto-Caspian species particularly successful invaders to the North and Baltic Seas then Great Lakes-St. Lawrence River, but less so to Chesapeake Bay. Nevertheless, approximately eight tenths of invaders established in only one region, indicating disparate invasion patterns and a high potential for future aliens to accrue from increasingly diverse source pools and pathways. These results support biosecurity strategies that consider a broad range of geographic origins and taxonomic groups to limit the translocation, arrival and spread of alien species worldwide.

Crayfish serve critical roles in aquatic ecosystems as engineers, omnivores, and prey. It is unclear how increasingly frequent extreme-flow events and warming air temperatures will affect c...

Limestone quarries are known to be places where the diversity of xerothermophilic organisms is promoting diversity and in some, there are water bodies that potentially support the presence of hydrobionts. These include dragonflies (Insecta: Odonata), which, as amphibiotic insects, use both aquatic and terrestrial habitats. The purpose of this paper was to determine whether there was a high diversity of odonatofauna in an old limestone quarry with well-developed aquatic habitats, located in an urban environment in the Central-European city of Krakow (S Poland). For this purpose, dragonflies in the quarry were monitored regularly, focusing on the reproductive status and relative abundance of each species. In 2017–2018, 37 species belonging to seven families of Odonata were recorded in the quarry, which is 50% of the Poland’s odonatofauna. Of these, 33 species were considered indigenous to the quarry. Among them, 30% were moderately urbanophobic or urbanophobic taxa. Habitat specialists made up 39% of the species. Some rare and declining species, i.e. Leucorrhinia pectoralis and L. rubicunda, were abundant at this site. The study shows that a well-preserved secondary habitat, located in the centre of a city and not subject to urban management, can support a high diversity of odonates. Such limestone quarries in highly transformed urban environments can be valuable sites for this indicator group of organisms and should be identified, evaluated and conserved.

Addressing the impact of dams and other water control structures on fish communities and aquatic ecosystems is a major concern for fisheries managers in the Laurentian Great Lakes. Although nature-like and technical fishways (i.e., vertical slot, pool and weir, Denil) and, when suitable, barrier removals have been implemented across the basin, these fish passage applications are vastly outnumbered by barriers to fish movement. Lowermost barriers are the first structure that blocks fish passage within a tributary; and, in the Laurentian Great Lakes, they present a unique situation where restricting access to upstream habitat is a major component of a half a century long strategy to control invasive sea lamprey Petromyzon marinus. Solutions for passage at lowermost barriers must therefore consider alternative management actions surrounding increased connectivity and invasive species control. These actions are underlined by the primary management objective of enhancing production/diversity of native and recreationally desirable fishes. This review surveys the current state of fish passage technologies deployed in the Laurentian Great Lakes and other fish passage solutions under development, providing a reference for resource managers making decisions about barriers and fish passage that are critical for invasive species control and fishery restoration.

The integrity of the homestead pond supply depends on how various macrobenthic communities make their living more diversified and contribute to complex food webs. In addition, the macrobenthic community are significantly used as indicator organisms to detect the pollution impacts in aquatic ecosystems. In this study, we show the data about the diversity and community structure of macrobenthos and their relationship with environmental variables in homestead ponds of Noakhali coast from January 2019 to August 2019. The current study yielded 17 species belonging to seven taxonomic groups with a mean density of 3630 ind./m2. The Nematode community, comprising 48.86% of the total taxonomic groups with Prionchulus sp. as the dominant macrobenthic species represented more than 31% of the total macrobenthic taxa, and showed a significant negative correlation with the value of salinity, DO, pH. The environmental variables and diversity indices were detected significant variations (P

Every pond has its own ecosystem, but the historical ponds have their unique identity. The historical ponds of Darrang district are not only important for historical perspective but also for socio-cultural aspect. Therefore, with the help of modern technology, we have examined the importance of the historical ponds. The historical pond data has been collected through an unstructured interview with local people and validation has been done through Google Earth and a topographic map of survey of India. Further, to understand the ecological relevance we have used the presence/absence method for wetland birds, reptiles, and amphibians. We have recorded thirty-seven species of waterfowl birds, four species of reptiles, and one species of amphibians. Further, we have identified few ponds that need immediate attention for ecological restoration for wetlands birds, mammals, and reptiles.

MDFRC item.December 2011. DOI: 10.1899/11-009.1 A publication output from S. Perryman PhD Thesis see (Microbial Community Structure and Function: The response of denitrifiers on an environmental gradient – stream urbanization - M/PER/28).Urbanization is an important ecological modifier of stream catchments and significantly alters C type and concentration and heavy metal input to aquatic systems. C and heavy metals are important determinants of microbial community structure (population dynamics) and function (physiological processes). Understanding how changes at the landscape scale affect key nutrient-transformation processes (e.g., denitrification) and C metabolism (e.g., methanogenesis) at the micro scale requires simultaneous determination of the structural and functional responses of bacterial communities. We compared total bacterial (16S ribosomal ribonucleic acid [rRNA] gene) and denitrifying bacterial (nosZ gene) community structures in sediments taken from an urban and a nonurban stream before and after C and Zn additions. Microcosms containing stream sediment were supplemented with either proteinaceous or leaf-leachate C, increasing the C content by 36 and 130 mg/L, respectively. C was added in the presence and absence of Zn addition (200 mg/kg). Changes in community function were determined simultaneously with additions by measuring the rates of CO2, N2, and CH4 accumulation in the headspace of each mesocosm. Site had the greatest effect on total and denitrifying bacterial community structures. Added C caused a small but significant change in total bacterial community structure, but did not change denitrifying bacterial community structure. C enrichment caused a significant and rapid change in community function. Rates of methanogenesis were significantly higher at the nonurban than at the urban site and were significantly affected by C type (significant site × C interaction). Denitrification and CO2 production were unaffected by C additions but differed between sites. Zn addition changed total bacterial community structure but not denitrifying bacterial community structure. Zn affected the rate of methanogenesis, but the effect size was less than for C type. Community structures remained different between sites at the end of the study despite exposure to Zn concentrations that reflected conditions in urbanized streams and C sources that mimicked those from urban or nonurban streams. Our study supports previous observations that microbial community structure is strongly influenced by prior sediment history. The broader implication is that landscape-scale changes like urbanization alter other physical and chemical properties of the stream sediment that influence community structure more than the Zn or C concentrations in our study.

Murray-Darling Freshwater Research CentreMDFRC item.Urbanization leads to degradation in water quality and has a major effect on the biota of streams, but its effect on microbial communities is not as well understood. DNA-techniques that target functional genes are being used to examine microbial communities, but less frequently applied to freshwater aquatic systems. Our aim was to determine whether terminal restriction fragment length polymorphism and sequence analysis of polymerase chain reaction-amplified (PCR) nosZ gene sequences could be used to show if there were measurable differences in the denitrifying community in two urban streams in catchments with contrasting degrees of catchment urbanization. Community structure in the sediments and associated riparian zones were studied at the contrasting sites. We showed that the denitrifying community in the sediments and riparian soils of the two streams were significantly different. There were also significant differences between the sediment and riparian zone communities within each of the sites. Terminal restriction fragment length polymorphism analysis proved to be a valuable technique that could resolve patterns of the denitrifying community in streams of contrasting degrees of urbanization, but sequence analysis was required to confirm the identity of the amplified products.

Environmental context Organic phosphorus can be one of the major fractions of phosphorus in many aquatic ecosystems. This paper discusses the distribution, cycling and ecological significance of five major classes of organic P in the aquatic environment and discusses several principles to guide organic P research into the future. Abstract Organic phosphorus can be one of the major fractions of phosphorus in many aquatic ecosystems. Unfortunately, in many studies the ‘organic’ P fraction is operationally defined. However, there are an increasing number of studies where the organic P species have been structurally characterised – in part because of the adoption of 31P NMR spectroscopic techniques. There are five classes of organic P species that have been specifically identified in the aquatic environment – nucleic acids, other nucleotides, inositol phosphates, phospholipids and phosphonates. This paper explores the identification, quantification, biogeochemical cycling and ecological significance of these organic P compounds. Based on this analysis, the paper then identifies a number of principles which could guide the research of organic P into the future. There is an ongoing need to develop methods for quickly and accurately identifying and quantifying organic P species in the environment. The types of ecosystems in which organic P dynamics are studied needs to be expanded; flowing waters, floodplains and small wetlands are currently all under-represented in the literature. While enzymatic hydrolysis is an important transformation pathway for the breakdown of organic P, more effort needs to be directed towards studying other potential transformation pathways. Similarly effort should be directed to estimating the rates of transformations, not simply reporting on the concentrations. And finally, further work is needed in elucidating other roles of organic P in the environment other than simply a source of P to aquatic organisms.

MDFRC item.Common carp Cyprinus carpio are a declared pest fish throughout the Murray-Darling Basin. Successful management of this highly-invasive species aimed at mitigating its detrimental effects on aquatic ecosystems is therefore a priority issue for wetland restoration and rehabilitation programmes for the benefit of native fish communities. As part of a large-scale, field-based experiment on carp impacts, a population of carp was extensively sampled from 2009 to 2011 at Brenda Park wetland (lower River Murray, South australia) under both drought and flooding conditions. A consistent young-of-year (YoY) cohort was present in the 2009–10 breeding season, indicating successful spawning within the wetland. However, the same cohort appeared not to leave the wetland later in the season, possibly as a result of drought-induced low-flow conditions. Conversely, there was no evidence for within-wetland spawning in 2010–11 and 2011–12. Following a major flood event in Summer/autumn 2011, a consistent stock-size (210–440 mm tL) component was present in the carp population. Despite one successful spawning event out of the three breeding seasons of sampling, it cannot be ruled out that Brenda Park can act as a recruitment hot-spot for carp, especially in light of the large-scale population dynamics of this species. Measures for wetland rehabilitation should account for this and rely on a combination of flow regulation practices, enhancement of native fish passage and integrated carp management/control measures involving use of selective traps or exclusion screens, removal programmes and, whenever feasible, water draw-downs.

Murray-Darling Freshwater Research CentreMDFRC item.

A need exists to understand how drought and its linked consequences threaten aquatic ecosystems and their associated biota in semi-arid countries, as climate change is predicted to increase the effects of these events. South Africa experienced one of the worst droughts in its history from 2015 to 2017 and, as a result, all but the permanent waterbodies of the lower Phongolo River floodplain (PRF) in northern KwaZulu-Natal dried up. This study examined the resilience of aquatic invertebrates associated with the PRF and what the colonization and succession trends of aquatic invertebrates would be once floodplain pools were to receive water again following a 2-year drought. Water and aquatic invertebrates were collected 11 times from nine field mesocosms over a 5-week period for chemical and biodiversity analysis, respectively. Zooplankton hatched from resting stages and macroinvertebrates colonized the mesocosms from nearby permanent waterbodies within the first week of inundation, suggesting that the drought had not affected the ability of aquatic biota to continue natural colonization and succession. Although the biota appeared unaffected, an extension of such a drought could lead to habitat fragmentation and total desiccation of permanent waterbodies, potentially causing the local extinction of aquatic populations and a loss of biodiversity.

New Zealand mud snails (Potamopyrgus antipodarum) were first introduced to the United States in 1987 and have subsequently invaded water bodies across the United States. At high densities, P. antipodarum can outcompete native fauna, disrupt community interactions, and alter ecosystem function, making them a threat to aquatic habitats worldwide. In this paper, we detail the invasion, population dynamics, and secondary production of P. antipodarum at seven sites in the Green River below Flaming Gorge Dam (0.8–49 km below the dam). New Zealand mud snails were first detected in the Green River in 2001. For more than a decade, densities of P. antipodarum in the Green River remained relatively low ( 19,000 individuals m−2. Annual secondary production estimates of P. antipodarum for the year 2016 ranged from

Global reduction in wildlife populations together with rising incidences of hormone-related disorders in humans are principally linked to chemicals that cause alterations in the endocrine system. The use of chemicals exhibiting hormonal disrupting properties has been significantly increased in the industrial, agriculture, and pharmaceutical sectors over the past few decades which poses a great threat to animal life and mankind. Endocrine disruptors; when enters the aquatic ecosystem; not only interfere with the aqua fauna but also with terrestrial and aerial animals linked directly or indirectly with water for food and other ecological interactions. The food chain and food web are responsible for transferring these chemicals to animals of different trophic levels. Several developmental, neurological, reproductive, metabolic, and immune disorders are the consequent effect of EDCs exposure to animals and humans. In the present communication, a detailed analysis of endocrine disruptors in aquatic systems, their impact on animals and human health has been done through the literature available in recent years. Several remedial measures to reduce EDCs levels have also been recommended.

Characterizing biological communities and knowledge on the distribution of biodiversity allows the assessment of ecological quality. This provides valuable information for conservation biology and monitoring purposes. While obtaining such data has been challenging in the past, environmental DNA (eDNA) sampling represents a promising tool to describe biodiversity on a broad taxonomic scale. In this study, we provide the first broad-scale biodiversity assessment for ten Neotropical water bodies in Nicaragua (a major river, two great lakes, and seven relatively young and small crater lakes) using eDNA sampling to determine how abiotic factors structure the distribution of prokaryotic and eukaryotic biodiversity across these environments. Further, we explored to what extent levels of biodiversity are associated across different taxonomic groups and environments. We found that prokaryotic and eukaryotic α-diversity was consistently higher in the great lakes (i.e., Lakes Nicaragua and Managua) as well as in Río San Juan compared with the young and small crater lakes. Differences of prokaryotic and eukaryotic communities (β-diversity) were significantly correlated, indicating that biological communities are similarly structured across environments. Accordingly, differences in salinity were correlated with prokaryotic and eukaryotic communities, whereas differences in dissolved oxygen were only correlated with prokaryotic communities (β-diversity). Yet, salinity and dissolved oxygen only affected prokaryotic α-diversity, suggesting different effects of these two abiotic factors on biodiversity within aquatic environments. Moreover, α-diversity of different phyla was positively correlated, although more strongly in prokaryotes, showing that biodiversity patterns are congruent across a broad range of lineages, particularly in prokaryotes. published

Freshwater systems are critical to life on earth, yet they are threatened by the increasing rate of synthetic chemical pollution. Current predictions of the effects of synthetic chemicals on freshwater ecosystems are hampered by the sheer number of chemical contaminants entering aquatic systems, the diversity of organisms inhabiting these systems, the myriad possible direct and indirect effects resulting from these combinations, and uncertainties concerning how contaminants might alter ecosystem metabolism via changes in biodiversity. To address these knowledge gaps, we conducted a mesocosm experiment that elucidated the responses of ponds composed of phytoplankton and zooplankton to standardized concentrations of 12 pesticides, nested within four pesticide classes, and two pesticide types. We show that the effects of the pesticides on algae were consistent within herbicides and insecticides and that responses of over 70 phytoplankton species and genera were consistent within broad taxonomic groups. Insecticides generated top-down effects on phytoplankton community composition and abundance, which were associated with persistent increases in ecosystem respiration. Insecticides had direct toxic effects on cladocerans, which led to competitive release of copepods. These changes in the zooplankton community led to a decrease in green algae and a modest increase in diatoms. Herbicides did not change phytoplankton composition but reduced total phytoplankton abundance. This reduction in phytoplankton led to short-term decreases in ecosystem respiration. Given that ponds release atmospheric carbon and that worldwide pesticide pollution continues to increase exponentially, scientists and policy makers should pay more attention to the ways pesticides alter the carbon cycle in ponds via changes in communities, as demonstrated by our results. Our results show that these predictions can be simplified by grouping pesticides into types and species into functional groups. Adopting this approach provides an opportunity to improve the efficiency of risk assessment and mitigation responses to global change.

Knowledge of the distribution and dissemination of antibiotic resistance genes (ARGs) is essential for understanding anthropogenic impacts on natural ecosystems. The transportation of ARGs via aquatic environments is significant and has received great attention, but whether there has been anthropogenic ARG pollution to the hadal ocean ecosystem has not been well explored. For investigating ecological health concerns, we profiled the ARG occurrence in sediments of the Mariana Trench (MT) (10 890 m), the deepest region of the ocean. Metagenomic-based ARG profiles showed a sudden increase of abundance and diversity in the surface layer of MT sediments reaching 2.73 × 10-2 copy/cell and 81 subtypes, and a high percentage of ∼63.6% anthropogenic pollution sources was predicted by the Bayesian-modeling classification method. These together suggested that ARG accumulation and anthropogenic impacts have already permeated into the bottom of the deepest corner on the earth. Moreover, six ARG-carrying draft genomes were retrieved using a metagenomic binning strategy, one of which assigned as Streptococcus was identified as a potential bacterial host to contribute to the ARG accumulation in MT, carrying ermF, tetM, tetQ, cfxA2, PBP-2X, and PBP-1A. We propose that the MT ecosystem needs further long-term monitoring for the assessment of human impacts, and our identified three biomarkers (cfxA2, ermF, and mefA) could be used for the rapid monitoring of anthropogenic pollution. Together our findings imply that anthropogenic pollution has penetrated into the deepest region of the ocean and urge for better pollution control to reduce the risk of ARG dissemination to prevent the consistent accumulation and potential threat to the natural environment.

Organism biomass, a continuous quantity, may be useful for general community and diversity assessment. Body length and biomass of benthic macroinvertebrates from two aquatic environments with different impact levels are determined in this study, classifying organisms using functional and taxonomic characteristics. Lyophilized benthic macroinvertebrate biomass was quantified to test for significant differences between an impacted and reference (less environmental impact) site. Results show that macroinvertebrate assemblages from the less impacted stream had higher average biomass than the assemblage from the perturbed site, and significant differences in biomass of Plecoptera, Trichoptera, predators, filterers and gills breathers were found between sites. The biomass signature was calculated for each analyzed scenario, weighting the presence of all specimens sampled considering the total biomass in a single regression curve equation. The cubic polynomial model had the best fit to the data. More background from theory to practice should be considered in biomonitoring research; hence we propose the application of macroinvertebrate biomass as an additional metric that will help evaluate the ecological status of streams, thus contributing to the knowledge of community-based biomonitoring of benthic macroinvertebrates.

A Comparative study was carried out in a pond of Tripura to observe the density and seasonal succession of rotifer and copepod fauna and the observation recorded 26 species of rotifer and 6 species of copepod fauna. Percentage composition of different families as well as percentage composition of each species in the recorded total rotifer and copepod fauna was also noted. Rotifer fauna showed maximum density in the winter and minimum density during summer. On the contrary, copepod fauna showed maximum density in the summer and minimum density in monsoon season. Rotifer fauna showed significant positive correlation with water temperature, free carbon dioxide, total alkalinity, nitrate-nitrogen, phosphate phosphorus and negative correlation with transparency. On the contrary, copepod fauna showed positive correlation with water temperature and pH and negative correlation with dissolved oxygen, total alkalinity and nitrate nitrogen. The observation infers that the densities of rotifer and copepod fauna varies with seasons which might be the dynamic nature of the aquatic ecosystem and might also be due to optimal condition in the water quality parameters of the studied pond ecosystem.

All animals carry specialized microbiomes, and their gut microbiota are continuously released into the environment through excretion of waste. Here we propose the meta-gut as a novel conceptual framework that addresses the ability of the gut microbiome released from an animal to function outside the host and alter biogeochemical processes mediated by microbes. We demonstrate this dynamic in the hippopotamus (hippo) and the pools they inhabit. We used natural field gradients and experimental approaches to examine fecal and pool water microbial communities and aquatic biogeochemistry across a range of hippo inputs. Sequencing using 16S RNA methods revealed community coalescence between hippo gut microbiomes and the active microbial communities in hippo pools that received high inputs of hippo feces. The shared microbiome between the hippo gut and the waters into which they excrete constitutes a meta-gut system that could influence the biogeochemistry of recipient ecosystems and provide a reservoir of gut microbiomes that could influence other hosts. We propose that meta-gut dynamics may also occur where other animal species congregate in high densities, particularly in aquatic environments.

The Sele Plain was once a marshy area that has recently been reclaimed. The analysis of skull and dental remains of small mammals, collected during the restoration of the Temple of Neptune, testifies the ancient existence of ecosystems that have now been greatly reduced in this area. In particular, the high percentage of remains of Arvicola italicus, a rodent that is now very rare throughout Italy, confirms the presence of aquatic environments.

Glaciers represent important biomes of Earth and are recognized as key species pools for downstream aquatic environments. Worldwide, rapidly receding glaciers are driving shifts in hydrology, species distributions and threatening microbial diversity in glacier-fed aquatic ecosystems. However, the impact of glacier surface snow-originating taxa on the microbial diversity in downstream aquatic environments has been little explored. To elucidate the contribution of glacier surface snow-originating taxa to bacterial diversity in downstream aquatic environments, we collected samples from glacier surface snows, downstream streams and lakes along three glacier-fed hydrologic continuums on the Tibetan Plateau. Our results showed that glacier stream acts as recipients and vectors of bacteria originating from the glacier environments. The contributions of glacier surface snow-originating taxa to downstream bacterial communities decrease from the streams to lakes, which was consistently observed in three geographically separated glacier-fed ecosystems. Our results also revealed that some rare snow-originating bacteria can thrive along the hydrologic continuums and become dominant in downstream habitats. Finally, our results indicated that the dispersal patterns of bacterial communities are largely determined by mass effects and increasingly subjected to local sorting of species along the glacier-fed hydrologic continuums. Collectively, this study provides insights into the fate of bacterial assemblages in glacier surface snow following snow melt and how bacterial communities in aquatic environments are affected by the influx of glacier snow-originating bacteria. This article is protected by copyright. All rights reserved.

Submerged aquatic vegetation (SAV) creates highly productive habitats in coastal areas, providing support for many important species of fish and wildlife. Despite the importance and documented loss of SAV across fresh to marine habitats globally, we lack consistent baseline data on estuarine SAV resources, particularly in the northern Gulf of Mexico (NGOM) estuaries. To understand SAV distribution in the NGOM, SAV biomass and species identity were collected at 384 sites inter-annually (June–September; 2013–2015) from Mobile Bay, Alabama, to San Antonio Bay, Texas, USA. Coastwide, SAV distribution and biomass were consistent across years, covering an estimated 87,000 ha, and supporting approximately 16 ± 1% total cover with an average biomass of 24.5 ± 1.9 g m−2. Differences in hydrology (i.e., precipitation, freshwater input, water depth) and exposure (i.e., wave and wind energy) manifested in unique SAV assemblages and biomass distributions across the region (i.e., Coastal Mississippi-Alabama, Mississippi River Coastal Wetlands, Chenier Plain, Texas Mid-Coast) and estuarine gradient (i.e., marsh zones defined as fresh, intermediate, brackish, saline). Descriptive cluster analyses identified indicator SAV species, known as medoid observations that represented combined salinity, turbidity, and depth conditions unique to different region and marsh zone combinations. While the presence of SAV is often used as an indicator of ecological health, identifying a medoid-based SAV indicator species in aquatic habitats can be used to describe estuarine conditions in more detail and develop aquatic habitat zones. Exploration and the use of this type of field data could be developed as a means to track, manage, and define aquatic habitats across regional and estuarine gradients and further develop ecosystem-based assessment and restoration activities. Identifying aquatic zones through a representative medoid associates SAV species with locations defined by both long-term salinity and salinity variability, water depth, and exposure, which is a powerful potential tool for managers and restoration decision-makers.