Occurrence Of Fish Research Articles

Increase in mercury and methylmercury levels with depth in a fish assemblage

Despite their remoteness, deep-sea species bioaccumulate mercury, mostly in the form of the neurotoxin methylmercury (MeHg). Although the concentration of MeHg in the water column is known to increase with depth down to a maximum found at the base of the permanent thermocline, the knowledge of the relationship between MeHg content in marine species and their depth of occurrence is limited. We analyzed total mercury (THg) and MeHg concentrations in 25 species of fish inhabiting the Avilés Submarine Canyon and its adjacent shelf (Cantabrian Sea, North-East Atlantic) between 50 and 1868 m depth. THg concentrations ranged from 0.03 μg g−1 in wet weight (ww) in Chauliodus sloani and 4.0 μg g−1 ww in Coryphaenoides guentheri. 65% of the species analyzed exceeded 0.5 μg g−1 ww of MeHg, the maximum level for safe consumption recommended by FAO/WHO. THg and MeHg contents in muscle tissue increased with the depth of occurrence of fish and was influenced by their habitat so that demersal species had higher THg content than pelagic species inhabiting the same depth. MeHg accounted for an average 76 ± 3.9% of THg (mean ± SD), which is lower than that reported for other fish communities and can be explained by the high concentration of Hg present in sediments of the Nalón estuary, which discharges right off the Avilés Canyon head. The % of THg as MeHg was also strongly correlated with δ15N values, confirming that MeHg can be an indicator of the trophic identity of a species within the food web.

Drivers of phylogenetic structure in Amazon freshwater fish assemblages

AbstractAimPhylogenetic relatedness among species can provide useful information on the diversification history and past dispersal events that may have shaped contemporary assemblages. Here, using of the most comprehensive fish occurrence database currently available and a global molecular phylogeny of ray‐finned fishes, we evaluate the respective roles of historical and contemporary processes in generating and maintaining fish assemblage phylodiversity patterns among 97 sub‐drainages covering the Amazon River basin.LocationAmazon River basin.TaxonFreshwater fishes.MethodsUsing a large comprehensive database of freshwater fish species distributions, and a global molecular phylogeny of ray‐finned (actinopterygian) fishes, we estimated historical and contemporary environmental effects on sub‐drainage fish phylodiversity patterns using three phylogenetic metrics standardized for richness effect: Phylogenetic Diversity (ses.PD), Mean pairwise Phylogenetic Distance between species capturing patterns at older evolutionary timescales (ses.MPD), and Mean Nearest Taxon Distance capturing patterns at younger evolutionary timescales (ses.MNTD).ResultsWe found significant effects of elevation gradients, contemporary climate, and water types on assemblage phylodiversity patterns. Furthermore, we found significant relationships among the three phylogenetic metrics used, and between these metrics and the distance of sub‐drainages to the Amazon River mouth, representing the Amazon basin West‐East longitudinal gradient.Main conclusionsPhylogenetic diversity showed a highly non‐random spatial distribution across the Amazon basin. Beyond significant regional effects of several contemporary and historical drivers, there was a significant West‐East decline in sub‐drainage assemblages phylogenetic clustering, along with an increase in phylogenetic diversity. These latter patterns suggest deeper evolutionary divergences among taxa located to the East, and more recent radiations in the Western sub‐drainages. Based on these findings and given that assemblages are, on average more species‐rich in sub‐basins of the Western part of the basin than in their Eastern relatives, we conclude that Western Amazon can be seen as an evolutionary “cradle” of biodiversity for freshwater fishes.

IPODfish – A new method to infer the historical occurrence of diadromous fish species along river networks

Available information on diadromous fish species historical occurrences is generally biased and incomplete across species distribution range and spatial scales. This work aims to establish a new methodological framework (iPODfish – Inferring Past Occurrences of Diadromous Fish) to obtain a more complete representation of the historical occurrences of diadromous fish species over their full distribution range. The iPODfish is based on assumptions, rules and thresholds derived from the interplay between freshwater network features, diadromous fish species ecology and known historical occurrence. These are used to establish historical pseudo-occurrences at the segment scale, i.e., locations where the species was most likely to be present or absent. The methodology is expressed by a tree-like representation of a stepwise, information supported, decision process. It has five steps (separating main river segments from tributary segments; accounting for segments specificities; imposing the relative distance threshold; imposing the Strahler value threshold, and; establishing the sub-basin Strahler threshold), divides into two moments of application (main river followed by the tributaries) and establishes presences, pseudo-presences and pseudo-absences. The iPODfish can deal with multiple information sources, cope with data bias and provide a reliable consistent historical occurrence output at the segment scale for the known historical geographical range of the species. Despite its inference nature, iPODfish is still a conservative procedure leading to ecologically coherent outputs that may be applied to any diadromous fish species (with a relevant amount of historical data available) in any river network throughout the globe because the concepts and definitions used are general ecological features of diadromous and freshwater networks. The method outputs are applicable in biogeographical and/or macroecological studies using historical data and may prove useful to the management and conservation of diadromous fish species.

On the occurrence of the short-nosed tripod fish Triacanthus biaculeatus (Bloch, 1786) in the North of Basrah, Southern Iraq

In this article, we report on the occurrence of the short-nosed tripod fish Triacanthus biaculeatus (Bloch, 1786) in the North of Basrah, West of Al-Dair district which was not reported in this region before. Two specimens were obtained in November 2018 and identified as, T biaculeatus. They have a total length ranged from 69.0 to 137.0 mm. The first dorsal fin has 5 spines, the second spine is much less than half the length of the first one. The ventral surface of the pelvis is slightly tapered to words the posterior end.

Fish occurrence in the Kuban River Basin (Russia).

BackgroundThis publication describes a dataset containing information on 1328 occurrences of fishes in the Kuban River Basin, the longest river of Northern Caucasus and representing its own freshwater ecoregion (428 Kuban Ecoregion). All observations have precise geo-referencing with the names of water bodies (rivers, lakes etc.). The dataset is based on both literature data (509 occurrences) and our own sampling (814 occurrences). Observations were carried out between 1889 and 2020.New informationThe majority (> 61%) of occurrences in the presented data are published for the first time. This extended dataset contributes significantly to fish fauna survey in the Kuban River ecoregion.

A New Signal of Tropicalization in the Northeast Atlantic: The Spread of the Spotfin Burrfish Chilomycterus reticulatus in Madeira Archipelago and Its Invasion Risk

Current trends in the global climate facilitate the displacement of numerous marine species from their native distribution ranges to higher latitudes when facing warming conditions. In this work, we analyzed occurrences of a circumtropical reef fish, the spotfin burrfish, Chilomycterus reticulatus (Linnaeus, 1958), in the Madeira Archipelago (NE Atlantic) between 1898 and 2021. In addition to available data sources, we performed an online survey to assess the distribution and presence of this species in the Madeira Archipelago, along with other relevant information, such as size class and year of the first sighting. In total, 28 valid participants responded to the online survey, georeferencing 119 C. reticulatus sightings and confirming its presence in all archipelago islands. The invasiveness of the species was screened using the Aquatic Species Invasiveness Screening Kit. Five assessments rated the fish as being of medium risk of establishing a local population and becoming invasive. Current temperature trends might have facilitated multiple sightings of this thermophilic species in the Madeira Archipelago. The present study indicates an increase in C. reticulatus sightings in the region. This underlines the need for updated comprehensive information on species diversity and distribution to support informed management and decisions. The spread of yet another thermophilic species in Madeiran waters provides further evidence of an ongoing tropicalization, emphasizing the need for monitoring programs and the potential of citizen science in complementing such programs.

First record of the rendezvous fish, Polymetme corythaeola (Alcock, 1898), in the Mediterranean Sea

The occurrence of the rendezvous fish, Polymetme corythaeola (Alcock, 1898) in Mediterranean Sea is here reported for the first time. A single individual of this benthopelagic fish was caught in February 2020 during a scientific trawl survey. The specimen was collected at a depth of 369 m (upper slope) in the Gulf of Roses (Catalonia, north-western Mediterranean). This circumglobal species could have naturally expanded its distribution through the Strait of Gibraltar, but we cannot totally exclude that its Mediterranean occurrence has been overlooked thus far. This finding highlights the importance of continuous monitoring of Mediterranean deep-sea habitats for a better understanding of their diversity and ongoing transformation.

Tidal influence on fish faunal occurrence and distribution in an estuarine mangrove system in Ghana

This study assessed the effects of tidal stages and habitat conditions on nekton assemblage and distribution in the Kakum River estuarine mangrove system in the Central Region of Ghana. Teleosts and crustaceans were sampled using pole seine and cast net from a tidal mangrove pond and a channel, and characterised using morphometry and ecological guilds concept. In total, 1 146 specimens were collected, with 35 species from 19 families represented. The most abundant species encountered were Liza spp. (Mugilidae; 36%), Sarotherodon melanotheron (Cichlidae; 16%), Elops lacerta (Elopidae; 6%) and Sardinella aurita (Clupeidae; 5%), which exhibited pronounced spatial distribution. Sarotherodon melanotheron showed preference for ponds with minimal water flow and depth, Sardinella aurita occurred only in deeper sections of the mangrove channel with significant flow velocity, and Elops lacerta in the pond and all channel stations. Mugilids were found exclusively in the channel, whereas Palaemonidae (Macrobrachium macrobrachion and M. vollenhoveni) occurred in specific locations in the channel, with species- specific preferences for tidal stages. Most species encountered were identified to be predominantly marine migrants with bentophagous feeding habit. Site selection and tidal stages were found to affect the occurrence and distribution of fishes over a tidal cycle and interactively influence species diversity.

COMPARATIVE ANALYSIS OF GONADO-SOMATIC INDEX AND DOBRIYAL INDEX FOR DETERMINATION OF SEXUAL MATURITY IN NEMACHEILUS DENISONI DAY

Fishes exibit different types of spawning tendencies due to difference in habitat and climatic conditions of different regions. In order to achieve success in fish culture, it is important to assess the exact maturation period with fecundity of cultivable fishes. Studies on the maturation and spawning biology were conducted with the help of macroscopic observations (Gonado-somatic index and Dobriyal index), microscopic observations (development, Intra-ovarian maturity, occurrence of fish of various maturity stages during different months of the year and observations of mature and spent fishes) and also some field observations (observations of eggs and fry in the habitat).

Winter variability in the diets of groundfish inhabiting a subarctic sound with a focus on Pacific herring and walleye pollock piscivory

Piscivorous groundfish have been implicated as a major hindrance to Pacific herring (Clupea pallasii) population recovery within Prince William Sound, Alaska (PWS); however, the key piscivores have not been identified. To address this knowledge gap, groundfish were collected from PWS herring nursery fjords (2009–2012) during winter, a period when juvenile herring energy levels decrease, suppressing predator avoidance. Three species, Pacific cod (Gadus macrocephalus), walleye pollock (G. chalcogrammus), and big skate (Beringraja binoculata) were identified as key herring consumers based on diet frequency of occurrence. Their stomach contents were examined to document any variability in prey occurrences and to explore whether pollock or other prey types could mediate herring consumption. For Pacific cod, there was strong evidence of seasonality in herring consumption, with herring occurring in 7% and 50% of stomachs in November and March, respectively. Walleye pollock and big skate diets were more influenced by body size and longitude, respectively. Pacific cod consumed notably more adult herring (ages 3+) than the other piscivores, big skate consumed herring ages 3+ and younger, while walleye pollock was a major consumer of age 0 herring. As groundfish body size increased, all three species consumed larger, age 2+ pollock, suggesting pollock presence mediates herring overwintering mortality and that pollock cannibalism is an important dietary pathway in PWS. By identifying the key groundfish consumers of herring and pollock in PWS, and the spatial, temporal, and biological variables that influence the occurrence of these forage fishes in their diets, this research contributes to a larger body of knowledge seeking to explain the mechanisms responsible for their lack of recovery in PWS and offers novel insight into the importance of pollock as a forage fish in PWS.

HydroClim Data Portal: Cyberinfrastructure for providing high-resolution GIS modeled streamflow and water temperature data to researchers

Freshwater ecosystems play a key role in sustaining aquatic biodiversity. However, human alterations to watersheds and climate change are reducing critical habitat and the viability of populations of many aquatic species. The environmental changes have also had significant adverse impacts on water temperatures and streamflow. The changes in temperature and precipitation forecast over the next century are expected to affect the freshwater ecosystems and their biodiversity to an even greater extent than in the past. The aims of the HydroClim project are to provide openly accessible data on two key measures of stream conditions in the United States (US) and Canada for use in research, to increase public understanding of issues involving water resources, and to provide training opportunities for scientists who will be responsible for the conservation of freshwater biodiversity in the future. The project has used contemporary air temperature and precipitation data and future climate data from multiple Global Climate Model scenarios to generated high-resolution, spatially explicit, monthly streamflow and water temperature data for all watersheds across the US and Canada from 1950–2099 through multiple Soil and Water Assessment Tool (SWAT) hydrologic models. This presentation describes a cyberinfrastructure we developed for hosting the HydroClim data, consisting of a relational database and a web-based data portal that allows scientists to query and download the data. We have imported almost 1.9 billion HydroClim data records into the system. At the time of this submission, 1.3 billion records of historical data and predicted streamflow and water temperature model data are available in the HydroClim data portal for 26 watersheds in the United States. The HydroClim data are also being integrated with fish occurrence data from Fishnet 2, via the Fishnet 2 API (Application Programming Interface), which provides occurence data records for over 4.1 million species lots representing over 40 million specimens in ichthyological research collections. Our plan is to extract and merge environmental data from Hydroclim API, with fish occurrences containing geospatial information from the Fishnet 2 API, displaying the integrated data on web-based interactive hydrological maps in different time-series, and providing a tool for visualizing ecosystem diversity. The combined Hydroclim and Fishnet2 data can be used for ecological niche modeling applications, such as predicting the future distribution of threatened and endangered freshwater fish species. I will describe the cyberinfrastructure of HydroClim data portal and some of the ways the data can be used in biodiverisity research in the future.

Characteristics of the natural flow regime paradigm explain occurrence of imperiled Great Plains fishes

AbstractThe natural flow regime (NFR) paradigm posits that naturally occurring temporal fluctuations in streamflow are necessary for maintaining natural ecological communities. Conservation actions guided by the paradigm have contributed to stream organism conservation on a global scale, yet NFR applications in highly altered Great Plains streams are lacking. We analyzed historical (1980–2017) fish occurrence and flow data from sixteen gage locations across three Great Plains river basins with the goal of relating flow indices calculated for one year prior to each fish collection with the occurrence of fishes belonging to the highly imperiled pelagic‐broadcast spawning (PBS) reproductive guild. We fit random forest models using flow indices, gage identification, and watershed area as predictor variables and PBS fish occurrence as the response variable for all suspected or confirmed PBS fishes in each basin. Results revealed that flow indices from all NFR characteristics were useful for predicting PBS fish occurrence, but the identity of the most important flow indices varied by species and river basin. We also found that gage location was an important predictor variable, indicating flow–ecology relationships are spatially contingent and suggesting the influence of other factors that vary spatially (e.g., river fragmentation and water quality). Partial dependence plots identified thresholds in flow indices such as the timing of maximum flows and fall rate that may be associated with the presence or absence of PBS fishes, and these plots can be used to identify flow index target values to benefit conservation efforts. Time series predictions for likelihood of occurrence at a single gage in the Brazos River basin revealed a positive correlation between likelihood of occurrence and non‐drought years for three of four species present, supporting recent findings that drought suppresses PBS fish populations. This study provides insight into the flow requirements of some of the most imperiled stream fishes in North America and contributes to environmental flow science on a global scale by establishing a robust methodology for delineating flow–ecology relationships.

Evaluation of Classification Algorithms to Predict Largemouth Bass (Micropterus salmoides) Occurrence

This study aimed to evaluate classification algorithms to predict largemouth bass (Micropterus salmoides) occurrence in South Korea. Fish monitoring and environmental data (temperature, precipitation, flow rate, water quality, elevation, and slope) were collected from 581 locations throughout four major river basins for 5 years (2011–2015). Initially, 13 classification models built in the caret package were evaluated for predicting largemouth bass occurrence. Based on the accuracy (>0.8) and kappa (>0.5) criteria, the top three classification algorithms (i.e., random forest (rf), C5.0, and conditional inference random forest) were selected to develop ensemble models. However, combining the best individual models did not work better than the best individual model (rf) at predicting the frequency of largemouth bass occurrence. Additionally, annual mean temperature (12.1 °C) and fall mean temperature (13.6 °C) were the most important environmental variables to discriminate the presence and absence of largemouth bass. The evaluation process proposed in this study will be useful to select a prediction model for the prediction of freshwater fish occurrence but will require further study to ensure ecological reliability.

Obstetricians’ engagement for successful recruitment of participants in a randomized controlled trial promoting healthful fish consumption during pregnancy

BACKGROUND AND AIM: Human biomonitoring trials depend on the voluntary participation of citizens, who donate biological samples and personal information related to the investigated chemical exposures. Pregnant women are vulnerable to exposure to mercury, a potent developmental neurotoxicant. In Europe, the primary source of exposure to mercury relates to fish consumption. At the same time, fish consumption during pregnancy provides essential nutrients for optimal fetal brain and eye development. The benefits can outweigh the risks if suitable dietary advice is provided during pregnancy. METHODS: Cyprus, a small coastal Southeastern European country, used national data of fish consumption and mercury occurrence in fish to develop the first ever recommendations for Cypriot pregnant women. These are tested in the European “HBM4EU-mom” randomized control trial (10/2020 – 12/2021, Horizon2020 Programme Contract No.733032 ) with the involvement of 130 women of 18-45 years in a healthy singleton pregnancy, willing to eat fish. 15 trained obstetricians nation-wide recruit women under their care and take their hair sample during routine pregnancy appointments. RESULTS:Within one month, 78 pregnant women, corresponding to 60% of the recruitment target, were successfully recruited and provided hair samples. Virtually all women invited to join the study, consent to participation. Some women provide their informed consent at the time of invitation, while others review the information for participants at home and return the completed certificate of informed consent at the next scheduled meeting. Based on current data, it is predicted that the recruitment target will be reached within two months total. CONCLUSIONS:Recruitment of pregnant women and sampling by obstetricians is successful because it builds on the trust that the pregnant women feel towards their health care provider. It also overcomes obstacles due to the COVID-19 pandemic, creates educational opportunities for the doctors and facilitates the communication of personal results to the participants via their health care provider. KEYWORDS: Community-engaged research, Policy, Chemical exposures, Heavy metals, Exposure assessment, Pregnancy outcomes

New early Campanian characiform fishes (Otophysi: Characiformes) from West Texas support a South American origin for known Late Cretaceous characiforms from North America

Fossil characiform dentaries from the “Lowerverse locality” in the lower Campanian portion of the Aguja Formation of West Texas represent a rare Late Cretaceous occurrence of characiform fishes in North America. Two morphotypes are represented. Both of them exhibit ventrally encased, mandibular laterosensory canals and distinctive anterior lobes unique to the characiform symphyseal ‘hinge’. The first, dentigerous morphotype closely resembles fossil characiform dentaries from the Campanian Dinosaur Park Formation of Alberta, Canada. All of these are collectively referred herein to Primuluchara laramidensis gen et sp. nov. The second morph is edentulous as in extant curimatids and pertains to a different new species herein referred to Eotexachara malateres gen et sp. nov. Numerous Weberian vertebral centra recovered at Lowerverse suggest that characiforms were abundant in the coastal, subaquatic paleoenvironment here. The early Campanian age of the Aguja Formation characiforms supports previous temporal estimates regarding the arrival of characiforms in North America from either Europe or South America as inferred from previous molecular and/or paleontological studies. The presence of morphologically related, but geotemporally divergent species in Campanian strata of West Texas and Alberta indicates a south-to-north radiation among Laramidian characiforms and points to a southerly origin for ancestral forms. Santonian – Maastrichtian occurrences of characiforms in Europe suggests that they reached the limit of their dispersal there and were unable to invade southern Laramidia by the early Campanian. Whether the likely dispersal of characiforms from South America occurred via an archaeo- or telolimnitic progression remains unclear. However, it is plausible that euryhalinity played some role in their coastal dispersal.

Stressor controllability modulates the stress response in fish

BackgroundIn humans the stress response is known to be modulated to a great extent by psychological factors, particularly by the predictability and the perceived control that the subject has of the stressor. This psychological dimension of the stress response has also been demonstrated in animals phylogenetically closer to humans (i.e. mammals). However, its occurrence in fish, which represent a divergent vertebrate evolutionary lineage from that of mammals, has not been established yet, and, if present, would indicate a deep evolutionary origin of these mechanisms across vertebrates. Moreover, the fact that psychological modulation of stress is implemented in mammals by a brain cortical top-down inhibitory control over subcortical stress-responsive structures, and the absence of a brain cortex in fish, has been used as an argument against the possibility of psychological stress in fish, with implications for the assessment of fish sentience and welfare. Here, we have investigated the occurrence of psychological stress in fish by assessing how stressor controllability modulates the stress response in European seabass (Dicentrarchus labrax).ResultsFish were exposed to either a controllable or an uncontrollable stressor (i.e. possibility or impossibility to escape a signaled stressor). The effect of loss of control (possibility to escape followed by impossibility to escape) was also assessed. Both behavioral and circulating cortisol data indicates that the perception of control reduces the response to the stressor, when compared to the uncontrollable situation. Losing control had the most detrimental effect. The brain activity of the teleost homologues to the sensory cortex (Dld) and hippocampus (Dlv) parallels the uncontrolled and loss of control stressors, respectively, whereas the activity of the lateral septum (Vv) homologue responds in different ways depending on the gene marker of brain activity used.ConclusionsThese results suggest the psychological modulation of the stress response to be evolutionary conserved across vertebrates, despite being implemented by different brain circuits in mammals (pre-frontal cortex) and fish (Dld-Dlv).

Effects of human footprint and biophysical factors on the body-size structure of fished marine species.

Marine fisheries in coastal ecosystems in many areas of the world have historically removed large‐bodied individuals, potentially impairing ecosystem functioning and the long‐term sustainability of fish populations. Reporting on size‐based indicators that link to food‐web structure can contribute to ecosystem‐based management, but the application of these indicators over large (cross‐ecosystem) geographical scales has been limited to either fisheries‐dependent catch data or diver‐based methods restricted to shallow waters (<20 m) that can misrepresent the abundance of large‐bodied fished species. We obtained data on the body‐size structure of 82 recreationally or commercially targeted marine demersal teleosts from 2904 deployments of baited remote underwater stereo‐video (stereo‐BRUV). Sampling was at up to 50 m depth and covered approximately 10,000 km of the continental shelf of Australia. Seascape relief, water depth, and human gravity (i.e., a proxy of human impacts) were the strongest predictors of the probability of occurrence of large fishes and the abundance of fishes above the minimum legal size of capture. No‐take marine reserves had a positive effect on the abundance of fishes above legal size, although the effect varied across species groups. In contrast, sublegal fishes were best predicted by gradients in sea surface temperature (mean and variance). In areas of low human impact, large fishes were about three times more likely to be encountered and fishes of legal size were approximately five times more abundant. For conspicuous species groups with contrasting habitat, environmental, and biogeographic affinities, abundance of legal‐size fishes typically declined as human impact increased. Our large‐scale quantitative analyses highlight the combined importance of seascape complexity, regions with low human footprint, and no‐take marine reserves in protecting large‐bodied fishes across a broad range of species and ecosystem configurations.

Environmental DNA metabarcoding elucidates patterns of fish colonisation and co‐occurrences with amphibians in temperate wetlands created for biodiversity

Abstract Wetlands are biodiversity hotspots that provide several essential ecosystem services. On a global scale, wetlands have greatly declined due to human activities. To counteract wetland loss, created wetlands are used as a conservation tool to facilitate biodiversity and provide habitats mainly for birds and amphibians. Fishes are likely to colonise the created wetlands and potentially affect the diversity and occurrence of amphibians. Still, species occurrence data for fish in created wetlands are largely lacking. Using eDNA metabarcoding, we investigated occurrence and co‐occurrence patterns of fish and amphibian communities in 52 wetlands (some of which are ponds) created to benefit mainly bird and amphibian communities in south‐central Sweden. Altogether, 17 fish and five amphibian species were detected in the created wetlands out of the 32 fish and six amphibian species found in the regional species pool. Amphibians were less common in wetlands physically connected to other wetlands. Connected wetlands were more fish‐rich than isolated ones, suggesting potential fish avoidance. Additionally, the amphibian community occupied a narrower environmental niche compared to the fish community. Nevertheless, we observed only five statistically significant negative fish–amphibian species co‐occurrences (out of 14 species considered). Even though our results suggest amphibian avoidance/exclusion from the created biodiversity wetlands, they also show that fish and amphibians frequently co‐exist. Increased habitat heterogeneity in terms of water vegetation, size, shape, and structure of the wetland could be possible factors enabling the co‐existence of these two taxa. With this study, we contribute to the general knowledge of fish occurrence patterns in created biodiversity wetlands. By comparing the frequencies of fish occurrence in natural and created wetlands, we have shown that there was some mismatch in what is common in natural compared to created wetlands. This mismatch probably comes from species‐specific habitat requirements, stocking, and differences in detectability when using eDNA metabarcoding (small species detected) versus conventional multi‐mesh gill‐net methods (small species missed). Therefore, our results obtained using eDNA metabarcoding can complement the pre‐existing knowledge of amphibian and fish associations and increase our understanding of how to create wetlands to facilitate biodiversity of several taxa.

Hydroids (Cnidaria, Hydrozoa) from the Vema and Valdivia seamounts (SE Atlantic)

In this report, we analyse the benthic hydroids collected on the Vema and Valdivia seamounts during a survey conducted in 2015 in the SEAFO Convention Area, focused on mapping and analysing the occurrence and abundance of benthopelagic fish and vulnerable marine ecosystem (VMEs) indicators on selected Southeast Atlantic seamounts. A total of 27 hydroid species were identified, of which 22 belong to Leptothecata and only five to Anthoathecata. Monostaechoides gen. nov. was erected within the family Halopterididae to accommodate Plumularia providentiae Jarvis, 1922, and a new species, Monotheca bergstadi sp. nov., is also described. Campanularia africana is recorded for the first time from the Atlantic Ocean, and the Northeast Atlantic species Amphinema biscayana, Stegopoma giganteum and Clytia gigantea are also recorded from the South Atlantic. Three species were identified to the genus level only, due to the absence of their gonosomes. None of the reported species are endemic, and the hydroid community is clearly dominated by species with a wide geographical distribution in the three major oceans. Only Monotheca bergstadi sp. nov. presently has its distribution restricted to the Vema Seamount and the South African coast.

Landscape features and study design affect elements of metacommunity structure for stream fishes across the eastern U.S.A.

Abstract Metacommunity ecology includes connectivity in the investigation of local and regional processes to understand community assembly. The elements of metacommunity structure (EMS) framework classifies metacommunities into categorical archetypes based on patterns of three metrics indexing β diversity: coherence, turnover, and boundary clumping. Although the EMS framework is most commonly used to classify metacommunity types, an elements‐based approach of examining how factors affect each specific continuous EMS variable could provide a more mechanistic understanding of how metacommunities are structured at the landscape scale. Moreover, few studies have sought to quantify how methodological issues such as number and spacing of local communities affect observed outcomes of EMS‐based analyses. Using a large dataset of stream fish occurrences in the eastern U.S.A., we used mixed effects models to investigate how (1) landscape‐scale variables and (2) methodological issues such as number and location of sampling sites affect coherence, turnover, and boundary clumping individually; as well as (3) how landscape‐scale variables influence overall metacommunity patterns derived from the EMS framework. Coherence, turnover, and boundary clumping were related to temperature, density of dams, developed land use, and γ diversity. Interestingly, distance among sampled sites in metacommunities negatively affected turnover, and the number of sampling sites positively affected all three variables. Elevation affected overall observed metacommunity patterns, with metacommunities transitioning from Clementsian to clumped species loss patterns with increasing elevation. Our results suggest that metacommunity structure is affected by both natural and anthropogenic landscape‐scale variables. Observed metacommunity properties are also influenced by sampling density and site location within the catchment. Accounting for important natural, anthropogenic, and methodological issues will be critical for improving the inferential power of metacommunity analyses to begin understanding which landscape‐scale variables should be the focus of conservation and management of fish communities at a catchment scale.