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Background: Mountain ecosystems are critical hotspots of global biodiversity, yet the dynamics of community assembly along their elevational gradients are not well understood. This gap is primarily due to the complexity of environmental and biotic interactions that influence species distribution and community structure. Although extensive research has been conducted on certain taxa, such as small mammals and bats, comprehensive studies encompassing entire mammal assemblages are lacking. Our research aims to bridge this gap by examining the taxonomic, phylogenetic, and functional diversity, as well as the assemblage structures of mammal communities across elevational gradients in the Central and East Himalayas, exploring how diverse ecological and evolutionary processes impact community assembly. Methods: We analyzed mammal elevational diversity patterns using species richness, functional diversity (FD), and phylogenetic diversity (PD). We compared the observed values of community structure, such as mean pairwise phylogenetic distance (MPD) and mean pairwise functional distance (MFD), with null-model corrected effect sizes to identify patterns and processes of community assembly. Using structural equation modeling and hierarchical partitioning, we investigated the relationships between climate, productivity, and various facets of diversity, describing the organization of each component across different elevations. Results: Taxonomic, functional, and phylogenetic diversity generally decreased with elevation but showed varied patterns such as mid-elevation peaks, low-elevation plateaus, or monotonic declines across different regions. Richness-controlled functional diversity increased towards mid-low elevations and decreased at higher elevations in both regions, whereas richness-controlled phylogenetic diversity lacked consistent patterns. Phylogenetic structures tended to cluster from mid to high elevations, indicating closer relationships than those observed in random communities, likely due to significant environmental turnover near tree lines. Functional structure showed greater clustering at high elevations and increased over-dispersion at lower elevations, suggesting that species are more functionally similar than expected at higher elevations and more diverse at lower elevations. Our results revealed that environmental factors, evolutionary histories, and trait-driven ecological processes collectively shape species richness along these gradients. Conclusions: Our results showed incongruent community structures across phylogenetic and functional diversity. Generally, functional traits are closely linked to environmental conditions, reducing the chance of observing traits that are misaligned with their surroundings. Species with similar ecological roles or distinct evolutionary lineages often show convergent adaptations to highland environments. Additionally, our findings emphasize that community assembly varies with the biogeography and diversification history of individual mountain ranges, complicating the development of a generalized theory. Using multiple measures is important for accurate community structure assessments and effective conservation planning, as variable elevational patterns exist across different diversity dimensions. [ABSTRACT FROM AUTHOR]

Ireland and Britain are two islands located at Europe's westernmost edge, both of which act as the final breeding outposts for many bird species within their European ranges. Despite their similar geographic locations and geological histories, Ireland and Britain host different breeding avifauna assemblages. Diversity profiles, which can serve as more robust alternatives to classic diversity indices, were employed in this study to explore disparities in the two islands' breeding avifauna assemblages. Variations in assemblages were explored, along with their potential drivers, through analyses at three levels: island‐scale breeding bird assemblage compositions, island‐scale diversity profiles considering 49 common breeding species, and habitat‐specific diversity profiles considering assemblages in east/central Irish farmland and East Anglian farmland. Analysis of the two islands' breeding avifauna assemblages revealed that the Irish assemblage is a complete subset of the British assemblage. Analyses of Irish and British assemblages at both an island scale and a habitat scale revealed patterns linking land use to trends within the two islands' avifauna assemblages. Irish assemblages contained greater proportions of insectivorous farmland species by abundance, while British assemblages contained greater proportions of seed‐eating farmland species; both trends appeared to be related to structural differences in agricultural land use on the two islands. The British and East Anglian assemblages exhibited higher diversity across all analyses, which appeared to be driven by the assemblages' higher relative abundances of species that were most genetically distinct. This study highlights the ability of diversity profiles to impart more information than classic diversity indices by incorporating species similarity data. [ABSTRACT FROM AUTHOR]

Copyright of Ege Journal of Fisheries & Aquatic Sciences (EgeJFAS) / Su Ürünleri Dergisi is the property of Ege Journal of Fisheries & Aquatic Sciences (EgeJFAS) / Su Urunleri Dergisi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Being a biologically diversed hotspot in the global marine ecosystem, the Beibu Gulf is inhabited by a high diversity of fish and serves as a vital fishing ground in China. Due to continuous overfishing, the fishery resource has drastically declined in the Beibu Gulf. However, information about the ichthyoplankton assemblages in this area is still lacking. In this present study, ichthyoplankton diversity, spatial and temporal distribution patterns, and assemblage structures were examined using the specimens collected in the late summer–autumn and winter of 2022 in the Beibu Gulf, and the relationship between ichthyoplankton assemblage and environmental variables was studied. A total of 117 ichthyoplankton taxa, belonging to 13 orders and 42 families, were recorded. The most abundant families were Gerreidae, Leiognathidae, and Sillaginidae in late summer–autumn, accounting for 38.74%, 27.95%, and 9.94%, respectively. Sparidae, Platycephalidae, and Sillaginidae were the most abundant families in winter, accounting for 34.03%, 17.15%, and 8.20%, respectively. Cluster analysis identified five assemblages in late summer-autumn and four assemblages in winter. The most characteristic species in each cluster were Terapon jarbua, Sillago sihama, Leiognathus brevirostris, Mene maculate, and Scomberoides tol in late summer-autumn and Scomberomorus commerson, Acanthopagrus latus, Sillago sp., and Evynnis cardinalis in winter. The results of the canonical correspondence analysis indicated that pH, chlorophyll-a (Chl-a), depth, dissolved oxygen (DO), sea surface salinity (SSS), total nitrogen (TN), and total phosphorus (TP) were the major environmental variables affecting the ichthyoplankton assemblage structure in the Beibu Gulf. The finding of this study will provide valuable information in conserving fish spawning grounds and developing fishery management practices to protect fishery resources in the Beibu Gulf. [ABSTRACT FROM AUTHOR]

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to specific microclimatic conditions and accumulation of organic matter, bird nests are microhabitats that are often inhabited by various invertebrates, including mites (Acari). We tested whether nests of the ground-nesting passerine Phylloscopus sibilatrix (Bechstein) (Passeriformes: Phylloscopidae) [wood warbler] were associated with an increased local diversity of ptyctimous mites (Acari: Oribatida) on the forest floor in the Białowieża National Park, East Poland. In 2019–2020, we analysed 150 warbler nests shortly after they had been vacated by the birds, and additionally we sampled mites in leaf litter at 1 and 6 m distances from 21 of the collected nests. We found on average more mite species in nests sampled in 2020 than in nests sampled in 2019. Although the species composition largely overlapped between bird nests and the litter, bird nests contained a greater average number of mite species than litter samples, including species found only – Microtritia minima (Berlese) and Phthiracarus crenophilus Willmann – or mostly – Euphthiracarus cribrarius (Berlese) and Phthiracarus globosus (C.L. Koch) – in bird nests. The results suggest that the presence of bird nests may increase the local diversity of the invertebrate species assemblage. [ABSTRACT FROM AUTHOR]

Riparian environments are characterized by a gradient of environmental factors perpendicular to the watercourse, as the habitat changes from terrestrial to aquatic. These areas are highly diverse in comparison with adjacent ecosystems specially in arid and semi-arid regions, a pattern that may not be as marked in other climates where humidity and nutrient gradients are not so abrupt. We aimed to evaluate the diversity of small mammals in riparian and nonriparian environments in an area of Atlantic Forest, as well as the association between habitat structure and small mammal assemblages. A survey was conducted between October 2018 and August 2019 by sampling 17 plots—8 in riparian areas and 9 in nonriparian areas. No differences were found in composition and abundance of small mammals between riparian and nonriparian environments, because habitat structure did not differ between these environments. However, small mammal assemblages were structured by habitat characteristics such as understory obstruction, fallen trunks, and altitude. Water deficits are not marked throughout the year in the study area, therefore there is no such distinction between riparian and nonriparian environments. The most important habitat characteristics for the small mammals were those that represent shelter and resources' sources. [ABSTRACT FROM AUTHOR]

Stream restorations are increasingly critical for managing and recovering freshwater biodiversity in human‐dominated landscapes. However, few studies have quantified how rehabilitative actions promulgate through aquatic communities over decades. Here, a long‐term dataset is analyzed for fish assemblage change, incorporating data pre‐ and post‐restoration periods, and testing the extent to which native assemblage stability has increased over time. In the late 1950s, a large capacity dam was installed on Putah Creek (Solano County, CA, USA), which altered the natural flow regime, channel structure, geomorphic processes, and overall ecological function. Notably, downstream flows were reduced (especially during summer months) resulting in an aquatic assemblage dominated by warm‐water nonnative species, while endemic native species subsisted at low levels as subordinates. A court‐mediated Accord was ratified in 2000, providing a more natural flow regime, specifically for native and anadromous fishes in the stream. The richness of nonnative species decreased at every site following the Accord, while the richness of native species increased or stayed constant. At the three most upstream sites, native species richness increased over time and ultimately exceeded nonnative richness. Native assemblage recovery was strongest upriver, closer to flow releases and habitat restoration activities, and decreased longitudinally downstream. Rank–abundance curves through time revealed that, while species evenness was low throughout the study, dominance shifted from nonnative to native species in the upstream sites coincident with rehabilitation efforts. Mean rank shifts decreased following flow rehabilitation; thus the assemblage became increasingly stable over time following flow rehabilitation. Putah Creek's rehabilitation may represent a model for others interested in improving endemic freshwater communities in degraded ecosystems. [ABSTRACT FROM AUTHOR]

Assemblage structure and acquisition of high‐value resources will usually be affected by changes in resource availability and differential competitive abilities of assemblage members. In fragmented habitats where carrying capacity limits are exceeded due to high population densities and biomass, interspecific interactions can be expected to occur at a high frequency, potentially turning into an important cost for coexistence. We studied assemblage‐ and guild‐level patterns of interspecific interactions in two highly diverse isolated primate assemblages in southern Amazonia. Specifically, we assessed the effects of temporal variation in fruit availability on the rates of interspecific interactions between gray woolly monkeys (Lagothrix lagotricha cana), one of the largest tree‐dwelling mammals of the Amazon forests, and nine syntopic primate species. We found that fruit availability positively predicted rate of intraguild interactions in contrast to overall assemblage interaction rate. We did not find statistical evidence for the effect of fruit availability on the assemblage rates of type‐dependent (i.e., agonistic or non‐agonistic) and context‐dependent (i.e., feeding or non‐feeding) interactions. However, there was a clear trend toward increased feeding‐related and agonistic‐related interactions as fruit availability increased, with agonistic interactions mostly occurring at guild‐level. These results provide support for a significant role of fruit availability in structuring spatial–temporal intraguild interactions at our study sites. Costly interspecific interactions and spatial habitat overlap can be expected to occur at a high frequency in highly diverse assemblages living in human‐modified landscapes, which in turn, can have potentially negative impacts to the species involved. [ABSTRACT FROM AUTHOR]

Monitoring the impact of fishing pressure on the Singhiya River is critical for resource development and sustainability, and the present situation is alarming and causing critical concern among the public. This study aimed to identify fish community trends over time and space in the river, and to investigate the impact of environmental variables on fish abundance and dispersion. Monthly fish sampling was performed from October 2020 to September 2021 from the 5th to 10th of each month. We used three cast nets of various mesh sizes (0.5, 2, & 4 cm) and monofilament gill nets with mesh sizes of 6, 8, & 10 cm. A total of 7,593 fish were collected, representing 61 species from seven orders, 20 families, and 37 genera. Similarity percentage (SIMPER) analysis revealed 78.8% similarity among six stations, with the primary contributing species: Puntius chola (28.2%), Puntius sophore (13.5%), Pethia ticto (5.33%), Chagunius chagunio (3.76%), Barbonymus gonionotus (3.69%), Puntius terio (3.46%), Opsarius shacra (2.2%), and Opsarius bendelisis (2.1%). Analysis of variance (ANOVA) on canonical correspondence analysis revealed that four of the seven selected environmental variables had significant relationship with the fish assemblage such as water parameters velocity, temperature, pH, and hardness. Overfishing and direct discharge of industrial waste into water resources may be the primary causes for the decline in fish diversity in Singhiya River. [ABSTRACT FROM AUTHOR]

The offshore waters of the Yangtze Estuary are an important fish habitat, and the large gradient of environmental conditions leads to different fish assemblages. We studied the spatial and temporal variations in fish assemblages and their relationships with environmental factors in the offshore waters of the Yangtze Estuary during the autumns of 2012–2016. The fish assemblage consisted of 64 fish species from 39 families, of which 6 species were dominant. There were significant interannual differences in fish abundance, biomass, and species composition, with the highest abundance and biomass in 2013, the lowest abundance in 2016, and the lowest biomass in 2015. Redundancy analysis revealed that total suspended particles and dissolved oxygen drove interannual variation in fish abundance, biomass, and species composition, and depth drove spatial variation in the fish assemblage. According to the depth, the fish were classified as shallow assemblage and deep assemblage. Understanding the spatial and temporal patterns of fish assemblage in the offshore waters of the Yangtze Estuary is beneficial to the conservation of fish and the sustainable use of fishery resources in the offshore waters of the Yangtze Estuary. [ABSTRACT FROM AUTHOR]

Coastal freshwater lakes are distinctive landscape features in South America, and benthic macroinvertebrates are key to their ecological functioning. Identifying the main factors driving the assemblage structure of benthic macroinvertebrate is thus important for the development of management strategies in these ecosystems. However, studies on the drivers of macroinvertebrate assemblages are scarce in subtropical coastal lakes of the Neotropical region. Here, we evaluated the role of environmental (morphometric and water chemistry variables) and spatial factors in the assemblage structure of benthic macroinvertebrates in 36 coastal freshwater lakes in Brazil from 2008 to 2015. Macroinvertebrate family richness increased with ammonium, pH and water transparency, and decreased with nitrate content (slope ≈1 for all significant variables). Environmental factors explained most of the variation in macroinvertebrate composition (16%) compared to spatial ones (3.4%). In specific, Dugesiidae, Hydrobiidae, Corbiculidae, Sphaeromatidae, Noteridae, Hydropsychidae, Culicidae and Ceratopogonidae predominated in lakes with lower conductivity (<100 μS/cm) and higher water transparency (>1 m). Spatial factors summarized differences in macroinvertebrate assemblages between isolated and connected lakes. Although none of the lakes studied are directly impacted by organic pollution, our results suggest that benthic macroinvertebrate assemblages in subtropical coastal lakes are mostly structured by water chemistry, likely reflecting the major trends in land use along the study region (transition from agriculture to urban areas). We recommend that the conservation of macroinvertebrate biodiversity in southern Brazilian coastal lakes focus on the monitoring of water chemistry factors associated with human‐based land use. [ABSTRACT FROM AUTHOR]

Estuaries, as important fish nursery habitats, usually include a variety of larval fishes of different ecological guilds and exhibit complicated changing environmental conditions. We carried out a survey to examine the spatiotemporal dynamics of different ecological guild larval fishes and their relationships with environmental factors in the springs and summers from 2018 to 2020 in the Yangtze Estuary (China). The aims of the study were to provide detailed information on the characteristics of the larval fish assemblage and to explore the spatiotemporal variation in different ecological guild species and the effects of environmental variables on assemblage structure. More than 140,000 fish larvae from 26 families and 99 species were gathered during the six cruises, with the spring being the most prolific. The assemblage was dominated by a few species and was divided into three ecological guilds. Engraulidae was the most abundant family, followed by Cyprinidae and Gobiidae. Hemiculter bleekeri (freshwater), Pseudolaubuca sinensis (freshwater), Coilia mystus (brackish water), and Engraulis japonicas (marine) were the predominant species. Seasonal variations in larval fish assemblage structure were closely influenced by temperature, and the fluctuation in salinity mainly determined the spatial distribution of the larval fish community. Freshwater flows also played an important role in shaping the larval fish assemblage structure and dynamics. The conclusions improve the understanding of the ecological dynamics of larval fish assemblages in environmentally heterogeneous areas and may be applicable to other estuary ecosystems. [ABSTRACT FROM AUTHOR]

Nonsessile animals could partition the use of resources in different axes, reducing the effects of competition and allowing coexistence. Here, we investigated the spatial and trophic niche dimensions in four lizard assemblages in the Neotropical semiarid Caatinga to investigate the determinants of resource use and the extent to which lizards partition their niches. We sampled each lizard assemblage once, for 10 days, in the dry season of 2017 and 2018. In two lizard assemblages, we detected nonrandom niche overlap patterns that were higher or lower than expected by chance. The high niche overlap patterns suggest that either there is intense current competition for available microhabitats or an abundance of microhabitats. The lower niche overlap may be influenced by the presence of species adapted to sandy habitats (psammophilous), suggesting that spatial partitioning detected has historical basis, which is supported by the pPCA results and by the lack of patterns in the realized niche distribution of species across niche space. We detected trophic niche partitioning in three lizard assemblages. In one assemblage, we discovered random spatial and trophic niche overlap patterns, revealing that competition is not a determining factor in the structure of that assemblage. In fact, phylogenetic effects were predominantly the main determinants of resource use in the four studied lizard assemblages. Arid and semiarid habitats cover about one third of land surface of the world. Comparisons between our findings and those from other regions of the world may aid identify general trends in the lizard ecology of dry environments. [ABSTRACT FROM AUTHOR]

French Guiana forests are threatened by increasing human activity such as infrastructure development, facilitating access to the forest and, therefore, logging, mining, farming and hunting. To highlight the impact of human pressure on the forest fauna, dung beetle assemblage was analyzed near Saint-Georges-de-l'Oyapock and compared with other sites in French Guiana, considering the distance to the main city and forest cover loss as proxies of human activities. Hill numbers and beta diversity were calculated. Non-metric multidimensional scaling and redundancy analyses were carried out to disentangle the effect of the distance to the nearest city and forest cover loss as proxies of human pressure, but also temperature and rainfall as proxies of climatic variations on dung beetle assemblage. Species richness increased significantly with the distance to the nearest city and decreasing forest cover loss. Assemblage structure varied among sites mainly with distance to the nearest city but also with rainfall. It varied also with forest cover loss, but not significantly. This study showed that human disturbances and climatic conditions, even if represented by proxies, affected dung beetle assemblage structures in French Guiana forests. [ABSTRACT FROM AUTHOR]

Life-history timing, trophic interactions, and colonization potential of stream benthos are linked to a stream's flow regime. Modifications to flow regimes often alter the composition of benthic assemblages. We assessed the impacts of relatively large storage dams (>15 m in height, >400-ha impoundments) on crayfish assemblages in southern Appalachian Mountain streams, Alabama, USA. We sampled crayfishes at multiple sites in flowing sections upstream and downstream of dams in 3 impounded streams and along similar lengths of 2 unimpounded streams in the Bear Creek and Cahaba River drainages. We analyzed at 2 scales: within and between drainages. This multi-scale approach allowed us to assess the effects of impoundments on crayfish assemblages in 1 drainage and then assess whether impoundment effects could be generalized across drainages. We compared crayfish assemblages between impounded and unimpounded streams and examined changes in crayfish assemblages with distance from impoundments, considering land-use history as a potential confounding factor. Adult densities averaged 45% higher, and sizes 10% smaller, in downstream sections of unimpounded streams compared with impounded streams. Densities and sizes of adults in upstream sections did not differ between unimpounded and impounded streams. In both drainages, unimpounded stream crayfish assemblage structure gradually shifted along the stream length, with species present upstream differing from those present downstream. Conversely, in all impounded streams, species assemblages did not differ between upstream and downstream sections, illustrating that dams diminish crayfish diversity. Nonetheless, finer-scale assessments showed that crayfish density and richness increased with distance downstream of impoundments. This suggests that assemblage recovery is possible with increasing distance downstream of impoundments. Additionally, we detected fewer crayfish assemblage differences between impounded and unimpounded streams in the Cahaba River drainage than the Bear Creek drainage. In the Cahaba River drainage, urbanization and the presence of an invasive crayfish species in both streams may have hindered our ability to distinguish impoundment effects on crayfishes. Our results show that large dams negatively affect crayfishes and may affect hundreds of crayfish species in thousands of stream km, possibly altering stream systems by interfering with the numerous ecosystem functions influenced by crayfishes. [ABSTRACT FROM AUTHOR]

The molluscan assemblages inhabiting the coastal waters of Oualidia Lagoon, Morocco, were studied during winter and summer of 2013. The taxonomic composition and diversity were determined at 43 sample sites. Thirty-four mollusc taxa were recorded in total, including 12 species of bivalves, 20 species of gastropods, 1 species of polyplacophoran and 1 species of cephalopod. Twenty-six of these species are reported here for the first time in Oualidia Lagoon. The gastropod Peringia ulvae and the bivalve Abra alba were the most abundant taxa in both seasons. The deposit-feeder trophic group was highly dominant in both seasons. A classification analysis revealed the existence of three main clusters from downstream to upstream in both seasons: a marine assemblage, a transition assemblage and a lagoon assemblage. Canonical correspondence analyses indicated that the main environmental variables governing the spatial distribution of the molluscs in winter are salinity, temperature and granulometry, whereas in summer they are salinity and granulometry. This study provides a good baseline for future ecological research. [ABSTRACT FROM AUTHOR]

Chironomids are the most common and abundant benthic invertebrate family in freshwater environments worldwide, but most studies on chironomid assemblages focus on presence/absence of species rather than abundance and community composition. This makes the assessment of chironomid assemblage composition and diversity limited in any physiographic zone and at any scale. This study enhances knowledge of chironomid abundance in rivers in Central Europe, which is typical part of the temperate climatic zone, and investigates chironomid (inter-)assemblage characteristics. Benthic assemblages of seven lowland rivers were sampled monthly over annual cycles with a total of 61 chironomid species detected. PCA was used to determine the environmental profile of the rivers at study sites, while cluster and ANOSIM analysis and univariate diversity indices were applied to the chironomid samples of the assemblages grouped at the river level to identify their similarities and differences. The environmental profile explained much of the cluster and ANOSIM-based patterns of the rivers' compositional distances, and also some values of given univariate diversity indices. SIMPER analysis distinguished a group of 14 species that explained almost 60% of differences between the assemblages. The contribution of each species of the group was similar, ranging between 6.13% and 2.87%, yet on average several times greater than that of each of the remaining 47 species. Univariate diversity values differed from index to index and from river to river, and indicated that the application of few such indices, particularly one, may be misleading. The N1 gamma diversity of the whole region (calculated from 82 samples) was 18.31 species, which was multiplicatively decomposed into the average alpha component of 4.04 species, and beta component of 4.53 assemblages. [ABSTRACT FROM AUTHOR]

Studies on ecological communities often address patterns of species distribution and abundance, but few consider uncertainty in counts of both species and individuals when computing diversity measures.We evaluated the extent to which imperfect detection may influence patterns of taxonomic, functional, and phylogenetic diversity in ecological communities.We estimated the true abundance of fruit‐feeding butterflies sampled in canopy and understory strata in a subtropical forest. We compared the diversity values calculated by observed and estimated abundance data through the hidden diversity framework. This framework evaluates the deviation of observed diversity when compared with diversities derived from estimated true abundances and whether such deviation represents a bias or a noise in the observed diversity pattern.The hidden diversity values differed between strata for all diversity measures, except for functional richness. The taxonomic measure was the only one where we observed an inversion of the most diverse stratum when imperfect detection was included. Regarding phylogenetic and functional measures, the strata showed distinct responses to imperfect detection, despite the tendency to overestimate observed diversity. While the understory showed noise for the phylogenetic measure, since the observed pattern was maintained, the canopy had biased diversity for the functional metric. This bias occurred since no significant differences were found between strata for observed diversity, but rather for estimated diversity, with the canopy being more clustered.We demonstrate that ignore imperfect detection may lead to unrealistic estimates of diversity and hence to erroneous interpretations of patterns and processes that structure biological communities. For fruit‐feeding butterflies, according to their phylogenetic position or functional traits, the undetected individuals triggered different responses in the relationship of the diversity measures to the environmental factor. This highlights the importance to evaluate and include the uncertainty in species detectability before calculating biodiversity measures to describe communities. [ABSTRACT FROM AUTHOR]

Copyright of Croatian Journal of Fisheries is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Documenting responses of biotic assemblages to coal‐mining impacts is crucial to informing regulatory and reclamation actions. However, attributing biotic patterns to specific stressors is difficult given the dearth of preimpact studies and prevalence of confounding factors. Analysing species distributions and abundances, especially stratified by species traits, provides insights into how assemblage composition shifts occur. We evaluated stream habitats and fish assemblages along a mining intensity gradient in 83 headwater (2nd‐ and 3rd‐order) streams of the upper Clinch and Powell river basins in Virginia. Our multivariate gradient (MINE.PC1) was based on percentages of watershed area covered by surface mine, underground mine and valley fill to represent spatial variance in mining intensity. MINE.PC1 was positively correlated with conductivity and percentage of substrate as cobble. Forty fish‐assemblage metrics were analysed via boosted regression trees to assess assemblage responses to mining intensity, while accounting for environmental variation and spatial structure among sites. Conductivity and MINE.PC1 were strongly negatively related to occurrences of Fantail Darter (Etheostoma flabellare) and sculpin (Cottus) spp. Several taxonomic, trophic and reproductive metrics of assemblage composition responded strongly to mining intensity or its instream correlates. For example, coal mining favoured omnivore‐herbivores, but inhibited invertivores, simple lithophils and nonsimple nonlithophils. We revealed distinct negative and positive responses to mining‐related stressors, which suggest changes to macroinvertebrate prey availability and/or contaminant loads contribute to fish extirpations in coalfield streams. Future assessments of mining impacts on fish assemblages could be more instructive by including characterisations of physicochemical stressors and regionally calibrated biotic metrics with demonstrated sensitivity to mining. [ABSTRACT FROM AUTHOR]

Invasive poeciliid fishes have been negatively affecting recipient ecosystems globally. However, the ecological consequences of their invasions can vary seasonally and spatially, and according to species, limiting our ability to predict their effects. It is also unclear how their impacts differ from those of native fishes. We compared the effects of the invasive mosquitofish (Gambusia affinis) and guppy (Poecilia reticulata) with those of the similar-sized native rice fish (Oryzias curvinotus) and half-banded barb (Puntius semifasciolatus) on invertebrate assemblages, primary-producer biomass, and nitrogen loadings in mesocosms during the wet and dry seasons in tropical Hong Kong. Invasive poeciliids and native fishes reduced invertebrate abundance and richness, and altered assemblage composition, but had no effects on algal biomass or nitrogen loadings. These outcomes were consistent between seasons, although the guppy effects on invertebrates were weaker in the cool dry season. The mosquitofish and the half-banded barb had the strongest influence on invertebrates, followed by the guppy, while rice fish had the smallest effects. This study adds to the scant knowledge of poeciliid invasions in tropical Asia. It reveals that invasives do not always have stronger impacts than native counterparts, and that invasive poeciliids differed in the intensity of their ecological effects. [ABSTRACT FROM AUTHOR]

Bird and mammal nests provide microhabitats that support a range of other species, including invertebrates. However, the variation between communities of nest-dwelling invertebrates in different nests is poorly understood. The major aim of this study was to analyze the assemblage structure of mites from the suborder Uropodina (Acari: Mesostigmata) and from superfamily Crotonioidea (Acari: Oribatida) inhabiting nests of the wood warbler, Phylloscopus sibilatrix (Aves: Passeriformes), located on a forest floor in Białowieża Forest, in eastern Poland. We also assessed the correlation between the nest material used by the birds with the assemblage structure of Uropodina mites, and compared the results with published studies of the nests of other birds and a mammal (common mole, Talpa europaea), and also with communities of mites inhabiting the soil. The field research was conducted in the strict nature reserve of the Białowieża National Park, a near-primeval European temperate forest. In 2019, immediately after the breeding period, 69 wood warbler nests and 439 soil samples were collected. Analyses revealed assemblages of Uropodina mites inhabiting the nests that consisted of 14 species, mostly common soil species. Only five species of oribatid mites from superfamily Crotonioidea were present in the nest material. Analyzed nests had a high percentage of tree leaves and grass blades, whereas moss was the least frequent component of the nest material. The Uropodina mites were more abundant in the nests that had greater amounts of grass blades, but similar relationships were insignificant for the nests with varying amounts of tree leaves or moss. The assemblages of Uropodina mites inhabiting wood warbler nests were very similar to those found in soil and nests of the common mole, but they lacked typical nest-dwelling species of Uropodina (i.e., specialized nidicoles). [ABSTRACT FROM AUTHOR]

A study on the patterns of richness, diversity and abundance of the Odonata from Santiago Dominguillo, Oaxaca is presented here. A total of 1601 specimens from six families, 26 genera and 50 species were obtained through monthly samplings of five days each. Libellulidae was the most diverse family (21 species), followed by Coenagrionidae (19), Gomphidae (4) and Calopterygidae (3). The Lestidae, Platystictidae and Aeshnidae families were the less diverse, with only one species each. Argia was the most speciose genus with 11 species, followed by Enallagma, Hetaerina, Erythrodiplax and Macrothemis with three species each and Phyllogomphoides, Brechmorhoga, Dythemis, Erythemis and Orthemis with two species each. The remaining 17 genera had one species each. Argia pipila Calvert, 1907 and Leptobasis vacillans Hagen in Selys, 1877 were recorded for the first time for the state of Oaxaca. We also analysed the temporal patterns of taxonomic and phylogenetic divergence for the Santiago Dominguillo Odonata assemblage: the Shannon diversity value throughout the year was 21.07 effective species, while the Simpson diversity was 13.17. In general, the monthly phylogenetic divergence was higher than expected for taxonomic distinctness, and lesser for average taxonomic distinctness. Monthly diversity, evenness and taxonomic divergence showed significant positive correlations (from moderate to strong) with monthly precipitation values. The analysis of our results, however, indicates that an increase in rainfall not only influences the temporal diversity of species, but also the identity of supraspecific taxa that constitute those temporal assemblages, i.e. there is an increase in temporal phylogenetic divergence. [ABSTRACT FROM AUTHOR]

Aim: For seabirds, food supplies and nest sites are largely driven by oceanographic gradients and island habitats, respectively. Research into seabirds' ecological roles in insular ecosystems is crucial to understanding processes that structure seabird nesting assemblages. We examined the influence of island physiography and oceanographic factors on the spatial variation in α‐ and β‐diversity of nesting seabird assemblages. Location: South‐eastern Pacific Ocean. Taxon: Birds. Methods: We compiled data from 53 seabirds breeding on 41 coastal and oceanic islands using different sources: our field records, online databases, environmental reports and literature. We used generalized linear models (GLM) to describe the effect of island physiography (area, elevation and isolation) and oceanographic factors (surface temperature, salinity and primary productivity) on seabird species richness (α‐diversity). We applied multivariate GLM to test the effects of physiographic and oceanographic predictors on species composition (β‐diversity). We used Jaccard dissimilarities on species occurrences per island to calculate β‐diversity partitioned into turnover and nestedness. Polynomial models allowed us to model these metrics against geographical and environmental gradients and so analyse patterns in seabird β‐diversity across spatial scales. Results: Species richness was highest in Galápagos, Pitcairn and Rapa Nui. Changes in seabird α‐diversity across islands were determined by island area and distance to South America but not by oceanographic variables. Physiographic and oceanographic factors were significant in determining β‐diversity. Changes in β‐diversity were mostly due to species replacement (β‐turnover) across three major island Systems (Galápagos Archipelago, Chilean coastal islands and oceanic islands of the south‐eastern Pacific). The contribution of β‐nestedness was restricted to small scales (within archipelagos). Main conclusions: Physiographic and oceanographic factors explain species diversity of seabird assemblages on islands of the south‐eastern Pacific. Oceanographic variables did not affect species richness but significantly influenced species composition. Change in species composition reflects gradients across three marine biogeographical realms: Temperate South, Eastern Indo‐Pacific and Tropical Eastern Pacific. The low degree of species nestedness may reflect multiple evolutionary origins. [ABSTRACT FROM AUTHOR]

Assemblage structure analysis was conducted based on seasonal fish species composition data collected four times a year during 2009–2013 from 10 stations around Korea (except the western coast of Korea) using set nets. A total of 154 fish species were identified, of which Trachurus japonicus (22.1%) was the most dominant, followed by Konosirus punctatus (9.2%) and Scomber japonicus (8.7%). Species richness was highest in Jumunjin (in the mid-eastern coast of Korea) and lowest in Gijang (in the east-southern coast of Korea), and species diversity was highest in Gangjeong (southern Jejudo Island) and lowest in Hanrim (northern Jejudo Island). Based on a Bray-Curtis similarity index value of 38%, the 10 stations were divided into three groups: group A comprised four stations in the eastern coast of Korea, group B comprised four stations in the east-southern coast of Korea and Jejudo Island, and group C comprised two stations in the westsouthern coast of Korea. One-way analysis of similarities showed significant differences among groups (global R: 0.822, p = 0.001). The characteristics of the sea currents (e.g., Tsushima Warm Current, North Korea Cold Current) and water masses (e.g., Yellow Sea Bottom Cold Water) might have influenced this grouping. [ABSTRACT FROM AUTHOR]

Human impacts on aquatic ecosystems are causing shifts in the composition and distribution of species, leading to subsequent changes in community structure. However, these changes may not be fully realised because of inadequate baseline information. In Texas, such baseline information is generally lacking for cryptic aquatic species such as unionid mussels, which will be likely to impede identification of impacted populations, potential causal factors, and the setting or achieving of management goals.The Navasota River, located in central Texas, is an exception, having been comprehensively surveyed more than 40 years ago, prior to large‐scale impoundment of this system. Hierarchical cluster analysis, nonmetric multidimensional scaling, and fuzzy set ordination were performed to compare assemblage structure from the 1975 survey to that of a recent survey in 2016 at similar sampling locations.Comparing sites based on the presence–absence of mussel species, we found no significant differences between the number of taxa and species present; however, we did find significant filtering of mussel life history strategies. Specifically, prior to impoundment, we found that mussel assemblages were filtered based on longitudinal patterns in life history strategy from taxa that are adapted to disturbed habitats to those favoured in more stable habitats with low environmental variation.However, following large‐scale impoundment after 1975, we saw a shift in the hydrologic regime towards consistent, homogenised flows and a shift in assemblage structure towards equilibrium species. This shift appears to represent a discontinuity, wherein river impoundment alters physical parameters of the hydrologic regime and these changes in turn modify biotic patterns and processes.Our results provide another example of how large dams can restructure mussel assemblages, highlight the importance of incorporating reference or baseline conditions wherever possible when evaluating the conservation status of aquatic biota, and provide further evidence for the use of life history theory and the serial discontinuity concept in predicting the consequences of flow alteration and river impoundment. [ABSTRACT FROM AUTHOR]

Natural barriers formed by avalanche deposits, landslides, and debris flows are commonly distributed along deep incised rivers where they block river channels and create diverse river habitats. However, little is known about the effects these naturally-occurring features have on the diversity of macroinvertebrate assemblages. We, therefore, conducted a field study to assess how α- and β-diversity of stream macroinvertebrates were influenced by these deposits. The Nujiang River (upper Salween River) basin in China has more than 200 debris-flow deposits in the 300-km long Grand Canyon reach. We assessed differences in environmental variables and macroinvertebrate assemblages among 5 habitat types, including portions of the main channel and tributaries without these deposits and 3 other habitat types associated with debris deposits. We calculated α-diversity for each habitat type as individual-based rarefied richness and β-diversity among sampled patches within each habitat type with the Whittaker Index. Generally, patches within the debris-flow deposits had lower α-diversity, density, and biomass compared with patches in the non-deposit reaches. These results indicate that the different habitat types in the debris-flow reaches had markedly different abiotic and biotic conditions than the non-deposit main channel reaches and tributaries. However, patches in the debris-flow deposits had higher β-diversity than non-deposit reaches. By creating diverse habitat types, the debris-flow deposits enlarged the environmental gradients for macroinvertebrate assemblages, which increased regional aquatic biodiversity. [ABSTRACT FROM AUTHOR]

Being an essential driving factor in dry grassland ecosystems, uncontrolled fires can cause damage to isolated natural areas. We investigated a case of a small-scale mid-summer fire in an abandoned steppe pasture in northeastern Ukraine and focused on the post-fire recovery of arthropod assemblages (mainly spiders and beetles) and vegetation pattern. The living cover of vascular plants recovered in a year, while the cover of mosses and litter remained sparse for four years. The burnt site was colonised by mobile arthropods occurring in surrounding grasslands. The fire had no significant impact on arthropod diversity or abundance, but changed their assemblage structure, namely dominant complexes and trophic guild ratio. The proportion of phytophages reduced, while that of omnivores increased. The fire destroyed the variety of the arthropod assemblages created by the patchiness of vegetation cover. In the post-fire stage they were more similar to each other than at the burnt plot in the pre- and post-fire period. Spider assemblages tended to recover their pre-fire state, while beetle assemblages retained significant differences during the entire study period. [ABSTRACT FROM AUTHOR]

Poyang Lake plays a significant role in maintaining and replenishing the macrozoobenthos biodiversity in the middle Yangtze River. However, due to human activities and natural factors, the habitat of Poyang Lake has been seriously degraded, resulting in a decline in macrozoobenthos biodiversity. Here, we analyzed the effect of human activity and environmental elements change on the diversity of macrozoobenthos based on a systematic investigation of Poyang Lake Basin in 2016–2017. The current species richness, density, and biomass of macrozoobenthos were lower than those in the historical period. At the same time, the community structure of the macrozoobenthos assemblage exhibits significant temporal and spatial differences. In addition, the spatial turnover component was the main contribution to beta diversity, which indicated that a number of protected areas would be necessary to conserve the biodiversity of macrozoobenthos. Water depth, dissolved oxygen, water velocity, and chlorophyll‐a were significantly correlated with macrozoobenthos distributions and assemblage structure based on RDA. These results indicated that human activities have seriously destroyed the macrozoobenthos habitat and led to the decline in macrozoobenthos diversity. Therefore, habitat restoration and the conservation of macrozoobenthos have become urgent in Poyang Lake Basin, and an integrated management plan should be developed and effectively implemented. [ABSTRACT FROM AUTHOR]

We contrasted near- and offshore zooplankton biomass and assemblage structure in 15 reservoirs in the central United States. In particular, we evaluated whether season and the dominant pelagic planktivore, Gizzard Shad (Dorosoma cepedianum), influenced near- and offshore zooplankton dynamics in reservoirs. Independent of Gizzard Shad, nearshore areas had greater zooplankton biomass in all seasons than did offshore areas. This difference was consistent for all cladocerans, copepods, rotifers, and all other zooplankton combined (including Chaoborus , ostracods, Trombidiformes, and mussel veligers). Gizzard Shad presence drove the spatial dynamics of major taxonomic groups, and time of year also influenced the structure of zooplankton assemblages. Additionally, Gizzard Shad presence was correlated with more copepod and rotifer taxa than cladoceran taxa. The relative distribution of these taxa at near- and offshore sites, however, remained consistent whether or not Gizzard Shad were present. Gizzard Shad had the most pronounced effect on zooplankton assemblage structure in the middle of the growing season. Mean annual zooplankton biomass per unit volume was approximately 50% greater in nearshore areas than in offshore areas for reservoirs with and without Gizzard Shad. Our findings, therefore, show that dominant planktivores can alter the assemblage structure and distribution of zooplankton in reservoirs, as they do in natural lakes. [ABSTRACT FROM AUTHOR]

To study how fish assemblages changed at different fillings stages, we compared the present fish assemblages (2015–2017; after the third filling in 2009) with those from periods prior to impoundment (1975), after the first closure (1997–2000), after the first filling (2005–2006), and after the second filling (2006–2009) in the upper, middle and lower sections of the Three Gorges Reservoir, the largest in the world. Our results demonstrated that species richness was higher in the upper section than in the lower and middle sections, whereas the overall richness was lower than that prior to damming. The present assemblages were different among sections associated with their specific habitats; i.e., the proportion of rheophilic fishes decreased, whereas those of limnophilic and eurytopic fishes increased from the upper to the lower sections. Temporal comparisons suggested significant declines in proportions of rheophilic and migratory fishes, whereas small‐bodied and eurytopic fishes increased after the impoundment. Fish biomass (CPUE) was greater in the upper section than in the lower and middle sections, and significantly increased after the third filling in the upper section. Overall, our results indicated that the Three Gorges Dam significantly impacted fish assemblages, and the effects of impoundment were magnified by the increased filling scales. The fish assemblages in the upper section were less impacted, demonstrating the high conservation value offered by the upper section to the fish species inhabiting the upper reaches of the Yangtze River. [ABSTRACT FROM AUTHOR]

This study describes the structure and temporal dynamics of brachyuran crab assemblages established in association with seaweed beds of two localities on the southeastern Brazilian coast. Collections were conducted each month over the course of 1 year from algal beds of Sargassum cymosum in a rocky intertidal zone on Grande (GR) and Domingas Dias (DD) beaches at low tide. A total of 1948 specimens (1115 in GR and 833 in DD) were obtained, which were distributed in six superfamilies, nine families, 13 genera, and 23 species. Epialtus bituberculatus was observed with highest density in GR (d = 5.97 ind./L) and DD (d = 12.10 ind./L), where it was observed in 100% and 91.7% of samples, respectively. Cross-correlations were observed between the volume of algae and richness in GR (1 lag time; r = 0.796; p <0.05) and between algae volume and density in DD (0 lag time; r = −0.595; p <0.05). Positive correlations were observed between algae volume at GR and volume at DD (0 lag time; r = 0.868; p <0.05), richness at GR and richness at DD (0 lag time; r = 0.761; p <0.05), and density at GR and density at DD (0 lag time; r = 0.690; p <0.05). Crab assemblages in the beds of Sargassum algae were diverse in both localities, represented by different taxonomic groups characterized by distinct lifestyles and feeding strategies. A temporal variation in the assemblage structure was observed between localities. This study shows that this temporal variation in crab assemblages may be related to seasonality in the structural complexity of algae beds as a result of bottom-up and top-down drivers acting on the algae. [ABSTRACT FROM AUTHOR]

The polychaete assemblages inhabiting the coastal waters of the Oualidia lagoon were studied during winter 2013 and summer 2013. Taxonomic composition and diversity were determined at 43 sample sites. Among the 13 species of polychaetes recorded, 10 were newly reported for Oualidia lagoon. Hediste diversicolor and Capitella sp. were the most abundant taxa in both seasons. Temperature and salinity were higher, and chl-a and OM were lower, in summer than in winter. The structure of the polychaete assemblages was characterized by forming three main clusters, either based on sampling stations or on polychaete species. These clusters were organized according to a downstream gradient, with the stations having fine sediments and a H. diversicolor assemblage in the inner lagoon being replaced by stations with medium grain-sized sediment and a Capitella sp. assemblage in the mid-lagoon, which were in turn replaced by stations having sandy sediments and assemblages dominated by Glycera alba (winter) and P. africana (summer) in the areas closer to the lagoon inlets. The shift was, in fact, from a classical, brackish, lacunar assemblage to two different, temporal aspects of a marine assemblage (close to the inlets), with a transition assemblage in between. This corresponded with a typically paralic spatial structure whose main descriptors responded to a confinement gradient. Despite the absence of a river, the organization of the polychaete assemblages closely resembled that of an estuarine system, with the tidal regime playing a major driving role. [ABSTRACT FROM AUTHOR]

Abstract: Global climate change is altering community composition across many ecosystems due to nonrandom species turnover, typically characterized by the loss of specialist species and increasing similarity of biological communities across spatial scales. As anthropogenic disturbances continue to alter species composition globally, there is a growing need to identify how species responses influence the establishment of distinct assemblages, such that management actions may be appropriately assigned. Here, we use trait‐based analyses to compare temporal changes in five complementary indices of reef fish assemblage structure among six taxonomically distinct coral reef habitats exposed to a system‐wide thermal stress event. Our results revealed increased taxonomic and functional similarity of previously distinct reef fish assemblages following mass coral bleaching, with changes characterized by subtle, but significant, shifts toward predominance of small‐bodied, algal‐farming habitat generalists. Furthermore, while the taxonomic or functional richness of fish assemblages did not change across all habitats, an increase in functional originality indicated an overall loss of functional redundancy. We also found that prebleaching coral composition better predicted changes in fish assemblage structure than the magnitude of coral loss. These results emphasize how measures of alpha diversity can mask important changes in the structure and functioning of ecosystems as assemblages reorganize. Our findings also highlight the role of coral species composition in structuring communities and influencing the diversity of responses of reef fishes to disturbance. As new coral species configurations emerge, their desirability will hinge upon the composition of associated species and their capacity to maintain key ecological processes in spite of ongoing disturbances. [ABSTRACT FROM AUTHOR]

Sponges harbor great diversity and an abundance of organisms. Although this community can vary temporally, and between and within sponge species, it is not known how an induced change in habitat-specific environmental conditions might affect the structure of macroinvertebrate assemblages associated with sponges. Here, a reciprocal transplant experiment of individuals of the estuarine sponge Halichondria melanadocia was conducted between two neighboring habitats (seagrass and mangrove prop root habitats) in the Southern Gulf of Mexico. Transplanted sponges experienced different hydrodynamic and light conditions. Multivariate analyses showed differences in community structure of associated assemblages among treatments, which were mainly driven by changes in the abundance of common species. Sponges moved from seagrass to mangrove habitat experienced a significant increase in abundance and taxonomic richness of 88 and 35%, respectively. Given that changes in the volume and aquiferous system (oscula diameter and density) of the hosts and in salinity were also recorded during the study period, it is concluded that the structure of the H. melanadocia-associated assemblages was not only influenced by the habitat change but also by other factors such as host morphology and short-term variations in the population abundance of associated organisms. [ABSTRACT FROM AUTHOR]

Prairie stream fish assemblages experience seasonal shifts in habitat conditions, often coupled with powerful disturbance regimes, where systems fluctuate widely between drought and deluge. These abiotic drivers, more often than biotic factors, structure fish assemblages. Scouring floods may reset stream communities to early successional seres, and droughts may progressively eliminate species from communities. Therefore, fish assemblage structure resilience depends on recolonisation and reproductive success following a disturbance. Many plains fishes have life history traits that facilitate the wide dispersal and immediate contribution of offspring following disturbance events. However, descriptions of temporal and spatial patterns in larval assemblage structure in prairie streams are scarce, and few studies evaluate the effect of disturbances on reproduction. The objectives of this research were to (i) study the timing and contribution of native prairie stream fishes to drifting larval fish assemblages in three eastern South Dakota basins (Vermillion, James and Big Sioux) and (ii) describe larval fish responses to floods in the James River. We sampled drifting larval fish diversity during the spawning season from 2010 to 2012 throughout each basin. We also examined the effect of flooding on larval fish assemblage structure using data collected near the confluence of the James and Missouri rivers during baseflow (2003, 2004 and 2012) and flood conditions (2010). Subtle variability in spawning traits of prairie fishes and an apparent seasonal progression of larval fish taxa that secondarily respond to disturbance regimes suggests reproductive efforts are adapted to maximise the potential for successful recruitment in these severe systems. [ABSTRACT FROM AUTHOR]

Copyright of Knowledge & Management of Aquatic Ecosystems is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Habitat degradation leads to biodiversity loss and concomitant changes in ecosystem processes. Tropical river floodplains are highly threatened by land cover changes and support high biodiversity and important ecosystem services, but the extent to which changes in floodplain land cover affect fish biodiversity remains unknown., We combined fish and environmental data collected in situ and satellite-mapped landscape features to evaluate how fish species with different ecological strategies and assemblage structures respond to deforestation in floodplains of the Amazon River. We surveyed 462 floodplain habitats distributed along a gradient of land cover, from largely forested to severely deforested. Rather than analyse only taxonomic metrics, we employed an integrative approach that simultaneously considers different aspects of fish biodiversity (i.e. β diversity and taxonomic and functional assemblage structure) to facilitate mechanistic interpretations of the influence of land cover., Spatial patterns of fish biodiversity in the Amazon River floodplain were strongly associated with forest cover as well as local environmental conditions linked to landscape gradients. Several species and functional groups defined by life-history, feeding, swimming/microhabitat-use strategies were positively associated with forest cover. Other species, including some that would usually be considered habitat generalists and species directly dependent on autochthonous resources (e.g. planktivores), were most common in areas dominated by herbaceous vegetation or open water habitats associated with the opposite extreme of the forest cover gradient. β diversity and the degree of uniqueness of species combinations within habitats were also positively associated with forest cover., Synthesis and applications. Our results demonstrating that spatial patterns of fish biodiversity are associated with forest cover, indicate that deforestation of floodplains of the Amazon River results in spatial homogenization of fish assemblages and reduced functional diversity at both local and regional scales. Floodplains world-wide have undergone major land cover changes, with forest loss projected to increase during the next decades. Conserving fish diversity in these ecosystems requires protecting mosaics of both aquatic habitats and floodplain vegetation, with sufficient forest cover being critically important. [ABSTRACT FROM AUTHOR]

Spring larval fish assemblages in the Strait of Georgia (British Columbia, Canada) were characterized for the first time based on three spatially extensive field surveys in late-April of 2007, 2009 and 2010, a period which spanned both warm and cold environmental conditions. The abundance, diversity and community structure of the assemblages were examined to investigate interannual variability, and responses to environmental fluctuations. A total of 49 taxa from 23 families were identified. The dominant taxa were Clupea pallasi, Gadus chalcogrammus, Merluccius productus, Leuroglossus schmidti, Lyopsetta exilis and Sebastes spp. Total larval abundance was much lower in 2009 (c. 32 per 1000 m3) than in 2007 and 2010 (c. 200 per 1000 m3). However, the mean size of individuals from several species was largest in 2009. Assemblage structure varied dramatically; from dominance by M. productus in 2007, to dominance by C. pallasi and G. chalcogrammus in 2009, followed by a shift to dominance by benthic species including Sebastes spp. and several flatfishes in 2010. Variability in assemblage structure among the three study years was primarily related to water temperature, whereas within-year patterns were more closely associated with salinity and chlorophyll, both of which were affected by estuarine circulation. This study provides baseline information about the status of the larval fish community in the Strait of Georgia in recent years, and offers a better understanding of their short-term dynamics and response to environmental fluctuations. [ABSTRACT FROM AUTHOR]

Mesophotic coral ecosystems (MCEs) extend from 30 to 150 m in depth and support diverse communities of marine organisms. We investigated changes in the structure of mesophotic reef fish assemblages (27-100 m) in the Northwestern Hawaiian Islands (NWHI) along depth and geographical gradients using open- and closed-circuit trimix diving. There were clear changes in the assemblage structure from the southeastern to the northwestern end of the NWHI and from shallow to deep waters. Interactive effects of depth and location were also detected. MCEs in the NWHI can be treated as three regions: southeastern and mid regions primarily separated by the presence and absence, respectively, of the introduced species Lutjanus kasmira, and a northwestern region where fish assemblages are largely composed of endemic species. These spatial patterns may be explained, at least in part, by differences in temperature among the regions. [ABSTRACT FROM AUTHOR]

Estuaries are recognised globally as areas of high production, diversity and high economic value. Exploitation of the economic potential of estuaries and attendant infrastructural development plus expansion of human populations has resulted in degradation of estuaries worldwide. Many estuaries of northern Australia, in contrast, remain in good ecological condition. The estuarine fish fauna of the South Alligator River, Kakadu region of northern Australia was investigated to determine seasonal and spatial variation in composition. Beam trawls were used at 94 locations over the wet and dry seasons of 2012. In total, 81 taxa were collected, 26 of which had not previously been recorded in the river. Sciaenidae and Engraulidae dominated species richness and abundance. Samples were heterogeneous in terms of composition and abundance in a manner unrelated to any measured aspect of the habitat over which trawls occurred. Species richness was higher in the lower estuary than the upper estuary and more species were detected during the wet season. Turnover in assemblage structure between sampling occasions was associated with seasonal variation in discharge concordant with changes in salinity and potentially productivity. Compositional variation was largely ascribed to differential spawning phenology of adults and tolerance to fluctuating salinity. The Kakadu region supports a rich fish fauna moderately distinct from that observed elsewhere in the Northern Territory. Pronounced temporal turnover in assemblage structure and spatial variation at a variety of scales (i.e. within samples, and within and between rivers) collectively pose a challenge to management in light of ongoing and proposed development of the water resources of northern Australia, including its estuaries. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Neotropical Mammalogy / Mastozoologia Neotropical is the property of Sociedad Argentina para el Estudio de los Mamiferos and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT Aim In ectotherms, the colour of an individual's cuticle may have important thermoregulatory and protective consequences. In cool environments, ectotherms should be darker, to maximize heat gain, and larger, to minimize heat loss. Dark colours should also predominate under high UV-B conditions because melanin offers protection. We test these predictions in ants (Hymenoptera: Formicidae) across space and through time based on a new, spatially and temporally explicit, global-scale combination of assemblage-level and environmental data. Location Africa, Australia and South America. Methods We sampled ant assemblages ( n = 274) along 14 elevational transects on three continents. Individual assemblages ranged from 250 to 3000 m a.s.l. (minimum to maximum range in summer temperature of 0.5-35 °C). We used mixed-effects models to explain variation in assemblage cuticle lightness. Explanatory variables were average assemblage body size, temperature and UV-B irradiation. Annual temporal changes in lightness were examined for a subset of the data. Results Assemblages with large average body sizes were darker in colour than those with small body sizes. Assemblages became lighter in colour with increasing temperature, but darkened again at the highest temperatures when there were high levels of UV-B. Through time, temperature and body size explained variation in lightness. Both the spatial and temporal models explained c. 50% of the variation in lightness. Main conclusions Our results are consistent with the thermal melanism hypothesis, and demonstrate the importance of considering body size and UV-B radiation exposure in explaining the colour of insect cuticle. Crucially, this finding is at the assemblage level. Consequently, the relative abundances and identities of ant species that are present in an assemblage can change in accordance with environmental conditions over elevation, latitude and relatively short time spans. These findings suggest that there are important constraints on how ectotherm assemblages may be able to respond to rapidly changing environmental conditions. [ABSTRACT FROM AUTHOR]

This paper presents results of the studies of ciliate assemblage in benthos of lowland river influenced by sewage discharged from the municipal wastewater treatment plant. During the presented research the 47 ciliate species, including 45 species from the benthos of the river and 18 from the activated sludge of aeration chamber were identified. Only two species registered in the activated sludge were not observed in the river. Against the background of the lowest number of species in the point located in the distance of 50 m below the discharge of sewage the maximum amount and biomass of these species were observed. Whereas, 200 m below the discharge the decrease in number and biomass of ciliate to the level noted for location before the discharge was observed. Thus, generalizing, one may state that influence of municipal WWTP sewage discharge for ciliate assemblage in the river's benthos was clearly visible but local. [ABSTRACT FROM AUTHOR]

This paper presents results of the studies of ciliate assemblage in benthos of lowland river influenced by sewage discharged from the municipal wastewater treatment plant. During the presented research the 47 ciliate species, including 45 species from the benthos of the river and 18 from the activated sludge of aeration chamber were identified. Only two species registered in the activated sludge were not observed in the river. Against the background of the lowest number of species in the point located in the distance of 50 m below the discharge of sewage the maximum amount and biomass of these species were observed. Whereas, 200 m below the discharge the decrease in number and biomass of ciliate to the level noted for location before the discharge was observed. Thus, generalizing, one may state that influence of municipal WWTP sewage discharge for ciliate assemblage in the river's benthos was clearly visible but local. [ABSTRACT FROM AUTHOR]

In the Tennessee River, USA, we examined lengthwise patterns in fish community structure and species richness within and among nine reservoirs organized in sequence and connected through navigational locks. Within reservoirs, the riverine, transition and lacustrine zones supported distinct, although overlapping, nearshore fish assemblages; differences were also reflected in measures of species richness. Spatial patterns were most apparent for rheophilic species, which increased in species richness and representation upstream within each reservoir and downstream across the chain of reservoirs. This pattern resembled a sawtooth wave, with the amplitude of the wave peaking in the riverine zone below each dam, and progressively higher wave amplitude developing downstream in the reservoir chain. The observed sawtooth pattern supports the serial discontinuity concept in that the continuity of the riverine fish community is interrupted by the lacustrine conditions created behind each dam. Upstream within each reservoir, and downstream in the chain of reservoirs, habitat characteristics become more riverine. To promote sustainability of rheophilic fishes and maintain biodiversity in impounded rivers, conservation plans could emphasize maintenance and preservation of riverine environments of the reservoir's upper reaches, while remaining cognizant of the broader basin trends that provide opportunities for a lengthwise array of conservation and management policy. Published 2015. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

The effects of riparian forest removal on a neotropical stream fish assemblage were assessed in the Mata Atlântica. Fish assemblage structure and fish feeding patterns were quantified at three sites along a pristine-to-deforested gradient in a Serra do Mar stream: (1) a pristine site fully covered by canopy with no light penetration and transparent waters, (2) an intermediate site with partially removed forest and (3) a fully removed forest site with no canopy and full light penetration where siltation and turbid waters predominate. Fish assemblage structure, fish densities and their feeding patterns differed widely among sites. Whilst the same five fish species occurred at the three sites, forest removal favoured the occurrence of sediment-tolerant iliophagous benthic species at the deforested site. At the pristine site, invertebrate prey predominated in water column fish diet and feeding overlap among species was low. Severe shifts in the feeding patterns were noticed in both deforested sites. Invertebrates were replaced by detritus, organic matter and algae at both sites and feeding overlap increased markedly. The overwhelming feeding adaptability of these neotropical fishes appeared capable of buffering the deleterious effects of forest removal on stream quality in terms of increased light penetration, siltation and water turbidity. Forest cutting in this Mata Atlântica stream clearly caused strong functional changes associated with forest clearance through important modifications in the assemblage organization and trophic patterns of the main species, but did not eliminate species. [ABSTRACT FROM AUTHOR]

The impoundment of running waters is a threat to freshwater mussels and has only been cursorily examined in Texas. To address this, we evaluate mussel assemblage structure in the Sabine River downstream of a flood control and hydropower reservoir. We use the serial discontinuity concept (SDC) and the Life History Continuum model (LHCM) to explain relationships between stream position (i.e., downstream distance from either dam) and mussel species richness, catch-per-unit effort (CPUE), and life history strategy. Using 90th, 85th, and 80th quantile regression models, we observed that mussel species richness and abundance were reduced for stream segments located near Lake Tawakoni and Toledo Bend Reservoir and that these reductions decreased with distance from either reservoir. We also observed significant shifts in life history composition of mussel assemblages depending on stream position from either dam. Opportunistic strategists were more abundant in reaches located immediately downstream of Lake Tawakoni and Toledo Bend Reservoir whereas periodic and equilibrium strategists were most abundant in reaches located at intermediate distances from either reservoir. Findings from this study confirm the negative impact large impoundments have on downstream mussel populations and demonstrate the value of using the SDC and LHCM for evaluating mussel response to river impoundment. [ABSTRACT FROM AUTHOR]

According to classic ecology, resource partitioning by segregation along at least one of the three main niche axes (time, food, and space) must take place for the coexistence of species with similar ecological requirements. We used nocturnal light traps to investigate the assemblage structuration of two moth families: Sphingidae (23 species) and Saturniidae (13 species). Because competition for food among adults potentially occurs only among sphingids, only for this family did we expect less overlap of diel activity patterns than expected by chance and also a greater temporal niche width compared to saturniids. Moreover, we expected a greater number of sphingid species pairs to differ in activity timing compared to saturniid pairs. We also hypothesized that in the case of a lack of temporal structuration, sphingids would be morphologically structured in relation to proboscis length. Contrary to what we expected, both families overlapped their activity patterns more than expected by chance alone and sphingid moths were not morphologically structured. Nevertheless, there were 173 significant pairwise differences in temporal activity between sphingids, contrasting with no interspecific differences between saturniids. Sphingid species also showed a wider temporal niche width than saturniids, as expected. Predation risk and abiotic factors may have caused the overall similarities in activity patterns for both families. The temporal niche seemed not to be determinant for the assemblage structuration of moths as a whole for either of the studied families, but segregation along the temporal niche axis of some potentially competing species pairs can be a relevant factor for the coexistence of nectar-feeding species. [ABSTRACT FROM AUTHOR]