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The upper Gulf of California is one of the most energetic regions owing to its tidal range and strong tidal currents, making the upper gulf and the archipelago zone highly turbulent regions; the abundance of zooplankton should be associated with mixing phenomena. We aimed to determine the latitudinal distribution of zooplanktonic organisms in this region and the influence of the islands on their distribution and abundance using historical data. Distribution of abundance followed the current patterns, the archipelago influences abundance favorably but does not affect diversity. Latitudinal zooplankton richness had a quasi-parabolic shape. A decrease in richness was observed at 27.5°N, in the archipelago region, with maximum richness at 26.5°N and 28.5°N. The distribution of latitudinal ranges is consistent with geometric constraints models; taxa with wide ranges are in the central area, while those with narrow ranges are near the boundaries and the Upper Gulf. Zooplankton responds in some way to the existence of the southern boundary as shown by the decrease of richness in this region. At the whole scale of the Gulf, the distribution of richness followed geometric constraints model, while at smaller scales, distribution and abundance are conditioned by the hydrodynamics of the Gulf. We compared zooplankton spatial distribution with Sea Level Anomaly, Sea Surface Temperature, and Chlorophyll-a concentrations from Copernicus to establish relationships between these factors. We performed Cluster and Redundancy Analysis to characterize similarities between stations in terms of biomass and taxon composition and to assess the importance of environmental variables on the distribution of zooplankton.

River water degradation arising from wastewater effluents is a major factor contributing to the deterioration of river ecosystems; yet direct evidence of the beneficial influence of long-term sewerage development on such ecosystems is scarce at a basin scale. The present study, over 12 years, examined changes in sewerage connection rate, water quality, and invertebrate assemblages at 10 study sites in the Shigenobu River, southwestern Japan, and investigated the relationships between them. Sewerage connection rates increased in the three main municipalities in the basin during the study period (range: 8.6%–31.4%). At the lowland sites, the concentration of total inorganic nitrogen (TIN) decreased by 38.9% on average and the richness metrics of invertebrate assemblages significantly increased at several sites. Furthermore, the richness metrics negatively related with TIN concentration, implying that invertebrate diversity recovery was the result of water quality improvement. Our findings strongly suggest that sewerage system improvement is an effective measure for restoring river ecosystems.

River water degradation arising from wastewater effluents is a major factor contributing to the deterioration of river ecosystems; yet direct evidence of the beneficial influence of long-term sewerage development on such ecosystems is scarce at a basin scale. The present study, over 12 years, examined changes in sewerage connection rate, water quality, and invertebrate assemblages at 10 study sites in the Shigenobu River, southwestern Japan, and investigated the relationships between them. Sewerage connection rates increased in the three main municipalities in the basin during the study period (range: 8.6%–31.4%). At the lowland sites, the concentration of total inorganic nitrogen (TIN) decreased by 38.9% on average and the richness metrics of invertebrate assemblages significantly increased at several sites. Furthermore, the richness metrics negatively related with TIN concentration, implying that invertebrate diversity recovery was the result of water quality improvement. Our findings strongly suggest that sewerage system improvement is an effective measure for restoring river ecosystems. [ABSTRACT FROM AUTHOR]

Freshwater biodiversity underlies severe threats, mainly suffering from habitat degradation by anthropogenic land use, in particular by urbanisation. However, recent long-term studies indicate recovery of stream macroinvertebrate diversity due to improved water quality at least in North America and Europe. We monitored macroinverbrates at 56 urban stream sites over a 12-year period (2009–2020) in Braunschweig, a German urban district. We utilised these data to investigate spatio-temporal changes in taxon richness and assemblage structure as well as factors potentially affecting the resulting patterns. Overall taxon richness was increasing over the study period, comprising both all taxa and taxa being indicators for healthy stream conditions. 53.6% of the sites had significant positive trends becoming most eminent since 2014, despite decelerating since 2018, the beginning of an extra-ordinary dry period. Only 10.7% of the study sites had negative trends. Assemblage structure was shaped by environmental factors like stream width and water quality. Over-average taxon richness including positive trends and higher numbers of indicator taxa of healthy stream conditions was found in streams with higher flow velocity, good saprobic conditions and more natural streambed structure. In contrast, low taxon richness and predominance of tolerant taxa were found in streams with more degraded conditions. Most of the environmental conditions having positive effects on taxon richness were improved by various programs set up by the environmental authorities. We therefore conclude, if urban stressors like organic pollution and structural degradation can be mitigated by revitalisation and water quality improvement, urban streams can have good potential for increasing biodiversity and improving ecological functioning.

We present a large-scale survey of mesozooplankton (size range 0.2–20 mm) across coastal, shelf, and slope locations in Northeast Greenland (latitudes 74–79° N, August 2015 and September 2017). Our study is centred on the Video Plankton Recorder (VPR) for non-invasive in situ observations of taxa distribution and abundance while simultaneously recording oceanographic profiles. A modified WP-2 plankton net (85-μm mesh size) was used primarily not only to verify taxa detected by the VPR but also to make a preliminary comparison of abundance estimates by the two gears. A total of 35 zooplankton taxa were identified with 10 genera alone among copepods (Hexanauplia). Selected taxa from the VPR (N=16) were associated with the temperature-salinity spaces and the chlorophyll a-depth profiles in the study area. From surface to > 900 m depth, the overall temperature and salinity ranged between −1.9 and 6.8 °C and 26.6 and 35.3, respectively. Two copepod genera dominated, i.e. Pseudocalanus prevailed in the upper sub-zero layers in coastal waters whereas Calanus was omnipresent, but mainly abundant in the warmer Atlantic waters at the shelf break. Chlorophyll a levels were in general very low (< 2 mg m-3) and peaked at 30–50 m depth, suggesting post-bloom conditions. Overall, zooplankton abundances tended to increase from the coast towards the slope (9–344×103 individuals m-2). Biodiversity in terms of taxon richness, on the other hand, showed the opposite trend and decreased from 16 taxa at the coast to 5 taxa further offshore. [ABSTRACT FROM AUTHOR]

Globally, freshwater systems are threatened by climate change, so projections under various climate change scenarios are needed to inform efforts to protect and conserve already vulnerable taxa.Here, the change in distribution of stream vertebrates was investigated under different greenhouse gas emission scenarios. Using occurrence data from multiple stream surveys in Washington State spanning 559 sites and 24 years, species distribution models for 23 aquatic vertebrate taxa (21 fish and two amphibians) were developed.Models projected changes in taxon distributions for 2070 under representative concentration pathways (RCPs) ranging from 2.6 to 8.5 W m−2. To assess potential biological impacts of these predictions, changes in taxon richness and beta diversity of stream vertebrates were also investigated. Moreover, predictor variables were examined to assess which ones were more important in determining taxon distributions.Substantial changes in the spatial distribution of stream vertebrates were projected for all RCP scenarios by 2070, but the greatest changes were expected to occur under RCP 6.0 and 8.5. The taxa evaluated were predicted to experience substantial increase, decrease, or shift in distribution.Taxon richness of stream vertebrates was forecasted to increase with RCP scenario relative to historical conditions, suggesting that distributional expansions outpaced distributional contractions. However, beta diversity was predicted to decrease considerably, suggesting increased biotic homogenization. Variables important for determining future distributions varied by taxa, with most species influenced by a combination of variables.These results indicate that failing to reduce greenhouse gas emissions will lead to dramatic impacts on stream vertebrates. The magnitude of predicted future impacts was dependent upon RCP scenario, so advancements in policy to reduce carbon emissions are necessary. We also recommend as potential conservation measures preserving cold‐water refugia and increasing efforts to lower stream water temperatures by, for example, expanding the riparian cover and/or linking surface water to groundwater. [ABSTRACT FROM AUTHOR]

Estimation of biodiversity patterns in poorly known areas is hampered by data availability and biased collecting efforts. To overcome the former, patterns can be estimated at higher taxonomic levels and larger spatial units. To deal with the latter, species distribution models (SDMs) can be employed. We explored the ability of higher-rank taxonomic units to surrogate patterns of species diversity at different aggregation levels and the use of SDMs to correct collection bias. We used Chile as a study case and employed three biodiversity measures (taxon richness, weighted endemism and turnover), four spatial aggregation levels or resolutions (100, 75, 50 and 25 km grid cells) and three taxonomic levels (species, genera and operational taxonomic units (OTUs)) to evaluate the spatial agreement of biodiversity measures. OTUs are monophyletic groups at the finest taxonomic resolution given the available phylogenetic information. We used a specimen database of 3684 species (84%) of the Chilean vascular flora and evaluated its redundancy. Agreement in spatial patterns was calculated using the fuzzy Kappa index. SDMs were generated for the three taxonomic levels to estimate taxon richness. For each spatial aggregation level, we calculated agreement between specimen-based and SDM-based richness and surrogacy among taxonomic levels with and without SDMs. Density of sampling for specimen-based data allowed for a resolution of 25 km before reaching a critical low redundancy value for all taxonomic levels. Genera and OTUs are good surrogates of species for all biodiversity measures, but their predictive power decreases with spatial scale. Agreement in richness patterns between taxonomic levels is greatest for SDMs at 100 and 75 km resolution, suggesting that biodiversity patterns are best estimated at 75 km resolution using SDMs for this data set. While these results cannot be extrapolated beyond the study area, this framework can be implemented in other data-deficient regions to describe biodiversity patterns and to choose the appropriate aggregation level for downstream biodiversity studies, such as spatial phylogenetics, where species-level data availability is a more generalized problem, since sequence data are normally available for only few species. [ABSTRACT FROM AUTHOR]

Freshwater biodiversity underlies severe threats, mainly suffering from habitat degradation by anthropogenic land use, in particular by urbanisation. However, recent long-term studies indicate recovery of stream macroinvertebrate diversity due to improved water quality at least in North America and Europe. We monitored macroinverbrates at 56 urban stream sites over a 12-year period (2009–2020) in Braunschweig, a German urban district. We utilised these data to investigate spatio-temporal changes in taxon richness and assemblage structure as well as factors potentially affecting the resulting patterns. Overall taxon richness was increasing over the study period, comprising both all taxa and taxa being indicators for healthy stream conditions. 53.6% of the sites had significant positive trends becoming most eminent since 2014, despite decelerating since 2018, the beginning of an extra-ordinary dry period. Only 10.7% of the study sites had negative trends. Assemblage structure was shaped by environmental factors like stream width and water quality. Over-average taxon richness including positive trends and higher numbers of indicator taxa of healthy stream conditions was found in streams with higher flow velocity, good saprobic conditions and more natural streambed structure. In contrast, low taxon richness and predominance of tolerant taxa were found in streams with more degraded conditions. Most of the environmental conditions having positive effects on taxon richness were improved by various programs set up by the environmental authorities. We therefore conclude, if urban stressors like organic pollution and structural degradation can be mitigated by revitalisation and water quality improvement, urban streams can have good potential for increasing biodiversity and improving ecological functioning. [ABSTRACT FROM AUTHOR]

Climate change is causing frequent and large floods, creating a need for information regarding the impact of severe flood disturbances on stream invertebrates. We briefly describe the response of invertebrate assemblages to an extreme flood event in 2018 in the western Ehime Prefecture of Japan. We compared invertebrate data collected in past regional-scale surveys with those gathered by revisiting 27 study sites after the flood and examined the relationship between catchment characteristics and the invertebrate response across the study area. Heavy rainfall was recorded in the catchment of each study site during the flood (range 565–1081 mm). Stream invertebrates may be eliminated by the historical flood, although the degree was small compared with that in previous reports on the effects of severe flood disturbances (abundance − 19.1%, taxon richness − 9.0%), likely owing to the absence of severe bed disturbance. Our results imply that high primary productivity, possibly caused by low elevations and the development of farms, accelerated the recovery of invertebrates after the disturbance. They also suggest that assembling pre-disturbance data is the key to understanding the impact of extreme floods on stream invertebrates and managing stream ecosystems during climate change. [ABSTRACT FROM AUTHOR]

For Rapa Nui (Easter Island) and its largest islet, Motu Nui, the change of the species assemblage over time was analysed, and a trait‐based approach to evaluate the potential losses in seabird function across the past centuries was applied. At a finer scale, the seasonal changes in seabird species composition in the current seabird assemblage was assessed to better understand the dynamics of the long‐term inferred patterns.For Rapa Nui, the composition of the seabird assemblage between the prehistorical, historical, and current time has changed significantly. The most critical change, probably associated with human colonization, was observed between prehistoric and current times. The current diminished number of nesting seabird species was probably the result of local extirpation without evidence of colonization by new species.For Motu Nui, changes in species composition were also followed by changes in trait structure, which were smaller than observed in Rapa Nui. This is probably due to the presence of a relatively high number of related species (i.e. Procellariids) with high similarities in their foraging behaviour.The nesting seabird assemblages in Rapa Nui and Motu Nui differ in exposure to risk; thus, conservation strategies applied to the islands should be planned on a fine spatial scale. For Rapa Nui, which is an urban wildlife area with several invasive species and a low number of remaining native seabird species, management should focus on fencing and pets control. For Motu Nui, management should instead focus on the establishment of quarantine and other biosecurity tools to avoid both the entry and proliferation of new invasive species. [ABSTRACT FROM AUTHOR]

Introduction: Eichhornia crassipes is a dominant aquatic plant of neotropical-river floodplains and is invasive in warm waters of different continents. Plants provide food and habitat for fish, especially Prochilodus lineatus and Gymnotus omarorum, which are relevant to subsistence fishing by local indigenous communities. Objective: In this study we describe the main traits of E. crassipes floating meadows, and analyze the abundance and composition of macroinvertebrate assemblages associated with their roots in two floodplain wetlands of the Paraná River (within the Ramsar site Wetlands Chaco) and of the Pilcomayo River (within the Pilcomayo River National Park). Methods: During spring and summer, the macroinvertebrates were collected in monospecific stands of E. crassipes with a net of 962 cm² area and 500 Îm mesh size. Leaf density, the biomass of leaves and roots, the length of leaves and roots, and the water quality were measured simultaneously. Results: Temperature, oxygen concentration, and nutrient content were significantly higher and electrical conductivity was lower in the Pilcomayo than in the Paraná floodplain. E. crassipes growing in the Pilcomayo floodplain had longer leaves and less root biomass than those found in the Paraná floodplain. The number of macroinvertebrates per 1 000 g root dry weight and per m² was significantly different between both floodplains, but the taxon richness was similar. Non Metric Multidimensional Scaling analysis differentiated the abundance of 14 selected taxa between both floodplains, and showed a high correlation between the environmental variables and macroinvertebrate abundance. The most abundant taxonomic groups in the Paraná River floodplain were oligochaetes (Naididae), ostracods mainly Cytheridella ilosvayi and larvae of non-biting midges (Chironomidae). Two families, Hydrobiidae (Heleobia parchappii) and Chironomidae accounted for 49.3% of the total abundance in the Pilcomayo floodplain. The prawns Macrobrachium jelskii and M. amazonicum, frequent in the Pilcomayo floodplain, were not found in the Paraná floodplain. Conclusions: The different environmental conditions in both floodplains affect the abundance, composition, and the dominance of macroinvertebrate assemblages; however, the total taxa richness was similar. The area occupied by E. crassipes in the floodplains of these rivers provides the habitat that contributes most to overall biotic diversity, which must be considered in management strategies. [ABSTRACT FROM AUTHOR]

Freshwater gastropods are imperilled globally and are among North America's most vulnerable major animal groups. Habitat loss, invasive species, and inadequate information about species distributions and assemblages all impair efforts to conserve freshwater gastropods. Conservation efforts are also impaired by difficulty obtaining and using distributional data for snails and other inconspicuous organisms, which are required to assess habitat associations.A gastropod‐specific sampling protocol was developed and used to survey 110 sites from 24 sub‐basins in two major river basins of the Intermountain West, USA. Habitat associations of individual taxa and groups of taxa that co‐occurred together more frequently than expected by chance were also examined.Using the gastropod‐specific sampling protocol, snails were found at most sites, even in regions where general macroinvertebrate sampling did not detect snails. Thus, these results show that general macroinvertebrate surveys do not accurately reflect the diversity of freshwater gastropods. Although snails of the same family are typically expected to live in the same habitats, this study found that in most cases, within a gastropod family, taxa exhibited unique habitat associations because they co‐occurred more frequently with taxa from different gastropod families. Five genera or sub‐genera were associated with specific mesohabitat or substrate types while two groups of co‐occurring taxa were associated with specific land classes or landform types.For diverse, inconspicuous taxa such as freshwater gastropods, qualitative, class‐specific sampling methods, and analyses of habitat associations based on co‐occurring taxa, rather than relatedness, should facilitate conservation efforts. [ABSTRACT FROM AUTHOR]

Species-area relationships (SAR) for aquatic invertebrates and phytoplankton were investigated in several shallow lakes from the Fizeș River catchment area. The lakes differed in their morphometric, physical-chemical, biotic and habitat characteristics, with two constant distinctive clusters: the lakes from the main river course, highly exploited for fish farming and generally characterized by higher organic and nutrient loads, and the lakes from the river tributaries, with better environmental conditions, increased depth and lower exploitation intensities. Lake area was a poor predictor of taxon richness for lacustrine invertebrates. Low-intensity exploitation regime, the presence of submerged vegetation, lake depth and natural land use in the catchment area represented the most important independent variables explaining the number of taxa for both planktonic and benthic invertebrates. In case of phytoplankton, however, lake area was an important predictor for taxon richness. Our results represent the first holistic approach to investigating SAR patterns of aquatic biota in natural and man-made lakes from the region. [ABSTRACT FROM AUTHOR]

The spatial distribution of benthic invertebrates is fundamental to the ecology of lakes and has implications for higher trophic levels and ecosystem processes. We conducted a lake-wide study of the spatial variation of benthic invertebrates in Lake Winnebago, Wisconsin (USA) with emphasis on the chironomid community. We asked: 1) What is the extent of spatial variation in benthic invertebrate community structure and abundance among and within major lake zones in the lake? 2) What factors are correlated with spatial variation of benthic invertebrates at multiple scales? 3) How has the chironomid community and the abundance of Chironomus varied temporally at the multidecadal scale in the lake? We collected benthic invertebrates from the profundal (33 sampling locations), offshore reef (17), and littoral (15) zones in August 2013. Profundal locations were sampled again in August 2014. Habitat variables, including water depth and temperature, Secchi depth, and benthic organic matter were measured with the goal of investigating potential causes of variation in the biota. The highest mean invertebrate densities occurred in the offshore reef and littoral zones (13,987 and 10,638 individuals [ind]/m2, respectively), relative to the profundal zone (2103 ind/m2). Zebra mussels were the numerically dominant taxon in both the littoral and offshore reef zones, whereas chironomids were the most abundant macroinvertebrates in the profundal. Large differences in chironomid community composition occurred among the 3 major zones. Within the profundal zone, the pattern of spatial variation in total chironomid abundance differed between the 2013 and 2014 sampling events. Local factors (e.g., sediment characteristics) and stochastic factors (e.g., wind and current speed) probably interact to influence the spatial distribution of chironomid taxa between and within zones in large shallow lakes, such as Lake Winnebago. [ABSTRACT FROM AUTHOR]

Changes in zooplankton community structure and function were analyzed in 24 lakes covering a wide salinity gradient (from 0.5 to 115 g l−1) in a semiarid region in northwest China. We hypothesized that species richness (S), species diversity (H), functional diversity (FD), biomass, and size of zooplankton would decrease with increasing salinity. We found that S, H, and FD did decrease with increasing salinity, whereas zooplankton sizes, size range, and biomasses did not. In fact, the sizes of microcrustaceans were mainly regulated by the abundance of small fish. Besides the impoverishment of FD, the zooplankton functional groups also varied along the salinity gradient. A shift occurred from selective raptorial to more generalist microphagous rotifers, from selective to more generalist filter feeder cladocerans, and from dominance of microphagous herbivorous copepods to microphagous carnivores. Our study indicates that the ongoing salinization of lakes with climate warming will result in important changes in the zooplankton, affecting not only the structure but also the functioning of this community. A weakened top-down control by zooplankton on phytoplankton at moderate high salinities may be an indirect consequence, leading to a worsening of eutrophication symptoms. Loss of fish at high salinities may, however, counteract this effect. [ABSTRACT FROM AUTHOR]

We investigated differences in the abundance, community composition and taxon richness of sublittoral macroinvertebrates in boreal lakes containing introduced invasive signal crayfish ( Pacifastacus leniusculus) or native noble crayfish ( Astacus astacus). We hypothesised that sublittoral macroinvertebrate assemblages in lakes containing noble crayfish, which reportedly prefer the shallow littoral, would differ little from those in lakes without crayfish, in contrast to assemblages in lakes containing signal crayfish, which reportedly forage at greater depths., In a set of 24 small and medium-sized Finnish lakes, eight lakes contained signal crayfish, eight had noble crayfish and eight control lakes had no crayfish. At three sites per lake, we sampled macroinvertebrates quantitatively from soft sediment in the sublittoral., The sublittoral macroinvertebrate assemblage in lakes with noble crayfish and control lakes was similar. In contrast, lakes with signal crayfish had a lower density of Trichoptera and Ephemeroptera, as well as a lower density and species richness of Chironomidae, and a lower overall benthic density and taxon richness., In contrast to some previous reports from other habitats, we infer that introduced signal crayfish have stronger negative effects than native noble crayfish on sublittoral macroinvertebrates. Hence, the ecological equivalence or differences of crayfish species cannot be generalised across habitats. [ABSTRACT FROM AUTHOR]

We analyzed the taxon richness and endemism of tortoises and freshwater turtles in the world's premier biodiversity conservation priority areas and countries with greatest turtle richness. Turtle hotspots include biodiversity hotspots (BHS), high-biodiversity wilderness areas (HBWA), and additional turtle priority areas (TPA) previously identified. We present taxon richness and endemism values for the 16 turtle hotspots with highest richness and endemicity. These 16 turtle hotspots together contain 262 species (83% of total), of which 149 (47%) are endemic to these areas combined, and 134 species (43%) are endemic to just a single priority area. At the terminal taxon (subspecies) level, these 16 areas harbor 342 taxa (79%), of which 210 (48%) are endemic to these combined areas, and 195 (45%) are endemic to a single priority area. These 16 BHS, HBWA, and TPA account for less than 24 million square kilometers, or 16.0% of planet Earth's land surface, with an estimated 10.4 million square kilometers of original habitat remaining, or 7.0% of the planet's land surface. Twenty-one countries are recorded to harbor 15 or more species of non-marine turtles, with the percentage of endemic species ranging from 0% to 88%. Collectively, these 21 countries are inhabited by 275 (87%) species and 352 (81%) taxa, of which 115 (37%) species and 175 (40%) taxa are endemic to just a single country. Identification of these conservation priority areas and countries should assist conservation of turtles worldwide by focusing on areas where the greatest number of species and taxa can be secured and where the authorities and institutions that exist hope to accomplish these goals. [ABSTRACT FROM AUTHOR]

The city of La Plata, Argentina, is situated in a low alluvial zone, with streams having insufficient drainage into the Río de la Plata estuary. In April 2013, a prodigious storm front caused unprecedented flooding in the city and environs that resulted in extensive loss of life and property, especially in the Del Gato stream basin. Through an analysis of water quality and the conditions of the habitat on the basis of the macroinvertebrates present as bioindicators of environmental quality, this work aims to contribute to a reevaluation of the role of the marshes adjacent to the stream as flood-alleviation elements, and then propose alternatives for flooding management in the basin. Consequently, quantitative seasonal samples of vegetation, sediments, and benthic organic matter were taken and limnologic parameters measured in three sectors of the basin having different land uses: rural, periurban, and urban-industrial. The macroinvertebrate assemblages, as analyzed through the application of ecological indices, exhibited a marked decline in richness and in the Pampean Biotic Index towards the low-lying basin. Principal-components analysis associated Site 1 with the dissolved-oxygen concentration, Site 2 with high nitrate values, and Site 3 with oxygen demands. Redundancy analysis indicated a positive relationship between Baetidae and Aeolosomatidae with the dissolved-oxygen concentration and between Enchytraeidae and Stratiomyidae with the conductivity. These marshes are fundamental in maintaining good environmental conditions and attenuating the effects of the flooding that is predicted to become increasingly catastrophic in this region as the climate changes.

We investigated the resident bacterial communities within the biofilm of 252 streams in New Zealand with the aim of assessing the community variation associated with natural and anthropogenic-influenced environmental characteristics. This work is part of a larger project investigating the use of bacterial communities as biological indicators, and here we assess how predictable the variation in bacterial community is in response to environmental influences., Samples of epilithic biofilm were collected in the Austral Summer of 2010, and bacterial communities were characterised using the DNA-fingerprinting technique automated ribosomal intergenic spacer analysis ( ARISA)., Multivariate analysis of the ARISA data revealed that geographical location (region) was a better predictor of bacterial community structure than land use., Our finding that taxon richness varied with geographical location, decreasing along a north to south (increasing latitude) gradient, and that land use had no significant effect on taxon richness suggests that bacterial communities have great potential to act as biological indicators of stream health. In particular, the maintenance of taxon richness at impacted sites is a key advantage since the local extinction of many traditional indicator organisms, such as fish or macroinvertebrates, often precludes their further use., Our conceptual model of bacterial community structure proposes that stream biofilm communities are comprised of four broad groups of bacteria: ubiquitous bacteria (found at all sites), region-specific bacteria (those representative of geographical areas), natural-state bacteria (those associated with unmodified systems) and impact-related bacteria (those associated with human activities). The proportion of these four groups at a particular sample site would provide the basis of a novel bacterial community index of stream health. [ABSTRACT FROM AUTHOR]

ABSTRACT Wetlands in the Lake Victoria basin serve as structural and hypoxic refugia for some native fishes against predation by introduced Nile perch ( Lates niloticus); however, little is known about the fine-scale patterns of distribution and abundance of these refuge inhabitants., This study sought to quantify wetland ecological gradients and determine where peaks in native fish abundance and richness ('peak refugia') occurred using Lake Nabugabo, Uganda as a model system., Extensive wetland transects were sampled between June and August, 2011 to measure ecological variation over distance from the lake-wetland edge., Wetlands were characterized by strong clines in water temperature, pH, dissolved oxygen (DO), depth and vegetation density, and narrow peak refugia were found precisely at the lake-wetland edge. Community richness and diversity tended to be greater in areas with higher DO and lower temperature, pH, and vegetation density. It is interesting that areas encroached upon by a native emergent macrophyte (hippo grass, Vossia cuspidata) had more extreme physico-chemical conditions and supported fewer native fish species., These results demonstrate the importance of wetland edges in the maintenance of native fish fauna in the Lake Victoria basin, and suggest that the continued expansion of hippo grass may reduce the accessibility of wetlands as refugia., We recommend that the use of spatially explicit management approaches such as the development of secure buffer zones surrounding wetland edges to protect peak refugia, and the need for hippo grass control to minimize its effects on this important refuge., Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Boreal lakes undergo broad-scale environmental change over time, but biodiversity responses to these changes, particularly at macroecological scales, are not well known. We studied long-term trends (1992-2009) of environmental variables and assessed α, β, and γ diversity responses of phytoplankton and littoral invertebrates to these changes. Diversity was assessed based on taxon richness ('richness') and the exponentiated Shannon entropy ('diversity'). Almost all environmental variables underwent significant monotonic change over time, indicating mainly decreasing acidification, water clarity and nutrient concentrations in the lakes. These variables explained about 54 and 38 % of variance in regression models of invertebrates and phytoplankton, respectively. Despite this, most diversity-related variables fluctuated around a long-term mean. Only α and γ richness and diversity of invertebrates increased monotonically through time, and these patterns correlated significantly with local and regional abundances. Results suggest that biodiversity in boreal lakes is currently stable, with no evidence of regional biotic homogenization or local diversity loss. Results also show that richness trends between phytoplankton and invertebrates were widely uncorrelated, and the same was found for diversity trends. Also, within each taxonomic group, temporal patterns of richness and diversity were largely uncorrelated with each other. From an applied perspective, this suggest that long-term trends of biodiversity in boreal lakes at a macroecological scale cannot be accurately assessed without multiple lines of evidence, i.e. through the use of multiple taxa and diversity-related variables in the analyses. [ABSTRACT FROM AUTHOR]

This is the second part of a world-wide revision of the genus Boehmeria, the previously-published part having dealt with the New World species. The Old World species are widely distributed in the tropics and subtropics from West Africa to islands in the Pacific Ocean and from Japan and China to Southern Africa, Madagascar and Australia, with the highest species richness in the Himalayas and their extension into China and Indochina. No indigenous species is common to both the Old and New World. The species represent taxonomic units of very different complexity: most species exhibit little infraspecific variation; in several others formal taxonomic infraspecific units can be recognised; however, in two, B. virgata and B. japonica, a highly complex variation is seen, fitting with difficulty into the normal hierarchy of taxonomic classification. With the conclusions reached here, 33 species, including 31 varieties, are recognised and over one hundred previously established names are placed in synonymy. Four new taxa are described: B. pilosiuscula var. suffruticosa, B. virgata subsp. macrophylla var. minuticymosa, B. virgata subsp. virgata var. velutina and B. virgata subsp. virgata var. maxima. The following new combinations are made: B. densiflora var. boninensis, B. heterophylla var. blumei, B. japonica var. silvestrii, B. japonica var. tenera, B. sieboldiana var. fuzhouensis, B. ternifolia var. kamley, B. virgata subsp. macrophylla, B. virgata subsp. macrophylla var. canescens, B. virgata subsp. macrophylla var. densiglomerata, B. virgata subsp. macrophylla var. longissima, B. virgata subsp. macrophylla var. macrostachya, B. virgata subsp. macrophylla var. molliuscula, B. virgata subsp. macrophylla var. rotundifolia, B. virgata subsp. macrophylla var. scabrella, B. virgata subsp. macrophylla var. strigosa, B. virgata subsp. macrophylla var. sumatrana, B. virgata subsp. macrophylla var. tomentosa and B. virgata subsp. virgata var. austroqueenslandica. [ABSTRACT FROM AUTHOR]

Abstract: In temporary ponds, reestablishment of zooplankton communities depends on recruitment from the egg bank, the arrival of dispersers from within the region, and on successful establishment of newly arrived species following interaction with local abiotic and biotic factors. When the ponds dry up, zooplankton species may survive as dormant eggs, and since not all eggs hatch in the next season, eggs will accumulate in the sediment over time, representing an archive of the pond''s historical biodiversity. To study the effect of “restoration age” (the time since a water body was restored), we studied groups of ponds that were restored in different years (1998, 2003 and 2007). The restoration process involved extensive dredging of sediments which were used to bury the ponds in the 1960s. Our expectation was that the oldest ponds would have the richest zooplankton community, as they have been accumulating biodiversity over a longer time period. We took weekly quantitative samples of zooplankton during four consecutive weeks after flooding to compare taxon richness and zooplankton community composition between ponds of different restoration age during an early stage of zooplankton community re-establishment. Taxon richness was high and similar to regional levels in all the ponds under investigation, suggesting restoration success and unlimited dispersal. Although cumulative richness at the end of the period was not significantly different between ponds, we observed temporal changes within the study period and certain age-related trends in relation to differences in zooplankton composition. These results suggest a difference in the succession of zooplankton communities depending on restoration age (which could be due to historical or local factors) and that this effect becomes evident from the beginning of the pond hydroperiod. [Copyright &y& Elsevier]

Abstract: Twelve sites of tyre track pools and puddles situated in woodland, heath and pasture in Dorset UK were examined to determine their macroinvertebrate species richness and community changes over the course of one year. 174 taxa were found with Diptera (59) and Coleoptera (48) contributing 61% of the total. The most frequently occurring and ubiquitous groups were nematoceran dipterans, Oligochaeta, Coleoptera, Crustacea and Lamellibranchiata. Species richness varied with season and on average was highest in March and November samples. On average only 26% (range 16–40%) of the combined total number of taxa found in spring (March) and autumn (November) samples from a site were also found there in each of these seasons individually, indicating a high species turnover through the year. The tyre track pools contributed to local aquatic biodiversity by adding 29 taxa to previously published taxa lists from aquatic habitats in the area. The relative richness of the tyre track pools is attributed to their successional variation in a heterogeneous landscape. Conservation value of 9 of the 12 sites was rated Very high to High and nine regionally notable or rare taxa were recorded. It is suggested that the important conservation status of the tyre track pools warrants greater recognition and further intensive study. [Copyright &y& Elsevier]

ABSTRACT Aim To test for a possible effect of environmental harshness on large-scale latitudinal and elevational patterns in taxon richness of macrofauna in arctic and alpine glacier-fed streams. Location Svalbard (79° N), Iceland (65° N), Norway (62° N), Switzerland and Italy (46° N), France (43° N), New Zealand (43° S) and Ecuador (0°), covering an elevational gradient from sea level to 4800 m a.s.l. Methods We gathered data from 63 sites along 13 streams and created an index of glacial influence (the glacial index, GI) as an integrative proxy for environmental harshness. The explicative power of the GI, environmental variables, latitude and elevation on taxon richness was tested in generalized linear models. Taxon richness along geographical gradients was analysed at standardized levels of GI in contour plots. Beta diversity and assemblage similarity was calculated at different GI intervals and compared with a null-model. Results Overall, taxon richness decreased exponentially with increased GI ( r2= 0.64), and of all included factors, GI had the highest explicative power. At low values of GI we found that local taxon richness varied along the coupled gradients of latitude and elevation in a hump-shaped manner. However, this pattern disappeared at high values of GI, i.e. when environmental harshness increased. Beta diversity increased, while similarity among assemblages decreased towards high GI values. Main conclusions In our study system, the number of taxa able to cope with the harshest conditions was largely independent of the regional taxon pool, and environmental harshness constituted a 'fixed' constraint for local richness, irrespective of latitude and elevation. Contrary to expectations, we found that beta diversity was highest and similarity lowest among the harshest sites, suggesting that taxon richness was not solely driven by niche selection based on environmental tolerances, but also stochastic ecological drift, leading to dispersal-limited communities. [ABSTRACT FROM AUTHOR]

ABSTRACT Restoring longitudinal connectivity is a key river restoration goal. This study tested the efficacy of a fish ramp and spoiler baffles for restoring indigenous fish communities upstream of a culvert., Before-after monitoring showed that installation of the ramp and spoiler baffles increased species richness (mean increase 80%) and total fish density (mean increase 45%) upstream of the culvert., Passage trials on the ramp and baffled culvert were carried out using inanga, Galaxias maculatus (Jenyns), a commonly occurring weak-swimming migratory fish. The trials showed that inanga were capable of successfully ascending both the ramp (overall 27.1% success) and culvert with baffles (overall 6.2% success) under the conditions tested (cf. 0% success for this species before retrofitting), but passage efficiency was still relatively low in both cases., Retrofitting of culverts can therefore be effective for restoring upstream fish passage. However, to maximize effectiveness it is essential that restoration goals are well defined and retrofitting solutions are designed appropriately for the target species. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Quantitative samples of benthic invertebrates were collected from a sandy riverbed of a mountainous stream (Kozu site of Takami-gawa stream, Nara Prefecture), central Japan by core samplers in five sampling occasions through the years 2008-2009. A total of 120 taxa were identified, representing 55 families and 97 genera. Insects formed about 92% of the total recorded taxa and 88% of individuals' abundance. A total of 111 taxa of aquatic insects, belonging to 49 families and 92 genera, were identified and represented by ten orders. Oligochaeta and Acari were dominant non-insect invertebrates. Diptera was the most diverse insect group, followed by Trichoptera and Ephemeroptera. Dominant taxa were mesoinvertebrates, younger stages of macroinvertebrates, both of which predominantly inhabit the interstitial zone of a sandy riverbed. Both taxon richness and invertebrate abundance were higher in February 2009 and lower in April and August 2008. A few major invertebrate taxa demonstrated distinct seasonal trends; i.e. Nymphomyia alba, Rheosmittia, and Corynoneura were abundant in February 2009. Newly hatched larvae of Larcasia akagiae were abundant in May 2008. This study also demonstrated the effectiveness of core samplers to collect small-sized benthic fauna that inhabit the interstitial or hyporheic zone of the sandy riverbed. [ABSTRACT FROM AUTHOR]

1. Although a latitudinal gradient in species diversity has been observed for various taxa, the factors generating the latitudinal gradient at broad spatial scales are difficult to identify because several candidate factors change simultaneously with latitude. We investigated latitudinal gradients in stream invertebrate assemblages in 30 headwater streams in Hokkaido Island, Japan, focusing on the regional scale to discount historical factors and to extract the effects of environmental factors on latitudinal gradients in diversity. 2. Taxon diversity (Shannon index) and taxon richness (number of taxa per unit area) increased with latitude. Abundance showed a similar latitudinal gradient, whereas evenness (Δ1) did not. Hence, we conclude that the observed latitudinal gradient in taxon richness was generated by directional variation in abundance (passive accumulation), leading to that in taxon diversity. 3. Precipitation, which is strongly related to flood disturbances, decreased with latitude and was an important factor explaining variation in taxon diversity, taxon richness and abundance. The probability of a taxon being present tended to increase from south to north, suggesting that the higher taxon richness observed in northern sites may be because of the presence of rare species. These findings indicate that flood disturbance varying with latitude may influence abundance and local extinction rates of rare species, consequently affecting taxon richness and taxon diversity. 4. By detecting the effects of an environmental factor (precipitation) on the latitudinal gradients in taxon diversity and taxon richness without interference by historical factors, this study demonstrates processes that can produce latitudinal gradients in the diversity of stream invertebrate assemblages. [ABSTRACT FROM AUTHOR]

The article examines the spatial patterns of phytoplankton richness, abundance and taxonomic composition in transitional waters in the eastern Mediterranean basin. Results show that the number of taxa and the cell density of phytoplankton guilds differed between season and across ecosystems. Moreover, the taxonomic composition varied significantly among lagoons. Findings suggest that the abundance and taxa richness follow different eco-regional patterns related to a variety of large-scale abiotic factors.

A large experimental channel was used to examine the responses of benthic invertebrate communities to artificial flushes. Two artificial flushes were done at a 20-day interval with a 2-fold difference in peak discharge and duration between them. The effects of the flushes on macroinvertebrates were monitored by comparing the abundance of individual taxa, taxon richness, diversity measures, and similarity indices. Taxon richness and abundances of invertebrates were drastically reduced by every flush. However, the diversity of invertebrates was not significantly reduced by the flushes, and the composition was similar before and after each flush. The fast recruitment of some taxa, having short life cycles, reduced the diversity of invertebrates in the interval between the two flushes. The flushes caused significant reductions in the abundance of epiphytes and fauna living in the streambed. The fauna more resistant to flushes were invertebrates that fasten their cases or retreats by silk threads to substrata. Taxa living in sediment under stones and having a sucking apparatus were also resistant to flushes. [ABSTRACT FROM AUTHOR]

The significance of different environmental drivers for the chironomid compositional changes during the Holocene was assessed using partial redundancy analysis. These drivers included pollen-inferredmean July air temperature, vegetation cover as pollen percentages, diatom-inferred water pH and total organic carbon (TOC), and sediment properties as loss on iginition (LOI). Variance partitioning showed that on the Holocene timescale, chironomid assemblages were significantly responding to changes in Betula percentages. This is explained by the co-occurring response of chironomids to the Holocene climatic development, which has also been responsible for the development of vegetation in the catchment. However, during the very early Holocene period from 10 500 cal. yr BP to 8300 cal. yr BP chironomids were responding more directly to the changes in water quality, ie, pH. During the latter part of the Holocene, no environmental variable appeared to be significant in explaining the variation in chironomid assemblages. This may be due to the underestimation of the actual water TOC by the diatom-based TOC model. However, for the latter part of the Holocene, from 5000 cal. yr BP to the present, the importance of limnological changes attributed to the development of marginal mires on the midges is evident. Our study shows that factors other than climate may have had more direct influence on the chironomid abundances at certain time periods. Although these factors are probably indirectly connected to climate through catchment processes, more understanding of the catchment-mediated climate effects on lake ecology and chironomids in high latitudes is needed, in addition to careful site selection, in order to better understand the environmental reconstructions. [ABSTRACT FROM AUTHOR]

The article focuses on the use of indicator taxa as a tool to assess freshwater biodiversity in the low land of Great Britain. However, it was said that the approach to identifying sites of conservation priority requires surveyors to possess proficient taxonomic knowledge. The study uses mussel abundance as surrogate that provides a rapid and straightforward alternative to conventional method of assessing freshwater biodiversity. Moreover, the results highlights the ecosystem-level consequences of allowing global decline of freshwater mussels to remain unchecked.

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Predictions of aquatic ecosystem change with global warming require basic data that accurately reflect the environmental conditions underlying species distributions. However, in remote arctic areas such baseline data are scarce. We assess the influence of environmental variables on chironomid distribution and taxon richness in shallow, isothermal lakes in a poorly studied arctic region. We pay particular attention to community variation along the treeline ecotonal zone where many environmental variables change abruptly in a relatively small area.Lake transect in Finnish Lapland spanning from boreal coniferous forest to arctic tundra.Chironomid assemblages were determined from surface-sediment samples of 50 shallow (< 10 m) natural lakes. Abundance and taxon richness data were related to 24 limnological variables using canonical ordination techniques (DCA, CCA, RDA). A Monte Carlo permutation procedure was used to assess the explanatory power of single variables. Between-vegetation zone differences of richness were tested for statistical significance using one-wayanova.In total, 7771 chironomid head capsules were identified, consisting of 13 species, 10 species groups, four subgenera, 41 genera, four genus groups, five types and three with uncertain taxonomic affiliation. A hump-shaped relationship between taxon richness and elevation was noted along the study transect with a peak in taxon richness occurring in mountain birch woodland lakes at middle elevations, decreasing then towards both warmer and colder ends of the elevation/temperature gradient. Of the individual parameters, sediment organic content, total organic carbon, pH, and lake-specific air temperature accounted for the greatest amount of variation in the chironomid data.Maximum taxon richness occurred at mid-elevations where aquatic algae also reached their maximum diversity. This area coincides with an ecotonal transitional zone, which seems more likely to account for the peak in species richness. Our study demonstrates that the factors most strongly affecting chironomids in Finnish Lapland (i.e. temperature, and ecosystem features) are those that with great probability will also change as a result of future climate change. This will likely have an effect on the distribution of chironomids in subarctic and arctic areas. [ABSTRACT FROM AUTHOR]

Abstract. The reef-dwelling oyster Dendrostrea frons occupied only a small proportion of space in coral reefs of the Quirimba Archipelago, Mozambique, but supported a disproportionately high variety of taxa. Assemblages on primary (substratum), secondary (dead coral heads) and ephemeral secondary space (D. frons shells) of similar area were compared across 5 depths (5, 10, 15, 20 and 25 m) and at four taxonomic levels (species, genus, class and phylum). Differences between the taxonomic richness of each type of space differed with both taxonomic level considered and depth. Of the three categories of space considered, ephemeral secondary space had the most taxa at all levels with the maximum at 10 – 15 m. Despite being small in space and time, animal externa, such as shells of D. frons, may provide important niches for particular organisms at many taxonomic levels. [ABSTRACT FROM AUTHOR]

Predicting the impacts of anthropogenic disturbance on deep-sea ecosystems requires a thorough understanding of both environmental and faunal drivers of ecosystem function. Studies of deep-sea ecosystems, however, typically consider environmental drivers only and seldom investigate the effects of seabed communities on ecosystem processes. Here, we describe spatial and temporal variation in sediment community oxygen consumption (SCOC), a measure of benthic metabolism and carbon mineralisation, across several sites on Chatham Rise, off the east coast off New Zealand's South Island, and investigate relationships between environmental factors, macrofauna community parameters, and SCOC in order to quantify their relative contributions to benthic metabolism. SCOC differed significantly among sites but not between the two sampling events in August and December 2015. SCOC was significantly and most strongly correlated with estimated particulate organic carbon flux in both August and December in marginal regressions (R2 = 0.53–0.61), followed by macrofaunal abundance (0.28–0.52), macrofaunal taxon richness (0.09–0.50) and water depth (0.30–0.35). Variation partitioning analysis showed that in late winter (August), most of the variability in SCOC was accounted for by environmental variables independently of macrofauna, whereas in summer (December), most of the variability in SCOC was accounted for by the combined effects of environment and macrofauna. We also observed a greater effect of macrofauna independent of environment in summer than in late winter (R2 = 0.13 and 0.05, respectively). Our findings indicate that the contribution of macrofauna to benthic metabolism can be substantial and vary temporally. In addition, our findings suggest that the shifts in ecosystem function resulting from anthropogenic stressors will be difficult to predict due to the interactive effects of environment and macrofauna on benthic metabolism. Nevertheless, if particulate organic carbon flux decreases on Chatham Rise as predicted in climate change scenarios, we anticipate that impacts on benthic metabolism will be most strongly felt in the less productive areas of the rise due to the stronger link between macrofauna and SCOC at low macrofaunal densities. • Benthic metabolism varied among sites but not sampling events. • POC flux and macrofauna abundance were main drivers of metabolism. • Stronger correlation between macrofauna and metabolism at low macrofauna densities. • Metabolism also driven by interaction of environmental and macrofaunal factors. • Future change in ecosystem function difficult to predict due to this interaction. [ABSTRACT FROM AUTHOR]