Fish distribution and assemblage structure in a hydrologically fragmented tropical estuary on the south-west coast of India

Fish composition and assemblage structure in three Eastern English Channel macrotidal estuaries: A comparison with other French estuaries

PDF HTML阅读 XML下载 导出引用 引用提醒 黄山陈村水库上游河源溪流的鱼类群落及其纵向梯度格局 DOI: 10.5846/stxb201304140706 作者: 作者单位: 安徽师范大学生命科学学院,安徽师范大学生命科学学院,安徽师范大学生命科学学院,安徽师范大学,安徽师范大学生命科学学院,安徽师范大学生命科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金(31172120, 31372227); 国家重点基础研究发展计划项目(2009CB119200) Fish assemblages and longitudinal patterns in the headwater streams of the Chencun Reservoir in the Huangshan Area Author: Affiliation: Provincial Key Laboratory of Biotic Environmental and Ecological Safety,College of Life Sciences,Anhui Normal University,Provincial Key Laboratory of Biotic Environmental and Ecological Safety,College of Life Sciences,Anhui Normal University,Provincial Key Laboratory of Biotic Environmental and Ecological Safety,College of Life Sciences,Anhui Normal University,Provincial Key Laboratory of Biotic Environmental and Ecological Safety,College of Life Sciences,Anhui Normal University,Provincial Key Laboratory of Biotic Environmental and Ecological Safety,College of Life Sciences,Anhui Normal University,Provincial Key Laboratory of Biotic Environmental and Ecological Safety,College of Life Sciences,Anhui Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:确定鱼类群落的分布格局及其对人类活动的响应,是合理保护、恢复和管理鱼类多样性的基础。基于2011年5月和10月自黄山陈村水库上游3条河源溪流共39个样点的调查数据,比较研究了溪流间鱼类群落及其纵向梯度格局的异同,着重探讨了人类活动对溪流鱼类群落纵向梯度格局的影响。研究结果显示,同人为干扰较轻的舒溪相比,人为干扰严重的浦溪和麻溪中水宽、底质和植被覆盖率等局域栖息地条件显著变化,这造成了后者的鱼类多样性显著下降及物种组成的显著变化,主要表现为敏感性的地方物种(如宽鳍鱲、光唇鱼、原缨口鳅等)数量减少、耐受性的广布物种(如泥鳅、麦穗鱼、高体鰟鲏等)数量增多。舒溪的鱼类物种数及其组成均与海拔显著相关,但这种"海拔-鱼类群落"关系在麻溪和浦溪中削弱甚至消失。底质、植被覆盖率对舒溪鱼类群落具有重要影响,但对浦溪和麻溪鱼类群落却无显著影响。研究结果表明,在子流域空间尺度上,诸如城镇化发展、土地利用、河道治理等人类活动可通过对局域栖息地条件的影响,导致溪流鱼类多样性下降及其物种组成的变化,破坏鱼类群落的纵向梯度格局,并改变栖息地与鱼类群落之间的联系。 Abstract:Studying the spatial and temporal patterns of stream fish assemblages and identifying how human land-use activities impact these patterns are crucial for fish species conservation, ecosystem restoration and management. The objectives of this study were (1) to examine the influences of human perturbations on the longitudinal patterns of fish species diversity and assemblage structures in headwater streams, (2) to assess the correlations between local habitat factors and fish assemblages, and their longitudinal and temporal patterns. We sampled fish at 39 segments during May and October 2011 from three headwater streams of the Chencun Reservoir in the Huangshan Area, which were influenced by different extents of human activities. A total of 4041 fish were collected, representing four orders, 10 families, and 28 species, among which family Cypriniformes comprised 67.9% of total species richness. 24, 22 and 24 species were sampled from the Shuxi, Puxi and Maxi Streams, respectively. Two-way ANOVA was used to test the influences of streams and seasons on habitat and fish-diversity variables, respectively. Results showed that habitat variables varied significantly across three streams and in different seasons. Results from the Shuxi Stream showed lower numbers in dissolved oxygen and wetted width but higher levels in substrate size and canopy cover than those from the Puxi and Maxi Streams, and May showed lower pH but higher water temperature and discharge than October. However, species richness, fish abundance and the Shannon's index varied significantly across streams but not between seasons. In overall, fish diversity was higher in the Shuxi Stream than that in the Puxi and Maxi Streams. Results of two-way crossed ANOSIM indicated that fish assemblage structures varied substantially across streams but not between seasons. The assemblage structures in the Puxi and Maxi Streams did not show significant differences, however, they significantly differed from those in the Shuxi Stream. SIMPER analysis indicated that some endemic specialized species (e.g., Zacco platypus, Acrossocheilus fasciatus, Vanmanenia stenosoma) were more abundant in the Shuxi Stream, while those cosmic generalized species (e.g., Misgurnus anguillicaudatus, Pseudorasbora parva, Rhodeus ocellatus) were more in the Puxi and Maxi Streams. The results of Pearson's correlation and redundancy analysis showed that fish species richness in the Shuxi Stream significantly increased with elevation decreasing in both May and October, respectively. However, this "species richness-elevation" correlation lessened in the Maxi Stream and even disappeared in the Puxi Stream. Similarly, elevation showed significant correlation with assemblage structures in the Shuxi and Maxi Streams but not the Puxi Stream. In addition, the effects of local habitat variables on fish assemblage structures were examined using linear regression model and redundancy analysis, respectively. Results showed that fish assemblages in the Shuxi Stream were significantly affected by substrate and canopy, but those in the Puxi and Maxi Streams were related to water temperature and wetted width. In conclusion, our results suggest that, at the sub-watershed scale, the alteration of local habitat conditions in headwater streams associated with human activities (e.g., urbanization, land-use and river-regulation) may decrease stream fish diversity, modify the correlations between local habitat and fish assemblage, and change the longitudinal pattern of fish assemblages. 参考文献 相似文献 引证文献

AimOur aim was to document geographical patterns of variation in the body‐size structure of European lake fish assemblages along abiotic gradients, and any differences in fish assemblage structure. We hypothesized that patterns in the body‐size structure of entire lake fish assemblages are primarily temperature driven and consistent with the dominant pattern of the temperature–size rule, which suggests a decrease in adult body size with increasing developmental temperature for many ectothermic species.Location356 European lakes.MethodsVariation in the body‐size structure of fish assemblages was explored on a continental scale along gradients of temperature, morphometry, productivity and fish assemblage structure for 356 European lakes. The mean fish assemblage body‐size and individual body‐size distributions were selected as size metrics. Separate analyses were conducted for lakes located within five ecoregion subsets (Borealic Uplands/Tundra, FennoScandian Shield, Central Plains, Western Plains and Western Highlands) and for lakes with different functional fish classifications (cold‐, cool‐ and warmwater fish assemblages).ResultsGeographical patterns of variation in the body‐size structure of European lake fish assemblages could be clearly discerned along a temperature gradient for both the continental dataset (356 lakes) and the smaller geographical (ecoregion) subsets. We found systematic changes in fish assemblage body‐size structure across temperature gradients in correspondence with the dominant thermal fish guild. The majority of the lakes, mainly located in the warmer European lowlands, were dominated by eurythermic cool‐ and warmwater fish assemblages, with smaller sized individuals characterized by linear individual body‐size distributions. Lakes located in colder regions and dominated by stenothermic coldwater salmonids with larger sized individuals were characterized by unimodal or bimodal size distributions. The mean body size of cold‐, cool‐ and warmwater fish assemblages changed uniformly along the temperature gradient.Main conclusionsPatterns of variation in the body‐size structure of European lake fish assemblages are consistent with the temperature–size rule. Temperature modifies fish assemblage size structure uniformly within the thermal fish guilds and in different ecoregions. Furthermore, our results indicate an increasing predictive power of temperature to explain variability in body‐size structure when moving from warmer to colder geographical regions.

Oceanic islands harbor unique yet fragile marine ecosystems that require evidence-based environmental management. Among these islands, the Galapagos archipelago is well known for its fish diversity, but the factors that structure communities within and between its islands remain poorly understood. In this study, water quality, physical habitats and geographical distance were assessed as potential predictors for the diversity and structure of fish assemblages. Differences in the structure of fish assemblages of the two studied islands (Santa Cruz and Floreana) were most likely driven by temperature and nutrient concentrations. In the relatively highly populated island Santa Cruz, the structure of fish assemblages was more affected by water conditions than physical habitats while the contrary was true for the more pristine area of Floreana. A wide variety of species with different geographical origins were distributed over the different islands, which indicates that most fish species are able to reach the islands of the archipelago. However, temperature gradients and elevated nutrient levels cause large differences in the structure of local fish assemblages. In addition, in Santa Cruz nutrient concentrations were negatively correlated with α diversity. Since pollution is a clear pressure on the fish assemblages of oceanic islands, environmental management of the coastal areas is of paramount importance.

Site d'etude: zone situee sous le barrage de Markles; problemes d'echantillonnage; nombre d'especes incluses dans l'analyse. Inclusion des jeunes d'un an dans cette analyse; interpretation et nouvelle analyse des modeles alternatifs

We collected fishes and environmental variables in three zones (upper, middle and lower) of a small open tropical estuary during flood tide. The aim was to test for differences in fish assemblages along a gradient from freshwater to marine waters and to detect any seasonal variation in fishes and environmental variables across these zones. A total of 111 species (18 in the upper, 50 in the middle and 66 in the lower estuary) were recorded, forming three distinct fish assemblages, with the family Eleotridae dominating in the upper, Gerreidae in the middle, and Sciaenidae in the lower estuary. Only two species (Geophagus brasiliensis in the upper and the middle zones, and Eucinostomus argenteus in the middle and the lower zones) composed more than 1% of the total number of individuals in more than a single zone. Short‐term (tidal) changes in salinity in the middle estuary were associated with different assemblages in the three estuarine zones, even in winter, when the differences in salinity are lowest between the middle and the lower zones. Seasonal variation in salinity was irrelevant, except in a protected sidewater lagoon in the middle estuary. Low salinity seasonal change may be related to the lack of seasonal variation in the structure of fish assemblages in all estuarine zones.

Spatial patterns of an estuarine habitat used by fish assemblages were determined for a protected adjacent lagoon and two areas of the main estuarine channel in a small tropical estuary. The tested hypotheses are that protected areas in estuarine zones support comparatively higher fish richness and abundance and have more small-sized fishes than the main channel. The lagoon and channel areas had distinct fish assemblage structures. Several abundant species (e.g. Atherinella brasiliensis, Eugerres brasilianus, Geophagus brasiliensis, Achirus lineatus and Centropomus parallelus) were of a smaller size in the lagoon compared with the estuarine channel and probably use the lagoon as nursery grounds. Moreover, some species (e.g. Anchoa tricolor, Anchoa januaria, Gobionellus oceanicus and Poecilia vivipara) were abundant and occurred only in the lagoon, whereas others (e.g. Trinectes paulistanus, Ctenogobius shufeldti and Citharichthys arenaceus) reached their highest abundance in the lagoon and were rarely found in the estuarine channel. Seasonal variation in the fish assemblage structure was not significant, which may be related to dominance of estuarine resident species. We found that the lagoon supported comparatively higher fish richness and abundance compared with the main estuarine channel because of the more sheltered and structured habitat. These results provide a better understanding of the role of adjacent habitats to fish assemblage and an improved basis for estuarine rehabilitation.

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

Assemblage Organization of Stream Fishes: The Effect of Rivers on Adventitious Streams

Summary Flood‐related disturbances are predicted to be seriously altered by climate change effects, and this will have strong implications for stream communities. Predicting how and why community structure responds to changes in disturbance regimes will require measures of disturbance that are closely linked to community variability. A range of disturbance measures have been tested for their ability to explain patterns in stream periphyton and invertebrate assemblages, but assessments of fish have largely focussed on flow measures as predictors. Consequently, the mechanisms driving fish assemblage responses to disturbance are poorly known. Stream disturbance was quantified using seven measures, three based on disturbance of the streambed (assessed using painted tracer particles), three associated with variation in stream discharge and one from a subjective measure of stream channel stability. Twenty streams were sampled on five occasions to evaluate which disturbance measure explained the most variation in fish assemblages and also to quantify the influence of disturbance on spatial and temporal assemblage variability. To determine whether disturbance affected fish directly or via its effect on benthic food supply (i.e. stream invertebrates), a one‐off survey of 52 streams was conducted. Path analysis on data from the 20 streams indicated that fish biomass responded most strongly to flow‐mediated bed movement, not flow variability. Consequently, bed‐movement measures were better predictors of spatial and temporal variability in fish biomass and assemblage structure than purely hydrological measures. Furthermore, variations in fish biomass and assemblage structure were higher in more disturbed streams. A second path analysis conducted on data from the 52 stream survey compared the effects of physical habitat and food‐related components of bed disturbance on fish biomass. It indicated that both had a similar influence on disturbance‐related reductions in fish biomass. These results indicate that variation in fish assemblages can best be understood by measuring or predicting bed movement, because bed disturbance is likely to encompass more effectively major factors that influence stream fish, such as habitat availability and food supply. A shift in disturbance regime is likely to change the biomass of fish a habitat can support and fish assemblage structure.

Aim To evaluate the relationship between marine fronts and (1) fish diversity patterns, (2) fish biomass distribution, and (3) fish assemblage structure.Location Patagonian Shelf, Southwestern Atlantic Ocean.Methods Three main frontal systems and eight nearby zones (frontal vs. non‐frontal areas) were compared. An extensive fishery database, obtained during an a priori sampling scheme (spatial resolution 1 × 1) from 1978 to 1979, was employed. Analyses of 248 trawling stations were performed using a combination of diversity measures (species richness, Shannon diversity and evenness), biomass analyses and multivariate analyses [nonparametric analysis of similarity (ANOSIM), non‐metric multidimensional scaling ordination (NMDS) and similarity percentages (SIMPER)] to evaluate the effect of fronts on fish communities.Results In total, 46 fish taxa were identified. Demersal fish diversity increased at the tidal front of Península Valdés but decreased in the frontal zones of the Southern Shelf‐Break and Magellan frontal systems. The richness and biomass of pelagic fish were higher at the Península Valdés Tidal Front, while the biomass of demersal fish was higher at its non‐frontal counterpart. Fish diversity did not differ consistently along the Northern Shelf‐Break Front. However, a higher fish biomass was registered at the non‐frontal zone. Demersal and pelagic fish assemblages differed between frontal and non‐frontal zones.Main conclusions The Patagonian Shelf Large Marine Ecosystem has diverse frontal types that appear to have different effects on fish diversity and assemblage structure. Seasonal (tidal) or permanent fronts have different effects on the parameters analysed, which could be due to productivity–diversity relationships. The Península Valdés Tidal Front, a relatively short temporal scale system, demonstrates a stronger influence on fish diversity, biomass and assemblage structure than the other frontal areas studied. The seasonality of nutrient input owing to frontogenesis, which begins during the austral spring, may play an important role in determining local diversity. At permanent frontal features, diversity decreases when the nutrient availability is high. This is potentially because, when food resources increase, a few species become dominant.

Seagrasses worldwide provide key habitats for fish assemblages. Biogeographical disparities in ocean climate conditions and seasonal regimes are well-known drivers of the spatial and temporal variation in seagrass structure, with potential effects on associated fish assemblages. Whether taxonomically disparate fish assemblages support a similar range of ecological functions remains poorly tested in seagrass ecosystems. In this study, we examined variation in the abundance, diversity (from a taxonomic and functional perspective), and assemblage structure of fish community inhabiting nine meadows of the seagrass Cymodocea nodosa across three regions in the Mediterranean (Mallorca and Alicante) and the adjacent Atlantic (Gran Canaria), and identified which attributes typifying the structure of meadows, and large-scale variability in ocean climate, contributed most to explaining such ecological variation. Despite a similar total number of species between Mallorca and Gran Canaria, the latter region had more taxonomically and functionally diverse fish assemblages relative to the western Mediterranean regions, which translated into differences in multivariate assemblage structure. While variation in the abundance of the most conspicuous fish species was largely explained by variation in seagrass structural descriptors, most variation in diversity was accounted for by a descriptor of ocean climate (mean seasonal SST), operating at regional scales. Variation in fish assemblage structure was, to a lesser extent, also explained by local variability in seagrass structure. Beyond climatic drivers, our results suggest that lower temporal variability in the canopy structure of C. nodosa meadows in Gran Canaria provides a more consistent source of food and protection for associated fish assemblages, which likely enhances the more abundant and diverse fish assemblages there.

High‐flow pulses affect river ecosystem dynamics in many important ways including by forming connections between the channel and oxbow lakes. This study assessed the influence of discharge on fish assemblage structure and diversity in the channel and oxbows of the Guadalupe River, Texas. Local assemblages of two oxbows and two channel sites were surveyed using standardized methods to test four hypotheses: (1) assemblage structure in oxbow lakes differs from those in the river channel, (2) α diversity decreases during extended periods of low discharge, (3) β diversity decreases during high discharge and increases during extended periods of low discharge, and (4) species turnover and assemblage nestedness decline during periods of high discharge. We found evidence to support the first three hypotheses. Unsurprisingly, lotic‐adapted fishes were observed more frequently in the river channel, whereas lentic‐adapted species generally were more common in the oxbow lakes. Species richness declined during periods of low discharge possibly due to harsher environmental conditions or stronger species interactions (e.g., predation). Discharge was inversely associated with both β diversity and species turnover, suggesting a stronger mass effect during high‐flow pulses, and stronger species sorting during low‐flow conditions. Contrary to our fourth hypothesis, assemblage nestedness increased during periods of high discharge. Finally, we also found evidence to support the hypothesis that species turnover decreased as discharge declined. The results of this study demonstrate the importance of flow pulses for maintaining fish diversity and assemblage structure in floodplain river systems. With additional research involving more sites and longer time series, it should be feasible to define and identify thresholds for flow regime changes that alter assemblage structure and species diversity.

Using seasonally collected data (2009-2010) from 15 sampling sites that represent first- to fifth-order streams within the Qingyi watershed, we examined the spatio-temporal patterns of fish assemblages along two longitudinal gradients to explore the effects of a large dam on fish assemblages at the watershed scale. No significant variation was observed in either species richness or assemblage structure across seasons. Species richness significantly varied according to stream order and gradient. Dam construction appeared to decrease species richness upstream substantially, while a significant decrease between gradients only occurred within fourth-order streams. Along the gradient without the large dam, fish assemblage structures presented distinct separation between two neighboring stream orders, with the exception of fourth-order versus fifth-order streams. However, the gradient disrupted by a large dam displayed the opposite pattern in the spatial variation of fish assemblages related with stream orders. Significant between-gradient differences in fish assemblage structures were only observed within fourth-order streams. Species distributions were determined by local habitat environmental factors, including elevation, substrate, water depth, current discharge, wetted width, and conductivity. Our results suggested that dam construction might alter the longitudinal pattern in fish species richness and assemblage structure in Qingyi Stream, despite the localized nature of the ecological effect of dams.

Landscape-scale patterns of freshwater fish diversity and assemblage structure remain poorly documented in many areas of Central America, while aquatic ecosystems throughout the region have been impacted by habitat degradation and hydrologic alterations. Diadromous fishes may be especially vulnerable to these changes, but there is currently very little information available regarding their distribution and abundance in Central American river systems. We sampled small streams at 20 sites in the Sixaola River basin in southeastern Costa Rica to examine altitudinal variation in the diversity and species composition of stream fish assemblages, with a particular focus on diadromous species. A set of environmental variables was also measured in the study sites to evaluate how changes in fish assemblage structure were related to gradients in stream habitat. Overall, fish diversity and abundance declined steeply with increasing elevation, with very limited species turnover. The contribution of diadromous fishes to local species richness and abundance increased significantly with elevation, and diadromous species dominated assemblages at the highest elevation sites. Ordination of the sampling sites based on fish species composition generally arranged sites by elevation, but also showed some clustering based on geographic proximity. The dominant gradient in fish community structure was strongly correlated with an altitudinal habitat gradient identified through ordination of the environmental variables. The variation we observed in stream fish assemblages over relatively small spatial scales has significant conservation implications and highlights the ecological importance of longitudinal connectivity in Central American river systems.