Modelling functional fish habitat connectivity in rivers: A case study for prioritizing restoration actions targeting brown trout

相似文献   

Spatial patterns of lacustrine fish assemblages in a catchment of the Mississippi Alluvial Valley

相似文献   

Compositional trends of fisheries in the River Ganges,India

Abstract Monthly surveys of local fisheries from five principal landing sites on the River Ganges at Bhagalpur, India, were conducted from 2001 to 2007. Fishes of a range of sizes with mostly periodic‐type life‐history strategies, including many catfishes and carps, dominated the catch. Average annual yield (total mean monthly catch in units of biomass) was highly variable but trended downward during the study. Statistical ordination revealed associations between assemblage composition and hydrological seasons. Overall yields in this reach of the River Ganges tended to be greatest when the annual flood pulse was sustained longer. Patterns of average stock yields and inter‐annual variability of yields were associated with species life‐history strategies, with the most abundant and least variable species having periodic‐type strategies of seasonal spawning, high fecundity, small eggs and no parental care. Although not appearing to have declined precipitously during the study, many stocks in this stretch of the River Ganges, including those of the largest and most valuable species, nonetheless seemed to remain below historical yield levels because of multiple impacts, including chronic intense fishing and other anthropogenic impacts.     

Seasonal habitat use of alligator gar in a river–floodplain ecosystem at multiple spatial scales

Alligator gar (Atractosteus spatula) populations are declining throughout their range in the United States, even where considered stable. Similar declines in other riverine species are occurring worldwide due to alteration of habitat in river–floodplain systems. Most rivers in the world are highly regulated, resulting in departures from historic hydrology that provides connection to the floodplain habitats used by riverine fishes. Knowledge of the seasonal habitat requirements of alligator gar and similar riverine fishes at a watershed scale is limited, hindering management practices. We used radiotelemetry to monitor movements and habitat use of adult alligator gar (N = 32; 25.0–84.5 kg; 149–224 cm) at macro‐ and microhabitat scales during 2 years of varying hydrology. Fish showed seasonal differences in their use of main channel and floodplain macrohabitats. Floodplain tributaries and their upper reaches were especially important to reproductive ecology. Minimum distance travelled per day varied seasonally. While using the main channel Fourche LaFave River, gar selected low velocity, shallow depth and complex structure along channel margins. The Fourche LaFave River is unique in its connection to floodplain habitats on a relatively predictable basis, with frequent flooding during the spring and summer reproductive period. Our study emphasises the importance of connectivity between the main river channel and floodplain habitats to a floodplain‐obligate riverine species. An intact, heterogeneous riparian zone creates essential microhabitat for the species. Understanding habitat requirements of alligator gar at multiple spatial scales in a river–floodplain system is crucial to management of many other species and river systems.     

Linking temperate demersal fish species to habitat: scales,patterns and future directions

Adoption of the ecosystem approach to fisheries management relies on recognition of the link between fish and other components of the ecosystem, namely their physical and biological habitat. However, identifying the habitat requirements of marine fishes and hence determining their distribution in space and time is scientifically complex. We analysed the methodologies and findings of research on temperate, demersal fish habitat requirements to highlight the main developments in this field and to identify potential shortfalls. Many studies were undertaken over large spatial scales (≥100s km²) and these generally correlated abundances of fish to abiotic variables. Biological variables were accounted for less often. Small spatial scale (≤m²), experimental studies were comparatively sparse and commonly focused on biotic variables. Whilst the number of studies focusing on abiotic variables increased with increasing spatial scale, the proportion of studies finding significant relationships between habitat and fish distribution remained constant. This mismatch indicates there is no justification for the tendency to analyse abiotic habitat variables at large spatial scales. Innovative modelling techniques and habitat mapping technologies are developing rapidly, providing new insights at the larger spatial scales. However, there is a clear need for a reduction in study scale, or increase in resolution additional to the integration of biotic variables. We argue that development of sound predictive science in the field of demersal fish habitat determination is reliant on a change in focus along these lines. This is especially important if spatial management strategies, such as Marine Protected Areas (MPA) or No Take Zones (NTZ), are to be used in future ecosystem‐based approaches to fisheries management.     

Trophic fingerprint of fish communities in subtropical floodplain lakes

Stable nitrogen isotope ratios (δ¹⁵N) and gut content analysis are commonly used to detect trophic relationships in aquatic systems. Nonetheless, the use of δ¹⁵N in determining the suitability of quantitative and qualitative dietary data as representations of trophic relationships in lake ecosystems remains unverified. Quantitative and qualitative dietary data on 46 fish species were obtained from field surveys in the floodplain lakes of the Yangtze Plain to calculate trophic position and benthivory. Dietary measures using the stable isotope approach were validated. The dietary approach yields comparable results in detecting trophic relationships in lake ecosystems. Our estimation of the benthivory of the 46 fish species ranged from 1.5% to 100%, with an average of 60.3%. These figures support the assumption that benthic energy pathways account for more than half of total fish consumption. Our feeding guild data confirm that more than 50% (including 25 species) of the studied fish species in the floodplain lakes of the Yangtze Plain are omnivorous, suggesting that omnivory is prevalent among subtropical floodplain lakes.     

The importance of spatial scales to analysis of fish diversity in Amazonian floodplain lakes and implications for conservation

The Amazon River Basin has the highest fish species diversity of any region in the world, but is under threat from anthropogenic perturbations including overharvesting, alien species and drought. We asked whether species diversity in this region is more a function of within‐lake species richness (i.e., α diversity) or differences among lakes (β diversity). Although many studies have reported on species richness and diversity in single habitats, the importance of measuring diversity at different spatial scales is not yet well established. We collected fish in 10 floodplain lakes along the Solimões River (Brazil), divided evenly between two lake types: those on islands in the river channel (island lakes) and those on the margins of the river (coastal lakes) during 2006. We partitioned fish diversity into three spatial scales: α = within each lake; β₁ = among lakes of the same type (coastal or island) and β₂ = between the two types of lakes, and compared their relative contributions to regional (γ) diversity. β₁ + β₂ contributed as much or more to γ diversity than did α. Although many of the 116 fish species were shared between lake types (S = 72), 32 species were found exclusively in coastal lakes and 12 species were found exclusively in island lakes. Coastal lakes, which were deeper and cooler than island lakes, consistently had higher fish species richness than island lakes. We suggest that it will be necessary to set areas large enough to contain multiple lakes of both types to preserve regional fish diversity.     

Influences of local habitat and stream spatial position on fish assemblages in a dammed watershed,the Qingyi Stream,China

Abstract – Identifying the underlying mechanisms that explain the spatial variation in stream fish assemblages is crucial for the protection of species diversity. The influences of local habitat and stream spatial position on fish assemblages were examined from first‐order through third‐order streams within a dammed watershed, the Qingyi Stream, China. Based on linear regression models, the most important environmental variables influencing fish species richness were water temperature and wetted width, but stream spatial position variables were less important. Using canonical correspondence analysis, five environmental variables were identified to significantly influence fish assemblages, including three habitats (elevation, substrate and water depth) and two spatial variables (C‐link and Link). Our results suggest that, in a heavily dammed watershed, by blocking the migration routes of fishes, dams weaken the influence of stream spatial position on fish species richness. However, fish species compositions are significantly influenced by both local habitat environment and stream spatial position, which is perhaps owing to the distribution of fish species according to ecological requirements not related to spatial processes.     

Spatiotemporal patterns of fish community composition in Great Lakes drowned river mouths

Freshwater river mouths in large lakes are centres of biological activity, yet little is understood about the spatial and temporal dynamics of fish communities in these systems. In the Laurentian Great Lakes, we sampled littoral fishes over 3 years in six drowned (i.e., protected) river mouths to: (i) quantify spatial (among river mouths) and temporal (among years) variation, (ii) evaluate associations with environmental conditions and (iii) assess spatial patterns of community similarity. We sampled 6787 fish representing 43 species over the course of the study. Multivariate analyses indicated that variation in fish species composition was more strongly partitioned among river mouths than among years. Fish communities across the six river mouths were partitioned into three groups, a pattern we attribute to variability in anthropogenic disturbance and environmental conditions. Canonical correspondence analysis showed that fish species composition was associated with specific conductivity, vegetation cover, turbidity and pH, suggesting species–environment relationships are similar to those shown for Great Lakes coastal wetlands. Finally, we found a negative relationship between geographic distance and community similarity, suggesting that dispersal and/or environmental gradients play a role in shaping these river mouth fish assemblages. We conclude that Great Lakes drowned river mouths can harbour diverse and spatially variable fish assemblages that are driven by a combination of local and regional factors.     

长江安庆新洲江段仔稚鱼的群聚特征

安庆新洲江段是长江下游典型的干流-沙洲生境,为掌握该水域仔稚鱼群聚特征,于2018年4月15日—8月4日开展了逐日调查。调查期间,共采集鉴定仔稚鱼121246尾,隶属于6目8科34种,贝氏䱗（）为第一优势种。新洲南汊、北汊分别采集仔稚鱼79338尾和41908尾,数量占比依次为65.44%和占34.56%。所有渔获物中,产漂流性卵鱼类物种数最多（16种,47.06%）,产浮性卵鱼类数量最多（92623尾,76.39%）。就时间特征而言,南汊、北汊仔稚鱼丰度日变化趋势基本一致,表现出与水位上涨高度关联,共监测到三次高峰,其中7月13日达到峰值（2001.28 ind/100 m³）;就空间特征而言,近岸采样点丰度高于河道中泓采样点,南汊丰度总体高于北汊。冗余分析结果显示,与新洲江段仔稚鱼丰度相关性较强的环境因子为水位、浊度、水温和透明度,其中水位为主要的正相关因子。空间尺度的聚类分析将新洲江段6个采样点分为3个群组,表明新洲江段不同采样点仔稚鱼群聚结构差异显著（=0.017）。研究表明,安庆新洲江段仔稚鱼补充量显著大于上游输入量,新洲对该江段仔稚鱼群聚特征具有显著影响,总体表现为南汊的鱼类繁殖条件显著优于北汊。研究结果补充了安庆新洲江段鱼类早期资源的基础数据,为长江下游渔业资源评估与保护提供了依据。     

Small fish diet in connected and isolated lakes in a Neotropical floodplain

Hydrological connectivity interferes directly in dispersal rates of organisms and in similarity of environmental conditions among floodplain environments. Consequently, connectivity promotes changes in food resources availability to fish. Here we tested the predictions that (a) isolated floodplain lakes have greater environmental heterogeneity than connected lakes, (b) fish diet differs more among isolated than among connected lakes and (c) trophic niche breadth of the species is smaller in isolated than in connected lakes. We used one invertivorous and one algivorous species of fish to test these two last predictions. The environmental heterogeneity (evaluated in relation to abiotic variables and the macrophyte composition) tended to be greater in isolated lakes. Diet of both species differed significantly in all isolated lakes populations, and in the majority of the populations in connected lakes; however, the main items consumed for invertivorous species were common in all connected lakes. Trophic niche breadth of the invertivorous fish was significantly greater in the connected lakes; however, the algivorous species showed no significant difference between connected and isolated lakes. Our findings suggest that connectivity can facilitate the dispersal of organisms, allowing the increase in food item richness and consequently, trophic niche breadth, as observed for invertivorous species. However, connectivity likely plays a minor role on the algivorous species, whose diet may be more affected by local conditions, such as habitat structure. Our results support the view that regional (dispersion) and local (habitat structure) factors interact with feeding habit to determine fish food composition in the floodplain lakes we studied.     

Fish nursery habitat function of the main channel,floodplain tributaries and oxbow lakes of a medium‐sized river

Small, adventitious tributaries (<3 orders of magnitude smaller than the stream it flows into) are a conspicuous feature of many river–floodplain systems, but their value as fish reproduction and nursery habitat is not well understood compared to oxbow lakes and the main river channel (MRC). Moreover, connectivity of tributaries to the MRC is often less impacted by anthropogenic modifications (e.g., dams and levees) compared to oxbow lakes. From April to July 2012, larval and juvenile fish were collected in the Fourche LaFave River (Arkansas, USA) system to better understand fish nursery habitat function of tributaries relative to oxbow lakes and the MRC. Nonmetric multidimensional scaling ordination of juvenile and larval fish genera revealed distinct fish assemblages in MRC and floodplain habitats. Ordination of juvenile fish at the species level resulted in distinct fish assemblages in tributary versus oxbow lake habitats. Tributaries had more unique species and higher abundance of shared species than oxbow lakes and MRC. Additionally, of the 46 species identified, all but six were collected in lower tributary reaches. Connectivity was strongly associated with both ordinations and was important in describing patterns of fish variation among habitats and between tributaries. Of the tributaries sampled, the least fragmented stream had the most similar fish assemblages between upper and lower sections. Findings of this study revealed tributaries are an important, yet overlooked, feature in the river–floodplain model. Especially in years of drought, channel–floodplain connectivity can be limited, but tributaries can be used by fishes for reproduction and nursery habitat.     

Influence of water quality,local knowledge and river–floodplain connectivity on commercial wild crayfish harvesting in the Atchafalaya River Basin

Water quality and river connectivity influence fisheries, but their role is not understood in wild crayfish harvest, or how water quality and river connectivity are incorporated into crayfish harvest strategies. In Louisiana, wild harvesting practices were evaluated with field observations and interviews with individual harvesters. Field observations included trap locations, water quality, water stable isotopes (2016) and habitat components over two seasons (2015 and 2016). Traps were set in less turbid water (NTU < 69.4), in depths from 1 to 3 m or 3 to 3.6 m and in locations associated with river water inputs. Harvester interviews indicated the importance of tradition (35%‐47% respondents), depth (88% respondents) and water colour (>40% respondents; a surrogate for turbidity and connectivity) in harvesting initiation and trap locations. Harvesters appeared to follow lateral water movements onto and within the floodplain, likely based on local environmental knowledge.     

Controls of local young-of-the-year fish species richness in flood plain water bodies: potential effects of habitat heterogeneity, productivity and colonisation–extinction events

Abstract –  This study reports on the relationships between young-of-the-year (YOY) fish species richness and landscape and local factors in 20 backwaters of the Seine River flood plain. Using multiple linear regression, we tested the importance of three types of variable for explaining total species richness (TSR), phytophil species richness (PSR) and lithophil species richness (LSR): (1) colonisation–extinction processes, (2) habitat heterogeneity and (3) productivity. At the local scale, no variables describing habitat heterogeneity correlated with TSR, PSR or LSR. Productivity was correlated only with TSR according to a polynomial model. In contrast, variables relating to the colonisation–extinction process correlated with TSR, PSR and LSR: TSR varied mainly with backwater size, which is a surrogate of extinction, whereas PSR and LSR correlated with the relative longitudinal position of backwaters and the size of their connection to the main channel. In conclusion, it seems that the total fish richness varies as a function of local factors, whereas the components of fish diversity are rather influenced by landscape factors.     

Spatial scale effects on habitat associations of the Ashy Darter,Etheostoma cinereum,an imperiled fish in the southeast United States

Abstract – The ashy darter, Etheostoma cinereum, is an imperiled fish within the Cumberland and Tennessee drainages of the southeast United States. An understanding of habitat associations and the relationship of habitat use across multiple spatial scales are critical elements in its conservation. Our objectives were to quantify habitat associations at the stream reach and microhabitat scales for adult and juvenile darters, and to understand the linkage between the two scales based on gradients of habitat use. We focused our efforts within the Rockcastle River, Kentucky (Cumberland River drainage), because the watershed was known to contain a relatively large ashy darter population. Three hundred twenty‐two individuals were collected from 21 reaches. The species was restricted to the mainstem of the river and the lower reaches of the larger tributaries. The distribution and abundance of adult and juvenile darters differed significantly at each spatial scale, and both groups demonstrated non‐random use of the available habitat. Gradients of stream size and substrate size were identified as important factors. A threshold of environmental quality was determined based on the habitat use patterns among the two scales. Habitat use between the two scales was independent within the threshold, indicating that the specific quality of the microhabitats did not necessarily matter within a stream reach. However, beyond the threshold, a decrease of at least 48% in adult and juvenile darter abundance was seen, indicating that a sufficient network of suitable microhabitats is needed to support a good population of darters within a stream reach.     

Seasonal and diel patterns in the migrations of fishes between a river and a floodplain tributary

Nunn AD, Copp GH, Vilizzi L, Carter MG. Seasonal and diel patterns in the migrations of fishes between a river and a floodplain tributary. Ecology of Freshwater Fish 2010: 19: 153–162. © 2009 John Wiley & Sons A/S
Abstract –  The population behaviours associated with the migrations of fishes in lowland river ecosystems are amongst the most poorly-understood dispersal mechanisms of temperate freshwater organisms. This study evaluated the influence of four environmental variables (light levels, river discharge, water temperature and water velocity) on the timing, intensity and direction of fish movements between the River Avon (Hampshire, England) and a small floodplain tributary, Ibsley Brook, over a 12-month period. Using canonical correspondence analysis (CCA) to identify patterns of movement (by groups of species) and the relative strengths of explanatory variables in the data, the probability of fishes migrating between the river and tributary was determined using Bayesian modelling. The intensity and direction of fish movements between the river and tributary varied temporally, both on a diel and seasonal basis, and there were species- and age-specific patterns in behaviour. Diel movements appeared to be triggered by changes in light intensity and brook water velocity, whereas seasonal movements were mostly driven by changes in river discharge and water temperature, particularly those associated with floods. This study emphasises the importance of connectivity in river systems, as fishes migrated in all conditions, but especially during rapidly-rising discharge.     

Concurrent assessment of fish and habitat in warmwater streams in Wyoming

Abstract  Fisheries research and management in North America have focused largely on sport fishes, but native non-game fishes have attracted increased attention due to their declines. The Warmwater Stream Assessment (WSA) was developed to evaluate simultaneously both fish and habitat in Wyoming streams by a process that includes three major components: (1) stream-reach selection and accumulation of existing information, (2) fish and habitat sampling and (3) summarisation and evaluation of fish and habitat information. Fish are sampled by electric fishing or seining and habitat is measured at reach and channel-unit (i.e. pool, run, riffle, side channel, or backwater) scales. Fish and habitat data are subsequently summarised using a data-matrix approach. Hierarchical decision trees are used to assess critical habitat requirements for each fish species expected or found in the reach. Combined measurements of available habitat and the ecology of individual species contribute to the evaluation of the observed fish assemblage. The WSA incorporates knowledge of the fish assemblage and habitat features to enable inferences of factors likely influencing both the fish assemblage and their habitat. The WSA was developed for warmwater streams in Wyoming, but its philosophy, process and conceptual basis may be applied to environmental assessments in other geographical areas.     

Larval and early juvenile fish dynamics in main channel and backwater lake habitats of the Illinois River ecosystem

The spatial and temporal complexity of large river ecosystems likely promotes biological diversity within riverine larval fish assemblages. However, the focus of most previous riverine studies of larval fish distribution has tended to concentrate mainly on backwater habitats. There has been less focus on the value of the main channel for larval fishes. We sampled two habitats types (three main channel sites and three backwater lakes) along 20 km of the Illinois River ecosystem during 2 years to compare the larval fish distribution along both spatial and environmental gradients between these habitats. Across the 2 years of this study, we found similar trends in the spatial and temporal distribution of larval fish, although there were some differences in densities between years. The relative abundance and size of many of the different fish taxa varied among habitats. Centrarchids, clupeids, poeciliids, cyprinids (excluding common carp) and atherinids were more abundant within backwater lake habitat. In contrast, common carp (Cyprinus carpio), sciaenids, moronids and catostomids were more abundant in main channel habitats. Furthermore, sciaenid and clupeid larvae captured in the backwater lake habitat were larger as the season progressed than those captured in the main channel. Our study suggests that larval fish show habitat specialisation, similar to adults, indicating that both the backwater lakes and the main channel are both important for larval fish and preserving the diversity of the fish assemblages in large floodplain rivers.     

Large‐scale patterns of fish diversity and assemblage structure in the longest tropical river in Asia

Although the Mekong River is one of the world's 35 biodiversity hot spots, the large‐scale patterns of fish diversity and assemblage structure remain poorly addressed. This study aimed to investigate the fish distribution patterns in the Lower Mekong River (LMR) and to identify their environmental determinants. Daily fish catch data (i.e. from December 2000 to November 2001) at 38 sites distributed along the LMR were related to 15 physicochemical and 19 climatic variables. As a result, four different clusters were defined according to the similarity in assemblage composition and 80 indicator species were identified. While fish species richness was highest in the Mekong delta and lowest in the upper part of the LMR, the diversity index was highest in the middle part of the LMR and lowest in the delta. We found that fish assemblages changed along the environmental gradients and that the main drivers affecting the fish assemblage structure were the seasonal variation of temperature, precipitation, dissolved oxygen, pH and total phosphorus. Specifically, upstream assemblages were characterised by cyprinids and Pangasius catfish, well suited to low temperature, high dissolved oxygen and high pH. Fish assemblages in the delta were dominated by perch‐like fish and clupeids, more tolerant to high temperatures, and high levels of nutrients (nitrates and total phosphorus) and salinity. Overall, the patterns were consistent between seasons. Our study contributes to establishing the first holistic fish community study in the LMR.     

Relationships between fish assemblages and habitat characteristics in Iowa’s non‐wadeable rivers

Abstract Non‐wadeable river systems are some of the most diverse aquatic ecosystems, but little work has been conducted to quantify the relationships between fish assemblages and habitat characteristics in them. In 2007 and 2008, 21 reaches were sampled on 16 non‐wadeable rivers across Iowa, USA. Fish were sampled in each reach with three different gears, and habitat characteristics (channel morphology, current velocity, instream cover) were measured using standard procedures. Fish assemblages were structured based on drainage basin and reaches and could be categorised as belonging to one of three groups. Reaches in the Missouri River basin group were narrow and had a high proportion of fine substrate. Reaches in the Mississippi River A group were also narrow but had a high proportion of large rocky substrate. Reaches in the Mississippi River B group tended to be wider, deeper and have higher proportions of fine substrate than the other groups. Fish assemblages were closely related to habitat characteristics and reflected differences among the three groups. Results of this study suggest that stream geomorphology may have a substantial influence on fish assemblage structure in large rivers.