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1.
Luciana L. Santos Naraiana L. Benone Bruno E. Soares Ronaldo B. Barthem Luciano F. A. Montag 《Ecology of Freshwater Fish》2019,28(3):424-433
Studies of trait–environment relationships provide important tools for the prediction of the response of biological communities to environmental alterations. The Amazon basin presents enormous potential for the development of research on this type of relationship, given the diversity of both its fish fauna and the aquatic ecosystems this fauna inhabits. The present study investigated the association between local environmental variables and the functional traits of fish in 54 streams of six major Amazonian basins. We identified the relationship between the characteristics of the streams (channel morphology, channel habitat units, riparian vegetation cover, large woody fragments and instream cover for aquatic organisms) and fish traits related to locomotion, habitat use and feeding behaviour. The fish fauna of the broader, deeper and more slowly flowing streams was dominated by nektobenthic species that exploit autochthonous resources such as fish and invertebrates. In narrow, fast‐flowing streams, by contrast, there was a predominance of benthic fishes with varying feeding habits, including periphytivorous and invertivorous species. Narrow, shady streams were inhabited by nektonic species adapted for the exploitation of resources from the marginal vegetation. The results of this study contribute to the understanding of the association between the functional structure of fish assemblages and local environmental variables in Amazonian streams. We hope that these findings will stimulate further research into the natural variation in stream fish assemblages that will ensure the development of more effective management strategies that better protect these important aquatic ecosystems. 相似文献
2.
Jose Luis Poveda-Cuellar Edwin Orlando Lpez Delgado Pamela Tatiana Zúiga-Upegui Francisco Antonio Villa Navarro 《Ecology of Freshwater Fish》2022,31(1):87-101
Understanding the mechanisms that structure communities have been a major challenge in ecological theory. Functional trait-based approaches are increasingly used for studying the processes underlying community assembly. However, species-poor systems of Andean streams these processes are largely unknown. Tropical Andean streams are highly variable in space-time and characterised by the harsh or stable environment, resulting in a high taxonomic and ecological diversity. In this study, we tested the influence of environmental variables on the fish functional structure. We proposed that in ecosystems with harsh environments, environmental filtering will structure fish assemblages, and in ecosystems with a more stable environment, limiting similarity will prevail, increasing functional diversity. We analysed fish assemblages using functional diversity indices, fourth-corner RLQ analyses and multiple regression models. Environmental variables such as altitude, stream width, sub-Andean vegetation and pH influenced functional diversity. For instance, high values of functional redundancy were registered at high elevation streams, reflecting fish assemblages composed of highly dominant species with similar functional traits such as species of the genus Astroblepus. However, we found differences between Astroblepus species in the number and distance of gill rakers which might indicate resource partitioning and coexistence. On the other hand, our results show both stochastic dynamics and environmental filtering are structuring fish assemblages in low and high elevation Andean streams respectively. 相似文献
3.
Environmental and spatial processes: what controls the functional structure of fish assemblages in tropical rivers and headwater streams? 
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下载免费PDF全文 In this study, we investigated functional structure patterns of tropical headwater and river fish assemblages. We hypothesised that environmental conditions are primarily structuring headwater streams leading to functionally clustered assemblages, whereas processes that favour functional overdispersion would guide river assemblages. For 27 headwater streams and 22 rivers, we used eight functional traits for calculating two functional indexes: mean pairwise distance (MPD) and net relatedness index (NRI). We performed linear regressions between indexes and species richness, a multiple regression between NRI and eight environmental variables and a variation partitioning to disentangle the role of environment and space on NRI. Our findings indicate that fish assemblages of headwaters are structured by environmental conditions as most assemblages in this habitat displayed a tendency to clustering and MPD/NRI were not correlated with species diversity, whereas the opposite pattern was observed for river habitat. Four environmental variables (channel depth, water velocity, dissolved oxygen and turbidity) explain 56% of functional structure variation. These variables seem to function as selective filters in headwaters, whereas channel depth may be determinant for functional overdispersion of river fish assemblages. Components associated with space are also influencing the functional structure. Limitations of species dispersal through space (between both habitat types) appear as a possible cause to this. In this sense, both environmental conditions and processes linked with space are capable of influencing the functional structure of tropical headwater streams and river fish assemblages. 相似文献
4.
Alan M. Friedlander 《Aquarium Sciences and Conservation》2001,3(1-3):135-150
Extensive and unregulated harvest of marine ornamental fishes can lead to localized depletion of target species and habitat degradation from inappropriate collecting techniques. One potential solution to these problems is the creation of marine reserves where fishing is prohibited. Marine reserves have been shown to increase fish abundance and protect ecosystems from habitat destruction associated with fishing. If protective areas are to be effective, they must include the diversity of habitats necessary to accommodate the wide range of fish species that are of interest to the marine ornamental fish trade.Fish assemblages with high diversity and abundance are often associated with habitats of high structural complexity. A relationship between fish size and reef complexity suggests the importance of shelter as a refuge for certain fishes in avoiding predation. Many species tend to aggregate to spawn in structurally complex habitats to reduce their risk of predation. Closing of spawning areas during aggregation periods has been shown to be a highly effective management strategy for these species. The limited home ranges and high degree of habitat specificity associated with many marine ornamental fishes should make marine reserves a highly effective strategy for managing these resources. 相似文献
5.
6.
C. W. Hargrave 《Ecology of Freshwater Fish》2009,18(1):24-32
Abstract – Biodiversity is declining across aquatic ecosystems because of biological invasions and species extinctions. Because fishes have pervasive effects on ecosystems through species-specific food web interactions, alterations to species and functional richness, and composition of natural assemblages could have negative effects on aquatic ecosystem function. In this study, I tested the effects of fish species and functional richness, and assemblage composition on primary production (PPR), benthic invertebrate density, and benthic particulate organic matter (BPOM) in a 42-day experiment in artificial stream mesocosms. I found that fish species richness and assemblage composition were important predictors of PPR in stream mesocosms. However, the effect of species richness on PPR increased with time, suggesting that richness-related effects might strengthen as the magnitude of community-level interactions increases in ecosystems. There was no effect of fish species or functional richness or assemblage composition on benthic invertebrate densities or BPOM. These data provide additional support that fishes can be important regulators of ecosystem function in aquatic systems, and suggest that positive effects of fishes on ecosystems can be strengthened by increased species richness and composition of the assemblage. This study broadens the applicability of the biodiversity ecosystem-function literature to a new suite of taxa, supporting the overall hypothesis that ecosystem functions and services are likely to decline in response to species extinctions. 相似文献
7.
Trevor J Kenchington 《Fish and Fisheries》2017,18(1):160-170
The Convention on Biological Diversity calls for networks of ‘representative’ MPAs, the effectiveness of which requires that the protected ecosystems be independent of external anthropogenic pressures. One principal pressure, fishing, severely depletes the oldest age classes of the target fish even if optimally managed. As many fishery resource species had high natural abundance and large individual sizes, while most fish show indeterminate growth and ascend the trophic pyramid as they grow, elimination of older age classes equates to removal of once‐dominant top predators. Because archetypal resource species are also migratory, that loss is transported throughout the range of the exploited populations, including into MPAs, through a lack of large migrants. The ecological implications remain uncertain in marine ecosystems, which are typically under ‘bottom‐up’ control. ‘Top‐down’ effects, such as mesopredator release, species replacement and trophic cascades, have been observed, however, meaning that elimination of top predators may affect ecosystem structure. It follows that, while exceptions doubtless exist, in general ‘representative’ MPAs should not be expected to fulfil their declared purposes, unless they are made so large as to encompass the whole migratory circuits of principal resource species – implying indefinite closure of the fisheries affected. Some compromise may be possible if MPAs were combined with fishing mortality rates far below current ‘optimal’ levels or where fishing can be concentrated on younger adults, while older fish are protected from exploitation. In any case, societies must choose between seafood production and recovery of selected marine areas to near‐pristine conditions. 相似文献
8.
基于河流网络体尺度的皖河河源溪流鱼类群落的空间格局 总被引：2，自引：0，他引：2
2013年7-8月对大别山皖河河源1～3级溪流的鱼类进行了调查,着重从河流网络体空间尺度研究了鱼类多样性及群落结构的空间格局,探讨了局域栖息地条件和支流空间位置对鱼类群落的影响.1～3级溪流间,鱼类物种数随溪流级别增大显著增多,但个体数无显著变化(P＞0.05);长河、潜水和皖水3条支流间鱼类物种数和个体数均无显著差异(P＞0.05).鱼类物种数受局域栖息地条件(海拔)和支流空间位置(河流级别和下游量级)的联合影响,但鱼类个体数仅受局域栖息地条件(海拔)的影响.不同溪流级别和不同支流间的群落结构均无显著差异(P＞0.05).同物种数类似,鱼类群落结构也受局域过程(海拔)和空间过程(汇合量级和下游量级)的联合影响.本研究表明,总体上皖河河源溪流网络体中的鱼类群落是局域过程和空间过程联合作用的产物.因此,为合理保护和管理皖河河源的溪流鱼类物种,有必要兼顾局域栖息地条件与河流网络连通性的保护和恢复. 相似文献
9.
Marah J. Hardt 《Fish and Fisheries》2009,10(2):143-158
Since Pre-Columbian times, humans have exploited Jamaican marine ecosystems with significant consequences for flora and fauna. This study focuses on the history of reef fish exploitation in Jamaica, from first human occupation to the present day, to determine how past fishing activities contributed to subsequent declines in the coral reef ecosystem. The pattern of declining reef fish populations was nonlinear. Reef fish first declined in prehistoric times but then potentially recovered, following genocide of the native human population. Reduced fishing pressure lasted until the mid-19th century. At that time, depletion of reef fish populations again occurred with a precipitous decline from the 1850s to the 1940s. The final shift from relatively abundant to overfished marine fauna corresponded to subtle changes in fish trap design as well as development of recreational fishing. Government subsidies throughout the second half of the 20th century exacerbated the declines. This analysis shows that local artisanal fisheries with relatively low levels of effort and seemingly subtle shifts in technology can significantly impact the coral reef ecosystem and that declines occurred decades to centuries before modern ecological studies began. This research shows how historical analysis can be a powerful tool to minimize shifted baselines and establish realistic targets for recovery and sustainable management of marine ecosystems. 相似文献
10.
Hugo de Oliveira Barbosa Pedro Paulino Borges Renato Bolson Dala‐Corte Patrick Thomaz de Aquino Martins Fabrício Barreto Teresa 《Fisheries Management and Ecology》2019,26(2):119-130
Understanding variability in the composition of aquatic assemblages requires a multiscale perspective, since processes operating at different spatial scales (from regional to local) drive the community assembly. Here, the relative importance of environmental variables on fish species composition in streams of the Brazilian savanna (Cerrado) is assessed and quantified at local and landscape scales. The importance of both local and landscape environmental variables in structuring fish assemblages was supported. Local variables explained a substantially higher amount of variance of fish assemblages than landscape variables. However, the shared explanation indicate that landscape variables had a complementary effect. The streams sampled were mostly headwaters at similar altitudes and with similar watershed sizes, so the sensitivity of the fish assemblages, even to small landscape gradients, is highlighted. Maintaining these important instream habitat characteristics close to natural conditions seems to be essential for conserving stream fish species, and for this, the landscape context should be taken into account. Considering the near‐pristine condition of the streams studied, these findings can be used as a reference for further studies addressing the effects of human modifications on stream fish biodiversity of the Cerrado. 相似文献
11.
Fishes and aquaticenvironments are often overlooked in conservation and sustainabledevelopment projects in Amazonia, yet the diversity of fishes(> 3 000 species) and the socio-economic value of thefisheries and the aquatic habitats have a great importance forthe region. Fishes are not only the principal source of proteinfor local people (> 70 kg/capita), many are also traded asornamental fishes in a worldwide market. The middle Rio Negrobasin is the major fishing grounds for live ornamental aquariumfish. Nearly 20 million live fishes are exported from the regionannually, generating more than US$ 2 000 000 annually forthe local economy. The trade in ornamental fish now contributesover 60% of the income revenue in the municipality. The goal ofProject Piaba is to promote an economically viable fishery forlocal fishers, and an ecologically sustainable resource for agreen aquarium industry. To arrive at these goals first requiresan understanding of the ecosystems and sociocultural systems ofconcern. The Project Piaba team has made baseline studies on thediversity of fishes and habitats, and socio-economic processes ofthe ornamental fishery. Five principal project goals are:(1) To collect baseline data on the ecosystem, socio-economy and diversity of fishes, to analyze the impact of the ornamental fish trade on social and natural environments.(2) To diagnose diseases, to introduce fish care techniques, to improve the survival and quality of fishes and turtles, and eventually to establish quarantine protocols at each level of the trade.(3) To provide environmental education and socio-cultural history to local fishers, distributors and public, and to promote career development in aquarium science and conservation.(4) To create community based fishery management strategies which would include managed harvest levels, stock enhancement of fishes and turtles and the development of aquaculture.(5) To assist in the revision of policies by regulatory agencies in order to protect vulnerable species and enhance the economic viability of the region 相似文献
12.
- 1. Marine protected areas (MPAs) are expected to function simultaneously as biological conservation and fisheries management tools, but empirical evidence linking biodiversity conservation with fisheries benefits is scarce. Around the Medes Islands marine reserve (Spain, NW Mediterranean) patterns of fish catch diversity, catch (CPUE) and income (IPUE) were assessed and the economic value of diversity for local fisheries was explored by combining a Geographic Information System (GIS) analysis with geostatistics.
- 2. Catch data were derived from the trammel net fleet operating around the MPA to gain information on species diversity, functional diversity, functional redundancy, CPUE and IPUE.
- 3. Results revealed significant impact of both the fishing prohibition in the MPA and the presence of seagrass beds on diversity metrics, catch and income. Clear differences in functional redundancy in fish assemblages were found within the study area, indicating greater resilience of the fish assemblage against fishing pressure or human impact close to the MPA (?2 km). In contrast, fish assemblages beyond 2 km of the MPA border are more vulnerable to disturbance. High values of diversity, CPUE and IPUE overlapped close to the MPA border and close to seagrass beds.
- 4. The spatial approach developed suggests that, in addition to the more commonly studied effect of density‐dependent spillover of adult fish, increased levels of ecological diversity and economic diversity can also result in fisheries benefits of an MPA. Hence, the fishing regulations in and around the Medes Islands marine reserve have shown that biological conservation and fisheries benefits can be complementary in the long‐term, which should be considered in future policies for MPAs or MPA networks.
13.
Fish assemblages in Atlantic Forest streams: the relative influence of local and catchment environments on taxonomic and functional species 下载免费PDF全文
下载免费PDF全文 Bianca de F. Terra Robert M. Hughes Francisco G. Araújo 《Ecology of Freshwater Fish》2016,25(4):527-544
Streams are under environmental pressures acting at different scales that influence the ecological organisation of their fish assemblages. However, the relative influence of the different scale‐related variables on assemblage composition and function is poorly understood. We evaluated the importance of local‐ and catchment‐scale environmental variables, as well as the spatial structure of the sampling sites, in shaping fish assemblages in Atlantic Forest streams. Local‐scale variables were those measured at the sampling sites, describing the local habitat conditions (e.g. depth, substrate type, altitude). Catchment‐scale variables were those integrating the upstream landscape of the sampling sites (e.g. catchment land use). Spatial distances were calculated from watercourse distance using principal coordinates of neighbour matrices. Altogether, 28 local and seven catchment variables were initially subjected to two processes of eliminating co‐linearity. Redundancy analysis was applied to the three matrices (spatial, local and catchment) to quantify the variance in the structure of the fish assemblages explained by each matrix. Local variables explained more variability in both taxonomic and functional assemblage structure, than catchment and spatial variables. Local variables also changed along the longitudinal gradient, which consequently influenced fish assemblage structure. This pattern was also influenced by anthropogenic alteration and non‐native species, which were more abundant in downstream sites. These results highlight the need to assess Atlantic Forest streams under different environmental scales, especially through the use of quantitative local‐scale metrics, and to consider the effects of longitudinal patterns in structuring fish assemblages when developing and implementing monitoring programmes, impact studies and conservation plans. 相似文献
14.
Abstract – Effects of local environmental influences on the structure of fish assemblages were evaluated from 159 sites in two regions of the Great Plains with limited anthropogenic disturbance. These regions offered an opportunity to evaluate the structure and variation of streams and fish assemblages within the Great Plains. We used canonical correspondence analyses to determine the influence of environmental conditions on species abundances, species occurrences and assemblage characteristics. Analysis of regions separately indicated that similar environmental factors structured streams and fish assemblages, despite differences in environmental conditions and species composition between regions. Variance in fish abundance and assemblage characteristics from both regions was best explained by metrics of stream size and associated metrics (width, depth, conductivity and instream cover). Our results provide a framework and reference for conditions and assemblage structure in North American prairie streams. 相似文献
15.
The carrying capacity of marine shelf ecosystems in southern Brazil for harvestable species is analyzed by (1) quantifying the amount of available primary production appropriated by fisheries catches, (2) evaluating the trend in the mean trophic level of fisheries, and (3) simulating the ecosystem effects of “fishing down the food web” in an intensively exploited shelf region. Fisheries utilize ca. 27 and 53% of total primary production in the southern and south-eastern shelf regions, respectively. Regional variation in the carrying capacity appropriated by fisheries results from differences in the primary production, catch volume and trophic transfer efficiencies. Overall, fisheries landings do not display a trend of decreasing trophic level with time due to the collapse of the sardine fishery and the recent increasing of offshore fishing for higher trophic level species, mainly tunas and sharks. However, the simulations show that fishing down the food web through fisheries that target small pelagic planktivorous fishes, while at first increasing catches in intensively exploited regions, has the potential of decreasing yields, by interrupting major energy pathways to exploited, high-trophic level species. The consequences of these results to the design of precautionary measures for future fishing policies are discussed. 相似文献
16.
Trap mesh selectivity and the management of reef fishes 总被引：1，自引：0，他引：1
The regulation of mesh size has frequently been proposed as a management measure for fish traps, the predominant gear used by the reef fish fisheries in the Caribbean. Studies on trap mesh selectivity show that mesh size is a determinant of catch rates and the size at which fish recruit to fish traps. Mesh size also affects the species composition in fish traps, probably through size selectivity. Other factors also affect catch rates, and the fish size and species composition in traps, for example, soak time, trap design, trap size, species body shape. Given the variety of growth rates and maturity schedules of reef fish commonly taken in fish traps in the Caribbean, no single mesh size will optimise the yield or protect against recruitment overfishing for the entire range of exploited species. Preliminary data suggest that the fishing power of traps may decrease with increased mesh size. This would reduce the effective fishing effort and thus mortality on fully recruited size classes. Studies indicate that the mesh sizes currently in use in most Caribbean countries are too small, and that a minimum mesh size of at least 3.8–5.1 cm would be required to optimise yields for local consumption. Comparative fishing experiments indicate that an increase in mesh size in areas of high fishing mortality typically results in a reduction in catch per trap. Thus increasing trap mesh size can be expected to result in short‐term loss in revenue for fishers. However, no studies have examined the times that would be required for catches to return to the levels prevailing before the increase of mesh size, and thereafter, for fishers to recover the losses incurred during the transition period. To provide managers with an estimate of the impacts that mesh‐size regulation could have on fishers, the recovery time of catches and the financial recovery times for fishers should be modelled for a hypothetical assemblage of 10–15 reef fishes using available information. These studies would enable managers to plan for the implementation of mesh‐size increases and to communicate the potential benefits to fishers in quantitative terms. 相似文献
17.
Luciano F. A. Montag Kirk O. Winemiller Friedrich W. Keppeler Híngara Leo Naraiana L. Benone Naiara R. Torres Bruno S. Prudente Tiago O. Begot Luke M. Bower David E. Saenz Edwin O. Lopez‐Delgado Yasmin Quintana David J. Hoeinghaus Leandro Juen 《Ecology of Freshwater Fish》2019,28(2):317-329
The Amazon rainforest has experienced rapid land‐use changes over the last few decades, including extensive deforestation that can affect riparian habitats and streams. The aim of this study was to assess responses of stream fish assemblages to deforestation and land cover change in the eastern Amazon. We expected that percentage of forest in the catchment is correlated with local habitat complexity, which in turn determines fish assemblage composition and structure. We sampled 71 streams in areas with different land uses and tested for relationships between stream fish assemblages and local habitat and landscape variables while controlling for the effect of intersite distance. Fish assemblage composition and structure were correlated with forest coverage, but local habitat variables explained more of the variation in both assemblage composition and structure than landscape variables. Intersite distance contributed to variance explained by local habitat and landscape variables, and the percentage of variance explained by the unique contribution of local habitat was approximately equivalent to the shared variance explained by all three factors in the model. In these streams of the eastern Amazon, fish assemblages were most strongly influenced by features of instream and riparian habitats, yet indirect effects of deforestation on fish assemblage composition and structure were observed even though intact riparian zones were present at most sites. Long‐term monitoring of the hydrographic basin, instream habitat and aquatic fauna is needed to test for potential legacy effects and time lags, as well as assess species responses to continuing deforestation and land‐use changes in the Amazon. 相似文献
18.
长江口青草沙水库正式供水前的鱼类群落结构特征 总被引：7，自引：0，他引：7
为研究上海青草沙水库的鱼类物种组成、多样性及其空间变化,2010年7--10月在该水库共捕获鱼类993尾,隶属5目,18种,其中淡水鲤形目鱼类最多,占总物种数的72.2％.群落优势种为贝氏(鳖)、刀鲚、鲫、光泽黄颡鱼.聚类分析表明,鱼类群落类型存在较显著的空间差异,刺网网目大小对渔获物物种组成有较显著的影响.物种多样性与丰富度和均匀度均显著正相关,但更多地受丰富度的影响.单因素方差分析表明,鱼类物种多样性在空间上无显著差异.4种摄食功能群中,无脊椎动物食性(44.4％)和杂食性(33.3％)鱼类物种数比例较高;4种生态类群中,定居性鱼类占绝对优势(77.8％).青草沙水库鱼类群落表现出淡水或长江口低盐淡水区鱼类区系的主要特征,与以近海鲈形目鱼类为优势的长江口邻近水域的鱼类群落差异巨大,推测水库建设导致的隔离与盐度下降是形成该水库鱼类群落趋于淡水区系的主要原因. 相似文献
19.
A multigear sampling method to quantify fish richness and abundance in Amazonian Terra firme streams was assessed. This method is based on the four‐pass removal method using the combined application of different nets. The efficiency of the method was explored over 10 replicated sites along three streams over day, night and seasons. Use of four successive passes allowed both abundant and rare species to be collected and the abundance of common species to be estimated. On average, a high proportion (41%) of rare species was collected per sample (only one or two individuals) after four fishing passes. The efficiency of the sampling method to detect species richness per sample between successive passes was estimated using an autosimilarity approach. Although species richness and abundance increased with successive passes, no major differences were obtained between the third and fourth pass. A single pass considerably underestimated the richness and abundance of species in these type of streams, and night sampling also increased beta‐diversity by at least 20%. Abundance estimates demonstrated high efficiency with an overall sampling error of only 8 and 11% for samples and single species, respectively. Capture efficiency differed among fish species exhibiting different ecological traits and showed significant differences among seasons for total samples. Results supported the robustness of the method and its suitability to quantify fish richness and abundance in small, wadeable Amazonian Terra firme streams inhabited by highly diverse fish assemblages. 相似文献