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1.
Jiménez‐Segura LF, Palacio J, Leite R. River flooding and reproduction of migratory fish species in the Magdalena River basin, Colombia.
Ecology of Freshwater Fish 2010: 19: 178–186. © 2010 John Wiley & Sons A/S Abstract – In most tropical rivers subject to a single‐yearly flooding, migratory fish usually spawn in the onset of the flooding and larvae drift to their nursery habitats. To define when the migratory fish species reproduce, its relationship with the water level and when nursery areas in floodplain lakes are supplied with ichthyoplankton in the Magdalena River, a two‐yearly peak flooding river, we sampled the ichthyoplankton weekly throughout 2 years. The fish species Pseudoplatystoma magdaleniatum, Prochilodus magdalenae, Leporinus muyscorum, Sorubim cuspicaudus and Curimata mivartii spawn twice a year in the main channel and its larvae input into the floodplain lakes are not always associated with flooding. Spawning in the main channel and larvae inputs into the floodplain lakes suggest that the habitat used by the migratory fishes may be consistent with some hypotheses on habitats used by these fishes.  相似文献   

2.
The Tonle Sap River and Lake (TSRL) is South‐East Asia's largest tropical flood pulse with a flow‐reversal system that supports one of the world's largest freshwater fisheries. However, among the world's tropical floodplains, the resources of the TSRL have received little ecological research. Here, we described the spatiotemporal TSRL fish diversity and community variation using daily records from 2012 to 2015 on fish abundance from six sites covering the TSRL system. We found that high fish diversity occurred in sites located in the middle of Tonle Sap Lake, and the lowest diversity was observed in the southern section. The spatial abundance distribution patterns displayed a river–lake gradient, with three fish assemblages that were clustered based on their composition similarities and were characterised by 96 indicator species. In the southern section, fish assemblages were characterised by longitudinal migratory fishes; in contrast, in the middle system, fish assemblages were represented by species with combined ecological attributes (i.e. longitudinal and lateral migratory species and floodplain residents). Towards the northern section, fish assemblages were composed of lateral migratory and floodplain resident species. Species richness and abundance peaked at approximately 2–2.5 and 4 months, respectively, after the peak flow in early October, during which Tonle Sap River resumes its normal flow direction (outflow). This suggests that seasonal flood pulses (i.e. rising and falling water levels) play a pivotal role in structuring spatiotemporal variation in the TSRL fish assemblages. Our study has implications for fisheries monitoring and conservation initiatives.  相似文献   

3.
Abstract –  The objective of this study was to quantify fish species diversity in Terra firme streams of the Río Amazonas drainage. Fish diversity was quantified as the number of species collected or species richness in two sites of Yahuarcaca stream, a typical, first order tributary of the central Río Amazonas near Leticia (Colombia). The extremely high species richness recorded, 131 and 133 for the two study sites for a total of 171 species, was primarily due to species of low abundance (rare species) mostly with adults <5 cm in total length. The nonasymptotic tendencies of accumulated species richness over time for the 1999 samples at the two study sites and for the combined samples of 1999, 2001 and 2005 at site 2 suggested that the real number of fish species may be still greater. These findings emphasise the importance of long-term sampling designs to quantify species richness in these systems. Terra firme streams actually sustain greater fish richness than previously reported for similar sized streams that in turn, represent a substantial per cent of the total species richness reported for vast areas of the main stem of Río Amazonas including tributaries and lakes. Terra firme streams should be considered critical hotspots for conservation and management efforts which are urgently needed given the rapid development of ornamental fisheries on small streams throughout Río Amazonas drainage.  相似文献   

4.
Abstract  Loss of river-floodplain (lateral) connectivity has impacted on fish communities and fisheries around the world. However, evidence of the impacts of reduced lateral connectivity on Australian native fish remains scant. To document these impacts, isolated pools located immediately downstream of two major regulators (or weirs) that control flows from the Murray River to an extensive off-stream floodplain, were pumped out five times between 2001 and 2006. A total of 20 980 fish (16 228 native, 4752 non-native) comprising 15 species (five non-native) were collected. Five fish species collected are classified as threatened, while turtles and macroinvertebrates were also present. Regulator operation appeared to affect the number of fish becoming stranded, with the highest number coinciding with longer regulator openings and extended floodplain inundation. Hundreds of floodplain regulators exist on Australian rivers, and all have the potential to impact upon native fish. Trial of several potential management and engineering solutions is recommended to improve river–floodplain connectivity in lowland rivers.  相似文献   

5.
Abstract  Floodplain borrow pits created during dike construction for flood protection along regulated lowland rivers are suggested as convenient surrogate habitats for fish communities where natural floodplain features have been lost. Fish community structure and reproduction success in three borrow pits located in the channelised floodplain of the River Dyje, Czech Republic were studied over 3 years. Short-term floods supported the spawning of phytophilic and phyto-lithophilic species; batch spawners capitalised on late summer flood conditions. The highest species richness of 0+ juvenile fishes occurred at sites with extended periods of flooding, at least for 2 months. Flooded vegetation was inhabited mainly by juvenile cyprinids, while 0+ percids were distributed evenly along the littoral zone. Shoreline remained bare even during higher water levels before complete inundation because of the steep banks, and therefore fish were not able to benefit from higher water levels. Borrow pits appear to function as a substitute habitat for fish and their reproduction, but only if they are properly constructed with shallow areas providing appropriate nursing conditions for 0+ fish growth and survival.  相似文献   

6.
Fish-environment relationships in ponds with several different combinations of fish species are analysed. The study was carried out in 18 earthen fish ponds in a farm at Lohamei HaGetaot, Israel, during the 1986 fish culture season. Water was analysed for temperature, dissolved oxygen, pH, ammonium, nitrite, nitrate, and phyto- and zooplankton. Factor analysis was applied to the physico-chemical and plankton datasets to identify respectively the main ecological processes and species groups in the ponds. The general linear model was applied to analyse the effect of fish species combination and month on the ecological and plankton factors identified. The main source of water quality variability was accounted for by three factors: pond loading (CHF1), oxygenation of the water (CHF2), and pH effect on the second step of nitrification (CHF3). The main source of variability in the plankton composition was due to presence or absence of a blue-green algal bloom (PLF1). Another four plankton factors were identified. Each factor was differently affected by the fish species combination in the pond and the month. The complex nets of interactions between common carp, tilapia and mullet, and how these fish in different cominations affect pond water quality and food webs are discussed.  相似文献   

7.
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.  相似文献   

8.
Abstract – Aquatic macrophytes form the most productive habitat of the Amazon floodplain and account for more than 60% of the net primary production of the ecosystem. Aquatic grasses are the dominant macrophytes and the main feeding ground of Amazonian larval fish. The present study used stable isotopes of nitrogen and carbon to measure the contribution of aquatic grasses to the production of eight larval fish, and describes the structure of the trophic chain. The carnivore larvae were at the third trophic level, and the detritivores were at the second and third trophic levels. The contribution of aquatic grasses to larval fish production was variable. It could reach a mean value of 25% for three species, but its contribution probably did not exceed 12% in the other five species.  相似文献   

9.
Long‐term monitoring is critical for documenting population and community trends and for management, especially in large river‐floodplain ecosystems that provide important services. Levees have reduced active floodplains in most large rivers, but connectivity in some reaches could promote community resilience. Using multivariate tools and regression, we examined spatial and temporal structure in fish community samples from two decades (>1000 samples, >100 sites) in one of the largest relatively intact river‐floodplain ecosystems in North America – the Atchafalaya River (ARB), Louisiana. Assemblages exhibited significant structure temporally and spatially, with most substantial effects of year and hydrologic subdivisions; however, season and water level also influenced community structure. Temporal trends in communities were limited to few areas, while declines in species richness were more widespread; however, rarefied richness trends suggested that declines were slight. Recent and long‐term declines in abundance of economically important species (e.g., Black Crappie, Largemouth Bass, Bigmouth Buffalo) and increases in others (e.g., Smallmouth Buffalo, Blue Catfish, Freshwater Drum) drove differences among time periods. Our results suggest that the hydrologic subdivisions of the ARB may be an appropriate scale at which to manage fish populations, hydrology and water quality. Although we could not account for several important factors affecting fish communities in the ARB (e.g., hurricanes, major floods), and were limited by sampling variability, our findings highlight the utility of long‐term datasets from large river‐floodplain ecosystems for identifying important scales for management, determining species contributions to community change and forming hypotheses about anthropogenic and environmental drivers of variation in fish communities.  相似文献   

10.
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.  相似文献   

11.
To determine the distribution of marine birnavirus (MABV) in cultured populations of different marine fish species, 1291 pooled tissue samples from 2672 fish belonging to 22 species and one hybrid were collected from Kagawa Prefecture, Japan, during 1999-2001. Using cell-culture MABV was isolated from three species: yellowtail, Seriola quinqueradiata Temminck & Schlegel (positive number/sample number, 10/419), amberjack, S. dumerili (Risso) (4/72), and Japanese flounder, Paralichthys olivaceus (Temminck & Schlegel) (41/481). Using PCR on MABV-negative samples, the MABV genome was detected in the same three species [yellowtail (9/409), amberjack (4/68) and Japanese flounder (93/440)] and two additional species, spotted halibut, Verasper variegatus (Temminck & Schlegel) (5/11), and goldstriped amberjack, S. lalandi Valenciennes (1/5). These MABV-positive species can be taxonomically divided into two groups: the genus Seriola and flatfish. In Japanese flounder, MABV was detected during all seasons, and the infection rate was correlated with water temperature. Aquaculture sites with MABV-positive fish were evenly distributed over the surveyed area, suggesting that MABV is widely distributed at aquaculture sites in Kagawa Prefecture. The nucleotide sequence at the variable region, the VP2/NS junction, revealed that the 39th base mutation occurs host-specifically for flatfish. Flatfish are suspected to be the main reservoir of MABV and might be responsible for establishing the infection cycle in aquaculture environments.  相似文献   

12.
The factors effecting fish species richness, evenness and relative abundance in 19 floodplain lagoons in the Pantanal (Brazil) were examined. Richness and evenness were strongly correlated with the lagoon's: (i) isolation time from the main river; (ii) depth; and (iii) distance from the main river. Abundance of the five dominant fish species was correlated mainly with: (a) macrophyte cover; (b) the distance from the main river; and (c) piscivore abundance. These results suggest that the species select lagoons to avoid or minimize their confinement in inappropriate floodplain habitats. A combination of strategies, together with variations in the lagoon's connection period, determines the diversity and abundance of the fish species in the Nhecolândia Pantanal.  相似文献   

13.
根据澜沧江下游一级支流补远江2006年鱼类洄游季节3～6月的采样数据,分析了该流域鱼类多样性,并结合同期水文、水质数据,应用人工神经网络分析环境因子与鱼类多样性的关联。结果表明,2006年3～6月共采集补远江鱼类34种,隶属于3目8科22属,其中有8种洄游鱼类。3月份多样性指数最高,各月均匀度指数无差异,4、6月优势度指数高,主要是优势种马口鱼、月斑长臀鲃造成。4、5月鱼类组成相似性最高。最低水位对鱼类数量影响最大,其次是平均流速和平均水温;最高水温对鱼类体重影响最大,其次是总磷和溶解氧。人工神经网络下模拟值与实测值相关性高,具较好的适用性。  相似文献   

14.
  1. Frugivorous fish provide often conflicting ecosystem services of seed dispersal and food provisioning in tropical rivers. Fishing may reduce the size and abundance of frugivorous fish, thus affecting their potential as seed dispersers, which could affect the conservation of these fish and of floodplain forests.
  2. The goal of this study was to assess the influence of co-managed protected areas in the form of extractive reserves (RESEX) and small-scale fisheries on frugivorous fish in the Tapajós and Negro rivers, in the Brazilian Amazon. The study examined whether: (i) frugivorous fish are important for fisheries and selectively caught; and (ii) frugivorous fish abundance, size and fisheries catch per unit of effort are higher inside the RESEX than outside.
  3. The analyses included fisheries-dependent data (3,753 fish landings) and independent data (12,730 sampled fish) collected in 16 fishing communities (eight for each river). In both rivers, frugivorous fish are among the 10 species caught the most and frugivorous biomass was proportionately higher in landings than in samplings, indicating fisheries selectivity towards these fishes.
  4. In both rivers, catches of frugivorous fish were higher outside the RESEX than inside. Catch per unit effort and the proportion of frugivores in the catch were higher outside the RESEX in the Tapajós River but did not vary between sites inside and outside the RESEX in the Negro River. Frugivorous fish were larger inside the RESEX in the Negro, but smaller inside the RESEX in the Tapajós.
  5. The results indicated that the ecosystem services of seed dispersal and food source provided by frugivorous fish are not in conflict in the tropical rivers studied. Therefore, these clearwater and blackwater rivers in the Brazilian Amazon show a balance between fisheries and conservation of frugivorous fish, which play an essential role in the functioning of tropical floodplain forest ecosystems.
  相似文献   

15.
Abstract –  The fish assemblage of the floodplain of the Mamoré River (Bolivia) was estimated in eight lakes, corresponding to four habitat types, situated on an environmental gradient related to the river distance: lakes situated near the river, in the forested floodplain, at the floodplain edge and lakes isolated in the savanna. This paper documents the diet of 71 fish species (among the 140 recorded) and compares the taxonomic and trophic structure of fish assemblages between four lake types. The diet analysis was conducted to determine five trophic guilds: algivores/iliophages, herbivores, zooplanktivores, invertivores and piscivores. The taxonomic and trophic structures of the fish assemblages were not similar in the different lake types of the Mamoré River. The trophic structure of assemblages showed a coarse pattern of dominance of algivores/iliophages and invertivores, but different situations were observed in relative abundance of the trophic groups in relation to the spatial position of the lakes (except for piscivores). Lakes close to the river appeared more favourable to the microphages (algivores/iliophages, zooplanktivores) although remote lakes appeared more favourable to the macrophages (invertivores, herbivores). These results support the general idea that fish distribution follows a pattern linked to the ecology of the species, and related to environmental characteristics of the lakes.  相似文献   

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17.
The diets of demersal fish, principally haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus) and several flatfish species, sampled from four Scottish sea lochs (Hourn, Kishorn, Duich and Nevis) which support aquaculture sites, were examined in order to determine whether the impact of aquaculture on benthic biodiversity would affect the diets of demersal fish. Loch Kishorn had the highest maximum planned aquaculture production, loch Nevis follows and lochs Hourn and Duich have the lowest planned production. Samples were collected from locations less than and more than 2000 m from fish farm cages. Fish close to the fish farm cages were on average of greater individual weight than those further away from fish farms. Haddock ate predominantly Malacostracan crustacea, Ophiurid echinoderms and Polychaete annelids; whiting ate predominantly Malacostracan crustacea and teleost fish and flatfish ate Malacostracan crustacea, Polychaete annelids and Ophiurid echinoderms. A small number of saithe sampled had eaten mainly fish farm pellets. Dietary variation in each species was analysed in relation to loch, proximity to aquaculture facilities and fish size. Diet of whiting varied with body size. Dietary differences were observed between the lochs and between sites close to and far from farms in two lochs although these differences cannot be specifically attributed to aquaculture development. Controlling for differences between individual lochs, proximity to aquaculture facilities did not consistently affect diet composition.  相似文献   

18.
For understanding the reproductive dynamics of fish assemblages and their relationship with environmental conditions, we need to know more about spawning areas and periods. Studies on temporal and spatial patterns of occurrence of fish eggs and larvae are important for obtaining this kind of information quickly and accurately. In this study, we analysed spatial and temporal patterns of fish larvae in different biotopes in a stretch of the floodplain of Upper Parana River, in Ilha Grande National Park, southern Brazil. We carried out night sampling during six spawning periods, from 2001 to 2008. We selected 18 sampling sites distributed in the mainstream, tributaries and lagoons, encompassing several types of biotopes. We observed significant spatial and temporal differences among biotopes in the composition and structure of the fish larvae assemblages. Lentic environments favoured the development of sedentary and migratory species, whereas tributaries were used as migratory routes and spawning areas. The assemblage in period I differed from the assemblages of other periods, probably because of the presence of dams in the Parana River. No association was observed between environmental variables and spatial and temporal patterns of the ichthyoplankton assemblages. Hence, conservation measures are essential to maintain the environmental integrity of spawning (tributaries) and development areas (lagoons) for the maintenance of biodiversity in the floodplain of Upper Paraná River.  相似文献   

19.
Abstract –  Many floodplain lake fish communities have been influenced by large-scale shifts in processes of water-level stability that degrade habitat quantity and quality. Efforts to restore rivers and their floodplains have recently taken a priority yet many restoration approaches are in their developmental stages and potentially controversial. We measured fish community changes in response to a water stabilisation technique in an Illinois River floodplain lake, achieved by levee renovations in 1997, using data collected prior to (1991–1993) and after (2000–2002) stabilisation. Our results indicate fish community composition (presence/absence) showed little variability and did not differ ( R  = 0.037; P  = 0.60) between the two time periods; whereas, fish community structure (abundance) differed ( R  > 0.50; P  ≤ 0.10). Increased abundances of desirable species like gizzard shad Dorosoma cepedianum (Lesueur), white crappie Pomoxis annularis (Rafinesque), black crappie Pomoxis nigromaculatus (Lesueur) and largemouth bass Micropterus salmoides (Lacepede), coupled with declines of less desirable species like common carp Cyprinus carpio (Linnaeus) contributed to community changes. These changes suggest positive responses to water stabilisation practices that may act as an intermediate step in restoring river–floodplain function in certain situations.  相似文献   

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