首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
1. Spatial patterns at regional and local scales were examined for evidence that species interactions can influence distribution and abundance within a guild of benthic fishes in upland streams of Oklahoma, U.S.A. Three groups of community patterns were examined: the species–area relationship, species–habitat associations, and interspecific associations.
2. The species–area relationship for riffle habitats was compared to a null species–area model based on random placement. The observed species–area curve was steeper resulting in less species per unit area in small streams than predicted by the null model.
3. Small, species-poor streams had summed fish densities at least as high as larger, species-rich streams, suggesting density compensation.
4. Several significant patterns of negative covariation were found among species at the regional scale, before and after statistically accounting for effects due to measured habitat variables.
5. For two of these negatively covarying taxa ( Cottus carolinae and Etheostoma spectabile ), the influence of each species on the distribution of the other was evaluated experimentally in field enclosures varying in depth and current velocity. The sculpin C . carolinae caused a shift in habitat use by the darter E . spectabile , but no reciprocal shift was found.
6. These results indicate an agreement between local and regional patterns of distribution for C . carolinae and E . spectabile and suggest that biotic interactions can influence regional patterns of distribution for species within this guild.  相似文献   

2.
G. L. Miller 《Oecologia》1984,63(1):106-109
Summary The ecomorphological model which attempts to identify important variation in the total morphology of groups of animals has been used with some success in communities of fishes. The applicability of the model to subsets of the community, such as guilds of ecologically similar species, is uncertain, and the effects of the possible changes in correlations among morphological variables caused by demographic changes across seasons is unknown. An ecomorphological model is applied to a guild of benthic stream fishes from the Tombigbee River, Mississippi. The model is found to describe structuring in the guild based on aspects of the trophic morphology and the length of the body. Morphologically distinct groups of species are described by the model. The effect of indeterminate growth seems not to be of sufficient magnitude to change groupings across seasons. However, species associations within morphological groups change seasonally. I conclude that ecomorphological models may be properly applied to community subsets, but the interpretation of the model must consider the nature of the data set with respect of seasonality.  相似文献   

3.
Recent work has shown that benthic invertebrate assemblages may be influenced in an ongoing fashion by dispersal. Water-column movements of meiofauna, juvenile insects and marine postlarvae are common and can act to alter greatly local dynamics such as predator-prey and competitive interactions in marine and stream ecosystems. These findings are important because past research on the role of dispersal in invertebrate dynamics has focused almost exclusively on how planktonic larval supply influences the establishment and maintenance of local assemblages, on the colonization of newly opened sites, or on the settlement success of new recruits. The emerging framework is that dispersal needs to be viewed as a regional process that may routinely influence local benthic dynamics, because fauna can move to and from water-column dispersal 'pools' and may do so at frequent intervals.  相似文献   

4.
Habitat use and foraging behavior of two benthic insectivorous gobies, Rhinogobius sp. CO (cobalt type) and Rhinogobius sp. DA (dark type), were examined in relation to their predation effects on local prey density in a small coastal stream in southwestern Shikoku, Japan. Correlations among the foraging range, frequency of foraging attempts and current velocity indicated that individuals using fast-current habitats had small foraging ranges and infrequently made foraging attempts while those in slow currents frequently foraged over large areas. The former and the latter were recognized as ambush and wandering foragers, respectively. Interspecific comparisons of habitat use, foraging behavior and prey preference suggested that Rhinogobius sp. CO selectively forage mobile prey by ambushing in fast currents, whereas Rhinogobius sp. DA randomly forage available prey by wandering in slow-current habitats. A cage experiment was conducted to assess prey immigration rate and the degree of predation effects on local prey density in relation to current velocity. The results of the experiment support, at least in part, our initial predictions: (1) prey immigration rates increase with current velocity and (2) the effects of fish predation on local prey density are reduced as current velocity increases. Overall results illustrated a link between the foraging modes of the stream gobies and their predation effects on local prey density: fish adopt ambush foraging in fast currents, where the decrease in prey density tends to be less, whereas fish actively forage over large areas in slow currents, where the decrease in prey is relatively large.  相似文献   

5.
6.
Synopsis The densities, habitat use, and feeding behaviors of 13 fish species belonging to the benthic invertebrate-feeding guild were studied by snorkeling at three localities in the Little River of eastern Tennessee, U.S.A. Resource partitioning occurred by habitat, feeding behavior and time of activity. Differences were also found at the generic level.Cottus was a nocturnal feeder, whereasPercina andEtheostoma were, for the most part, diurnally active.Percina moved about rapidly and spent most of its time above the bottom. In contrast,Etheostoma varied considerably in the amount of time spent under cover, spent little time above the bottom, and exhibited low levels of swimming activity. Nearly all species sought cover at night, suggesting they may be particularly sensitive to predation at night. Species with small adult sizes (Etheostoma, Cottus andP. evides) were concentrated in shallow water habitats, whereas species with large adult sizes (Percina) were more abundant in deep water habitats. The habitat use data are consistent with the hypothesis that size-selective predation by centrarchid bass may cause smaller fish to avoid deep water areas. Large species should have a lower risk of predation due to their size and behavior.  相似文献   

7.
David O. Duggins 《Oecologia》1981,48(2):157-163
Summary Interspecific relationships and trophic function within the urchin guild are considered in light of experiments and observations performed in situ. Two conclusions are reached: 1) interactions between members of the guild contribute to its persistence, and 2) the plant-herbivore interactions so important in structuring this community can best be evaluated when guild members are treated as a unit. As with other mixed species trophic units, the mechanisms of interspecies facilitation operate to reduce the effects of predation and increase foraging efficiency.  相似文献   

8.
9.
The present study was aimed to determine dietary composition and feeding guild structure of the fishes inhabiting mudflat habitat of Indian Sundarbans. In addition, partitioning of food resources by the fish species belonging to the carnivorous feeding guild was also performed to understand the survival strategies of fish in a mudflat estuarine habitat. Seventeen prey categories were isolated from the stomachs of 31 studied fish species. Overall, five feeding guilds (viz. plankti-benthivore: 12 species, herbivore: one species, detritivore: three species, omnivore: one species and carnivore: 14 species) were identified on the basis of the prey abundance within their stomachs, considering 64 % Bray–Curtis similarity. Among the carnivorous, maximum trophic richness was obtained for Uroconger lepturus followed by Ophichthus apicalis. Teleost and decapods were the main animal prey items preferred by majority of the carnivorous fishes. However, O. apicalis and Terapon jarbua showed their preference toward maximum number of prey categories among carnivores, which was also ratified by the high values for standardized niche breadth presented by them. The maximum degree of interspecific dietary overlap was found between Uropterygius marmoratus and Pseudapocryptes elongatus as both of them were recognized as cranci-piscivore. The lowest was observed between Hyporhamphus limbatus and Coilia neglecta. As food resources are not limiting in the mudflats of Indian Sundarbans, the general patterns of resource partitioning and niche differentiation in resident ecological communities will improve the understanding of the mechanisms underlying species coexistence and community structure.  相似文献   

10.
11.
12.
1.?A fundamental question in ecology is which factors determine species richness. Here, we studied the relative importance of regional species pool and local environmental characteristics in determining local species richness (LSR). Typically, this question has been studied using whole communities or a certain taxonomic group, although including species with widely varying biological traits in the same analysis may hinder the detection of ecologically meaningful patterns. 2.?We studied the question above for whole stream macroinvertebrate community and within functional feeding guilds. We defined the local scale as a riffle site and the regional scale (i.e. representing the regional species pool) as a stream. Such intermediate-sized regional scale is rarely studied in this context. 3.?We sampled altogether 100 sites, ten riffles (local scale) in each of ten streams (regional scale). We used the local-regional richness regression plots to study the overall effect of regional species pool on LSR. Variation partitioning was used to determine the relative importance of regional species pool and local environmental conditions for species richness. 4.?The local-regional richness relationship was mainly linear, suggesting strong species pool effects. Only one guild showed some signs of curvilinearity. However, variation partitioning showed that local environmental characteristics accounted for a larger fraction of variance in LSR than regional species pool. Also, the relative importance of the fractions differed between the whole community and guilds, as well as among guilds. 5.?This study indicates that the importance of the local and regional processes may vary depending on feeding guild and trophic level. We conclude that both the size of the regional species pool and local habitat characteristics are important in determining LSR of stream macroinvertebrates. Our results are in agreement with recent large-scale studies conducted in highly different study systems and complement the previous findings by showing that the interplay of regional and local factors is also important at intermediate regional scales.  相似文献   

13.
1. Ecological stoichiometry has been used to better understand dynamics in consumer growth and the role of consumer‐recycled nutrients because it focuses on more than one element. Most research has focused on pelagic rather than benthic consumers. Variation in elemental composition among benthic consumer taxa would suggest that taxa differ in their susceptibility to nutrient limitation or in their role in recycling nutrients. 2. We collected benthic macroinvertebrates from streams in two regions (Indiana–Michigan and Wisconsin, U.S.A.) to examine taxonomic and regional variation in benthic macroinvertebrate body carbon (C), nitrogen (N), and phosphorus (P) concentrations and ratios. 3. Elemental composition varied little within taxa common to both regions. In contrast, elemental composition differed greatly among taxa and appeared to be related to phylogeny. The elemental composition of macroinvertebrates clustered into three distinct groups: insects, mollusks, and crustaceans. To a lesser extent, insects and mollusks also differed in elemental composition among genera. 4. Functional feeding groups (FFGs) differed in elemental composition, with predators having a higher N content than other groups. Substantial elemental imbalances between C and N were found between most primary consumers and their likely food sources, and the magnitude of the imbalance depended in part on the FFG. 5. Our results support an assumption of most ecological stoichiometry models that, within a species, the elemental composition of aquatic invertebrates is relatively constant. Variation in elemental composition among taxa at various higher taxonomic levels suggests that susceptibility of stream invertebrates to nutrient limitation and their role in nutrient cycling will strongly depend on phylogeny.  相似文献   

14.
Diel distribution patterns of fishes in a temperate large lowland river   总被引:4,自引:1,他引:4  
During the day, juveniles and typical inshore species in the lower Oder River, Germany, inhabited the littoral (0·05–1·50 m deep) while potamal species inhabited the mid‐channel (40–100 m from the banks). During the night, two behavioural groups were distinguished: 1) potamal species and large individuals of other species, moved from offshore to the littoral, and 2) nocturnal foraging species, became active and increased in inshore and offshore habitats. Inshore, the most significant differences at night was the increasing density of silver bream Blicca bjoerkna increasing both total biomass and total length of fishes caught. Offshore, the increasing density of whitefin gudgeon Gobio albipinnatus at night was most significant. Additional night electrofishing improved the assessment of the abundance, age and size structure of typical potamal fish species. It should be incorporated in large river fish monitoring programmes.  相似文献   

15.
The relationship between biodiversity and ecosystem functioning (B–EF) was investigated by examining top-down effects of aquatic detritivore diversity on the functional process of leaf-litter breakdown. This study was undertaken in tropical Hong Kong where the stream detritivore guild is depauperate and loss of one or a few species might have strong effects on processes. Effects of detritivore richness and composition were investigated by comparing feeding rates of three species of detritivores with their two- and three-species mixtures in laboratory trials. The detritivores were a caddisfly larva (Anisocentropus maculatus: Calamoceratidae), a snail (Brotia hainanensis: Pachychilidae) and a shrimp (Caridina cantonensis: Atyidae). Liquidambar formosana (Hamamelidaceae) litter was provided as food. All three detritivore species had positive non-additive effects on litter processing. Per capita and mass-specific feeding rates of each species were faster in mixtures than when they were alone, although the non-additive effects of shrimps and snails were larger than those attributable to caddisflies, and thus, litter processing was strongly influenced by the composition of detritivore mixtures. The compositional effect appears to be evidence of facilitation indicating a lack of functional redundancy amongst these detritivores, probably due to their evolutionary distinctness, implying that extinction consequences in this species-poor guild will depend on the identity of the species lost.  相似文献   

16.
1. Seasonal changes in longitudinal patterns of environmental conditions and macroinvertebrate community distributions were examined in an alpine glacial stream (Roseg River, Switzerland). 2. Physico‐chemical parameters reflected seasonal changes in glacial influence via shifts in water sources and flowpaths (glacial meltwater versus ground water), and were best described by turbidity, particulate phosphorus and specific conductance. High nitrogen concentrations indicated snowmelt was the main water source in June. 3. Macroinvertebrate densities and taxon richness were highest during spring (4526 m–2 and 16 taxa, all sites combined) and late autumn/early winter (8676–13 398 m–2 with 16–18 taxa), indicating these periods may be more favourable for these animals than summer when glacial melting is maximal. Diamesa spp. (Chironomidae) dominated the fauna at the upper three sites (>95% of zoobenthos) and were abundant at all locations. Other common taxa at lower sites (1.2–10.6 km downstream of the glacier terminus) included other chironomids (Orthocladiinae, Tanytarsini), the mayflies Baetis alpinus and Rhithrogena spp., the stoneflies Leuctra spp. and Protonemura spp., blackflies (Simulium spp., Prosimulium spp.), and Oligochaeta. 4. Co‐inertia analysis revealed a strong relationship between environmental conditions and benthic macroinvertebrate assemblages. Furthermore, it elucidated temporal variability in longitudinal response patterns, as well as a similarity in temporal patterns among individual sites. 5. Our results suggest that zoobenthic gradients are not solely related to temperature and channel stability. Seasonal shifts in sources and pathways of water (i.e. extent of glacial influence), and periods of favourable environmental conditions (in spring and late autumn/early winter) also strongly influenced zoobenthic distributions.  相似文献   

17.
Seasonal dynamics in the activity of Arctic shelf benthos have been the subject of few local studies, and the pronounced among-site variability characterizing their results makes it difficult to upscale and generalize their conclusions. In a regional study encompassing five sites at 100–595 m water depth in the southeastern Beaufort Sea, we found that total pigment concentrations in surficial sediments, used as proxies of general food supply to the benthos, rose significantly after the transition from ice-covered conditions in spring (March–June 2008) to open-water conditions in summer (June–August 2008), whereas sediment Chl a concentrations, typical markers of fresh food input, did not. Macrobenthic biomass (including agglutinated foraminifera >500 μm) varied significantly among sites (1.2–6.4 g C m−2 in spring, 1.1–12.6 g C m−2 in summer), whereas a general spring-to-summer increase was not detected. Benthic carbon remineralisation also ranged significantly among sites (11.9–33.2 mg C m−2 day−1 in spring, 11.6–44.4 mg C m−2 day−1 in summer) and did in addition exhibit a general significant increase from spring-to-summer. Multiple regression analysis suggests that in both spring and summer, sediment Chl a concentration is the prime determinant of benthic carbon remineralisation, but other factors have a significant secondary influence, such as foraminiferan biomass (negative in both seasons), water depth (in spring) and infaunal biomass (in summer). Our findings indicate the importance of the combined and dynamic effects of food supply and benthic community patterns on the carbon remineralisation of the polar shelf benthos in seasonally ice-covered seas.  相似文献   

18.
Peter F. Sale 《Oecologia》1979,42(2):159-177
Summary Eupomacentrus apicalis, Plectroglyphidodon lacrymatus, and Pomacentrus wardi are territorial pomacentrid fishes which occupy contiguous individual territories within rubble patches on the shallow reef slope. Loss of residents, which is non-seasonal (except for juvenile Po. wardi), results in reallocation of space in rubble patches among the species. This reallocation is random in the sense that sites previously held by one species will not be more likely than any other sites to be reoccupied by that species or to be occupied by any other particular species. The results of a 38 month study of three neighbouring patches are used to determine patterns of recruitment, survivorship, and loss for each species. The rate of recruitment of fish is proportional to the area of the rubble patch, and is seasonal in at least one of the species. About half the recruits are juveniles and young adults from other sites. The others are newly settled from the plankton. Total space used in a rubble patch does not vary significantly during the 38 month period. Po. wardi recruits and is lost at higher rates than the other species and its survivorship is significantly lower. Juvenile Po. wardi are lost at a greater rate than are adults, and their loss rate varies seasonally. The other species are similar to one another in having low recruitment and loss rates, and correspondingly high survivorship. The data are used in a critical assessment of several competing hypotheses to explain the coexistence of these fish. The available data are most closely compatible with the chance allocation or lottery hypothesis, but a definitive conclusion is not possible, and is probably beyond current experimental techniques.  相似文献   

19.
We investigated the relationship between diversity and ecosystem function, which is controversial and has rarely been examined for consumer assemblages, for the process of leaf breakdown by the shredder guild in a tropical stream. We manipulated species richness, evenness and identity of four macroinvertebrate shredder species (three caddisflies and one mayfly) in microcosms and tested their effect on leaf breakdown rates measured as leaf mass loss per capita and per milligram of animal. Species richness, evenness and species identity all affected leaf breakdown rates. Breakdown rates tended to increase with higher richness, but only for the three caddisflies, probably through a release of intraspecific interference, although other mechanisms such as niche complementarity or facilitation cannot be discarded. Leaf breakdown by the caddisflies was reduced in the presence of the mayfly, possibly because of its mode of movement by swimming instead of crawling and its similarity to some predators that are common in leaf litter. Species identity was more important than species richness in determining leaf breakdown rates, indicating that some species within the shredder guild are not redundant, and suggesting important consequences of particular species loss for the functioning of the ecosystem.  相似文献   

20.
The abundance of a given species in a community is likely to depend on both the total abundance and diversity of other species making up that community. A large number of co-occurring individuals or co-occurring species may decrease the abundance of any given species via diffuse competition; however, indirect interactions among many co-occurring species can have positive effects on a focal species. The existence of diffuse competition and facilitation remain difficult to demonstrate in natural communities. Here, we use data on communities of fleas ectoparasitic on small mammals from 27 distinct geographical regions to test whether the abundance of any given flea species in a community is affected by either the total abundance of all other co-occurring flea species, or the species richness and/or taxonomic diversity of the flea community. At all scales of analysis, i.e. whether we compared the same flea species on different host species, or different flea species, two consistent results emerged. First, the abundance of a given flea species correlates positively with the total abundance of all other co-occurring flea species in the community. Second, the abundance of any given flea species correlates negatively with either the species richness or taxonomic diversity of the flea community. The results do not support the existence of diffuse competition in these assemblages, because the more individuals of other flea species are present on a host population, the more individuals of the focal species are there as well. Instead, we propose explanations involving either apparent facilitation among flea species via suppression of host immune defenses, or niche filtering processes acting to restrict the taxonomic composition and abundance of flea assemblages.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号