Effects of within-patch habitat structure and variation on fish assemblage characteristics in the Bernecei stream, Hungary

Abstract –  Over a 3-year period we examined variability in physical habitat structure and species richness, abundance and assemblage composition of fishes in 13 habitat patches in the Bernecei stream, Hungary. Principal component analysis of habitat structure data from patches elucidated a riffle-run-pool habitat gradient across patches. Temporal habitat variability increased significantly from riffle to pool patches. Fish assemblage characteristics displayed relatively continuous change over the habitat gradient and were relatively stable within patches. Assemblage structure properties (e.g., species richness) displayed different responses to the habitat gradient and to within-patch habitat variability. In general, pool patches had more diverse assemblages and greater within-patch assemblage variability than riffle patches. However, within-patch dynamics were largely determined by the population dynamics of a habitat generalist (i.e., minnow). Broad scale environmental variability (i.e., a catastrophic 100-year flood) also appeared to affect within-patch fish assemblage characteristics. Our results demonstrate that fish assemblage structure is influenced by physical variability (i.e., both floods and spatio-temporal habitat variability) within the Bernecei stream.     

The influence of instream cover and predation risk on microhabitat selection of stone loach Barbatula barbatula (L.)

Abstract— The microhabitat selection of stone loach ( Barbatula barbatula ) in relation to instream cover and predation risk was investigated in artificial streams. In one experiment, stone loach were presented different combinations of shelter structures, two at a time, that provided visual isolation, flow refuge, both, or none. In all cases, visual isolation shelters were selected by the fish, with little use of clear shelters and no apparent selection of flow refuges. In a second experiment, diel activity patterns and habitat selection of stone loach were measured when visual isolation structures were placed in the riffle only, pool only, both riffle and pool or in no habitat. Stone loach were marked with passive integrated transponder tags and a sensor plate was placed between the riffle and pool habitats to measure diel activity patterns. Habitat use was measured by releasing drop gates between the two habitats at the end of each trial. More stone loach used the pool than the riffle in all treatments, but use of the riffle increased when cover was present only there. Furthermore, stone loach were most active between 2100 and 0300. To determine the effect of predation threat on habitat use by stone loach, one adult brown trout ( Salmo trutta ) was added to each pool. The presence of trout caused stone loach to move into the riffle, especially the smaller loach. Overall, the study showed that stone loach used cover in a visual isolation context, preferring deeper water when there was no predation risk, but made more use of shallower water in the presence of brown trout.     

Long-term patterns of microhabitat use by fish in a southern Appalachian stream from 1983 to 1992: effects of hydrologic period, season and fish length

Abstract— We quantified microhabitat use by members of a southern Appalachian stream fish assemblage over a ten-year period that included both floods and droughts. Our study site (37 m in length) encompassed riffle, run and pool habitats. Previous research indicated that species belonged to either benthic or water-column microhabitat guilds. Most species exhibited non-random microhabitat use in all seasons, and benthic and water column species generally were over-represented in the deeper portions of the site. In addition, water column species generally were over-represented in microhabitats with lower average velocities. The majority of seasonal shifts in microhabitat use were passive (i. e. correlated with changes in microhabitat availability), whereas, most shifts associated with hydrological periods appeared to be active responses to changing environmental conditions. Most species exhibited length-related shifts in microhabitat use, which were strongly affected by hydrologic period for four of ten species. Microhabitat use patterns of assemblage members appeared to be a consequence of species-specific responses to changing environmental conditions. The highly flexible patterns of microhabitat use exhibited by these species necessitate that decisions regarding their management be based on data covering a range of environmental conditions.     

Functional vs scenic restoration – challenges to improve fish and fisheries in urban waters

Abstract Two rehabilitation projects were compared to determine their feasibility for successfully improving habitat for fish in urban waters. The first re‐meandering project involved channel reconstruction in the Müggelspree upstream of Berlin to create an aesthetically pleasing, stable, meandering channel. The second project addressed a typical habitat bottleneck for fish found in urban waterways; that of nursery habitats lost due to river engineering works. Rehabilitated and control sites were sampled before and after in the Müggelspree and once in the urban Spree River. A total of 30 303 fish belonging to 27 species were collected. The fish assemblage was dominated by generalist species with 81% roach, Rutilus rutilus (L.), and perch, Perca fluviatilis L. Species diversity did not improve in either the rural or urban stretch. In the Müggelspree, the loss of riverine habitats was mirrored by significant declines in the densities of chub, Leuciscus cephalus (L.), ide, Leuciscus idus (L.), gudgeon, Gobio gobio (L.), rheophilic and lithophilic species. By contrast, densities of rheophilic species around the artificial structures created in the urban Spree River, although the main effect was an overwhelming increase in roach and perch. The results suggest that if underlying bottlenecks can be identified, artificial structures can provide functional fish habitat that replaces the natural equivalent in urban river stretches. Consequently, even the most heavily degraded waters provide opportunities to improve fish diversity and fisheries using artificial habitat structures.     

Mixed stream channel morphologies: implications for fish community diversity

• 1. Stream classification systems are widely used in stream management and restoration. Whereas the principal morphological types of these classification systems are increasingly recognized for their ecological connections, the roles of intermediate and mixed morphologies are still poorly understood, yet may be biologically significant.
• 2. Twenty‐five stream reaches in north‐western Vermont were classified by channel morphology to determine whether fish community diversity differed among pool‐riffle, mixed (i.e. pool‐riffle/cascade, pool‐riffle/other) and forced pool‐riffle stream morphological groups. Stream reach surveys included cross‐sectional surveys, longitudinal profiles, bed substrate characterization, and fish surveys.
• 3. Three fish community diversity measures were calculated: (1) species richness (S); (2) Shannon–Weaver Index (H′); and (3) Simpson's Index (1/D). Multivariate analysis of covariance (MANCOVA) followed by analysis of variance (ANOVA) were used to explore potential differences in fish diversity among stream morphological groups. Fish diversity was significantly different for all three community diversity measures (P?0.05), with pool‐riffle/cascade morphology consistently exhibiting the greatest fish diversity and forced pool‐riffle the lowest.
• 4. These results suggest that fish community diversity is significantly associated with distinct channel morphologies. Generally, pool‐riffle/cascade and pool‐riffle/other stream morphological groups supported habitats that fostered greater species diversity than more homogeneous and uniform pool‐riffle reaches. The observed patterns of diversity are likely to be the result of habitat patches created by variations in flow and other physical characteristics in reaches of mixed morphologies.
• 5. These results support fish sampling schemes that incorporate morphological heterogeneity, such as proportional‐distance designation. Sampling strategies that focus on homogeneous reaches may underestimate diversity, and misrepresent stream condition when fish community data are used in indices of biological integrity (IBIs). Reaches of mixed stream morphologies should be recognized as areas of biological importance in stream and catchment management and in conservation efforts.

Copyright © 2008 John Wiley & Sons, Ltd.     

Factors affecting fish assemblage structure during seasonal stream drying

Abstract –  We evaluated fish assemblage structure during stream drying in north west Arkansas in 2002 and 2003. We sampled fish with a seine and backpack electrofisher and measured habitat variables along transects. Linear regression models were selected a priori and ranked according to Akaike's Information Criterion. In 2002, total fish density was negatively related to pool area and maximum depth, and positively related to canopy openness and substrate diversity. Similarly, central stoneroller ( Campostoma anomalum , Rafinesque) and creek chub ( Semotilus atromaculatus , Mitchill) densities were negatively related to maximum pool depth. In 2003, fish species richness was positively related to pool area whereas total fish, central stoneroller, and creek chub densities were negatively related to maximum pool depth. In addition, total fish density was negatively related to substrate diversity. Results indicated that physical factors are important predictors of fish assemblage structure during stream drying. However, differences among response variables between years indicated that the magnitude of stream drying might be critical in intermittent streams.     

Effect of predation and habitat quality on growth and reproduction of a stream fish

Billman EJ, Tjarks BJ, Belk MC. Effect of predation and habitat quality on growth and reproduction of a stream fish.
Ecology of Freshwater Fish 2011: 20: 102–113. © 2010 John Wiley & Sons A/S Abstract – Anthropogenic disturbances are rarely independent, requiring native fishes to respond to multiple factors to persist in changing environments. We examined the interaction of predation environment (presence of introduced brown trout, Salmo trutta) and habitat quality on growth and reproduction of southern leatherside chub, Lepidomeda aliciae, a small‐bodied stream fish native to central Utah, USA. Southern leatherside chub were sampled from four streams representing a complete two‐factor cross of predation environment and habitat quality. Growth was estimated using increment analysis of annuli on otoliths, and reproductive traits were measured for both sexes. Southern leatherside chub growth was greater in high‐quality than in low‐quality habitats, and greater in predator than in nonpredator environments. However, fish exhibited a greater growth response to presence of brown trout in low‐quality habitats. Southern leatherside chub growth followed predictions of plastic responses to resource availability based on habitat quality and predation environment (lethal vs. nonlethal effects). Reproductive allocation (gonad wet mass) was significantly greater in low‐quality versus high‐quality habitats, but was unaffected by predation environment. Other female life‐history traits were affected either by both effects or their interaction. Reproductive responses to habitat quality and predation environment were consistent with predictions based on differential mortality. Southern leatherside chub growth and reproduction responded differently to the combination of habitat quality and predation environment, thus demonstrating the importance of assessing interacting effects of anthropogenic disturbances to more fully comprehend impacts on native species and to appropriately manage, recover and restore these species and their habitats.     

Fish use of ecohydraulic‐based mesohabitat units in a low‐gradient Illinois stream: implications for stream restoration

• 1. A classification scheme for ecohydraulic‐based mesohabitat units was developed for a summer low‐flow period. Mesohabitat unit designations were based on the integration of three‐dimensional channel hydraulics, geomorphic maintenance processes of bed morphology, and biological resource needs of fish. Ecological relevance of the units was evaluated by a study of fish mesohabitat use patterns, and species relationships to feeding guild. By portraying the stream as a mosaic of hydraulic habitat patches that provide specific biotic resource needs, this study's aim was to advance how ecological information may be incorporated into the stream restoration design process.
• 2. Nine mesohabitat units were designated, including pool‐front, ‐mid, and ‐rear units, scour pool, simple and complex riffles, glide, submerged point bar, and channel expansion marginal deadwater. Physical habitat structure differed among the nine mesohabitat units by length, water depth, and bed slope and complexity. Fish were collected in specific unit volumes by use of prepositioned areal electrofishing devices, in which distinct patterns of fish mesohabitat use were observed.
• 3. A key finding was the differences in fish assemblages among the pool units, in which fish densities were greatest in the pool‐front and scour pool units. Also, fish density in the pool‐front unit was positively correlated with pool entrance slope. Biomass was greatest in the pool‐front and ‐mid units, and it was correlated with maximum mid‐pool depth. Density and biomass were generally lowest in the pool‐rear unit. Other unique relationships were also observed among the mesohabitat units.
• 4. Based on feeding guild, patterns of fish mesohabitat use were observed for this summer low‐flow period; insectivores dominantly used pool‐front and scour pool units, herbivores dominantly used complex riffle units, and piscivores used pool‐front and ‐mid units.
• 5. Useful ecological information was derived from fish species‐habitat relationships observed in this study, linking mesohabitat units with species requirements for food resources. Such findings support advancements to ecological design strategies for stream restoration that promote hydraulic habitat diversity.

Copyright © 2008 John Wiley & Sons, Ltd.     

Physical habitat utilization of fish in a Sonoran Desert stream, Arizona, southwestern United States

Abstract– The physical habitat utilization of 7 species of native fishes in a Sonoran Desert stream, Aravaipa Creek, Arizona is described. The species occupied significantly different depths and velocities of water. Longfin dace ( Agosia chrysogaster ), speckled dace ( Rhinichthys osculus ) and loach minnow ( Tiaroga cobitis ) used similar depths and velocities. Two of the three larger species (Sonora sucker [ Catostomus insignis ] and roundtail chub [ Gila robusta ]) used areas of greater depth and reduced velocity. Desert sucker ( Catostomus clarki ) grouped with loach minnow and speckled dace in the velocity of water occupied, but utilized deeper waters. The spikedace ( Meda fulgida ) aligned very closely with desert sucker in use of all 3 physical habitat variables.     

A patch perspective on summer habitat use by brown trout Salmo trutta in a high plains stream in Wyoming, USA

Abstract –  We quantified the use of habitat patches by brown trout, Salmo trutta , during summer conditions in a plains stream in the western United States. A Global Positioning System was used to map discrete habitat patches (2–420 m²) consisting of macrophytes, wood accumulation, or deep water. Habitat use by brown trout was monitored by radio telemetry. Brown trout used habitat in a nonrandom manner with 99% of all daytime observations and 91% of all nighttime observations occurring in patches that consisted of combinations of deep water, wood accumulations or macrophytes even though such patches constituted only 9.8% of the available habitat. Brown trout used deep water almost exclusively during the day but broadened their habitat use at night. Most fish stayed within a large plunge pool created by a low-head dam. This pool supplemented the deep-water habitat that was naturally rare in our study area and illustrates how human modifications can sometimes create habitat patches important for stream fishes.