Effects of turbidity on the foraging abilities of brook trout (Salvelinus fontinalis) and smallmouth bass (Micropterus dolomieu)

Sedimentation is the major pollutant of waters in North America. Most research on the effects of increased sedimentation has focussed on its effects on stream habitat and its ramification on the reproductive potential of fish. Although relatively large sediment loads may be necessary to alter stream habitat, only small loads are needed to raise mean stream turbidity levels. Turbidity may be an important, yet relatively unexamined factor in stream fish production. With this, I sought to determine the influence of elevated turbidity on the foraging abilities of two predatory species representing both cold and warm water stream habitas, brook trout (Salvelinus fontinalis ) and small mouth bass (Micropterus dolomieu).;This research was conducted in an artificial stream at West Virginia University and consisted of determination of effects of turbidity on reactive distance and foraging success of both species and determination of the effects of turbidity on brook trout mean daily consumption and specific growth rates. During reactive distance and foraging success experiments, three fish were tested at a time creating a situation of competition. (Abstract shortened by UMI.)

Development of a fish leaping framework for low-head barriers

Leaping is an indispensable part of the upstream spawning migration of a fish species. The natural barriers replaced with artificial dams and obstacles can obstruct the leaping process and destruct the life cycle of fish species, causing their extinction in extreme scenarios. To help design and improve the artificial barriers, many studies have been conducted to model the leaping success of fish species. However, generic results were scarcely obtained to be extended for a wide range of barriers. The main reasons can be identified as the lack of thorough understanding of the interaction between fish locomotion and water flow regime upstream of the investigated barriers. Hence, the aim of this study is to propose a leaping framework compatible with a diverse range of fish species and barriers. This framework includes a detailed hydraulic sub-model as well as locomotion model capable of tracing fish in both water and air environments. The functionality of the proposed framework is further discussed using a selected case study

Factors influencing movement behaviour and home range size in ide Leuciscus idus

Seventeen individuals of ide Leuciscus idus were radio-tracked weekly from September 2003 to September 2004 in the River Elbe, Czech Republic, to examine migration patterns and the influence of environmental factors on their diurnal behaviour. Of the 10 environmental factors measured, L. idus were significantly influenced by turbidity, which increased diurnal movement and the home range size of the species. The peak of longitudinal movement occurred in the spring, indicating pre-spawning migration. Migrating fish moved downstream and later returned upstream to the vicinity of their original locations, displaying a homing behaviour

Aquatic-terrestrial linkages in Appalachian streams: Influence of riparian inputs on stream habitat, brook trout populations, and trophic dynamics.

Riparian zones play a major role in the structure and function of headwater stream ecosystems. Inputs of leaf litter from riparian zones are the primary energy source for secondary production in these streams and inputs of large woody debris (LWD) help shape stream habitat. Riparian zones of Appalachian streams were degraded by past timber harvest activities. Streamside management zones (SMZs) now protect the riparian zone by limiting timber harvest activities near streams. The objective of this study was to examine aquatic-terrestrial linkages and how habitat and food resources influence brook trout ( Salvelinus fontinalis) populations in Appalachian streams. LWD was experimentally added to eight streams in the Middle Fork River watershed, Randolph Co., WV to determine if stream habitat and prey availability could be enhanced. Stream habitat was assessed and brook trout populations were monitored for one year prior to, and three years following habitat manipulations. Invertebrate drift and brook trout diets were collected to determine the effects of LWD additions on trophic dynamics and to assess the importance of terrestrial invertebrate prey to brook trout energetics. LWD additions had little effect on stream habitat by three years post-manipulation. Brook trout populations fluctuated over time, but did not show a consistent increase. Although, the number of locations where leaf litter was stored increased, invertebrate drift did not increase following the addition of LWD. Likewise, prey consumption by brook trout was not influenced by the LWD additions, but diet composition showed a shift with the proportion of the diet comprised of the shredder functional feeding group increasing by two years post-habitat manipulation. Terrestrial invertebrates comprised a large portion of the yearly consumed energy by brook trout. The results of this study illustrate the important linkage between terrestrial and aquatic systems in the trophic dynamics of headwater streams. However, the duration of the study was likely not long enough to detect significant changes in stream habitat and brook trout populations due to LWD additions. The benefits of these habitat manipulations may not be realized for several more years. These initial results may help guide resource managers in future stream restoration efforts

Session B7- Evaluating brook trout genetic response to population isolation

Brook trout (Salvelinus fontinalis) reside in a range of habitats including headwater streams where populations may become periodically isolated. Demographic consequences of population isolation include increased potential for localized extinction. Genetic consequences for population isolation, or populations of sustained small numbers, include increasing susceptibility to inbreeding, the expression of negative fitness traits, and overall loss of genetic variability, which may increase the risk of localized extinction. Reestablishment of connectivity -with larger populations through periodic gene flow into these small populations may act to offset loss of genetic diversity. Restoring population connectivity and degraded headwater habitats, especially those that historically harbored wild brook trout populations has been a focus of restoration efforts. To understand the degree of genetic isolation among headwater brook trout populations, we examined how variability in connectivity between brook trout populations bas resulted in the partitioning of genetic variation within a number of headwater brook trout populations in two locations: Nash Stream, New Hampshire, and Pennsylvania. Both locations bad multiple headwater brook trout populations, but varied by how populations were potentially isolated. In Nash Stream, potential causes of isolation were culverts or waterfalls. In Pennsylvania, isolation could be due to larger geographic distance, culverts or dams, or areas of poor stream quality. In both locations, overall estimates of variation in allele frequency among populations were high, indicating that populations were significantly genetically different, but the effect of the different barrier types varied based on the likely amount of gene flow allowed. For example, in Pennsylvania, significant correlations of genetic diversity were only observed with the presence of impaired stream sections, but not geographic distance or barrier effect. Understanding the effects of barriers on genetic diversity and gene flow can be useful to guide efforts to restore connectivity between populations

Disproportionate Relative Importance of a Terrestrial Beetle Family (Coleoptera: Scarabaeidae) as a Prey Source for Central Appalachian Brook Trout

Brook trout Salvelinus fontinalis and other salmonids in Appalachia typically inhabit headwater watersheds, where food resources may limit growth. We monitored the feeding trends of a brook trout population in central Appalachia over the course of 2 years to determine variation in feeding intensity and important prey items. One terrestrial beetle family, Scarabaeidae, provided a disproportionate amount of energy during the only time of year when brook trout were feeding substantially above maintenance ration. Scarab beetles contributed 39.6% of all energy consumed during May and June of both years, though the number of fish with one or more scarabaeids present in the stomach varied by month (22.2-51.7%). The species composition of scarab beetles consumed suggested that four species are of particular importance. Our findings imply that scarabaeids represent a considerably important prey taxon for brook trout in the region. Considering the foraging habits of the scarabaeid species in question, the phenomenon we witnessed probably occurs throughout Appalachia