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Effects of light pollution on fish feeding behavior and assemblage structure in reservoirsHarrison, Susanna January 2021 (has links)
No description available.
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Effects of interspecific competition, salinity, and hurricanes on the success of an invasive fish, the Rio Grande cichlid (Herichthys cyanoguttatus)Lorenz, O. Thomas 07 August 2008 (has links)
The Rio Grande cichlid (Herichthys cyanoguttatus) has been established in the Greater New Orleans Metropolitan Area (GNOMA) for at least 20 years. It is often the most common fish species in urban canals and has also been found in natural waterways outside of the GNOMA. The effects and potential for further spread of H. cyanoguttatus is uncertain. My research addressed how extensive the cichlids spread in the GNOMA, how H. cyanoguttatus interacted with L. macrochirus, a native fish, and what salinity tolerance this species has. Surveys on Lake Pontchartrain and in the GNOMA indicated that H. cyanoguttatus is well established in urban habitats. These surveys also indicate that H. cyanoguttatus has spread rapidly into Bayou Saint John and City Park in recent years and that H. cyanoguttatus populations were relatively unaffected by Hurricanes Katrina and Rita. There is little evidence that H. cyanoguttatus has become established outside of the GNOMA, but this lack of persistence cannot be explained by abiotic variables I measured. Salinity may be a factor and this was measured in growth trials of H. cyanoguttatus. Salinities up to 16 ppt, however, had no significant effect on H. cyanoguttatus growth. Interspecific behavioral experiments were conducted to examine potential biotic interactions with native fish species. Prior resident trials indicated that H. cyanoguttatus was aggressive whether holding territory or not, and that native bluegill (Lepomis macrochirus) was only aggressive while holding territory. Feeding experiments were performed to examine biotic interactions between H. cyanoguttatus and L. macrochirus. Lepomis macrochirus grew faster than H. cyanoguttatus when inter- and intraspecific trials were compared; however, no significant growth differences were seen when trials were structured with L. macrochirus as prior residents. The major findings of my research are a high salinity tolerance of H. cyanoguttatus, a potential mechanism for H. cyanoguttatus affecting native fishes through aggression as residents and invaders, and the presence of H. cyanoguttatus throughout the GNOMA, before and after the hurricanes.
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Nearshore habitat and land-use effects on trophic interactions and growth of largemouth bass and bluegill in Indiana's glacial lakesPatricia A Nease (7469945) 17 October 2019 (has links)
Glacial lakes, such as those in the Midwest region
of the United States, are ecologically and economically important, and they
provide a wide range of ecosystem services, such as habitat for wildlife and
fishes, flood control and recreational boating. Glacial lakes often support
locally important sport fisheries, such as largemouth bass <i>Micropterus salmoides</i> and bluegill <i>Lepomis macrochirus</i>,<i> </i>which
are partially dependent on suitable habitat within lakes. Nearshore vegetation
is often removed by lakeshore landowners for perceived aesthetics and boat
access, or by area managers as a form of indirect fisheries management and
invasive species control. The connection between nearshore vegetation and fish
population health, though widely studied is somewhat unclear. In the two
research chapters of this thesis we attempted to further understanding of the
environmental factors that influence vegetation abundance and distribution, how
vegetation abundance and distribution influences fish population abundance and
size structure, and how young-of-year (YOY) largemouth bass utilize habitats
within the nearshore environment. In the first research chapter, we used
structural equation modeling (SEM) and data collected by the Indiana Department
of Natural Resources to quantify the complexity of relationships among catchment
characteristics (e.g., catchment size), lake morphology, water quality,
vegetation abundance and distribution, and fish population abundance and size
structure. Across multiple lakes, lake productivity was more influential in
explaining cross-lake variation of largemouth bass and bluegill proportional
stock density (PSD) and largemouth bass catch per unit effort (CPUE) than
vegetation. This may be a result of the feedback between phytoplankton
production and rooted vegetation production. The models we constructed provide
insights into the complexity of environmental variables that influence
nearshore vegetation and fish populations. In the second research chapter we
used stable isotopes (δ<sup>13</sup> Carbon, δ<sup>15</sup> Nitrogen, δ<sup>18</sup>
Oxygen and δ<sup>2</sup> Hydrogen) to examine the consistency of habitat use
and foraging of YOY largemouth bass within Indiana glacial lakes. We observed
spatial variation in stable isotope ratios of YOY largemouth bass between
habitat types and sites. Additionally, there were significant, positive
relationships between δ<sup>13</sup>C of locally collected potential prey items
and δ<sup>13</sup>C of YOY largemouth bass suggesting localized foraging patterns.
Later in the summer, as young bass grew in size and likely switched to
piscivory, we did not observe similar spatial variation in young bass stable
isotopes or spatial relationships between prey and the young bass suggesting
more homogeneous foraging patterns. Understanding the habitat use patterns of
young bass may allow for more efficient and effective management of the
nearshore environment. Overall, a greater consideration for the complexity of
relationships between nearshore habitat and fish populations may facilitate
more effective management.
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The role of ultraviolet radiation in mediating warmwater fish invasion in transparent lakesTucker, Andrew J. 29 April 2011 (has links)
No description available.
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