The Role of Terrestrial Subsidies in Fish Communities With a Particular Focus Upon Cyprinids
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The importance of the fluxes of energy and nutrients that cross the terrestrial-aquatic ecotone has been recognized for several decades. Allochthonous energy and nutrients, such as terrestrial leaf litter falling into a stream where it is utilized by aquatic macroinvertebrates, is known as an ecological subsidy. Research on ecological subsidies has extended into more food-web linkages that include terrestrial arthropods subsidizing fish communities, emergent aquatic insects subsidizing riparian spider communities, and marine derived nutrients from salmonids that migrate upstream to spawn and die and their decaying carcasses are utilized by many species of terrestrial plants and animals. The primary objectives of this dissertation are to 1) assess the importance of terrestrial subsidies across a broader geographic and taxonomic level 2) determine the importance of terrestrial subsidies in a fish community inhabiting a semi-arid sub-tropical stream and examine the variation of terrestrial subsidy consumption among fish species in different habitat types, and 3) examine the variability in the carbon to nitrogen ratios of aquatic and terrestrial prey items that fishes commonly utilize and 4) determine the optimal growth temperature for Guadalupe bass (Micropterus treculii) to explore physiological similarities with co-occurring micropterids and assess how management of streamflow and the riparian area within the Llano River can help protect Guadalupe bass with respect to riparian and spring-flow influence. These results will help answer questions concerning the importance of terrestrial subsidies for fish communities outside of temperate salmonid streams, guide managers on the importance of terrestrial subsidies in systems that are markedly different from temperate salmonid streams, and assess how the nutritional quality of terrestrial and aquatic food items consumed by fishes might play a role in the consumption and nutrient dissemination between aquatic and terrestrial ecosystems.