Global patterns of freshwater fish communities in Mediterrannean biomes

Thesis (M.S., Biological Sciences) -- California State University, Sacramento, 2010Explaining patterns of species richness is a central theme in community ecology. Ecologists have focused on local (within a site), regional (among sites in a given region), or geographical (among regions) explanations of diversity patterns. In the case of freshwater fish, studies illustrate that biological factors (competition and predation), along with physical factors (habitat diversity, water chemistry, flow regime, temperature and channel morphology), interact to influence species richness within and among communities and that both operate within a range of spatial scales. \ud This study identified global patterns of species richness and trophic diversity in twelve Mediterranean biome freshwater fish communities located on six continents. Differences were found in both species richness and trophic diversity between continental river basins. This study also examined energetic, ecological, and historical factors that may explain freshwater fish species richness and trophic diversity among Mediterranean biome river basins. The energetic factor, average annual discharge, was found to explain species richness; and that none of the seven factors measured explained trophic diversity. This result is contrary to studies that have shown net primary productivity as explaining species richness in global freshwater fish communities. The difference presented in this study states that all basin studies were in one habitat type, the Mediterranean biome, whereas other studies examined several varying habitat types. The resulting specific knowledge can help conserve species richness and manage river basins altered by human activity.Biological Science