Podostemum ceratophyllum and patterns of fish occurrence and richness in a southern Appalachian river
Argentina, Jane Elizabeth
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We estimated percent cover of Podostemum ceratophyllum Michx. and fish richness at twenty randomly selected shoals within a 42 kilometer reach of the Conasauga River to determine if changes in species richness or species presence are related to variable levels of P. ceratophyllum coverage. We also assessed fish behavioral shifts with changes in P. ceratophyllum coverage in an experimental study. P. ceratophyllum was correlated positively with increasing bed sediment sizes and decreasing canopy cover, and negatively associated with drainage area. Fish species richness peaked in the center portion of the study reach, declining further downstream, coincident with range contraction of six lotic fishes. Benthic insectivorous fishes showed significant preference for habitat with increased P. ceratophyllum coverage compared with low coverage. River-wide changes in P. ceratophyllum could influence fish productivity through lower insect biomass and abundances, although water quality may have a greater effect on fish abundance and persistence.