Influences of Dams on Downstream Larval Fish Community Structure and Associated Water Quality Variables

Title:  Influences of Dams on Downstream Larval Fish Community Structure and Associated Water Quality Variables

Format:  Oral

Authors:  Hanks, R. Daniel.  West Virginia University; 864-200-8167; rhanks@mix.wvu.edu

Hartman, Kyle J.  West Virginia University; 304-293-4797; hartman@wvu.edu

Presenter:  R. Daniel Hanks

Student Presentation:  No

ABSTRACT

            In the context of the serial discontinuity concept (SDC), we investigated influences of dams on structuring water quality variables and larval fish communities along the stream continuum.  Six streams were sampled (two in each of MD, PA, and WV) for larval fish at predetermined distances below dammed sites. We tested the prediction that larval fish richness and diversity (Shannon Index) would increase with distance from dams.  Furthermore, we hypothesized that dams would influence water quality variables (DO, pH, conductivity, temperature), which would aid in explaining the structure of larval fish communities along the stream continuum.  Temperature, pH, and conductivity showed significant relationships with distance from dams (p<0.05; Pearson’s r 0.50, 0.30, and 0.58 respectively).  Species richness, diversity, and total number of individuals captured also increased with distance from dams but only total abundance was significant (p<0.05, Pearson’s r = 0.26).  Multivariate methods (PCA and NMDS) were used to summarize and interpret gradients in water quality and species data respectively.  We suggest that dams may impact larval fish richness and community structure in a longitudinal fashion that is congruent with the SDC.