•  
  •  
 

Abstract

Winter, spring, summer, and autumn samples were collected with a 15.24x15.24-cm Ekman grab from five stations on Dardanelle Reservoir, Pope County, Arkansas during the 24-year period from 1970-1993. Twenty-three taxa representing the eight phyla, Cnidaria, Nematoda, Nematomorpha, Entoprocta, Ectoprocta, Mollusca, Annelida, and Arthropoda, were collected. Numerically, oligochaetes comprised 36%, whereas chironomid larvae, Chaoborus larvae, and Hexagenia naiads mad up 29.7, 17, and 12%, respectively, of the samples. Asiatic clams, fingernail clams, amphipods, and Urnatella were collected frequently during the last 10 years but were not abundant. Other taxa were taken infrequently but consistently during the study period. Densities of all taxa fluctuated widely but generally not in close association with season, station, or year. A few significant differences (t-tests; cx=0.05) occurred between stations 5 (discharge) vs. 16 (intake) and 5 vs. 21 (upstream control), but most of them were due to natural differences in substrate composition. Margalef s Richness and Shannon's Heterogeneity Indices did not identify any time-based trends and, with one exception, did not indicate any significant differences between stations.

COinS