Impact of fish feed on four benthic invertebrate phyla abundance and taxa richness: benthic ecology implications

Abstract

The impact of fish feed on four benthic invertebrate phyla in channel catfish ponds was investigated. Benthic soil samples were collected from five fed and five unfed identical catfish ponds. Samples were collected from each pond December to February and the macro- and meo-invertebrates extracted. A paired-t-test was used to compare population densities, taxa richness, and hydrogen ion concentrations in fed and unfed ponds. Mean values for the entire sampling period were used for the analysis. The data collected and its analysis consistently revealed that fish feed had a reductive effect on the benthic invertebrates investigated. Density of the Mollusca and Gastrotricha were significantly reduced (P > 0.001) by fish feed. Fish feed had an eliminative effect on the Rotifera and Tardigrada as these phyla were not recorded in the fed ponds. The pH data revealed that fish feed significantly (P > 0.01) increased the acidity of the benthic soil as compared to the approximately neutral pH of the unfed ponds. Results of this study suggest that while fed ponds produce more fish, fish feed drastically decreased abundances and taxa richness of the benthic invertebrates investigated. Because fish feeding has a reductive impact on invertebrate taxa richness and taxa abundance, this could result in a reduction of ecological processes and functions ascribed to these invertebrates in their natural ecological habitat. The significant reduction of invertebrate biomass in fed ponds attests to this.