Microphyto benthic composition of the fecal matter of a benthic gastropod Pachymelania aurita (O.F. Müller, 1774) in an estuarine ecosystem: Microphyto benthos as important food source for benthic invertebrates.

Abstract

The microphyto benthic assemblage in the fecal matter of a benthic gastropod Pachymelania aurita in a tropical estuarine 
lagoon was investigated by microscopic examination of the fecal matter. Two hundred and forty specimens comprising 120 
juveniles and adults were used for this study. Comparison was made between microphyto benthos consumed by juveniles 
and adults. And to determine the actual source of the microphyto benthos recorded, comparison was also made between 
species recorded in the fecal matter of specimens direct from the wild and those exposed to sediment in the laboratory. The 
microphyto benthic organisms recorded consist of two major groups, blue-green algae (Anabaena, Aphanocapsa) and 
diatoms (Navicula, Synedra, Cyclotella, Nitzchia). Navicula and Cyclotella were the most important taxa in terms of 
abundance and frequency. There were no variations in the microphyto benthos consumed by the adults and juveniles. The 
assemblage observed in the fecal matter of specimens of P. aurita exposed to sediment in the laboratory represent a slightly 
different array of organisms with representation of Cyanobacteria which were absent in the fecal matter of specimens 
collected directly from the wild. The result of the study further buttresses the claim that benthic microalgae serve as major 
source of organic matter supporting benthic invertebrates.