The role of commercial digging of mudflats as an agent for change of infaunal intertidal populations

This study assessed the influence of commercial digging for worms and clams of a mudflat on the associated benthic infaunal community in Lowes Cove, Walpole, Maine, USA. Four replicate experimental sites were established within each of which were two 1 m(2) digging plots and one 1 m(2) undug, control plot. Digging was done with a four-tined hoe by thrusting the tines into the sediment surface and pulling the sediment towards the digger. Such digging was repeated until an entire plot was dug. Two digging intensities were analyzed: low frequency digging (plot was dug twice a month) and high frequency digging (plot was dug twice a week). By the end of the 2.5 month experiment, the density of polychaetes Heteromastus filiformis (Claparede), Streblospio benedicti (Webster and Benedict), and Tharyx acutus (Webster and Benedict) as well as the total number of taxa were significantly reduced in the plots that had been dug (regardless of frequency) relative to those of the control. Other densities (total number of individuals, Scoloplos fragilis (Verrill), Exogone hebes (Webster and Benedict), Hydrobia totteni (Morrison), total oligochaetes) were not affected by the digging. The lack of undug mudflats in Maine makes comparison of these results to benthic communities in undisturbed areas virtually impossible. (C) 1997 Elsevier Science B.V.