Title

Foraging by the Mud Snail, Ilyanassa obsoleta (Say), Modulates Spatial Variation in Benthic Community Structure

Document Type

Article

Publication Date

8-12-2003

Publication Title

Journal of Experimental Marine Biology and Ecology

Keywords

Spatial variation, Community structure, Ilyanassa obsoleta, Saltmarsh, Detritus, Annelids, Mud flat, Field manipulation

ISSN

0022-0981

Volume

292

Issue/No.

2

First Page

139

Last Page

157

Abstract

We investigated the foraging behavior of the mud snail, Ilyanassa obsoleta, and its consequences for macrobenthic community structure on mud flats on Long Island, NY, USA. Field sampling demonstrated strong spatial heterogeneity in the population densities of I. obsoleta. We experimentally tested three hypotheses: (i) I. obsoleta are strongly attracted to areas with high levels of detritus; (ii) local abundances of deposit-feeding annelids are limited by detritus; and (iii) the foraging activities of I. obsoleta negatively affects annelid assemblages. We manipulated the density of mud snails using inclusion fences and the levels of detritus using dried Ulva. Results showed that high densities of I. obsoleta were attracted to areas enriched with Ulva detritus. In addition, high densities of snails negatively affected abundances of annelids, with the opportunistic species, Capitella spp. and Paranais litoralis, being most affected. The addition of Ulva detritus had more specific effects on annelid assemblages. Only Capitella spp. showed a significant positive response, although previous evidence has demonstrated that higher experimental detrital inputs stimulated growth of other species of annelids and microphytobenthos. In an experimental treatment with enhanced detritus and low densities of snails, we found population abundances of opportunistic annelids (up to 200,000 m−2) substantially larger than has ever been recorded in 5 years of sampling. Because mud snails in natural areas actively search, locate and exploit areas with enhanced detritus and their foraging negatively affects abundances of opportunistic worms, I. obsoleta probably controls the upper limits of annelid abundance in the field. Foraging behavior of I. obsoleta therefore modulates spatial variation in benthic community structure in an environment where limiting resources are patchily distributed.

Comments

©2003 Elsevier Science B.V. All rights reserved.

DOI

10.1016/S0022-0981(03)00183-7

This document is currently not available here.

Peer Reviewed

Find in your library

Share

COinS