Islands of Mytilus as a habitat for small intertidal animals: effect of island size on community structure

Abstract

Patches of Mytilus edulis 1. composed of similar sized mussels were surveyed in order to investigate the effect of patch size on community structure of associated animals. Each patch included common components such as byssus, shell fragments, sediments. algae and associated animals. Volume of each component increased with patch size. With increasing patch size. species richness and number of individuals of associated animals increased, but decreased per unit patch size. Patch area affected population density more than patch volume. Volume of associated animals per unit patch area was relatively constant, but volume per unit patch volume decreased with increasing patch size. Mean body width of the polychaete Typosyllis adamanteus Jrun'lensis Chlebovitsh increased with patch size, Large individuals of the winkle Littorina brevicula Philippi were not found in smaller patches. At high tides, large numbers of the amphipod Hyale grandicomis Kroyer, which live among algae attached to the patches, were seen on rock surfaces covered by the barnacle Chthamalus challengeri Hoek around the patches. These results can be mainly explained in relation to accumulation of sediments and shell fragments of M, edulis in the patches, and the community structure of the Mytilus island is discussed with reference to species-area relations.

Recruitment of shore crabsCarcinus maenas on tidal flats: Mussel clumps as an important refuge for juveniles

“…Without mussel clumps in the tidal flats, the early benthic phases of shore crabs would be exposed to strong predation pressure from large epibenthic predators (Reise, 1985). Tsuchiya & Nishihira (1985) showed that the abundance of mussel-clump inhabitants increases with decreasing patch-size. Mussel-harvesting activities may therefore have a positive effect on the abundance of permanent and temporary mussel-clump inhabitants by scattering large numbers of relatively small mussel dumps onto tidal flats or into subtidal waters (Reise & Schubert, 1987;Reise et al, 1989;Nehls & Thiel, 1993).…”

“…Because many small animals are associated with mussel clumps (Tsuchiya & Nishihira, 1985;Thiel & Reise, 1993), we surmised that these clumps may serve as a spatial refuge for juvenile shore crabs. The spatial distribution of shore crabs with respect to mussel clumps as a micro-habitat was, therefore, a major focus of our study.…”

Sewage-induced disturbance on polychaetes inhabiting intertidal mussel beds of <i>Brachidontes rodriguezii</i> off Mar del Plata (SW Atlantic, Argentina).

“…On the other hand, López Gappa et al (1993) have mentioned that the study of the associated flora and fauna of these mussel beds could be suitable for assessing organic enrichment due to sewage along the argentine coasts. In fact, the matrix of B. rodriguezii (like other mussel beds, see Tsuchiya and Nishihira, 1985;Seed and Suchanek, 1992;Tokeshi, 1995;Günther, 1996;Ragnarsson and Raffaelli, 1999;Damianidis and Chitiroglou, 2000) creates a secondary sediment habitat that is occupied by several species, including nemerteans, polychaetes and other infaunal invertebrates (Penchaszadeh, 1973;Scelzo et al, 1996).…”

Sewage impact on the composition and distribution of Polychaeta associated to intertidal mussel beds of the Mar del Plata rocky shore, Argentina

“…The study of the mussel-associated flora and fauna could be suitable for assessing organic enrichment due to domestic sewage in the Argentine coast (LÓPEZ GAPPA et al, 1993). The mussel matrix creates sedimentary microhabitats that are occupied by small invertebrates, including several polychaetes (PENCHASZADEH, 1973;TSUCHIYA & NISHIHIRA, 1985;JACOBI, 1987;GÜNTHER, 1996;SCELZO et al, 1996;SVANE & SETYOBUDIANDI, 1996;RAGNARSSON & RAFFAELLI, 1999). However, no quantitative data about polychaete pattern are available from the southwestern Atlantic shore.…”