Invertebrate communities associated with blue mussel beds in a patchy environment: a landscape ecology approach

Abstract

Landscape ecology has evolved rapidly as a terrestrial discipline over the past centuries due to an increased concern over habitat loss and fragmentation. Proceedings in the marine realm have been comparatively scarce, even though many key habitats in marine ecosystems are becoming equally fragmented. We sampled the macrofauna associated with blue mussel beds in naturally patchy landscapes of islands and reefs in the non-tidal Baltic Sea and tested for the effect of island area, isolation and reef depth on local species richness and composition. The fauna was also compared among islands and reefs. Contrary to expectations, species richness did not increase with island size, and species diversity was higher on deep reefs compared to shallow reefs and islands protruding from the water. Region and depth also had an effect on species assemblage. Geographical distance to nearest island or reef showed no correlation with species richness but correlated positively with faunal density, i.e. a higher degree of isolation increased density. In accordance with other marine studies, our data, therefore, supports the nearest refuge hypothesis, postulating that mobile invertebrates disperse over areas of non-habitat and then concentrate in isolated habitats because habitats in isolation are the nearest available refuge. We show that terrestrial landscape approaches cannot be directly applied to the study system. This has important implications for the planning of marine protected areas and their management.

Population Dynamics at the Range Margin: Implications of Climate Change on Sublittoral Blue Mussels (Mytilus trossulus)

“…Blue mussels in the Baltic Sea experience constant physiological stress due to the low salinity conditions (Tedengren and Kautsky, 1986) which is accentuated during the spring period (Leiniö and Lehtonen, 2005). Despite being salinity stressed, they are dominant occupiers of space on the rocky bottoms, contributing to 90-95% of the animal biomass (Kautsky, 1982;Koivisto and Westerbom, 2012). Blue mussel beds are mainly found in the depth range 3-20 m, although mussels dominate the animal community down to at least 30 m. Traditionally, populations have been considered stable, living near the carrying capacity with regard to food and space (Kautsky, 1982).…”

Benthic conditions around a historic shipwreck: Vrouw Maria (1771) in the northern Baltic proper

“…Sampling point Ap3, downstream of the wreck, which mainly consisted of rocks and gravel and was dominated by the sessile blue mussel Mytilus edulis (Mollusca), may exemplify this. In this case, a coarser bottom grain size inhibited the occupation of burrowing species and lowered the macrofauna abundance, but increased the diversity by allowing sessile macrofauna species to appear as well as typical species associated to mussel assemblages (Westerbom et al, 2002;Koivisto and Westerbom, 2012;Jungerstam et al, 2014;Kraufvelin and Díaz, 2015). A further source for such differences in aggregation of zoobenthos might also be present in food availability (Hall et al, 1993;Vetter, 1995).…”

Sex‐specific distribution and diet of Platichthys flesus at the end of spawning in the northern Baltic Sea

“…In contrast, Karlson et al () showed experimentally that southern Baltic Sea P. flesus prefers M. balthica over M. edulis . In the Gulf of Finland, however, M. edulis is the most common non‐burrowing bivalve and extremely abundant in hard bottom habitats (Westerbom et al , ; Koivisto & Westerbom, , ). In this low salinity environment, byssus production of the mussels is weak (Young, ) and mussels detach easily from the substratum, which could explain the greater importance of M. edulis in the diet of P. flesus in the northern Baltic Sea.…”