Hydroiid snails conditioning green algae mats (Enteromorpha spp.) in the Northern Hemisphere

For the last decades dense mats of filamentous green algae Enteromorpha spp. have regularly occurred worldwide on tidal Àats. The development of green algal rnats on intertidal Àats is commonly achieved by overwintering and regrowth of adult plants or by the formation and detachment of propagules. Up to now the study of germlings as initiators of algal mats have received relatively little attention. It was known from one of our study sites (Konigshafen Bay, Germany) that shells of living mudsnails (Hydrobia ulvae) serve as the main substrate of overwintering Enteromorpha spores and initiate in this way extensive growth of Enteromorplza mats in spring. We investigated the presence of Enteromorpha germlings attached on hydrobiid snails in different places of Canada, England, Germany, Portugal, Sweden and the United States between November 1995 and November 1996. At all investigation sites huge amounts of hydrobiid snails were present during the last years and and intensive growth of Enteromorplm occurred during the course of the season. - During winter 1995 /96 hardly any Enteromorpha germlings were found on the snail houses, but depending on the site, germlings developed on up to 60 % of hydrobiid snails during spring. It is obvious, that at least in some areas the germling development was related to overwintering of spores on snails, due to poor biomass of adult Enteromorpha plants during winter. In our study we could demonstrate that hydrobiid snails can play an important role in soft sediments for the successfull development of green algal mats in soft sediments.

Keywords

Hydoid snails Green algae

URI

http://hdl.handle.net/10400.1/2785

Citation

Schories, D.; Albrecht, A.; Aníbal, J.; Fletcher, R.; Isaksson, I.; Lillebo, A. I.; Pihl, L.; Pye, K.; Reise, K.; Sprung, M.; Thiel, M. Hydroiid snails conditioning green algae mats (Enteromorpha spp.) in the Northern Hemisphere, Trabalho apresentado em 32nd European Marine Biology Symposium, In 32nd European Marine Biology Symposium, Lysekil, Sweden, 1997.