Ecology of deep-sea Asteroidea from Atlantic Canada

Gale, Katherine Sarah Petra (2013) Ecology of deep-sea Asteroidea from Atlantic Canada. Masters thesis, Memorial University of Newfoundland.

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Abstract

Sea stars (Echinodermata: Asteroidea) from shallow-water habitats worldwide are known to influence local biodiversity and community structure through their feeding behaviours. Deep-sea (> 200 m) asteroids may have similar ecological roles, but there is little information available for most species. To better understand the roles of asteroids in communities on continental margins, I investigated the diets, distributions, habitat use, and species associations of about 30 subtidal and bathyal asteroid species from 37–2243 m off Newfoundland and Labrador (NL), Canada. Stomach content analysis, stable isotope analysis, and live animal observations of seven bathyal species revealed asteroids to be either top predators of megafauna or secondary consumers (mud ingesters, infaunal predators, suspension feeders). Two of the predatory species consume corals and sponges, whereas the other species feed mainly on crustaceans, molluscs, and organic matter in sediment. Using a data set covering ~600,000 km2 and including over 350,000 individual asteroid records, I found most species to have wide depth ranges spanning > 1000 m. Using cluster analysis, I identified three different asteroid assemblages over the study area, including the Grand Banks, the Laurentian Channel, and the north-eastern Newfoundland shelf and slope. Multivariate analyses revealed asteroids associate with corals, sponges, bivalves, and other echinoderms, and that depth and local substrate influence assemblages. Most asteroids were found on silt or mud, while a few occurred mainly on hard substrates. This analysis contributes to the growing knowledge of benthic invertebrates in NL waters, providing baseline distribution and ecological information for many poorly-known bathyal asteroid species, and indicating that the feeding behaviours of some asteroids may affect deep-sea benthic communities.

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