Sources of organic matter for intertidal consumers on Ascophyllum-shores (SW Iceland): a multi-stable isotope approach

Abstract

Stable isotopes were used to examine the origin of organic matter in Icelandic Ascophyllum-based habitats, the role of diVerent organic matters in Wlling intertidal food webs and the food preferences of the most abundant suspension feeders, grazers and predators. We selected three intertidal sites on the SW coast of Iceland where we sampled in early September 2004, organic matter sources (POM, SOM and most abundant primary producers, A. nodosum and F. vesciculosus) and the most abundant macrofauna species (barnacles, mussels, gastropods, sponge and crabs). Even though the primary production (Ascophyllum-based) was the same at the three study sites, the isotopic composition of common-among-sites organisms varied due to local diVerences in the origin of available POM and SOM and in food web structures.

Do Red Knots (Calidris Canutus Islandica) Routinely Skip Iceland During Southward Migration?

“…In Iceland, Red Knots eat mainly gastropods (Littorina sp.) and bivalves (edible mussel, Mytilus edulis; Alerstam et al 1992) whose 13 C signature is similar to that of Wadden Sea shellfish (−15.9 and −17.1‰, respectively; Sarà et al 2007, Steinarsdóttir et al 2009). Combining this with the estimated stopover time from Wilson and Morrison (1992) and half-life times of blood cells and plasma, knots stopping over in Iceland are expected to arrive in the Wadden Sea with blood (cells) 13 C ratios that are halfway between tundra and marine signatures, while plasma 13 C ratios should approach the marine signature.…”

Amphipod intersex, metals and latitude: A perspective

“…Some 34 studies report lower fecundity and fertility, reduced pairing success and delayed maturation shores being considered pristine environments (Sarà et al, 2007), there is indication of heavy 79 metal background values being higher than in equally remote areas. Volcanic activity is 80 regarded as the probable cause (IME, 2001), mainly because eruptions substantially increase 81 metals concentration in Icelandic rivers.…”

Carbon and nitrogen stable isotopic inventory of the most abundant demersal fish captured by benthic gears in southwestern Iceland (North Atlantic)

“…The dominant algae along the SW coasts of Iceland are represented by Fucus spp. and Ascophyllum nodosum, whose carbon and nitrogen isotopic values were around those of the present study (Lesage et al 2001;Sarà et al 2007). Thus, SOM had isotopic values showing a mixed inXuence of near and oVshore, without or with a very negligible trace of terrestrial (sensu Sherwood and Rose 2005) and pelagic contributions (Takai et al 2002).…”

“…Insights into the trophic relationships and feeding habits of demersal species may be gained by using ratios of naturally occurring isotopes, often isotopes of carbon and nitrogen, in speciWc tissues (De Niro and Epstein 1978;. Stable isotopes represent a valid tool in investigating the origin of organic matter assimilated by organisms (Sarà et al 2007), and such an approach has helped ecologists to solve complicated dietary frames of organisms living in multi-trophic source environments (Michener and Schell 1994). In fact, the isotopic composition of organisms reXects that of the food available, apart from a certain degree of metabolic fractionation (i.e.…”