Amphipod-based food web: Themisto gaudichaudii caught in nets and by seabirds in Kerguelen waters, southern Indian Ocean

Stable isotope analysis reveals sexual and environmental variability and individual consistency in foraging of thin-billed prions

“…Another 2 diet samples were obtained from stomachs of 2 dead prions (1 adult and 1 chick). Consistent with previous studies (Strange 1980, Thompson 1989, Bocher et al 2001, Cherel et al 2002 Sample preparation and stable isotope analysis. Before isotopic analysis, the lipids of fish, crustacean and squid samples, as well as regurgitates, were extracted in a Soxhlet apparatus for 6 h using a 2:1 chloroform:methanol mixture.…”

“…data). In contrast, studies carried out during chick feeding consistently reported > 90% crustaceans in the diet (Strange 1980, Thompson 1989, Bocher et al 2001, Cherel et al 2002. Thus, there is strong indication of a diet switch from conventional data, which is matched by the present isotope data.…”

“…Thin-billed prions show the typical procellariiform pattern of a single-egg clutch and slow chick development, with an average fledging period of 50 d (Strange 1980, Quillfeldt et al 2007a. Over 90% of their diet during the chick-rearing period consists of pelagic crustaceans (predominantly Themisto gaudichaudii and Euphausiacea), with small amounts of pelagic fish, squid, and other organisms such as salps (Strange 1980, Thompson 1989, Bocher et al 2001, Cherel et al 2002 also being taken. During incubation, 2 analyses at New Island found that small squid form the main part of the diet (Thompson 1989, P. Quillfeldt unpubl.…”

Foraging under contrasting oceanographic conditions: the gentoo penguin at Kerguelen Archipelago

“…The Closed Sea colony, Longue Island, is located in the western part of the Morbihan Gulf, a sheltered bay of about 700 km 2 with kelp belts, muddy sand and low tidal amplitude. The Morbihan Gulf is a productive ecosystem, which supports important populations of meso-and macrozooplankton (Razouls et al 1997, Bocher et al 2001.…”

“…Closed Sea birds indeed foraged for 2 d during incubation but then performed daily trips during chick guard (0.98 d) and crèche (0.69 d), whereas birds from the Antarctic Peninsula, South Georgia and South Shetland Islands made even shorter trips, from 2 to 12 h ( Table 7). The short trips performed by Closed Sea birds were probably due to the proximity of abundant macrozooplankton species (Bocher et al 2001). For instance, Parathemisto gaudichaudii occurs in high densities in the Morbihan Gulf, and particularly in its western part (Bocher et al 2001, Bost et al 1994; therefore, around the Closed Sea colony.…”