Different feeding strategies in Antarctic scavenging amphipods and their implications for colonisation success in times of retreating glaciers

• Published in: Frontiers in Zoology
• Main Authors: Meike Anna Seefeldt, Gabriela Laura Campana, Dolores Deregibus, María Liliana Quartino, Doris Abele, Ralph Tollrian, Christoph Held
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2017
• Subjects: Southern Ocean; King George Island/ Isla 25 de Mayo; Potter Cove; Succession; Carrion-feeding; Food web; Zoology; QL1-991; 25 de Mayo; Antarctic; Fourcade; Fourcade Glacier; isla 25 de Mayo; King George Island; The Antarctic; Antarc*; Isla 25 de Mayo
• Online Access: https://doi.org/10.1186/s12983-017-0248-3; https://doaj.org/article/2523b001a61e47ffb258c151366cb552

Abstract Background Scavenger guilds are composed of a variety of species, co-existing in the same habitat and sharing the same niche in the food web. Niche partitioning among them can manifest in different feeding strategies, e.g. during carcass feeding. In the bentho-pelagic realm of the Southern Ocean, scavenging amphipods (Lysianassoidea) are ubiquitous and occupy a central role in decomposition processes. Here we address the question whether scavenging lysianassoid amphipods employ different feeding strategies during carcass feeding, and whether synergistic feeding activities may influence carcass decomposition. To this end, we compared the relatively large species Waldeckia obesa with the small species Cheirimedon femoratus, Hippomedon kergueleni, and Orchomenella rotundifrons during fish carcass feeding (Notothenia spp.). The experimental approach combined ex situ feeding experiments, behavioural observations, and scanning electron microscopic analyses of mandibles. Furthermore, we aimed to detect ecological drivers for distribution patterns of scavenging amphipods in the Antarctic coastal ecosystems of Potter Cove. In Potter Cove, the climate-driven rapid retreat of the Fourcade Glacier is causing various environmental changes including the provision of new marine habitats to colonise. While in the newly ice-free areas fish are rare, macroalgae have already colonised hard substrates. Assuming that a temporal dietary switch may increase the colonisation success of the most abundant lysianassoids C. femoratus and H. kergueleni, we aimed to determine their consumption rates (g food x g amphipods−1 x day−1) and preferences of macroalgae and fish. Results We detected two functional groups with different feeding strategies among scavenging amphipods during carcass feeding: carcass ‘opener’ and ‘squeezer’. Synergistic effects between these groups were not statistically verified under the conditions tested. C. femoratus switched its diet when fish was not available by consuming macroalgae (about 0.2 day−1) but ...