Contrasting resident time and scavenging communities on experimental invertebrate food falls in the Arctic deep sea

• Published in: Deep Sea Research Part I: Oceanographic Research Papers
• Main Authors: Rohlfer, EK, Scheer, Stella Luna, Bergmann, Melanie, Sweetman, Andrew K, Hoving, Henk-Jan T
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: PERGAMON-ELSEVIER SCIENCE LTD 2022
• Subjects: Arctic; Arctic Ocean; Eurythenes gryllus; Fram Strait; North Atlantic
• Online Access: https://epic.awi.de/id/eprint/54519/; https://hdl.handle.net/10013/epic.9c6be1a7-d5ad-4363-8010-939b2707a1fe

Deep-sea benthic communities depend on food that reaches the seafloor from the overlying water column as well as from in-situ autotrophic production. Sinking carcasses (food falls) from jellyfish and squid contribute to this nutrient flux, but natural medium-sized food falls are rarely observed. Consequently, little is known about scavenging communities associated with invertebrate food falls. The Arctic Ocean is known for rapid environmental change and strong benthopelagic coupling. To investigate if scavenging responses in the Arctic deep sea differ between different medium-sized food fall species we performed experiments in the Fram Strait at ∼2500 m depth. Baited free fall landers were equipped with a time-lapse camera (n = 5) and traps (n = 4) to document and capture scavengers. Squid (Loligo vulgaris) and jellyfish (Periphylla periphylla) were used as bait. Image analysis showed that the amphipod Eurythenes gryllus arrived within minutes and was the main scavenger on squid (MaxN = 166 individuals) while it was almost absent (MaxN = 3 individuals) on jellyfish. Nine additional scavenger taxa were identified in total, including Scopelocheirus and stegocephalid amphipods, various crustaceans and the gastropod Mohnia. The jellyfish bait was consumed 7.6 times slower than squid (jellyfish: 142 g d−1, squid: 1,294 g d−1), and almost three times slower than during similar experiments in the North Atlantic. Squid experiments incited higher consumption rates and scavenger diversity, but lower maximum abundances than similar experiments in the North Atlantic. Despite a small sample size of our experiments, differences in consumption rates, scavenger diversity and successional stages between food falls were apparent supporting that scavenging response depends on carcass species.