Scavenging deep-sea amphipods: Effects of food odor on oxygen consumption and a proposed metabolic strategy

In situ respiration rates as a response to the odor of food were measured for two species of scavenging amphipods, Paralicella caperesca from 3 650 m in the western North Atlantic Ocean and Orchomene sp. B from 1 300 m in the Santa Catalina Basin off southern California (USA). In addition, complementary laboratory starvation/respiration rates for a shallow-water species, Orchomene sp. A, were determined. Initial elevated O₂ consumption rates were found for up to 8 h in all deep-sea amphipods exposed to bait odor, followed by a period of lowered respiration equivalent to rates observed in individuals not exposed to bait. Orchomene sp. A revealed a response similar to that observed in the deep-sea species. A metabolic strategy is proposed whereby scavenging amphipods efficiently utilize large episodic organic falls in the food-limited environment of the deep sea. This strategy involves (1) the ability to withstand long periods of starvation, (2) rapid response to an organic fall, (3) rapid location of the organic fall, (4) maximal rate of food consumption with maximal quantity ingested, and (5) efficient utilization of the consumed food. Each of these attributes are explored with the expected and observed mechanisms employed to achieve them.