Meeting Abstract

79.4  Monday, Jan. 6 10:45  Taking their breath away: Metabolic adaptations to low-oxygen levels and salinity transfer in anchialine shrimps (Crustacea: Atyidae) HAVIRD, JC*; HENRY, RP; SANTOS, SR; Auburn University; Auburn University; Auburn University jhavird@auburn.edu

Invasion of extreme or stressful environments is often a result of, or results in, metabolic adaptations that allow the invaders to thrive in conditions where closely related species may perish. Shrimps from anchialine habitats (coastal ponds and caves) represent good candidates for studying these processes, since such habitats have fluctuating oxygen levels/salinity, and at least 3 shrimp lineages have independently colonized this niche. Here, we compared the metabolic rate (MR) of the Hawaiian anchialine shrimp Halocaridina rubra and four other anchialine shrimp species from across the Ryukyus Islands, Japan. Using closed-cell respirometry, we investigated: 1) if salinity transfer influenced MR; 2) if an oxygen debt must was paid following hypoxia/anoxia and; 3) if lactate and lactate dehydrogenase (LDH) levels responded to hypoxia or anoxia. Salinity transfer did not influence oxygen uptake rates in any of the species. However, oxygen uptake declined for H. rubra as environmental oxygen concentration decreased (or with experimental duration), while it remained constant over time for the other species. Furthermore, H. rubra survived in anoxia (0 torr) for > 7 days and paid an oxygen debt. In contrast, the other species perished quickly in anoxia and did not pay oxygen debts after either brief exposure to anoxia or prolonged exposure to hypoxia. For H. rubra, lactate increased during anoxia while levels of LDH remained high and constant. Taken together, these results suggest responses to low-oxygen conditions are not uniform across anchialine shrimp lineages and may be related to the evolutionary history of the species and/or the geographic/geologic context of the environments they inhabit.