Meeting Abstract
The bearded fireworm, Hermodice carunculata, is a resilient amphinomid annelid, found throughout the Atlantic Ocean under a wide range of environmental conditions. Due to the species’ ease of capture, culture, widespread, and abundant nature, it is very suitable for experimental studies of environmental tolerance. Here, we have subjected H. carunculata to intermittent (< 18 hours) and chronic (> 18 hours) hypoxia to investigate the species’ molecular and morphological responses to such stressful situations. For chronic hypoxia, five bearded fireworms were exposed to one of three levels of dissolved oxygen (DO) in 40-liter tanks for seven days: 2.5 (± 0.25) mg/l, 4.5 (± 0.25) mg/1, and 7 (± 0.25) mg/1 (normal DO). To investigate intermittent hypoxia responses, 16 worms were subjected to intermittent hypoxia (6 hours of hypoxia and 18 hours of normoxia) for 2 days and sampled for tissues at 6, 18, 24, and 42 hours. The morphological comparisons before and after hypoxia exposure show an increase in the surface area of branchial tufts. Differential gene expression analyses suggest up-regulation of stress response genes, metabolic depression, and an increase in efficiency of oxygen transport molecules under hypoxic conditions. This study allows us to infer the threshold DO level for hypoxic response in this abundant coral reef inhabitant, predict downstream responses to this stressful condition, and potentially predict the historical DO levels for an area where the worms are found.
