Difficulty Breathing: Assessing changes in behavior and measures of vitality of American lobster at reduced oxygen levels
Date:
Abstract: The American lobster, Homarus americanus, recently shifted its habitat use; fewer lobsters are using shelter-providing boulder habitat where populations had historically been concentrated. More lobsters are now found on featureless habitats. Field sampling in boulder habitats found reduced oxygen levels inside the rocky shelters that lobsters had naturally preferred to occupy. Additionally, in recent years, hypoxic events in Cape Cod Bay led to lobster mortality in traps. Experiments assessing lobster shelter selection behavior showed no preference between shelters with ambient oxygen levels and with reduced oxygen levels. However, those trials were conducted over the course of several hours. It is possible that chronic effects of low oxygen could be creating a stressful environment for lobster in complex boulder habitats that may be changing their sheltering behavior. To address this, a longer experiment is being conducted, exposing lobsters to reduced oxygen levels over the course of 14 days. Movement, agonistic behavior, and vitality reflexes are quantified as metrics of stress throughout the trials. Preliminary results suggest lobsters chronically exposed to low oxygen exhibit orthokinesis in an attempt leave low oxygen habitats and could explain the observed shifts in habitat use and behavior.
Authors: Jarrett, R., Steneck, R.
Ph.D. Dissertation Research at the University of Maine