Factors accounting for intraspecific variance in hypoxia tolerance of juvenile striped bass (Morone saxatilis).

The depletion of dissolved oxygen, called hypoxia, is a growing concern in coastal waters. Hypoxic zones occur annually during summer in the Chesapeake Bay when stratification of the water column, low oxygen solubility in warm water and oxygen utilization by decomposers combine to deplete oxygen in the lower layers of the water column. Climate change and growing coastal human populations threaten to expand coastal hypoxic zones and impact one of Maryland’s most valued sport and commercial fish, the striped bass (Morone saxatilis). Juveniles of this species tend to reside in deep water pockets that are prone to hypoxia. Approximately 70% of individuals from striped bass stocks north of Cape Hatteras, North Carolina are born in the Chesapeake Bay. Therefore, the spawning and nursery habitat in the Chesapeake Bay are important to the success of this species. Previous work by the applicant uncovered substantial intraspecific variance in tolerance of hypoxia in a closely related species, the European sea bass (Dicentrarchus labrax) that lives in French coastal waters (Figure 1).

Figure 1: Histogram of the time to loss of equilibrium amongst

 a cohort of similar-sized European sea bass (Dicentrarchus labrax).

The purpose of our work is to investigate whether a similar degree of variance in hypoxia tolerance is found among striped bass individuals, whether laboratory measurements of hypoxia tolerance are repeatable and to begin to probe for factors that might contribute to hypoxia tolerance.

Graduate student Genine Lipkey is running these experiments for her Master's thesis research: