Predicting the energy budget of the scallop Argopecten purpuratus in an oxygen-limiting environment

Low concentrations of oxygen determine marine species distribution and abundance along the Peruvian coast with consequences for human activity such as fishing and aquaculture. In order to assess bioenergetic consequences of oxygen limitation on the Peruvian scallop Argopecten purpuratus, we first developed a Dynamic Energy Budget (DEB) model of growth and reproduction calibrated on field experimental datasets. Then, we included oxygen availability as an additional forcing variable using a simple rule based on the ability of the scallop to regulate oxygen consumption. The resulting model was tested using growth/reproduction monitoring and simultaneous high frequency environmental records in Paracas Bay (Peru) at two different depths: suspended in the water column and on the sea bottom. Simulations indicated that scallops' growth and reproduction was not food-limited. The negative observed effects of hypoxia on growth and reproduction could be explained by a decrease in both assimilation and reserve mobilization. However, hypoxic conditions in summer were not sufficient to explain the observed losses in somatic tissue weights and the disruption of reproduction. The latter two patterns were better simulated when assuming increased somatic maintenance costs due to the presence of H2S during milky turquoise water discolouration events observed during summer.