The deep waters of the Gulf of St. Lawrence have low dissolved oxygen concentrations. The prevailing saturation levels in the Laurentian Through are so low that they can affect various aspects of the biology and ecology of populations and communities. In certain areas, they can even lead to the death of organisms. This information has rarely been integrated in research on distribution, migration, growth and production.

A team at the Maurice-Lamontagne Institute has put forth the hypothesis that dissolved oxygen availability is a factor limiting the productivity of benthic communities in the Gulf of St. Lawrence. They examine the structure of benthic communities in oxygen-poor and oxygen-rich environments. They also do laboratory measurements to determine the effects of in situ saturation levels on mortality and physiology of species that are found in hypoxic areas or that avoid these oxygen-poor areas.

Based on preliminary work done on a limited number of fish and invertebrate species, it appears that this factor plays an important role that could help explain many aspects of the ecology of benthic species. These include recovery times following natural or man-made perturbations with commercial or forage species. Low oxygen levels are a characteristic of the deep waters of the St. Lawrence, of the Baltic Sea and of other estuaries with a high nutrient load.

To assess the impact of hypoxia on deep-dwelling organisms, a dual approach has been chosen. First by doing laboratory experiments to measure the impact on individual performance and later on, by field observations.