Benthic Habitats and the Effects of Fishing

Sediment Oxygen Consumption in the Southwestern Gulf of Mexico

Elva Escobar and Luisa I. Falcon

doi: https://doi.org/10.47886/9781888569605.ch37

Abstract. Sediment oxygen consumption (SOC) is metabolically related to the benthic community productivity of continental shelves and margins. These areas have economical relevance for regional fisheries. The aim of this study is to evaluate SOC of the soft-bottom benthic communities in the southwestern Gulf of Mexico and provide rates in areas of varied trawling incidence in the region. Box-cored sediment was incubated at in situ temperature in benthic microcosm incubation chambers and sub-sampled for bacteria, meiofauna, and macrofauna. Environmental factors were measured in bottom water and sediment. The SOC values ranged from 6.12 to 79.9 mL O₂ • m^–2 • d^–1 and correlated significantly to depth, grain size, and nitrogen contents in the sediment. A significant correlation was also found between SOC and the infaunal biomass. The proportion of bacteria to meiofauna and bacteria to macrofauna could be related to SOC in different regions. The range of SOC values from the continental shelves in the southwestern Gulf of Mexico were within the range of values recorded in seasonally pulsed sites and highly organic matter enriched areas within the region. We found an order of magnitude difference between the metabolic rates derived from SOC in this study and those reported for the northern Gulf of Mexico. The SOC rates can indicate bottom conditions in a region and should be considered as a potential tool in evaluating natural change and the effects of fishing activities on seabed habitats.