Sustainability situations for the southern Gulf of Mexico seafloor, based on environmental, benthic, and socioeconomic indicators

Abstract

Currently, in tropical regions such as the southern Gulf of Mexico (sGM), there are no legal guidelines for assessing the quality of the seafloor. We aim to determine whether the seafloor sustainability of the sGM is evenly distributed, based on pressures that human activities produce upon the marine coastal environment, represented by the water quality, sediment quality, and benthic fauna. We analysed physicochemical characteristics and benthic fauna at 183 sites, sampled during five annual surveys (rainy and dry seasons) in the sublittoral and bathyal zones. Socioeconomic indicators were obtained from official national censuses. We calculated a pressure index (PI) based on water quality, sediment quality, and socioeconomic indicators. PI values ranged from 1 to 2.67, with the highest values being observed at coastal sites. Our approach determined that the benthic quality in the study area was related to depth and oil industry influence and that the sGM's seafloor sustainability was unevenly distributed. For sustainability, we determined specific situations for each site or group of sites: (1) sensitive - sites with high benthic quality and low PI; (2) naturally variable - sites for which the poor benthic quality was not related to the PI; (3) degraded - sites with poor benthic quality and high PI; and (4) resilient - sites with good benthic quality and high PI. This differentiation in sustainability situations might be used as a reference for linking socioeconomic activities in the coasts with the ecological status of marine environments from shallow to deep.