Influence of an anthropogenic disturbance gradient on the abundance and biochemical characteristics of heterotrophic bacteria on beaches of the central coastal zone of Veracruz

Before the increase in anthropogenic activities, the global coastal ocean was a net autotrophic system. From human activity and the evolution of the earth, changes have been generated in its continents, oceans, atmosphere and life. Transport of sediments and bioelements to the coastal zone has been drastically altered, and there is debate about whether this zone is autotrophic or heterotrophic. This work carried out an exploratory study of five sandy beaches in the central coastal area of the state of Veracruz, three urban beaches on a gradient of anthropogenic activities in the Metropolitan Zone of Veracruz (ZMV) and two natural, non-urbanized beaches far from the ZMV to determine the concentrations and biochemical characteristics of the heterotrophic bacterial groups found in samples of surface marine sediments during two contrasting seasons in the region: dry season and rainy season. The presence of heterotrophic bacteria reflected the degree of anthropogenic disturbance that each beach presents, with a tendency to concentrate mainly on those close to urban centers. On the other hand, the anthropogenic disturbance gradient did not influence the diversity of biochemical characteristics of heterotrophic bacteria.