Document Type : Original Research Paper
Postgraduate in Ecology and Fisheries, Veracruzana University, Mexico
Tecnological Institute of Boca del Río, Veracruz (ITBOCA), Mexico
Institute of Marine Sciences and Fisheries, Veracruzana University (ICIMAP-UV), Mexico
In a coastline with growing urbanization, we examined the condition of water and sediments in sandy beaches within a gradient of uses and modification, in contrast with a reference unmodified beach, to assess different disturbance sources and environmental impact grades. The gradient was analyzed depending on beaches proximity to the urban nucleus, accessibility, tourism and recreation activities, and construction of breakwater structures. Using an integrated approach, some physical, chemical, microbiological and morphodynamic parameters were measured during two sampling campaigns. The results indicate a higher content of organic matter in sediments of the beaches near to the Veracruz Reef System with respect to the reference beach, and in the cold fronts season than in rainy season. This temporal variation can be explained by the regional pattern of surface circulation, favoring downwelling in cold fronts season and upwelling in rainy season. Water temperature, salinity and dissolved oxygen concentrations also accounted for seasonal variations. The stress gradient was evident in the granulometric characteristics of sediments, fats and oils, total solids, and enterococci concentrations in pore water. Intertidal slopes and littoral currents indicated not only a marked seasonality of these parameters, but differences between unmodified and modified beaches by breakwaters. All parameters are discussed, particularly those that accounted for the perturbation gradient, increased by the presence of breakwaters. This study serves as baseline of the environmental spatial-temporal variation in intertidal of the sandy beaches of central Veracruz, and as a reference in assessments of other beaches worldwide with similar conditions.