Impact of the construction of a sand dam on the benthic ecology of an estuary in the mexican north Pacific

Abstract

The measure of the environmental impact of a sand dam in the Estero de Punta Banda is presented. The dam is part of the installations of an oil well jackets factory that was never finished. The purpose of the study is to evaluate the change in the benthic community in the dam area. The methodology proposed by Green (1979) in the suboptimal design was followed. Magnitude of change was searched by community ordination, with principal components technique and index of biological value. ANOVA test and the community ordination show a clear distinction between the dam area and the comparison areas. Descriptive indexes show that the dam biota is intermediate, between the control areas with influence of marsh and human activities. An ecological impact is assumed, consisting in the change of the sediment, with effects in food availability and risk of bird predation. The impact indicates that the system is frail to human encroachment.