Assessing anthropogenic disturbance in Estero de Urías coastal lagoon through the lens of annelid distribution

Abstract

The coastal lagoon Estero de Urías is subjected to several anthropogenic activities and was characterized in 1997 and 2008 through the study of benthic annelids. To reveal the current degree of perturbation, the spatial and temporal distributions of polychaete families and oligochaetes were analyzed. Sediment samples were collected in 2016 and 2017 from six collection sites located downstream of a shrimp farm, small shrimp farms surrounded by mangroves, a thermoelectric plant, a fish processing factory, domestic sewage, and a harbor for fishing fleets. ANOVA revealed significant temporal differences in annelid abundance, but no spatial differences. The Pearson correlations among abundance and environmental variables, a nonmetric multidimensional scaling ordination plot, and a SIMPER analysis did not show clear distribution patterns over the study area. Correlations (Spearman Rank) between common taxa and environmental variables indicated higher dependence of temperature, followed by depth and organic matter on most of these taxa. A canonical correspondence analysis using the abundance of the characteristic species and the environmental variables showed no clear associations among sites. The consistent presence of Capitellidae, Spionidae, Cirratulidae, and Nereididae suggests that the entire system was in a perturbed state during the study period. This differs from the previous characterizations, when different degrees of perturbation were clearly identified and related to each anthropogenic source. The slightly or nonperturbed zones previously detected have been degraded as small farms, tourism, and fishing fleets have increased; however, this interpretation should be considered tentative due to our study's small sample sizes and lack of salinity measurements.