Univariate and Multivariate Analyses of Metals in Water, Sediment, and Shrimp (Penaeus aztecus) from a Fishing Zone in Laguna Madre, Mexico

Abstract

The Laguna Madre artisanal fishery accounts for approximately 25% of the total shrimp catch in the Mexican Economic Exclusive Zone in the Gulf of Mexico. This coastal lagoon is vulnerable to metal pollution because of the use of agrochemicals in the surrounding agricultural and animal sectors. Spatiotemporal variations in metal contents (Cd, Cu, Fe, Mn, Ni, and Pb) in water, sediment, and shrimp (Penaeus aztecus) samples were evaluated using univariate and multivariate approaches to examine the variability of each metal individually, as well as the composition of all metals as a whole, additionally analyzing the relationship between metal levels in the three sample types. Seasonal variations in metal content were more important than differences across fishing sites, according to univariate and multivariate analyses. Furthermore, seasonal patterns in the mean metal levels were consistently similar in both sites. The correlation between the sediment and shrimp metal matrices was significant, indicating that the composition of metals (matrix of all metals together) in shrimp is associated with the sediment metals but not water metals. Additionally, metals content matrices in shrimp and sediment revealed significant correlations with various environmental factors (e.g., salinity, temperature, dissolved oxygen), which was not the case for metals in water. On the other hand, Cd and Cu levels in shrimp were positively related to the same metals in sediment, providing further evidence of the significant association between metals in sediment and the shrimp P. aztecus.