Physicochemical gradients in a coastal lagoon from the southern Gulf of Mexico; a multivariate approach

The high environmental variability that characterizes estuarine ecosystems can be approached through multivariate methods which would allow us to achieve an integrated view of the change ratios and direction of the environmental variables. The aim of this study was to make a spatio-temporal characterization of Términos Lagoon (TL) using a multivariate approach enabling us to better understand the high variability of the system and to recognize underlying gradients. Five samplings were carried out at TL in a period of two years during which physicochemical variables were measured along 25 stations. A principal component analysis was made to analyze changes and interactions between variables in the lagoon, using the scores values at each station to represent the spatial variation for each component. The mapped scores allowed us to detect multivariate gradients generated by the variable interactions in the new components. Each sampling displayed multivariate gradients composed by the interaction of different variables correlated to the principal components. Our results allow us to recognize the processes occurring in TL that are responsible for these gradients. One of the main processes was freshwater discharge, whose influence was irregular. The multivariate gradients proposed evidenced the high variability that characterizes TL and, likely, coastal systems in general. We thus consider that the present methodological approach is adequate for modeling both spatial and time variations in a coastal system. •PCA was used to determine the multivariate gradients created by the interaction of the environmental variables.•Each sampling period presented particular multivariate gradients.•Transparency was one of the main variables throughout the study period.•The multivariate gradients allowed us to recognize the processes and changes taking place in the lagoon.