Temporal trends in benthic macrofauna composition in response to seasonal variation in a tropical coastal lagoon, Celestun, Gulf of Mexico

Abstract

Aquatic habitats in some tropical coastal environments can change seasonally, causing changes in the community structure of the benthic macrofauna. A tropical coastal lagoon, the Celestun lagoon, on the north-west Yucatan peninsula, was sampled seasonally and faunal, water and sediment data were compared with conditions during the 1994–1995 weather cycle across a grid of 12 sites distributed along the lagoon’s salinity gradient. Habitat variation was expressed as physical factors associated with the water column (e.g. salinity) and bottom sediments (e.g. interstitial salinity, texture), whereas the benthic community response was assessed through changes in species composition, diversity and dominance. Taxonomic dominance varied according to changes in seasonal habitat characteristics. During the season of strong northerly winds (‘nortes’), molluscs dominated and polychaetes almost disappeared. Polychaetes then recovered during the dry season, becoming as common as crustaceans and molluscs. Finally, during the rainy season, polychaetes became the dominant group and molluscs declined. A conceptual model summarising the community structure changes associated with key physical and biotic factors is proposed. The results indicate that the benthic community of the Celestun lagoon is a resilient one, largely driven by natural weather variability in this tropical ecosystem to a greater extent than previously suggested.