Background.

The structure of benthic diatom assemblages (BDA) is related to the type of substrate where they flourish.

Goals.

assess the degree of variation shown by BDA growing on live and non-living substrata from a tropical coastal lagoon (Terminos lagoon). We tested the hypothesis that substrate influence would deem significantly distinct BDA.

Methods.

diatom samples were collected from live and non-living substrata from four sites within Terminos lagoon, México, where physicochemical variables were also measured. Diatom taxa were identified, and their relative abundances were estimated and used to compute community parameters (species diversity, equitability, dominance), along with the indicator value (IndVal). Also, similarity between the BDA from the four sites was measured and values were then compared using ANOSIM.

Results.

Although the IndVal showed a clear separation based on the dominant/constant taxa, ANOSIM indicated that differences between the sites were not significant. This may be related to the characteristic patchy distribution of BDA along environmental gradients.

Conclusions.

in coastal ecosystems the structure of BDA could be mainly influenced by environmental variables.