Mastogloia smithii var lacustris Grun.: A Structural Engineer of Calcareous Mats in Karstic Subtropical Wetlands

Authors

Evelyn E. Gaiser, Department of Biological Sciences and Southeast Environmental Research Center, Florida International UniversityFollow
Josette M. La Hée, Florida International UniversityFollow
Franco A.C. Tobias, Southeast Environmental Research Center, Florida International UniversityFollow
Anna H. Wachnicka, Southeast Environmental Research Center and Department of Earth and Environment, Florida International UniversityFollow

Abstract

Mastogloia smithii var. lacustris Grun. is the dominant diatom in periphyton mats of the calcareous, freshwater to brackish wetlands of Caribbean coasts. Despite oligotrophy, frequent desiccation, high irradiance and temperatures, and occasional fire, periphyton communities in these wetlands can produce over 2000 g m^-2 of organic biomass, prompting studies that examine stress resistance and maintenance of algal mats under extreme conditions. The diatom flora inhabiting periphyton mats from over 500 sites in the Florida Everglades and similar wetlands in Belize, Jamaica and Mexico was examined, and M. smithii var. lacustris was a persistent component, present in 97% of samples and comprising up to 80% of a diverse diatom assemblage. Valves at various stages of division were observed encased in extracellular polysaccharide that exceeded the cell volume; SEM observations confirm issuance from mantle pores resulting in suspension of the cell in a matrix dominated by cyanobacterial filaments. Using corresponding biophysical data from the collection sites, we define the optima for M. smithii var. lacustris along salinity, pH, phosphorus, and water depth gradients. Experiments revealed a collapse of M. smithii var. lacustris populations in the presence of above-ambient phosphorus concentrations and a rapid resurgence upon reflooding of desiccated mats. This widespread diatom taxon appears to play a critical role similar to that of cyanobacteria in microbial mats, and its disappearance in the presence of enrichment threatens biodiversity and the natural function in these systems that are increasingly influenced by urbanization

Comments

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Gaiser, E.E., J. La Hee, F. Tobias, A. Wachnicka. 2010. Mastogloia smithii var lacustris Grun.: A Structural Engineer of Calcareous Mats in Karstic Subtropical Wetlands. Proceedings of the Academy of Natural Sciences of Philadelphia 160(1): 99-112.