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

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

Morphology and Typification of Mastogloia Smithii and M. Lacustris, with Descriptions of Two New Species from the Florida Everglades and the Caribbean Region

The names Mastogloia smithii Thwaites ex Smith and M. smithii var. lacustris Grunow have been attributed to a variety of related diatom morphologies, partly due to the poor availability of type material and complicated nomenclatural history. The history is detailed, clarifying the type morphologies of M. smithii and reconfirming a neglected elevation of M. smithii var. lacustris to M. lacustris (Grunow) Grunow. Populations reported as M. smithii and M. lacustris from the temperate zone (Ontario, Canada and Iowa and Michigan, USA), karstic wetlands of the subtropical Everglades (Florida, USA) and the tropics (Jamaica, Mexico and Belize) are compared with each other. Based on morphological differences including density of partecta, striae and areolae, M. calcarea sp. nov. and M. pseudosmithii sp. nov. are described from the Everglades and the Caribbean region, and a lectotype of M. smithii and a neotype of M. lacustris are designated.

Evaluation of the use and management of fish resources in the pachitea river basin, Peruvian Amazon

The purpose of this study was to analyze the interrelations between the needs of local people and their usage and management of natural fisheries. Between June and August 2001, 177 households in the basin were interviewed regarding their fishing customs. The results were analyzed with parametric and nonparametric statistics considering a cultural and a geographic comparison. Results confirm that indigenous households rely more on fisheries as a resource than colonists. Fishing takes place throughout the year but is more common in the dry season. Fishing is commonly practiced using hooks and cast nets. More destructive techniques such as dynamite and "barbasco" (poisonous plant) were also used. Indigenous people use a greater array of techniques and they fish at a greater diversity of sites. Respondents also reported that fishing yields have decreased recently. Some of the most common fish genera captured are Pimelodus and Leporinus.