Of the 25 species of Naidinae registered on the Isla Martin Garcia, 9 (Table 1) were recorded only in the benthos, 7 in both the benthos and the
pleuston, and 7 exclusively in the
pleuston.
The degree of the advances in the Titikaka Lake eutrophication process was investigated by macrophytes (pleuston and limnophytes) assessment, phytoplankton diversity, physicochemical parameters (pH, turbidity, [BOD.sub.5], total nitrogen and soluble phosphorus) and microbiological (thermotolerant fecal coliforms) parameters at four places of lake.
Se tomaron muestras de las macrofitas flotantes pleuston) para su posterior identificacion en el Herbario Nacional de Bolivia y se estimo la cobertura relativa en superficie en cada area de muestreo.
However, apart from the possibility of initiating new evolutionary opportunities for freshwater species, these ecologically "foreign" members of the marine insect pleuston are important as a food source for surface feeders that normally consume marine pleuston.
The existence, identity, and fate of these nonmarine insects in the marine pleuston of various parts of the world are known to some extent.
El tamano de las plantas que integran el pleuston varia en un amplio intervalo, desde pequenas con hojas de 3,5mm (lentejas de agua) hasta aquellas con hojas que pueden superar 1,15m de longitud (camalote o jacinto de agua).
La diversidad del pleuston fue destacada por Rocha y Por (1998) para las areas vegetadas de la cuenca del rio Paraguay y por Junk y Robertson (1997) para la planicie de inundacion de distintos rios de la region amazonica.
The bases of the pelagic system: plankton, nekton and
pleustonPenthesilenula brasiliensis was found in the benthos and
pleuston of the alluvial valley of the upper Parana River.
Five of the hygrophilous communities are very close to each other (5 to 9); they are the rushes of Schoenoplectus californicus (5) which appear in rather deep depressions, flooded almost the whole year, with an upper layer of variable density of Schoenoplectus californicus and sometimes a lower layer very similar to the other hygrophilous communities or a Pistia stratiotes
pleuston. Community 9 is similar to this community, but the upper layer is a very dense population of Typha domingensis and hardly any other species.
Pleuston and neuston: on the categories of organisms in the uppermost pelagial.