TROPHIC STATUS OF A TROPICAL COASTAL LAGOON IN MARGARITA ISLAND, VENEZUELA

Punta de Piedras Lagoon is a coastal lagoon located south of Margarita Island, in the Venezuelan Caribbean Sea. This lagoon has ecological and economic importance for the inhabitants of nearby communities. Currently, the urban and industrial development in its surroundings represents a potential source of pollutants, providing concentrations of nutrients that could affect the ecological balance of the area. The trophic status of Punta de Piedras Lagoon was evaluated using various trophic indices. The concentrations of chlorophyll-a and nutrients (ammonium, nitrites, nitrates, and orthophosphates) were estimated in 10 stations with a monthly frequency from February 2005 to January 2006. These data were used to estimate the trophic condition based on the Karydis and TRIX trophic indices, and by comparison with Organization for Economic Co-operation and Development reference values. It was found that Punta de Piedras lagoon presented mesotrophic conditions in most of the water body having considerable differences between indices. The values of the closest station to Paseo Esther Gil corresponded to eutrophic waters. However, the circulation and residence time of water allow an exchange with the adjacent sea, which prevents the eutrophication process in the lagoon.

Habitat requirements of the Charetum intermediae phytocoenoses in lakes of western Poland

The study presents habitat and phytosociological analyses of the Chara intermedia phytocenoses, rare described in Europe. 16 physico-chemical water parameters were analysed, coming from the samples taken in 20 phytocenoses of 13 lakes located in western Poland. The analysed community appeared in naturally shallow lakes representing last stages of the disappearance of glacial water basins. The study attempts to estimate the bioindicative value of the charophyta meadow Charetum intermediae in relation to its habitat. A particular attention has been paid to the determination of the habitat trophic condition, and to the concentration of elements connected with the hardness of water and the content of humic substances. The study shows crucial habitat gradients of the C. intermediae association, taking into account also the species composition of phytocenoses.

Intraspecific morphological variation in a freshwater copepod (Crustacea) in relation to geographic distribution and environment

Intraspecific variation in morphology was studied by means of morphometric analysis in 52 populations of the freshwater planktonic copepod Cyclops scutifer G.O. Sars from Eurasia and North America. The species showed very conservative morphology over wide geographic areas and subspecies could not be established. Variations occurred irregularly, and morphologically very similar forms were found widely separated on different continents. Correlation analysis revealed that many morphological relations were correlated with environmental factors such as depth, temperature, and trophic condition. Variations in body proportions were thus related to environmental factors rather than to geographic distance.

External continent diversion. Technical aspects and development principles

The Authors briefly review the evolution of urinary diversion techniques. The introduction of the ileal conduit (Bricker) was the most important step to construction of continent pouches, both external and orthotopic, which share most surgical principles (intestinal detubularization, adequate capacity of the pouch, anti-reflux system for the ureters). External pouches present, as-an additional surgical challenge, the technical problems related to the construction of the continent valve at the stoma site: it is therefore not surprising that they are being performed with decreasing frequency. On the other hand there is increasing interest in the construction of an orthotopic neobladder also in the female patient, where such reconstructive surgery has traditionally been impaired by the anatomo-functional features of the female urethra. The Authors maintain that the following points should be considered with great attention: a) functional border between urethra and bladder neck; b) oncologic border between transitional and stratified epithelium; c) positioning of the pouch within the pelvis; d) trophic condition of the pelvic wall musculature.