Coast phytoplankton of the Río de la Plata river and its relation with the pollution

GOMEZ, N.; BAUER, D. E.; CONSTANZA MUNITIS, MARÍA

San Pablo

Congreso; XXVI Congress of International Association of Theoretical and Applied Limnology; 1995

Gómez N., Bauer D.E. and Munitis M.C. Instituto de Limnologia "Dr. Raúl A. Ringuelet" C.C. 712-1900 La Plata Buenos Aires, Argentina. COAST PHYTOPLANKTON OF THE "RIO DE LA PLATA" RIVER AND ITS RELATION WITH THE POLLUTION. The "Río de la Plata" shows different characteristics along its basin, the internal zone being the most affected because the discharge of sewer affluents and tributaries with pollution product of human activity. The objective of the present study is to evaluate the specific composition, the spatial distribution and environmental factors that affect the development of phytoplankton of the coast of the "Río de la Plata", located between 58° 32'W and 57° 41'W. This research form part of the wider study carried out by the group "South Fringe Coast" composed: "Administración General de Obras Sanitarias de la provincia de Buenos Aires", "Servicio de Hidrografía Naval", "Comisíón Nacional de Energía Atómica" and "Aguas Argentinas". A number of 87 samples were examined corresponding to September 1993 and October 1994. Most of them were along transects perpendicular to the coast, at a distance from 500 to 3000m; in some cases this dístance reaches up to 5000 and 10000 m. The phytoplankton showed a scarce development with the predominance of freshwater centric diatoms. The distribution of the phytoplankton throughout the studied zone was irregular and its diversity was low (0.51-1.87 bits. indiv·1). The principal factor affecting the development of phytoplankton was the low penetration of the Iight (Secchí 20-35 cm), due to suspended solids and pollution load. The analysis of correlation also showed that nutrients were not limitative factors.