Características ambientais e das comunidades fitoplanctônicas dos estuários dos rios Siriji e Botafogo no litoral Norte de Pernambuco

Abstract

The survey of the characteristics physical-chemical of the water and phytoplankton constitutes an important factor in the environmental zoning allowing the determination of the natural productivity of the bodies waters, its potential for man exploitation, besides supplying subsidies to the correct use of its natural resources. The estuary constitutes a transition environment between two adjacent ecosystems with morphologic and dynamic characteristics special of instability of the physical and chemical parameters. This environment plays important role in the transference of sediments, water and energy between the systems fluvial and marine besides functioning as natural coastal deposit, also contaminants, and protecting the coast in the flood control. The study area is situated in the coast north of the state of Pernambuco, including the estuary of the Botafogo and Siriji. During the period of study (abril/03 - mar/04 in the periods of increasing moon and receding tide), samples of water and plankton had been collected. The samples had been analyzed considering the values of temperature, salinity, dissolved oxygen, pH, chlorophyll-a, totals dissolved solids, nitrate, nitrite, ammonia, inorganic phosphate, and total phosphate. The determination of the phytoplankton a composition was made through direct counting, using the microscope. The results had been related with some ambient parameters such as: precipitation, temperature, salinity, transparency of the water and you leave nutrients. In the sea, the eutrofization caused for contamination, for example, for domestic or industrial sewers with raised load of nutrients, can propitiate the appearance of biddings of phytoplankton, represented for diverse groups that take to the reduction of the dissolved oxygen or specific toxin release. It the samples of the two estuaries, the taxa had been usually found in phytoplankton of continental waters. Considering the capacity of receiving ecosystems to dilute the effluent ones, it is probable that in coastal areas with low productivity, the discharge of eutrophics waters can, in the reality, to come to benefit the natural productivity of these environments, but for this a constant monitorament is necessary, since the capitation of waters for the until its exit (effluent) to the environment. Another point important to be considered is the constant addition of sediments that cause significant alterations in the coastal ecosystems that increase the amount of nutrients very and diminish the light ticket, leading the place to an eutrophication process.