HR: 1400h
AN: OS23D-02    [Abstracts]
TI: An approach to the coastal water circulation in the Piratuba Lake Biological Reservation, Northeast of Amapa State, Brazil
AU: * Takiyama, L R
EM: luis.takiyama@iepa.ap.gov.br
AF: Instituto de Pesquisas Cientificas e Tecnologicas do Estado do Amapa-IEPA, Centro de Pesquisas Aquaticas-CPAq Rod. JK, km 10, sn Fazendinha, Macapa, AP 68903-000, Brazil
AU: Silveira, O M
EM: silveira@ufpa.br
AF: Universidade Federal do Para-UFPA, Centro de Geociencias Av. Augusto Correa, 01 Bairro do Guama, Belem, PA 66075-110, Brazil
AB: This study shows the pioneer results of the water quality characterization of a lake region, including the Piratuba lake (within the limits of the Piratuba Lake Biological Reservation) and the Sucuriju river, localized at the northeast portion of the Amapa State, Brazil, and left margin of the Amazon River mouth. Due to the influence of the Amazon river and another important river, the Araguari river, the northeast coast of Amapa State receive little impact of salty water from the Atlantic ocean. The highest salinity values detected on this coastal area is 20 psu. The Piratuba Lake region which can be described as an unique wetland system formed by recent geological processes (Quaternary), it constitutes a very fragile environment and possesses a number of shallow water lakes distributed into a mixed mangrove and "varzea" type of vegetation and it is considered very important looking at the biological point of view. The borderline between this lake system with the coastal waters is a narrow portion of mangrove containing species of Rizhophora and Avicennia parallel to the coast line. A preliminary water circulation could be accessed through the detection of variation in water quality parameters throughout three field studies conducted on March, 2004, June 2005 and November 2005. Surface water sampling points spatially distributed on the study area with distances less than 2 km were set, covering almost 800 square kilometers. Among the parameters studied (pH, electrical conductivity, turbidity, concentration of suspended solids, depth, temperature, chloride, dissolved oxygen, nitrate, nitrite and phosphate) the turbidity, electrical conductivity and pH were the most important for identifying the entering of coastal waters into the lake region. Mainly, three points of direct contact were identified; one of them is a manmade illegal entrance to the Biological Reservation. The seasonal variation was also very important factor and as expected, during the dry season (July to November, represented by the study on November 2006), we could measured the highest values of conductivity, pH and turbidity in many of the lakes sampled. The implications of understanding, even preliminarily the water circulation in the study area is related to the influence onto the freshwater living species, environemtnal conservation management purposes, geomorphology process indicator and the possible biogeochemical exchanges dynamics, once the Amazon waters can be nutrient rich and the lake waters apparently have high dissolved organic carbon content.
DE: 1845 Limnology (0458, 4239, 4942)
DE: 1862 Sediment transport (4558)
DE: 1871 Surface water quality
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly