Diversity and biomass phytoplankton in marine shrimp farming in Para state

Abstract

This work aimed to evaluate the the phytoplanktonic community and the abiotic parameters during a cycle of cultivation of Litopenaeus vannamei in two stations in a pond in Curuçá (PA), northern Brazil. Were measured transparency, pH, dissolved oxygen, salinity and temperature. Considering the last four parameters, were registered in the surface water and the bottom set. Additionally, also were collected samples to study the fitoplankton and chlorophyll “a” concentrations. The temperature values were between 31,5 and 35 ºC; dissolved oxygen concentrations were between 4,2 and 15,5 mg/L; pH between 8,1 and 9,4; salinity from 26,9 to 30 ppm. The transparency decreased from 55 to 17 cm. The Chlorophyll a concentrations were from 2,33 to 471,34 mg/m3. The transparency decreased of 55 to 17 cm. Chlorophyll a from 2,33 to 471,34 mg/m3. Regarding the fitoplankton analyses, were identified 95 taxa and Bacillariophyta was the most representative group, with dominance of the Navicula sp, Pleurosigma sp and Nitzschia sp. The largest density registered was of 104.400 and to smallest was 3.600 org/L. The mean diversity at the station 01 was 1,49 bits/ind and in the station 02 was 1,43 bits/ind. Enter the main conclusions: the fitoplanktonic community was dominated by the diatom and the division Bacillariophyta was the most important group (wealth and density); the class dinophyceae revealed to be better adapted in the clearer waters; Chlorophyll “a” values presented a direct relationship to the feeding artificial, increasing with the time. Despite the great fluctuation of abiotic parameters such pH, dissolved oxygen and transparency, the cultivation system was considered  homogeneous. Key-words: Shrimp Farming, Litopenaeus vannamei, Microalgae.