Comunidade fitoplanctônica do açude Santos Anastácio, Campus do Pici, Fortaleza (Ceará, Brasil)

Abstract

The weirs are a lentic environment, which normally have a good primary productivity, mainly due to the nutrient supply that favors the development of phytoplankton, the largest primary producer and base of all food webs in the aquatic ecosystem. The work aimed to identify the phytoplankton community in the Santo Anastácio weir, in Fortaleza. Biweekly collections were carried out at the exit of the weir, between May and December 2017; the sample was filtered with a plankton net, concentrated to 10 mL and preserved in 4% formaldehyde. In the laboratory, they were identified and classified based on pertinent references to the subject, as well as, expert consultations and electronic addresses. In addition, data on water temperature, dissolved oxygen, pH, salinity and water transparency were obtained in situ. In the laboratory, the ammonia and nitrite contents were analyzed. Rainfall data were obtained from the website of the National Institute of Meteorology (INMET). In the rainy and dry period the diversity was good, with low species richness. And the equability was significant. A total of 29 species were identified included in the Cyanophyceae Classes (six species); Bacillariophyceae (two species); Euglenophyceae (one species); Chlorophyceae (16 species) and; Zygnematophyceae (four species). Thus, as bioindicator species of eutrophic ecossystem and/or poluited, we have: Chroococcus dispersus, Chroococcus sp., Merismopedia elegans, Merismopedia sp., Microcystis aeruginosa, Synedra sp., Euglena oxyurus e, Scenedesmus spp.