Phytoplankton and nutrient dynamics in two ponds of the Esmoriz wastewater treatment plant (Northern Portugal)

• Type: Article in International Scientific Journal
• Date: 2001

Authors

Pereira, E (Author) Other; Anne, I (Author) Other; Fidalgo, ML (Author) Other; Vasconcelos, V (Author) FCUP

Journal

Title: Limnetica

Vol. 20

Pages: 245-254

ISSN: 0213-8409

Publisher: Associacion Espanola de Limnologia

Indexing

ISI Web of Knowledge

Scopus - 8 Citations

Other information

Authenticus ID: P-007-W5F

Abstract (EN): Phytoplankton dynamics in two ponds of the Esmoriz wastewater treatment plant (Northern Portugal), were studied between December 1998 and July 1999. Ponds were characterized by a wide range of water temperatures (i.e. between 9.1 and 25.3°C), and dissolved oxygen concentrations (i.e. 0.9-10.8 mg l -1 in the facultative pond, and 2.8-18.2 mg l-1 in the maturation one). The maximum chlorophyll a concentration was reached in July in the facultative pond (i.e. 2054.6 mg m-3) and in February in the maturation pond (i.e. 2042.6 mg m-3). Mean chlorophyll a concentrations varied between 694.1 mg m-3 in the facultative pond and 942.1 mg m-3 in the maturation pond. Nutrient concentrations were 1.6 mgl-1 NH4 +-N, 0.1 mgl-1 NO 2-N, 10.2 mgl-1 NO3-N and 1.6 mgl-1 PO4 3-P. Chlorophytes and euglenophytes dominated the phytoplankton in the facultative pond; the first group represented almost 85 % of total phytoplankton density in January, May and June, whereas euglenophytes reached 96 % of total phytoplankton density in April. The genera Oocystis and Pandorina were dominant within the chlorophytes, while the genus Euglena was dominant within euglenophytes. Cyanobacteria in the maturation pond represented more than 95 % of total phytoplankton density in April, May and July. Dominant cyanobacteria were Planktothrix mougeotii (April and May), Microcystis aeruginosa and Pseudoanabaena mucicola (July). In the maturation pond, euglenophytes were less than 6 % of total phytoplankton abundance, except in March, when Euglena accounted for 67 % of total phytoplankton density. These densities indicate that the wastewater treatment plant (WWTP) may be an optimal habitat for cyanobacteria, and consequently, a possible source of cyanobacterial toxins. © Asociación Española de Limnologia.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10