Annual Variation of Environmental Variables, Phytoplankton Species Composition and Photosynthetic Parameters in a Coastal Lagoon

• Published in: Journal of plankton research Vol. 23; no. 7; pp. 719 - 732
• Main Authors: Macedo, M. F., Duarte, P., Mendes, P., Ferreira, J. G.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.07.2001; Oxford Publishing Limited (England)
• Subjects: Ammonium; Ammonium compounds; Animal and plant ecology; Animal, plant and microbial ecology; Annual variations; Bacillariophyceae; Biological and medical sciences; Biomass; Blooms; Brackish; Brackish water ecosystems; Check lists; Chlorophyll; Chlorophylls; Coastal ecosystems; Coastal lagoons; Diatoms; Dinoflagellates; Dominant species; Fundamental and applied biological sciences. Psychology; Inflow; Irradiance; Lagoons; Mathematical models; Parameters; Photosynthesis; Phytoplankton; Portugal; Portugal, Santo Andre Lagoon; Prorocentrum minimum; Saturation; Sea water; Species composition; Synecology; Temperature; Wind speed; Portugal; Europe; Portugal, Setubal, Santo Andre Lagoon; ANE, Portugal, Setubal, Lagoa de Santo Andre; Brackish water environment; Floristic composition; Annual variation; Algae; Environmental factor; Phytoplankton; Biomass; Photosynthesis; Coastal lagoon; Physicochemical properties; Thallophyta
• ISSN: 0142-7873; 1464-3774; 1464-3774
• DOI: 10.1093/plankt/23.7.719

Physical–chemical variables, phytoplankton biomass, species composition and photosynthesis–irradiance (P-I) parameters were analysed during 1 year in the Santo André Lagoon, SouthwestPortugal – a land-locked coastal ecosystem with temporary connections with the sea. When the lagoon stayed closed the observed phytoplankton blooms were mainly caused by Prorocentrum minimum, a potentially toxic dinoflagellate. It was dominant during most of the year but the seawater inflow to the lagoon triggered a decrease in phytoplankton biomass and an abrupt shift in species composition. The maximum photosynthetic rate (Pmax) ranged from 2.0 to 22.5 mg C (mg chlorophyll a)–1 h–1 and the light saturation index (Ik), ranged from 5.2 to 335.0 μE m–2 s–1, with winter minima and summer maxima. Pmax and Ik were both positively correlated to temperature. Abundance ofP. minimum was associated with high nitrate concentrations whereas diatoms appear when ammonium, salinity and wind velocity are high. A mathematical model to describe photosynthetic rate as a function of irradiance and temperature [P (I, t)] was applied to the samples in which P. minimum was the dominant species