Changes in Phytoplankton Communities in a Tropical Estuary in the Colombian Caribbean Sea

• Published in: Estuaries and coasts 2020-12, Vol.43 (8), p.2106-2182
• Main Authors: Córdoba-Mena, Noris, Florez-Leiva, Lennin, Atehortúa, Lucia, Obando, Erika
• Format: Article
• Language: English
• Subjects: Abundance; Acid production; Bacillariophyceae; Blooms; Coastal Sciences; Community composition; Community structure; Cruises; Cyanobacteria; Diatoms; Dinoflagellates; Dissolved oxygen; Domoic acid; Dry season; Earth and Environmental Science; Ecology; Environment; Environmental factors; Environmental Management; Estuaries; Estuarine dynamics; Freshwater & Marine Ecology; Geographical distribution; Halocline; Marine microorganisms; Nutrient concentrations; ORIGINAL PAPERS; Phytoplankton; Plankton; Rainy season; Seasonal variation; Seasonal variations; Seasons; Species composition; Species diversity; Temporal variations; Toxins; Trophic levels; Tropical climate; Water analysis; Water and Health; Water sampling; Wet season
• ISSN: 1559-2723; 1559-2731
• DOI: 10.1007/s12237-020-00750-z

Phytoplankton community species composition, diversity, biomass, and distribution experience constant changes because of seasonal and temporal variations. This study was done with the aim of describing the response to environmental and seasonal changes of the phytoplankton communities of a tropical estuary in the south of the Colombian Caribbean Sea (Gulf of Urabá) with an emphasis on potential producers of toxin genera. To do these, 15 sites along the Gulf were studied during two cruises in the rainy season and one during the dry season. In each site, water samples from above and below the halocline were collected. Environmental factors such salinity, pH, dissolved oxygen, and nutrient concentration were correlated with diatoms, dinoflagellate, cyanobacteria, and biotoxin producer abundance. The results showed that the number of diatoms was at a maximum of 11,166 cell/L in the fluvial zone. Dinoflagellates were at a maximum of 4250 cell/L in the same zone during the dry season and cyanobacteria blooms during the rainy season. Four genera of potential biotoxin producers were found: Dolichospermum, Prorocentrum, Dinophysis, and Pseudo-nitzschia; this last genus represents 44% of the total diatom abundance during the rainy season with a detectable domoic acid production in a range between 25.54 and 1580.7 pg/mL; this substance can affect different trophic levels in the Gulf, especially mammals due to its non-reversible amnesic effect. Overall, this study shows that the phytoplankton community structure in this tropical stratified estuary presents environment conditions during the rainy season that increase the abundance of phytoplankton that may thrive into blooms.