Changes in Phytoplankton Communities in a Tropical Estuary in the Colombian Caribbean Sea
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Changes in Phytoplankton Communities in a Tropical Estuary in the Colombian Caribbean Sea Noris Córdoba-Mena 1 & Lennin Florez-Leiva 1 & Lucia Atehortúa 2 & Erika Obando 2 Received: 23 September 2019 / Revised: 21 April 2020 / Accepted: 23 April 2020 # Coastal and Estuarine Research Federation 2020
Abstract 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. Keywords Phytoplankton . Tropical estuaries . Harmful algae . Community dynamics . Caribbean Sea . Domoic acid
Introduction Phytoplankton represent more than 45% of the net primary production of the planet and the first trophic level in marine food webs (Hernández 2014; Martínez et al. 2013; Vajravelu et al. 2018). Phytoplankton are the largest producers of oxygen on the planet and comprise approximately 5000 species in marine and estuarine waters, including chlorophytes, dinoflagellates, cyanobacteria, and diatoms (Cloern 1996; Hallegraeff 1993; Hernández 2014). Due to their importance, Communicated by James L. Pinckney * Noris Córdoba-Mena [email protected] 1
Ocean, Climate & Environment Research Group, Corporación Académica Ambiental, Universidad de Antioquía UdeA, Calle 70 No. 52-21, Medellín, Antioquia, Colombia
2
Biotechnology Research Group, Biology Institute, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín, Colombia
small variations in the phytoplankton community structure produce large impacts on ecosystems (Dogliotti
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