Incidencia estacional de mareas rojas en la bahía de Santa Marta y sectores adyacentes, Caribe colombiano

In order to describe the environmental and climatic conditions associated with the occurrence of six red tide events between 2010 and 2017, in Santa Marta (Colombian Caribbean), biological and physicochemical information during these events was collected. Additionally, precipitation data and the Oceanic Niño Index (ONI) between 2010 and 2017 were consulted. The results showed that the dinoflagellate Cochlodinium sp. was responsible for three events that occurred in October 2010, October 2011 and November 2015, reaching a maximum densities of 5 × 10 cells L. These events were associated with an increase in rainfalls and seawater surface temperature (29.7 oC) and a decrease in salinity (< 35.5). The Mesodinium cf. rubrum ciliate was responsible for three other events (January 2015, January 2017 and March 2017), recording maximum concentrations of 9.2 × 10 cells L. During these last events, there was no rainfall and high concentrations of nutrients, increases in salinity (> 36.6) and sea temperatures below 26 oC were evident. Associating the occurrences of red tide events and the ONI index, it was evidenced that Cochlodinium sp. blooms occurred during years influenced by moderate-strong climatic (thermal) events (ONI > ±1 oC) whereas the blooms of M. cf. rubrum occurred during neutral years (ONI between 0.5 and -0.5 oC). The red tides presented a temporal pattern of occurrence in the Magdalena region, influenced by the climatic and environmental variability of each period, without representing a risk to human health until now. KEYwoRDS: red tides, algae blooms, climatic variability, Colombian Caribbean Boletín de Investigaciones Marinas y Costeras • Vol. 49 (2) • 2020