The impact of Brazilian coast oil spill on the mesozooplankton of the tropical narrowest continental shelf.

The impacts of the 2019 Brazilian coast oil spill on mesozooplankton community were investigated using data of before and after spill off the coast of Salvador. The presence of oil droplets was detected in all samples collected in the continental shelf of Salvador, after oil spill (Oct/2020). The total density of oil droplets ranged from 5.03 to 20.37 droplets m^–3. The size of oil droplets found this study was similar to natural size of zooplankton foods. The highest percentages of oiled copepods 0.09% and 0.02% were recorded in stations BA1 and BA2 (closest to the coast), respectively. The presence of crude oil droplets was confirmed by the observation of crude oil fluorescence under UVA illumination. Zooplankton assemblage structure exhibited a significant reduction in the taxa number after oil spill. Seven copepods species were registered only before oil spill (Oct/2013, Feb/2014), and during October 2020 were registered 10 fewer species. The total zooplankton density varied from 38.2 to 110.4 org m⁻³ (October/2013), 87.1 to 803.2 org m⁻³ (February/2014), 9.4 to 27.4 org m⁻³ (October/2020) and 17.6 to 45.6 org m⁻³ (February/2021). The average density values for the period before spill were up to 10 times higher than the average value found after spill. The Analyze of Similarity used in this study revealed that zooplankton assemblages in the continental shelf of Salvador showed changes in its structure after the accident on the Brazilian coast, particularly on October 2020. Overall, our results indicate negative impact of oil spill in the coastal region of Brazil Northeaster on structure of zooplankton assemblages in the continental shelf of Salvador. [ABSTRACT FROM AUTHOR]