Dispersão das larvas do Coral-Sol (Tubastraea spp.) na plataforma continental da margem equatorial brasileira

Abstract

Originating from the Pacific Ocean, the Sun Coral (Tubastraea spp.) is considered an exotic and invasive organism in the Atlantic Ocean and had two species reported off the Brazilian coast: Tubastraea coccinea and Tubastraea tagusensis. In the state of Ceará, the species was initially recorded on a shipwreck in Acaraú, approximately 40 km off the coast, in the year 2016, later being documented on a shipwreck in Pecém, in the year 2020. The objective of the present work is to employ numerical modeling for the simulation of the dispersion of sun coral larvae on part of the Continental Shelf of the Brazilian Equatorial Margin. Delft3D was the model used to perform the simulations, using a grid with an average resolution of 700 m, and with a maximum resolution of 250 m in the Mucuripe harbor region. In situ bathymetric data from PCCE were used, interpolated to the depth data from the rest of the grid, which were obtained from the ETOPO 1 database. The wind forcing was configured with average data for the simulation period, obtained from the INMET database. As for the sea level, it was configured according to data from the tidal harmonics (M2, S2, N2, O1 and K1) obtained from FEMAR. The hydrodynamic model was implemented by a period of one year, corresponding to June/2011 until June/2012. The tidal validation was done by comparing the harmonic constants output data of the simulations with the observed values. As for the validation of the current field, it was done by comparing the magnitude time series and direction of the modeled and observed data. Finally, the particle module was used for the analysis of the dispersion of the larvae of the Sun Coral in the domain area, through experiments conducted at two launching points (Pecém Shipwreck and Acaraú Shipwreck), contemplating scenarios in the first and second half of the year. Thus, it was possible to explore the trajectory of the particles in different time intervals, exploring all the configured scenarios. In the results obtained, it was possible to observe the dominance of the tidal influence in the first 24 hours of dispersion, resulting in a wider dispersion at spring tide and a more concentrated one at quadrature. It was found that the plume disperses towards the northwest and overtakes the continental shelf break in all simulated scenarios. Besides the seasonal difference that influenced the dispersion of the plume, resulting in a greater distance traveled by the dispersed particles in the second half of the year due to higher wind intensity.