Conectividade ecológica entre a margem equatorial brasileira e o Caribe

Abstract

Understanding the processes involved in larval dispersal is critical to establishing connectivity among the most varied marine ecosystems. Spiny lobsters are widely distributed meroplanktonic organisms that occupy a prominent place in the tropical Atlantic fishery economy, but the characteristics of their larval dispersion regarding long distances is still unknown. Larval Pelagic Duration of these organisms is typically long (close to one year) which allows these organisms to migrate long distances through ocean currents. In this work the physical convectivity between the Equatorial Continental Shelf of Brazil and the Caribbean was tested and the action of low salinities developed by discharges of the Amazon as barriers for the transport of these larvae between these two regions were tested. Three scenarios (S32, S33 and S34) were generated by the introduction of a lethal salinity to the larvae of 32, 33 and 34, respectively. The simulations were performed for the years 2009 and 2016. The results indicate the existence of physical connectivity between the regions within the period referring to the larval pelagic duration of the Panulirus argus lobster. The connection occurs preferably between 90 and 120 days, but larvae arrived in the Caribbean region with only 56 days of drift. Drift buoys were detected with up to 61 days of trajectory duration between regions. The salinity was able to reduce connectivity but not block it althought. The simulations with higher lethal salinities promoted greater reduction of the connection. There was little interannual difference for both connectivity and performance of the Amazon discharge as a barrier. The depths were determinant in larval mortality due to salinity. In simulations with fixed larvae at certain depths, the greater depths resulted in lower mortality rates.