Efeitos da temperatura superficial marinha em peixes e zoantídeos de recifes no litoral da Paraíba – Brasil

Abstract

Marine species, particularly those in reef environments, are seriously at risk of population decline over the next few years, as temperatures rise due to endless human practices that release greenhouse gases into the atmosphere. Organisms such as fish and cnidarians for being ectothermic are sensitive to changes in ocean temperature, which brings a concern to these particular taxa. This problem is more accentuated when it comes to tropical regions, because in these areas the species tend to present a narrow range of thermal tolerance due to the relative temperature stability in the tropics. In this perspective, there are predictions for the next decades that emphasize the thermal heating of the ocean waters as the cause of the decrease of the abundance of fish and cnidarians, as the zoantídeos, being able to reach the local extinction of species. The objective of this work was to evaluate the effect of the increase of the temperature of the marine surface waters on fish and zoanthids of tropical reefs located in the coast of Paraíba (northeastern Brazil), through data collection in the field and laboratory experimentation exploring tolerance limits thermal. As a result, it was observed that the colonies of Palythoa caribaeorum of Seixas reefs showed better health in the last months of summer, with more healthy and less pale and dead areas. On the other hand, in the reefs of Picãozinho, the health of the colonies presented a stability during the summer months. As for the reef fish, it was observed that the maximum critical temperature (CTmax) of the three species (Stegastes variabilis, Haemulon aurolineatum, Haemulon squamipinna) did not differ, being around 37,4 ºC, unlike the maximum lethal temperature (LTmax) which S.variabilis recorded 40ºC, representing more than 1ºC in relation to the haemulídeos. Aiming at these results, zoanthids appear to be good indicators of environmental conditions, as well as thermal tolerance experiments provide important perspectives for possible predictions of impacts of ocean temperature elevation on fauna.