Abstract

GONCALVES, Rodrigo J et al. Responses of plankton and fish from temperate zones to UVR and temperature in a context of global change. Ecol. austral [online]. 2010, vol.20, n.2, pp.129-153. ISSN 1667-782X.

In the last decades, both temperature and UVB (280-315 nm) radiation on the surface of the Earth increased at growing rates as a result of human activities. Many studies had evaluated the effects of temperature on aquatic ecosystems, but now the field broadens as the combination and variations of temperature and radiation gains especial importance. In this work we attempt to revisit some of our knowledge about the effects of UVR and temperature on marine and freshwater plankton and fish from temperate regions (defined here as latitudes between 30-60º), especially from the Patagonia area, due to the special characteristics found in these sites. UVR affects (often negatively) almost all processes, from carbon fixation to behavior; and certainly all trophic levels in plankton, from virus to fish larvae. The most prominent UVR danger is probably the mutagenic action of UVB, which will affect a number of processes such as photosynthesis, growth and cell division, among many others. In metazoans, UVR may cause stress upon survival or show sublethal effects such as those in behavior and feeding. It is difficult to extract a general pattern, even in a group of organisms, as responses to UVR appear to be species-specific and strongly influenced by local conditions (e.g., UVR penetration, PAR/UVR ratios, and acclimation). While in many cases significant effects have been determined, a number of mechanisms are available to avoid and / or minimize the damage produced by UVR. However, this may not hold true for global temperature changes. In the case of fishes for example, temperature appears as the main factor driving habitat distributions, so the biogeography must be taken into account to consider the potential outcomes of UVR and temperature changes. Even in the different scenarios predicted by climatic models (including ozone layer recovery and temperature rise over the next decades) more research combining UVR and temperature as factors will be needed to understand responses of aquatic ecosystems into the context of global change.

Keywords : Climate change; Bacterioplankton; Phytoplankton; Zooplankton; Fish; Oxidative stress; Upper mixed layer.

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