Mechanisms Defining Thermal Limits and Adaptation in Marine Ectotherms: An Integrative View

It is widely accepted that marine biogeography is largely shaped by direct effects of temperature (Angel, 1991; Murawski, 1993). Temperature also influences biodiversity patterns at various latitudes (e.g.,Royet al.,1998; Astorga et al.,2003). Climate-induced effects on marine organisms are thus mostly attributed to a changing temperature regime. These effects may be direct, through effects of temperature itself, or indirect, through thermally-induced changes in the composition of the food chain or through fluctuating food availability in time and space. Such changes may start with fluctuations in phytoplankton availability influenced by temperature, changing ocean currents and stratification or changing levels of nutrients like iron (Gowen et al.,1995; Reid et al.,1998; Wiltshire & Manly, 2004; Wang et al.,2005). Recently, dramatic increases in biological productivity have been demonstrated to have occurred following glacier and ice shelf loss along the Antarctic Peninsula (Peck et al.,2010a). These patterns, combined with direct temperature effectsonhigher level foodchain components, may lead to changing availability of, for example, zooplankton for fish (e.g., Platt et al.,2003; Beaugrand & Reid, 2003; Beaugrand et al.,2003).