Recent climate change predictions have forecast a 3°C rise in ocean temperature by 2100 which is likely to increase water column thermal stratification, leading to nutrient poor surface waters and potentially decrease food availability for marine species. This could lead to behavioural alterations in foraging and physiological changes due to higher energy demand. This study tested the effects of higher water temperature and food reduction on behaviour, routine metabolic rate (RMR) and body condition of the two-spotted goby, Gobiusculus flavescens at the southern end of its distribution. Fish were kept in 4 treatments: either at ambient (15°C) or raised temperature (18°C), combined with being fed either ad libitum (twice daily) or a reduced amount (once on alternate days) for a 3 week period. Results suggest differences in some behaviours – more time spent foraging by less fed individuals. No difference was found in RMR between the 4 treatments, but thermal sensitivity increased under high temperature. Food availability had a greater impact than temperature on body condition. Females at 18°C and reduced feeding were in the poorest condition. Fish in reduced feeding treatments lost the most weight. These results suggest that increased water temperature could indirectly affect this species through food availability.
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