Warming decrease fish population densities and biomass

• Temperature impact all biota and ecosystems through its direct effect on the vital rates of primary producers and consumers. Still, how these changes in rates translates through ecosystem feed backs to the population level of top consumers are poorly understood. Here, we studied effects of temperature increase (+ 3 ̊C during ice free season) on fish population dynamics in a replicated large scale pond ecosystem experiment over 3 years. Increased temperature had no significant effect on whole ecosystem gross primary production while top down effects of warming on intermediate consumers changed from negative to positive due to negative effects of warming on fish population abundance. Total fish density and biomass and abundance of both mature and old fish decreased with warming, while proportion of young fish increased, with warming. The effects of warming on fish population demographics were likely due to that temperature increased cohort competition and fish energy requirements relative to resource production. Our results suggest that global warming may increase competition, favor young individuals and overall decrease fish population densities and biomass. 

Ämnesord

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Ecology (hsv//eng)

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