Dr Curtis Horne BSc (Hons), PhD

The size at which a species matures often decreases with rearing temperature. With average global temperatures predicted to rise by more than 2 degrees Celsius by the end of this century, reduced body size has been described as the third universal response to climate warming. Reduced oxygen availability, independent of temperature, has also been shown to decrease size at maturity. Deoxygenation is increasing in geographic extent and severity in regions of the world's oceans and in freshwater systems, and is predicted to significantly worsen over the coming decades. Climate warming combined with reductions in oxygen concentrations presents a double jeopardy to aquatic species. Shifts in the size of animals and size-spectra of biological communities as a result of climate change are likely to have worldwide ecological and economic impacts. This NERC-funded project aims to quantify, understand, predict and develop mitigation strategies to deal with warming and oxygen-induced changes in body size in aquatic ecosystems.

Major questions we aim to address include:

How do changes in temperature and oxygen concentration affect body size responses in aquatic species and how are responses impacted by the interaction of these two parameters?

How have body sizes changed in aquatic species in relation to temperature and oxygen availability over recent decades? Are these responses similar to patterns observed in the laboratory and across seasons and latitudes?
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What are the most important traits associated with variation in the strength of temperature- and oxygen-induced changes in adult body size, and can we use this information to accurately predict body size change in the future? Are some species more sensitive than others?

Does body size reduction with warming fully compensate for increased metabolic demand at higher temperatures, and how might this affect the total productivity and efficiency of transfer from food to flesh that can be supported in warmer conditions? Can we use this information to contribute to informed decision making in the aquaculture and fisheries industries?