The first global synthesis of copepod temperature-body size (T-S) responses in nature across seasons, published in Global Ecology and Biogeography.
Body size affects vital physiological rates and ecological processes. Ectotherms commonly grow to a smaller adult body size when reared in relatively warm conditions. Whilst temperature-body size (T-S) responses have been well studied under controlled experimental conditions and across geographical ranges, comprehensive analyses of temporal changes are lacking. What’s more, there remains considerable unexplained variation in body size responses within aquatic species.
We analyzed published literature on seasonal body size responses of planktonic copepods, including 140 responses from 33 locations worldwide. Temperature was a much better predictor of body size change than chlorophyll-a, and almost 90% of species reduced their body size with seasonal warming. These reductions appear strongest in current-feeding calanoid species, compared to ambush-feeding cyclopoid species, suggesting feeding strategy may play a significant role in dictating the extent of body size reduction with warming.
Copepods globally represent a primary resource for invertebrates and vertebrates, from fish to whales. Changes in body size will not only affect individual and population fitness, but may have an impact on feeding rates and alter food web connectivity given the size dependency of trophic processes, as planktonic food webs are especially highly size structured.
This work results from an ongoing collaboration between researchers from the Centre for Ocean Life, Queen Mary University of London, and the University of Liverpool.
Read the paper here
Reference:
Horne CR, Hirst AG, Atkinson D, Neves A, & Kiørboe T (2016). A global synthesis of seasonal temperature-size responses in copepods. Glob. Ecol. Biogeogr. DOI: 10.1111/geb.12460