A new study published in the journal Nature Climate Change suggests serious impacts on maximum body weights of marine fish, which in turn could have serious implications for trophic interactions of species, ecosystem functions and global protein supplies. The study is significant because it expands our understanding of the impacts of climate change on oceans into a new dimension, i.e. the impacts of changes in ecophysiology and distribution and associated impacts on key metrics for marine biota, such as body size.
Among the study’s conclusions:
- According to SRES A2 scenarios, the bottom layers of the world’s oceans, most pertinent for demersal fish, will increase by average rates of 0.029 C (Pacific); 0.012 (Atlantic); 0.017 (Indian); 0.038 (Southern), and 0.037) (Arctic), with oxygen predicted to fall between 0.1-1.1 mmolm-3 per decade;
- Most (more than 75%) of studied populations (600 species were studied) are projected to expedience a reduction in body weight of 5-39%, with a median of 10% in all ocean basins, with the magnitude larger for fish in the Pacific and Southern Ocean.
- Distributions of most fish species are projected to shift poleward at a media rate of 25.5-36.4 kms. per decade by 2050 relative to 2000; this and changes in abundance explains about half of the projected reduction in maximum body weights, with the other half attributable to changes in physiology;
- There’s little evidence that fish would be able to completely adapt to compensate for increased warming;
- Other anthropogenic impacts on fish species, including pollution and overfishing are likely to exacerbate negative impacts associated with reductions in body weight.