Organ damage in Atlantic herring larvae as a result of ocean acidification

The dissolution of anthropogenically emitted excess carbon dioxide lowers the pH of the world's ocean water. The larvae of mass spawning marine fishes may be particularly vulnerable to such ocean acidification (OA), yet the generality of earlier results is unclear. Here we show the detrimental effects of OA on the development of a commercially important fish species, the Atlantic herring (Clupea harengus). Larvae were reared at three levels of CO2: today (0.0385 kPa), end of next century (0.183 kPa), and a coastal upwelling scenario (0.426 kPa), under near-natural conditions in large outdoor tanks. Exposure to elevated CO2 levels resulted in stunted growth and development, decreased condition, and severe tissue damage in many organs, with the degree of damage increasing with CO2 concentration. This complements earlier studies of OA on Atlantic cod larvae that revealed similar organ damage but at increased growth rates and no effect on condition.

Beyond long-term averages: making biological sense of a rapidly changing world

Biological responses to climate change are typically communicated in generalized terms such as poleward and altitudinal range shifts, but adaptation efforts relevant to management decisions often require forecasts that incorporate the interaction of multiple climatic and nonclimatic stressors at far smaller spatiotemporal scales. We argue that the desire for generalizations has, ironically, contributed to the frequent conflation of weather with climate, even within the scientific community. As a result, current predictions of ecological responses to climate change, and the design of experiments to understand underlying mechanisms, are too often based on broad-scale trends and averages that at a proximate level may have very little to do with the vulnerability of organisms and ecosystems. The creation of biologically relevant metrics of environmental change that incorporate the physical mechanisms by which climate trains patterns of weather, coupled with knowledge of how organisms and ecosystems respond to these changes, can offer insight into which aspects of climate change may be most important to monitor and predict. This approach also has the potential to enhance our ability to communicate impacts of climate change to nonscientists and especially to stakeholders attempting to enact climate change adaptation policies.