Environmental stress decreases survival, growth, and reproduction in New Zealand mussels

To test the effects of environmental stress on mussel growth and reproduction, reciprocal transplants of two New Zealand mussel species, Mytilus galloprovincialis and Perna canaliculus, were performed between the high (high-stress) and low (low-stress) elevation edges of an intertidal mussel bed in New Zealand. Mussels transplanted to the high edge of the mussel bed exhibited slower growth, lower mass of reproductive tissue, and stress-induced spawning, indicating that stress impairs the ability of these organisms to grow and reproduce. P. canaliculus grew more quickly than M. galloprovincialis but allocated less relative energy towards reproduction. An anomalous high aerial temperature event led to differential mortality of the two mussel species in the field, indicating that P. canaliculus is less thermotolerant than M. galloprovincialis. These results suggest that the abundance of P. canaliculus, the competitive dominant on New Zealand rocky shores, may decrease in the face of increasing aerial temperatures predicted under global climate change scenarios, drastically altering intertidal community structure.