Climate warming reduces the reproductive advantage of a globally invasive intertidal mussel
Predicting the spread of invasive species in a warming world calls for a better understanding of the mechanisms behind the relative performance of both invasive and indigenous species as recipient communities can offer biotic resistance. A particularly important functional trait in this context is reproductive potential. The Mediterranean mussel Mytilus galloprovincialis is invasive world-wide and threatens the native brown mussel Perna perna on South African rocky shores. Where they co-exist, Mytilus dominates the high and Perna the low mussel zone, overlapping in the middle. Mytilus generally exhibits high individual reproductive output, but feeding time is reduced, physical conditions are stressful and adult densities are lower on the higher shore. We compared overall reproductive potential of populations of the two species using a 1-year data set for three sites, accounting for within-shore distribution and abundances. Despite the restriction of Mytilus to the more stressful upper-shore, its aggregate reproductive potential was comparable to that of Perna. We then used Dynamic Energy Budget modelling to test the effects of changing conditions by calculating aggregate reproductive potential under temperature conditions predicted for the end of the century by the International Panel on Climate Change. The results suggest increased aggregate reproductive potential for both species, but the effect was stronger for the native species at two of three sites, implying increased biotic resistance by Perna to the further spread of Mytilus. Combining ecological context and physiological performance elucidates how interactions between native and invasive species may alter. Such nuances are fundamental to anticipating winners or losers in a world where distribution shifts are increasingly common.
KeywordsReproductive output Physiological performance Species distribution Rocky shore Climate change Invasive species Dynamic Energy Budget model
This research was funded by the South African Research Chairs Initiative of the Department of Science and Technology and the National Research Foundation to CDM. CJM was supported by a Rhodes University post-doctoral fellowship. We are grateful to Carlota Fernández-Muñiz, Aldwin Ndhlovu, Diane Smith, and Jaqui Trassierra for assistance during laboratory and field work.
- Dinno A (2017) Conover.test: Conover-Iman test of multiple comparisons using rank sums. R package version 1.1.5 edn.Google Scholar
- IPCC (2014) Climate Change 2014—impacts, adaptation and vulnerability: regional aspects. Working Group II contribution to the IPCC 5th assessment report. Cambridge University PressGoogle Scholar
- Kooijman SALM (2010) Dynamic energy budget theory for metabolic organization. Cambridge University Press, CambridgeGoogle Scholar
- McQuaid CD, Porri F, Nicastro KR et al (2015) Simple, scale-dependent patterns emerge from very complex effects: an example from the intertidal mussels Mytilus galloprovincialis and Perna perna. In: Hughes RN, Hughes DJ, Smith IP, Dale AC (eds) Oceanography and marine biology: an annual review. CRC Press, Boca RatonGoogle Scholar
- Monaco CJ, Helmuth B (2011) Tipping points, thresholds and the keystone role of physiology in marine climate change research. Adv Mar Biol 60:124–154Google Scholar
- R Core Team (2016) R: A language and environment for statistical computing. R foundation for statistical computing, Vienna, AustriaGoogle Scholar
- Suchanek T (1992) Extreme biodiversity in the marine environment: mussel bed communities of Mytilus californianus. Northwest Environ J 8:150–152Google Scholar