Interaction of natural and anthropogenic stressors on rocky shores: community resistance to trampling

MENDEZ, MM; LIVORE, JP; BIGATTI, G

MARINE ECOLOGY PROGRESS SERIES

INTER-RESEARCH

Año: 2019 vol. 631 p. 117 - 126

0171-8630

The response of ecosystems to human stressors can be affected by local natural disturbanceconditions, yet the effects of a given combination of human and natural stressors arehard to predict as there are few studies on the subject. In the present work, we studied the effectsof varying intensities of trampling (i.e. human stressor) on mussel beds at 2 sites characterized bydistinct wave disturbance regimes (i.e. natural stressor) on southwestern Atlantic rocky shores(Patagonia, Argentina). We found that mussels at a wave-exposed site had greater attachment andcompressive strength than mussels from a wave-protected site. These enhanced physical attributes,therefore, were expected to provide wave-exposed communities with higher resistance tohuman trampling. This prediction was supported, with mussel cover loss on experimentally trampledplots being lower on the wave-exposed shore than on the wave-protected shore for all intensitiesapplied. Our results show antagonistic effects of a natural (wave exposure) and an anthropogenic(trampling) stressor on the same type of rocky shore community. As human stressors areintensifying globally, studies assessing the combined effects of natural and anthropogenic disturbancesare needed to properly understand how similar communities may be affected under varyingnatural conditions. This information is fundamental in order to propose appropriate conservationactions.