When environmental factors become stressors: interactive effects of vermetid gastropods and sedimentation on corals.
Environmental stressors often interact, but most studies of multiple stressors have focused on combinations of abiotic stressors. Here we examined the potential interaction between a biotic stressor, the vermetid snailCeraesignum maximum, and an abiotic stressor, high sedimentation, on the growth of reef-building corals. In a field experiment, we subjected juvenile massivePoritescorals to four treatments: (i) neither stressor, (ii) sedimentation, (iii) vermetids or (iv) both stressors. Unexpectedly, we found no effect of either stressor in isolation, but a significant decrease in coral growth in the presence of both stressors. Additionally, seven times more sediment remained on corals in the presence (versus absence) of vermetids, likely owing to adhesion of sediments to corals via vermetid mucus. Thus, vermetid snails and high sedimentation can interact to drive deleterious effects on reef-building corals. More generally, our study illustrates that environmental factors can combine to have negative interactive effects even when individual effects are not detectable. Such 'ecological surprises' may be easily overlooked, leading to environmental degradation that cannot be anticipated through the study of isolated factors.
Department of Biology, University of Florida, Gainesville, FL 32611, USA jzill@hawaii.edu.
Julie A
0000-0002-0626-7801
JA
Zill
Department of Biology, University of Florida, Gainesville, FL 32611, USA.
Michael A
0000-0002-0411-8378
MA
Gil
Department of Biology, University of Florida, Gainesville, FL 32611, USA.
Craig W
0000-0003-1918-7904
CW
Osenberg
D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D057894:Coral Reefs; D049851:Gastropoda / Q000502:physiology*; D019015:Geologic Sediments; D011114:Polynesia; D013312:Stress, Physiological
Moorea; abiotic; biotic; coral reefs; multiple stressors; vermetid gastropods