title: Nutrient enrichment coupled with sedimentation favors sea anemones over corals.
abstract: Fine sediments, which account for the majority of total fluvial sediment flux, have been suggested to degrade coral reefs on a global scale. Furthermore, sediment impacts can be exacerbated by extreme rainfall events associated with global climate change and anthropogenic nutrient enrichment. We report the findings from a series of mesocosm experiments exploring the effects of short-term sedimentation and nutrient enrichment on the interactions between the hard coral Acropora muricata, the sea anemone Mesactinia ganesis, and the green macroalga Codium edule. Mesocosms were manipulated to simulate either unimpacted reefs or reefs exposed to elevated levels of fine sediments for 10 or 14 days to simulate the effects of heavy rainfall. The first and second experiments were aimed to examine the effects of inorganic and organic sediments, respectively. The third experiment was designed to examine the interactive effects of nutrient enrichment and elevated sediment loads. Neither inorganic nor organic sediment loadings significantly affected the physiological performance of the coral, but, importantly, did reduce its ability to compete with other organisms. Photosynthetic efficiencies of both the green macroalga and the sea anemone increased in response to both sediment loadings when they were simultaneously exposed to nutrient enrichment. While organic sediment loading increased the nitrogen content of the green macroalga in the first experiment, inorganic sediment loading increased its phosphorus content in the second experiment. The coral mortality due to sea anemones attack was significantly greater upon exposure to enriched levels of organic sediments and nutrients. Our findings suggest that the combined effects of short-term sedimentation and nutrient enrichment could cause replacement of corals by sea anemones on certain coral reefs.
authors.affiliation: Graduate Institute of Marine Biology, National Dong Hwa University, Pingtung, 944, Taiwan; National Museum of Marine Biology and Aquarium, Pingtung, 944, Taiwan.
authors.forename: Pi-Jen
authors.initials: PJ
authors.lastname: Liu
authors.affiliation: Department of Life Sciences and Research Center for Global Change Biology, National Chung Hsing University, Taichung, 402, Taiwan.
authors.forename: Min-Chieh
authors.initials: MC
authors.lastname: Hsin
authors.affiliation: Department of Life Sciences and Research Center for Global Change Biology, National Chung Hsing University, Taichung, 402, Taiwan.
authors.forename: Yen-Hsun
authors.initials: YH
authors.lastname: Huang
authors.affiliation: Graduate Institute of Marine Biology, National Dong Hwa University, Pingtung, 944, Taiwan; National Museum of Marine Biology and Aquarium, Pingtung, 944, Taiwan.
authors.forename: Tung-Yung
authors.initials: TY
authors.lastname: Fan
authors.affiliation: Graduate Institute of Marine Biology, National Dong Hwa University, Pingtung, 944, Taiwan; National Museum of Marine Biology and Aquarium, Pingtung, 944, Taiwan.
authors.forename: Pei-Jie
authors.initials: PJ
authors.lastname: Meng
authors.affiliation: Department of Life Sciences and Research Center for Global Change Biology, National Chung Hsing University, Taichung, 402, Taiwan.
authors.forename: Chung-Cheng
authors.initials: CC
authors.lastname: Lu
authors.affiliation: Department of Life Sciences and Research Center for Global Change Biology, National Chung Hsing University, Taichung, 402, Taiwan; Biodiversity Research Center, Academia Sinica, Taipei, 115, Taiwan.
authors.forename: Hsing-Juh
authors.initials: HJ
authors.lastname: Lin
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000187:drug effects* / Q000502:physiology; D000460:Chlorophyta / Q000187:drug effects / Q000502:physiology; D057894:Coral Reefs; D017753:Ecosystem; D009584:Nitrogen / Q000378:metabolism / Q000494:pharmacology*; D052638:Particulate Matter / Q000494:pharmacology*; D010758:Phosphorus / Q000378:metabolism / Q000494:pharmacology*; D010788:Photosynthesis / Q000187:drug effects / Q000502:physiology; D012615:Sea Anemones / Q000187:drug effects* / Q000502:physiology; D012623:Seawater; D013624:Taiwan
chemical_list: D052638:Particulate Matter; D010758:Phosphorus; D009584:Nitrogen