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Sponge biomass and bioerosion rates increase under ocean warming and acidification
Author(s) -
Fang James K. H.,
MelloAthayde Matheus A.,
Schönberg Christine H. L.,
Kline David I.,
HoeghGuldberg Ove,
Dove Sophie
Publication year - 2013
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/gcb.12334
Subject(s) - bioerosion , reef , ocean acidification , coral reef , sponge , biomass (ecology) , coral , environmental science , effects of global warming on oceans , carbon dioxide in earth's atmosphere , carbonate , ecology , carbon dioxide , population , symbiodinium , oceanography , coral bleaching , global warming , biology , climate change , geology , chemistry , botany , symbiosis , paleontology , demography , organic chemistry , sociology , bacteria
The combination of ocean warming and acidification as a result of increasing atmospheric carbon dioxide ( CO 2 ) is considered to be a significant threat to calcifying organisms and their activities on coral reefs. How these global changes impact the important roles of decalcifying organisms (bioeroders) in the regulation of carbonate budgets, however, is less understood. To address this important question, the effects of a range of past, present and future CO 2 emission scenarios (temperature + acidification) on the excavating sponge Cliona orientalis Thiele, 1900 were explored over 12 weeks in early summer on the southern Great Barrier Reef. C. orientalis is a widely distributed bioeroder on many reefs, and hosts symbiotic dinoflagellates of the genus Symbiodinium . Our results showed that biomass production and bioerosion rates of C. orientalis were similar under a pre‐industrial scenario and a present day (control) scenario. S ymbiodinium population density in the sponge tissue was the highest under the pre‐industrial scenario, and decreased towards the two future scenarios with sponge replicates under the ‘business‐as‐usual’ CO 2 emission scenario exhibiting strong bleaching. Despite these changes, biomass production and the ability of the sponge to erode coral carbonate materials both increased under the future scenarios. Our study suggests that C. orientalis will likely grow faster and have higher bioerosion rates in a high CO 2 future than at present, even with significant bleaching. Assuming that our findings hold for excavating sponges in general, increased sponge biomass coupled with accelerated bioerosion may push coral reefs towards net erosion and negative carbonate budgets in the future.