How does rising atmospheric CO2 affect marine organisms?

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Earth's Coral Reefs: Probing Their Past to Foretell Their Future
Volume 17, Number 27: 2 July 2014

In a recent report dealing with the subject of this editorial, Pandolfi and Kiessling (2014) write that "global climate change is feared to lead to the collapse of living coral reefs, whose component organisms can respond in but three ways: migration, adaptation, and extinction." So if earth's coral reefs are to avoid extinction, there are but two ways to do so: adapt or migrate. And one or the other of these two responses must work pretty well, for after their analysis of the subject, they report that "coral reefs have shown a remarkable resilience to past climate change."

In the case of the first of these two potential responses, the two researchers write that "increased documentation of tropical species moving to higher latitudes in Florida, east and west Australia, and Japan (Marsh, 1992; Vargas-Angel et al., 2003; Yamano et al., 2011; Baird et al., 2012) provides a sense of the capacity for living reef corals to expand their geographic ranges as global warming increases." And in the case of the second of the two potential responses, we note that a sense of the capacity for living reef corals to adapt to global warming is provided by the studies of Kumaraguru et al. (2003), Maynard et al. (2008), Meyer et al. (2009) and Pettay et al. (2011).

But what about the more pressing and immediate anthropogenic-induced threats faced by earth's corals, which in the case of Australia's Great Barrier Reef have been known to include (1) rising nutrient levels caused by runoff from agricultural activity on land, (2) outbreaks of the coral-devouring crown-of-thorns starfish, (3) the barbed hooks and scything nets used in fishing, (4) tourists and the developers who build resorts and marinas for them, (5) increased sediment levels, (6) the nets of prawn trawlers stirring up the growing load of sediments, (7) the 6-10 tons of "bycatch" for each ton of prawns netted that are caught and die, which dramatically changes the composition of reef life, (8) sea life depleted to the point of exhaustion by over-fishing, (9) huge catamarans and dive boats that take thousands of visitors to the Barrier Reef each day and dump their sewage in the sea on the way home, (10) the live reef-fish trade, (11) fishermen using dynamite and cyanide, (12) coral diseases, and (13) pollution.

These being but some of the real-term here-and-now anthropogenic-induced threats to the well-being of earth's corals, Pandolfi and Kiessling rhetorically ask, in regard to these important species, "with so many imminent threats bearing down on them, how will it be possible for them to continue functioning?" Clearly, we must do all in our power to clean up our act, as it were, in regard to the many ways in which the everyday lives of a vast number of us ultimately directly impact the coastal environments of earth's oceans in a host of negative fashions. Earth's corals are well equipped to deal with climate change; but it is a far different story when it comes to direct attacks on their immediate environs.

Sherwood, Keith and Craig Idso

Baird, A.H., Sommer, B. and Madin, J.S. 2012. Pole-ward range expansion of Acropora spp. along the east coast of Australia. Coral Reefs 31: 10.1007/s00338-012-0928-6.

Kumaraguru, A.K., Jayakumar, K. and Ramakritinan, C.M. 2003. Coral bleaching 2002 in the Palk Bay, southeast coast of India. Current Science 85: 1787-1793.

Marsh, L.M. 1992. The occurrence and growth of Acropora in extra-tropical waters off Perth, Western Australia. Proceedings of the Seventh International Coral Reef Symposium, Guam, Vol. 2: 1233-1238.

Maynard, J.A., Baird, A.H. and Pratchett, M.S. 2008. Revisiting the Cassandra syndrome; the changing climate of coral reef research. Coral Reefs 27: 745-749.

Meyer, E., Davies, S., Wang, S., Willis, B.L., Abrego, D., Juenger, T.E. and Matz, M.V. 2009. Genetic variation in response to a settlement cue and elevated temperature in the reef-building coral Acropora millepora. Marine Ecology Progress Series 392: 81-92.

Pandolfi, J.M. and Kiessling, W. 2014. Gaining insights from past reefs to inform understanding of coral reef response to global climate change. Current Opinion in Environmental Sustainability 7: 52-58.

Pettay, D.T., Wham, D.C., Pinzon, J.H. and LaJeunesse, T.C. 2011. Genotypic diversity and spatial-temporal distribution of Symbiodinium clones in an abundant reef coral. Molecular Ecology 20: 5197-5212.

Vargas-Angel, B., Thomas, J. and Hoke, S. 2003. High-latitude Acropora cervicornis thickets off Fort Lauderdale, Florida, USA. Coral Reefs 22: 465-473.

Yamano, H., Sugihara, K. and Nomura, K. 2011. Rapid poleward range expansion of tropical reef corals in response to rising sea surface temperatures. Geophysical Research Letters 38: 10.1029/2010GL046474.