Cold-Water Corals and Their Newfound Importance


For most people, the first thing that comes to mind when someone utters the word ‘coral’ are the expansive, highly diverse (and very publicized) tropical coral reefs known for their brightly-colored façades and equally vibrant inhabitants. While these particular underwater landscapes are already fiercely protected by conservation biologists, their cold-water counterparts are not as equally protected. Cold-water corals are found all over the world, at a variety of depths, and reecent research conducted by Sandrine Baillon, Jean-François Hamel,  Vonda E Wareham, and Annie Mercier (affiliated university or research organization not listed) may give us reason to pursue the classification of cold-water corals as an essential fish habitat. (The term ‘essential fish habitat’ refers to “those waters and substrates necessary to fish for spawning, breed- ing, feeding, or growth to maturity” (Rosenberg et al. 2000)”.) Their study may suggest that cold-water corals serve as a habitat for the larvae of fish that are classified as endangered due to anthropogenic causes such as overfishing, thus giving the conservation biology community just cause to advocate for the protection of cold-water corals.

For years, various researchers have attempted to link the cold-water corals (abbreviated CWC’s) to the harboring of endangered fish larvae, and while most managed to infer some sort of link, none were ever able to provide definitive evidence of such a phenomenon until Baillon, Hamel, Wareham and Mercier. Their publication cites the work of various researchers who pursued the idea that cold water corals serve as a nursery for fish before them, namely, “Correlative studies and predictive models have shown increasing adult fish densities and sizes around deep- water corals compared with non-coral areas (Husebø et al. 2002; Auster 2005). Spring aggregations of swollen (pre- sumably gravid) redfish females were detected around the scleractinian coral Lophelia pertusa in Norway (Fosså et al. 2002), and catshark (Family Scyliorhinidae) egg cases were found attached to the gorgonian coral Callogorgia sp in the Mississippi Canyon, Gulf of Mexico (Etnoyer and Warrenchuk 2007).” (Baillon et al. 2012). Essentially, the prevalence of female fish carrying eggs and the increase in the density of fish in general around the cold-water corals served as a catalyst for the research that actually confirmed the presence of the fish larvae in the corals themselves.

So how did Baillon, Hamel, Wareham and Mercier go about making the discovery that fish larvae housed themselves in cold-water corals? The researchers collected coral samples in the cold waters off the coast of Canada, particularly in the Laurentian Channel and Southern Grand Banks. By dragging a mechanism across the ocean floor that collected colonies of coral (keep in mind that what might be perceived as a single piece of coral is actually a complex network of multiple individual coral organisms grouped together), the researchers were able to observe cold-water corals up close. Once the corals were collected, they were then frozen to preserve the state they were in when they were taken from the water, and then thawed in sea water. The corals were then dissected to search for any tangible fish larvae within their flesh. It was this sampling method that confirmed the presence of the fish larvae housed in cold-water corals, and concurrently the importance of cold-water corals in fostering the advancement of fish life cycles. Because of this, the science community can now infer that cold-water corals everywhere, not only those located off the coast of Canada, are essential in that they provide habitats for fish.

On a grander scale, the presence of fish larvae within the cold-water corals off of Canada’s coast demonstrates a more profound idea: that discoveries in the field of conservation biology can lead to important advancements in conservation policy, and thus advancements in humanity.

Journal Reference:

1. Baillon, S and Hamel, J.F and Wareham, V.E., and Mercier A., Deep Cold-Water Corals As Nurseries For Fish LarvaeESA Journals Research Communications, 2012.



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