Hawaiian corals rarity called into question

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In 2009, a petition was raised for 83 rare corals to become protected species under the United States Endangered Species Act. The list is currently under review by the National Oceanic and Atmospheric Administration (NOAA). The question has been raised as to whether or not all the species listed, are really individual species.

Currently, species definitions are based upon the corals’ skeleton, and coral skeletons can be so variable that it becomes difficult to distinguish between groups of corals.

Of the 83 species on the petition, nine are found in Hawaii. Scientists at the Hawaii Institute of Marine Biology (HIMB) examined both the genetic and structural features of the Hawaiian Montipora species. 

Three species of Montipora (M. dilatata, M. flabellata, M.patula) are under evaluation for being listed under the Endangered Species Act. However, researchers have found that the shape of the colony, colour and growth form can vary so much as to be misleading when determining species identification. This also makes it difficult to determine which species on the list are endemic, rare, or at risk of extinction, as it’s not always clear which corals interbreed.

The study, due to be published later this month via PLoS ONE, reveals two previously unknown species complexes in Hawaii; illustrating that rare species may very well interbreed with more common species. 

Dr. Zac Forsman, who led the HIMB investigation, states: "The scale of variation that corresponds to the species-level is not well understood in a lot of stony corals; this is a big problem for taxonomy and conservation. We need to determine if these species complexes contain species that are in the early process of forming, or if they just represent variation within a species. Either way, it could change our understanding of coral biodiversity." 

Co-author Dr. Rob Toonen added: "this study builds on previous work by Forsman and colleagues showing that species designations in the coral genus Porites were not well-defined, either. As more studies like this are coming out, we are getting a clear picture that we don't really know which coral species names are valid and which are just different growth forms of common species."