DISCOVRE 2008

Pre-Cruise Log: 10/03/2008

Genetics Studies of Deep Sea Corals and Associated Communities

Cheryl Morrison, Ph.D.

Little is known about how deep-sea corals reproduce or the frequency of larval exchange (i.e., degree of connectivity) between reef habitats. High dispersal should homogenize populations by mixing genes between adult populations. If exchange of recruits is common, reefs may have increased resilience to disturbance because of improved chances for re-colonization, whereas more isolated reefs may be more vulnerable. Understanding patterns of connectivity may help us protect deep reefs by avoiding sensitive reef habitats, and should contribute to effective design of protected areas and long-term maintenance of linkages between reefs.

The specific objectives for our genetics studies include: (1) the use of microsatellite markers to quantify local and regional patterns of genetic variation in Lophelia, including assessments of genetic connectivity between reefs, relative contributions of clonal (asexual) and sexual reproduction, and inferred larval dispersal patterns; (2) documentation of biodiversity in scleractinian (hard) corals using DNA sequences, and (3) characterization of linkages between Lophelia-associated invertebrates.

It takes many samples to obtain accurate estimates of gene flow, and obtaining samples of deep sea organisms is quite a task. We have been building our collections of corals and associated invertebrates for many years now and have had help from many collaborators. Our goal on this cruise is to collect additional Lophelia genetic samples to help refine our estimates of connectivity. Priority will be given to sites we haven't visited previously, and shipwrecks that have been colonized by Lophelia. Additionally, organisms observed in close association with Lophelia reefs, such as the squat lobster Eumunida picta, the urchin Echinus, and a eunicid polychaete, will be sampled for genetic characterization of the Lophelia reef community.

Preserving samples properly for DNA analysis is important and happens quickly once they are on board the ship. Sample jars of various sizes have been loaded on the ship, along with ethanol for preservative, sample labels, and a detailed list of instructions. The majority of work will occur once the preserved samples arrive at the USGS Leetown Science Center in West Virginia where DNA will be extracted, and appropriate genetic markers have been developed and are being utilized. Patterns of connectivity will be interpreted in light of data gathered from the physical and chemical environment from the benthic landers being deployed on the cruise.