Research - Featured Program

Featured Program - Deep Sea Corals

From May 22 to June 4, 2006 scientists from Olympic Coast National Marine Sanctuary, other NOAA organizations and other research partners explored areas of the sanctuary looking for communities of deepwater corals and sponges. Using the ROPOS remotely-operated-vehicle (ROV) they traveled over the seafloor at depths ranging from 100 to 650 meters (~300 to 2000 feet) During eleven dives they covered more than 15 study locations both inside and outside the Essential Fish Habitat Conservation Area recently established by the Pacific Fishery Management Council. The Conservation Area in Olympic Coast National Marine Sanctuary went into effect on June 12, 2006, closing the area to bottom trawling. The Conservation Area in the sanctuary covers 159.4 square nautical miles, or about 15 percent of the sanctuary. The 2004 discovery of Lophelia pertusa in the sanctuary was a factor in the Council's decision on the boundaries of the Conservation Area.

This research cruise was on the 224-foot NOAA ship McArthur II, with a crew and officers of 15, and 14 scientists and ROV operators. Operations were conducted around the clock to maximize ROV dive time. Because of the expense of mobilizing a large ship and ROV, NOAA scientists try to use every moment to study the sanctuary. The scientists and ROV crew worked two 12 hour shifts. Although rough weather was forecast, we only had to reposition twice due to weather - these were the dives in the relatively calmer waters of the Strait of Juan de Fuca.

Principal investigators for this deep-sea cruise were Ed Bowlby (OCNMS), Mary Sue Brancato (OCNMS) and Jeff Hyland (National Centers for Coastal Ocean Science). Additional scientists included Curt Whitmire (NOAA, Northwest Fisheries Science Center) and Peter Etnoyer (Aquanautix Consulting), and Outreach and Education Coordinator Robert Steelquist (OCNMS). Two of the video cameras and a 3-beam laser system to quantify the area surveyed (Jagielo et al. 2004) were provided by Washington Department of Fish and Wildlife as a pilot to try onboard the ROPOS ROV and WDFW shore-based staff support was provided by Farron Wallace and Eric Eisenhardt.

We made eleven dives primarily along the outer coast, between one and 20 miles offshore. Two dives were in the Strait of Juan de Fuca within the sanctuary boundaries. One dive was at the head of the Juan de Fuca Canyon, one of three submarine canyons in the sanctuary. Dive targets included boulder patches, walls and bedrock - areas previously identified using side scan sonar data as rock habitat.

Take a short virtual dive with us!

Researchers saw coral and sponge communities within 14 of the 15 areas surveyed, as well as other areas of the sanctuary. We shot hundreds of hours of video (one dive was 52 hours long!), thousands of photographs, and collected more than 100 samples. The ROV was equipped with four video cameras, one digital still camera, two manipulator arms, a core sampler, suction sampler and a "biobox" to store samples. The wealth of data will be analyzed over the next year to characterize the distribution, abundance and diversity of these resources; to evaluate their vulnerability to human activity and other potential environmental risks; and to provide new information to help support future resource management decision-making within OCNMS. The data will be peer-reviewed and used in reports, papers and discussions with fisheries co-managers including NOAA Fisheries, Pacific Fisheries Management Council, the Makah, Quileute, and Hoh Indian tribes and the Quinault Indian Nation, and Washington State.

We found at least 17 coral species and numerous sponges, including the reef building sponge Farrea occa. The stony coral, Lophelia pertusa, common in the North Atlantic Ocean, but rarely found in the North Pacific, was documented at several sites surveyed in the sanctuary - reconfirming the discovery of this coral in this area by NOAA scientists in 2004. Soft corals included the gorgonians Paragorgia, Swiftia, Primnoa, and Callogorgia and at least five species of sea pens. Stony corals or Scleractinia included Lophelia, Desmophyllum and Balanophyllia. The hydrocorals we observed included at least two species of Stylaster. In addition to the corals and sponge communities, we saw a multitude of invertebrate and fish species. Over the next several months the samples and photos will be sent to experts in the various taxonomic areas to confirm species identifications.

Project Overview

Preparing for the ROV cruise, the research team targeted areas of known potential coral-sponge habitat by reviewing, as a primary data source, side-scan sonar data for hard substrate features within the sanctuary at depths corals have generally been reported (>80m). Some of the side-scan sonar data were collected on a sister cruise to the ROV expedition, in April 2006, also aboard the NOAA ship McArthur II. Principal Investigator Steve Intelmann (OCNMS) conducted an 11-day side-scan sonar survey in the sanctuary. This information, along with previous side-scan sonar surveys from the sanctuary, were reviewed by OCNMS scientists to locate potential dive targets for coral-sponge habitat. For our planning maps, we drew polygons around the features to identify them as target dive sites.

Side scan coverage of the sanctuary is incomplete - only about 20 percent of the sanctuary has been mapped using side scan sonar. The majority of the potential ROV dive sites occurred within the 20 percent of the mapped area of the sanctuary. We selected a few additional sites in the canyon heads to expand the depth range since some corals (e.g., black corals) generally occur in deeper waters. These sites were picked based on depth, slope and a designation as an "untrawlable" area as defined by NOAA Fisheries scientist Mark Zimmermann (2003) and/or Washington Department of Fish and Wildlife Scientists (Jagielo et al. 2004). In addition to the side-scan sonar imagery, we reviewed bathymetry for all of the sites, prioritizing sites, only by depth and not slope. From this process, we identified 48 potential dive sites as the sample population, defined as the area of known potential coral/sponge habitat with known trawling history.

For this research, we used a stratified random approach to prioritize sites. The 48 sites were stratified into four strata: 1) trawled and inside the EFH Conservation Area; 2) trawled and outside the EFH Conservation Area; 3) not trawled and inside EFH Conservation Area; and 4) not trawled and outside the EFH Conservation Area. However, without a more comprehensive evaluation of the side-scan sonar data, one of these four strata yielded no potential dive sites (trawled and outside closure area). This may be due to the fact that the coral-sponge stratum is incomplete at this time with only about 20 percent of the sanctuary mapped. Half of the polygons within each strata were randomly selected for sampling this year, and about one third of the sites were successfully surveyed on this cruise, with the intention of sampling the remainder of the polygons at a future sampling date. The sites were stratified as inside trawlable or untrawlable habitat as identified by NOAA Fisheries (Zimmermann 2003) and WDFW (Jagielo et al 2004).

We also attempted to classify the sites by fishing intensity using logbook trawl set-points, however, this did not prove to be high enough resolution data. On board the cruise, NOAA Fisheries scientist Curt Whitmire used additional logbook data to perform a density algorithm so that the dive sites could be classified into low or high trawl intensity. These intensities were assigned to the already randomly selected sites.

In addition to this stratified random approach to dive site selection, sites within the Strait of Juan de Fuca were selected as "weather sites" to allow ROV dives to continue if the winds off the coast (but not in the relatively sheltered Strait) prevented launch and recovery of the ROV. With these sites the number of potential dive sites totaled 55.

We also evaluated bycatch data from NOAA Fisheries but because NOAA Fisheries (L. Clark and C. Whitmire pers. comm. 2006) indicated inconsistent reporting of bycatch by observers, this information was not used prioritize potential dive sites.

The sites selected were surveyed by video transect and digital photography. The video transects will be randomly or systematically sampled during post-processing to answer the research questions. The sample units obtained during post-processing will include items such as the following: enumeration of megafauna, living/dead, broken/whole, size (area and height), and evidence of fishing activity (gear, tracks, etc.). This survey pattern allowed for non-statistical objectives (e.g., Locate coral and sponge assemblages in the sanctuary) to be addressed as well those with a research question (e.g., Is the species diversity/abundance/richness of non-coral species different in coral areas than in adjacent areas without corals?).

Dowload the full cruise report, Observations of Deep Coral and Sponge Assemblages in Olympic Coast National Marine Sanctuary, Washington. (Pdf format, 3.1 Mb)

Jagielo, T., J. Tagart, F. Wallace and S. Wang. Density of demersal groundfish in untrawlable habitat on the continental shelf of Washington.

Zimmermann, M. 2003. Calculation of untrawlable areas within the boundaries of a bottom trawl survey. Can. J. Fish. Aquat. Sci. 60:657-669.

For more information contact one of the principal investigators:

Ed.Bowlby@noaa.gov

Mary.Sue.Brancato@noaa.gov

Jeff.Hyland@noaa.gov