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2010 Deep Sea Coral Cruise - east coast
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Mission Plan

During the cruise, researchers will address the following objectives:

Coral Mapping

We will use the ship’s sonar system to map locations of coral mounds.  Surveys conducted decades ago with less sophisticated sonar and less precise navigation will be used to direct mapping efforts along the Latitude 31-30 Transect.  With modern sonar and navigation technology such as GPS, we will be able to pinpoint sonar targets that can then be examined with the video and still cameras mounted aboard the ROV.  The ROV will enable us to “groundtruth” sonar signals, by documenting the specific bottom features such as coral mounds, coral thickets, or rock rubble, that produce specific sonar signals. 

How Old Is That Coral?

A small blackbelly rosefish shelters near a bamboo coral on the Blake Plateau off the coast of Georgia (Photo:  NOAA Office of Ocean Exploration and Research).
A small blackbelly rosefish shelters near a bamboo coral on the Blake Plateau off the coast of Georgia (Photo: NOAA Office of Ocean Exploration and Research).
We will use the ROV to collect coral samples that can be used to determine the ages of the corals.  This can be done by cutting sections through a small sample of a coral branch, and looking for patterns of chemical deposition, much like examining rings in a section of a tree trunk.  Determining the ages and growth rates of corals will enable us to predict how fast coral habitat can recover if it is damaged.  The analysis will also help us detect how natural fluctuations in bottom temperature and other conditions affect the growth of the corals.

Infaunal Invertebrate Communities

Grab sampler (Photo:  NOAA Office of Ocean Exploration and Research).
Grab sampler (Photo: NOAA Office of Ocean Exploration and Research).
Although much of the Blake Plateau is hard rocky bottom, there are areas of coarse sand and rubble.  In these areas, a diversity of invertebrates such as worms, clams and crustaceans burrow in the sand.  These animals form diverse communities and are important as food for fishes and other marine life.  In addition, pollutants such as hydrocarbons and heavy metals often accumulate in soft-bottom areas.  We will use a grab sampler to obtain samples of sediment to determine the kinds of animals that live there, the composition of the sediment, and the levels of contaminants that are found there.

We will use the data collected during this expedition to determine faunal change and human impact along a gradient of increasing depth and increasing distance from land, combined with variable hydrography and bottom complexity.  We will use ROV, grab and associated oceanographic and photo-documentation gear to describe diverse habitats, features, oceanography, and faunal assemblages. 

Acoustic Fish Mapping

We will use the fisheries acoustic system aboard the Pisces to look for large fish like wreckfish, barrelfish and red bream, which we have previously observed to be associated with coral mounds and rough rocky bottom on the Blake Plateau.  We want to determine what bottom type supports the greatest number of fish, and the acoustic system will enable us to map fish locations in relation to bottom features.  These three fish species have a gas bladder (swimbladder) in their bodies that helps them remain upright and buoyant in the water.  The bladder reflects sound very well, so these fish show up as sound reflectors on sophisticated sonar systems like the fisheries acoustic system on the Pisces.  We will use the system to map fish locations in relation to bottom features, and to look at their movements around coral features.  These fish feed on animals like small fish, squid, krill and salps that live much higher in the water column than the fish do, for at least part of the day.  We do not know if the fish migrate up above the bottom to feed, or if the food migrates down to the fish living on the bottom.  The acoustic system will enable us to look at daily movements of the fish in relation to the “deep scattering layer” to determine how energy is transmitted from the sunlit food-producing layers of the ocean to the deep, dark bottom where wreckfish live.

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