Detailed visual seabed survey at drilling site 7218/11-1
Detailed visual seabed survey at drilling site 7218/11-1
Detailed visual seabed survey at drilling site 7218/11-1
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Table3. Extractfrom EuropeanstandardCEN/TC230/WG2/TG7"W<strong>at</strong>er quality— Visual<strong>seabed</strong><strong>survey</strong>susing<br />
remotelyoper<strong>at</strong>edandtowedobserv<strong>at</strong>iongearfor collectionof environmental d<strong>at</strong>a".<br />
The ideal would be to record numbersof spongesper unit area of <strong>seabed</strong>,but this is simply not<br />
possiblewhile the ROVis in motion. Further,unlessthe ROVis set <strong>at</strong> an altimeter andwith standard<br />
pitch androll, suchquantific<strong>at</strong>ionsare difficult. Thereasonwe chosenot to use'fixed' navig<strong>at</strong>ionfor<br />
the ROVis the <strong>survey</strong> programmerequestedth<strong>at</strong> objectsof biologicalinterest are filmed, and this<br />
requireszoomingin or out asappropri<strong>at</strong>e.<br />
Giventhe short mobilis<strong>at</strong>iontime, we constructeda makeshiftsystemto <strong>visual</strong>iseour recordingsin<br />
termsof %coverof sponges(i.e.how muchof the unit of seafloorobservediscoveredby sponges).If<br />
the actualvaluesturned out to be "wrong", we reasonedth<strong>at</strong> we couldadjust them l<strong>at</strong>er; the main<br />
point wasobjectivityandconsistencybetweenthe different observers.Ourfirst improvisedsystemis<br />
shownin Figure17.<br />
Figure17. Improvisedconceptual<strong>visual</strong>is<strong>at</strong>ionof spongecoverage,usedin July,2012<br />
<strong>Detailed</strong> <strong>site</strong> <strong>survey</strong> <strong>at</strong> PL531 Darwin<br />
Akvaplan-niva AS Rapport 6051 - 1 23
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