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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Figure10. BarentsSea.Spongebyc<strong>at</strong>chin researchbottom trawling 1982-97 superimposedon fishing<br />
effort 2004(asdensityof VMSd<strong>at</strong>a points,NorwayMin. Env.2005-2006).Redstar indic<strong>at</strong>esthe approxim<strong>at</strong>e<br />
positionof Salina, JuksaandDarwin.<br />
3.3 About sponges in general<br />
Spongesare filter-feeders,and therefore act asa direct link betweenthe w<strong>at</strong>er columnand benthic<br />
fauna. Most feed on m<strong>at</strong>ter dissolvedor suspendedin the w<strong>at</strong>er column, suchas diverseorganic<br />
m<strong>at</strong>erial, algae and bacteria. Their an<strong>at</strong>omy varies from small, simple forms to large complex<br />
structures,but essentiallythe bodyhasone or severalchambersthroughwhichw<strong>at</strong>er is pumped.<br />
Becausespongesare sessile,and they dependon w<strong>at</strong>er flow, they are reputed to be sensitiveto<br />
sediment<strong>at</strong>ion.However,d<strong>at</strong>a basedon experimentalstudiesare spares,and as a result, ongoing<br />
studies in Norway (Akvaplan-niva, IRIS,Institute of Marine Research)and intern<strong>at</strong>ionally, are<br />
addressingsensitivity of spongesto various discharges. This note will not addressthe issue of<br />
sensitivity,but will focuson distribution recordsandchallengesrel<strong>at</strong>ingto assessingdensity.<br />
Akvaplan-niva AS, 9296 Tromsø<br />
16 www.akvaplan.niva.no
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