DBPapers
DOI: 10.5593/sgem2012/s03.v1032

MEGAFAUNAL DIVERSITY ASSOCIATED WITH DEEP-SEA NODULE-BEARING HABITATS IN THE EASTERN PART OF THE CLARION-CLIPPERTON ZONE, NE PACIFIC

V. STOYANOVA
Wednesday 1 August 2012 by Libadmin2012

References: 12th International Multidisciplinary Scientific GeoConference, www.sgem.org, SGEM2012 Conference Proceedings/ ISSN 1314-2704, June 17-23, 2012, Vol. 1, 645 - 652 pp

ABSTRACT

The abundance, composition and spatial distribution of megafauna were assessed
quantitatively from seafloor photographic transects carried out in July 2009 by the
Interoceanmetal Joint Organization (IOM). Studied area is located in the eastern part of
Clarion-Clipperton Zone, NE Pacific (10005’-10055’N and 119025’–120008’W) at depth
varying from 4200 to 4600 m. Analysis of over 11000 bottom photographs revealed
8675 epibenthic animals, entering into 32 taxonomic groups. The most abundant
megafaunal taxa were the sponges, sea urchins, ophiuroids, actinians and holothurians
that counted about 90% from a total number of animals identified on photographs. The
highest density, up to 222 ind/ha was recognized for the glass sponges (Hexactinellida)
belonging to group of sessile suspension feeders; thus the mean densities of suspension
and deposit trophic groups were approximately equal to 48%, and the carnivorous
compound only 4% from all identified animals. The spatial distribution of megafaunal
groups appears to vary with the nodule coverage, thus the polymetallic nodules clearly
provide a habitat for fixed megafaunal assemblage like sponges, whereas without
nodules the deposit feeders like holothurians dominated.
The data review was carried out in support of the IOM as a contractor with the
International Seabed Authority to provide adequate environmental baseline information
necessary to assess the potential environmental impact before commercial exploitation
of polymetallic nodule deposits.

Keywords: megafauna, polymetallic nodules, seafloor photographs, Interoceanmetal.