Abstract:
Patterns were investigated in juvenile fish use of unconsolidated sediments on the southeast United States continental shelf off Georgia. Juvenile fish and environmental data
were sampled at ten stations along a
110-km cross-shelf transect, including
four stations surrounding Gray’s Reef
National Marine Sanctuary (Gray’s
Reef NMFS). Cross-shelf stations
were sampled approximately quarterly
from spring 2000 to winter 2002.
Additional stations were sampled on
three transects inshore of Gray’s Reef
NMS and four transects offshore of
the Sanctuary during three cruises
to investigate along-shelf patterns in
the juvenile fish assemblages. Samples
were collected in beam trawls,
and 121 juvenile taxa, of which 33
were reef-associated species, were
identif ied. Correspondence analysis
on untransformed juvenile fish
abundance indicated a cross-shelf
gradient in assemblages, and the
station groupings and assemblages
varied seasonally. During the spring,
fall, and winter, three cross-shelf
regions were identified: inner-shelf,
mid-shelf, and outer-shelf regions. In
the summer, the shelf consisted of a
single juvenile fish assemblage. Water
depth was the primary environmental
variable correlated with cross-shelf
assemblages. However, salinity, density,
and water column stratification
also correlated with the distribution
of assemblages during the spring, fall,
and winter, and along with temperature
likely inf luenced the distribution
of juvenile fish. No along-shelf
spatial patterns were found in the
juvenile fish assemblages, but the
along-shelf dimension sampled was
small (~60 km). Our results revealed
that a number of commercially and
recreationally important species used
unconsolidated sediments on the shelf
off Georgia as juvenile habitat. We
conclude that management efforts
would be improved through a greater
recognition of the importance of these
habitats to fish production and the
interconnectedness of multiple habitats
in the southeast U.S. continental
shelf ecosystem.
