Krill Distribution and Patch Structure in the Deep Basins of the Gulf of Maine Based on Multi-Sensor Survey Data
Peter H. Wiebe, Biology
Gareth Lawson, Biology
Andone Lavery, AOPE
Grant Funded 2008
Krill are common members of marine pelagic ecosystems, and in the Gulf
of Maine are a key prey item for a number of predators, including
whales and commercially-important fish species. The distribution of
krill is highly variable, or ‘patchy,’ in space and time, and
understanding the factors causing this variability is important as the
patchiness limits krill availability to higher predators. Previous
studies have demonstrated that krill can be locally abundant and
important in the Gulf of Maine. Overall, however, relatively little is
known about the biological and physical processes leading to the
formation and persistence of krill aggregations, inter-annual
variations in krill abundance, and the interaction of krill with its
predators in this region. The long-term goals of this work are to
examine the distribution, abundance, aggregation structure, and
ecological importance, including availability to higher predators, of
krill in the Gulf of Maine, and to develop and apply new techniques for
the quantification of krill abundance. An essential first step to
achieving these longer-term goals is to capitalize on existing survey
datasets to test initial hypotheses, develop new ones, and identify
regions for more detailed externally-funded surveying. We therefore
propose here to analyze multi-sensor datasets collected during surveys
of the deep basins of the Gulf of Maine conducted during the falls of
1997-1999 under the Georges Bank GLOBEC program. These surveys, which
were originally designed to investigate the distribution and abundance
of copepods, combined a suite of sophisticated sampling technologies,
including acoustic, net, optical, and a variety of environmental
sensing systems. We will take advantage of recent advances in the
analysis of multi-frequency acoustic data to identify krill and other
zooplankton in the acoustic record based on net and video samples and
models of how the different zooplankton groups scatter sound, and will
then quantify and map their abundance over broad survey areas. The
objective is to assess spatial and inter-annual variability in krill
distribution, abundance, and aggregation structure in relation to
hydrographic conditions and bathymetric features.
This is an inter-disciplinary project, combining our expertise in ocean
acoustics, zooplankton ecology, and oceanography. Successful completion
of the project will supply critical new information on the factors
driving variability in krill distribution and will provide leverage in
seeking external funding for future survey work.