An Eye in the Ocean: High-resolution Vertical Distributions of Plankton and Particles and Coincident Hydrography in the Western Chukchi Sea - Data Synthesis

Carin Ashjian, Woods Hole Oceanographic Institution

In the Arctic Ocean, the biological response to climate change should be dramatic yet is
difficult to predict because many basic components of the ocean system are un-described.

Plankton community composition, spatial (vertical, regional) and temporal (diel,
seasonal, annual) patterns in distribution and abundance, and the associations of species
and taxa with water mass type remain enigmatic for much of the Arctic ecosystem. In
particular, the interaction of physical mechanisms with biological distributions is poorly
described, especially at dynamic boundaries. The western Chukchi Sea is strongly
influenced by the nutrient-rich Pacific Water that flows through Bering Strait northwards,
exiting the Chukchi Sea primarily through Herald Valley. Strong regional variation in
plankton distribution, abundance, and composition in association with the distinct water
mass types present should be observed. Herald Valley is a critical region where physical
mechanisms impact biological distributions. Such interactions are best observed using
instruments capable of resolving high-resolution distributions of planktonic taxa and
particles and coincident hydrographic and velocity characteristics.

The overall goal of the proposed work is to describe the distributions of zooplankton and
particles over a range of spatial and temporal scales. High-vertical resolution
distributions of plankton, particles, and coincident hydrography have been collected using
a Video Plankton Recorder (VPR) on three cruises to the Chukchi Sea, including the
western Chukchi, in 2004, 2009, and 2012 as part of the RUSALCA program. The
objective of this proposal is to synthesize the VPR data from the three years to determine
inter-annual variability, to incorporate species specific information from net sampling
conducted by collaborators R. Hopcroft and K. Kosobokova into the synthesis, to prepare
a manuscript presenting the VPR synthesis, and to archive the VPR data in the
RUSALCA data archive.

The proposed work is relevant both to NOAA’s Climate Goal that targets understanding
and predicting climate variability and its impact on ecosystems and to the performance
measures of the RUSALCA program. Predicting the impact of climate on ecosystems
requires an understanding of the important components and interactions in the ecosystem,
both to identify change and to develop a predictive modeling capability for the
ecosystem. This work will provide key distributions and processes for this understanding
and capability. The work will characterize the plankton communities of the water masses
and regions of the Chukchi Sea during ongoing climate change, will periodically survey
key variables (water masses, plankton) to identify responses to climate change, and will
document how the changing physical oceanographic environment is impacting those
communities and distributions.