Biology & Medicine

Dr. Polly Penhale Program Manager

B-307-L	NSF/OPP Award 03-38290
Station: R/V Laurence M. Gould
RPSC POC: Stephanie Suhr-Sliester
Research Site(s): R/V Laurence M. Gould
Dates in Antarctica: Late November to late December

Salpa thompsoni in the Southern Ocean: Bioenergetics, population dynamics and biogeochemical impact.

Dr. Patricia Kremer University of Connecticut Department of Marine Science pkremer@uconn.edu [No website]

Photo not available.

Deploying Team Members:

Jeffrey Godfrey . Erich Horgan . Patricia Kremer . Laurence P. Madin . Brennan Theodore Phillips . Kerri M. Scolardi

Research Objectives: Salps are holoplanktonic grazers that have a life history, feeding biology and population dynamic strikingly different from krill, copepods or other crustacean zooplankton. Salps sometimes occur in very dense populations that cover large areas, and these “blooms” have been shown to have major impacts from both grazing and production of fast-sinking fecal pellets. Nevertheless, the rates of feeding, metabolism, defecation, growth and reproduction for bloom-forming salps are still poorly understood, especially for Salpa thompsoni, the most abundant salp in the Southern Ocean. Although commonly acknowledged as a major component of the Southern Ocean zooplankton community, often comparable in biomass and distribution to krill, salps have received relatively little attention. This project will investigate S. thompsoni, which regularly occurs during the austral summer in high concentrations at various locations around Antarctica. Project team members will conduct their study near the northern end of the Antarctic Peninsula, a region that often has high densities of salps, and has time series data sets from the antarctic LTER (Long Term Ecological Research) and the AMLR Program (Antarctic Marine Living Resources) research efforts. Although extensive sampling has documented the seasonal abundance of S. thompsoni in the Southern Ocean, there still is a paucity of data on important rates that determine population growth and this species’ importance in grazing and vertical flux of particulates. In addition to the various rate measurements, investigators will make quantitative surveys of horizontal and vertical distribution of the salps. The length-frequency data will be examined for both the solitary (asexual) and aggregate (sexual) from these collections. The various rate measurements will be used to construct a model of salp population dynamics, the results of which will be compared with the cohort structure of the field data. Researchers will interpret both experimental and modeling results within the context of the physical and nutritional conditions to which the salps are exposed. This integrated approach will provide the best basis for understanding the growth dynamics of salp blooms in the Southern Ocean. This study represents an intensive investigation of the target species, Salpa thompsoni. The results from this species (endemic to the Southern Ocean) can be compared with existing data for congeneric species S. aspera and S. fusiformis that also occur in high densities in many locations. The combined results should yield insights into the environmental factors, energetics and population dynamics associated with the formation of salp blooms. The results of this study should enable scientists to better evaluate the importance of salps in biogeochemical cycles and in structuring the pelagic environment of the Southern Ocean.