LTER PI Robin Ross monitors operations on board Polar Duke.

Robin Ross - February, 1997

    From: Robin Ross, Aboard the Polar Duke

(UCSB researcher Robin Ross is a member of the LTER team we encountered throughout the live programs. She helped create and review the "Phytoplankton See the Light" and other Activities in the Teacher's Guide, and LFA 2 thanks her, as well as her husband and co-worker Langdon Quetin, very sincerely.)

Greetings from south of the Antarctic Circle!

We on the RV Polar Duke are nearing the end of the Palmer LTER's annual cruise for the summer of 1997, with over 60 stations completed. Of the thousands of samples taken, many await analysis, either back at our home institutions or in the days ahead. These data will provide additional pieces in the large puzzle that the Palmer LTER team is putting together. We can think of each year as an experiment, where nature varies the timing and extent of sea ice, and the research team observes what happens to the microscopic microbes and plants, and the krill and penguins under those experimental conditions. The Palmer LTER shows a pattern of a few years of low ice extent, with a complete cycle every 6-8 years. Each cruise gives us a snapshot view of one mid-summer, but results from this year and other years need to be put in the context of the long-term variability before we can really understand how the ecosystem functions. It will take us quite a few years to find all the pieces to our puzzle!
Researchers prepare to lower acoustic "fish" into water.

From what has been analyzed, the Palmer LTER team is getting an idea of how this sixth year of sampling stands in relation to other years. The satellite ice images for this past austral winter and spring show that sea ice advanced to above King George Island (over 600 kilometers north of where we are now!) by August, and retreated to about 100 kilometers south of Marguerite Bay (where we are now) by January. Parts of our study region that have been packed with ice and unreachable by ship for three years are free of ice this summer - and perhaps this relates to the unusual warm air temperatures that the LTER saw earlier this year. We plan to sample in those seldom-visited regions next week!

How do our results stack up against other years? Concentrations of the microscopic plants (phytoplankton) are fairly low, certainly much lower than last year when the phytoplankton clogged our krill nets. Low phytoplankton in turn means the stomachs of the krill have not been very full, and the adult females have not been producing many eggs. We are finding many krill that are one and two years old, which makes this two years in a row where winter-over survival of young krill has been good. Unlike what researchers have found at the northern tip of the Antarctic Peninsula, krill stocks do not seem to be declining in the Palmer LTER region. Why the difference is another question!
Two researchers check phytoplankton experiment.

Initially we also found lots of salps, a gelatinous barrel-shaped animal, mixed in with the krill, but their concentrations are now decreasing. Salps do well even when phytoplankton concentrations are low, and sometimes the net is so full of salps that we have trouble pulling it on board. Even with the salps around, krill concentrations were reasonably high in January within the foraging range of the Adelie penguins, allowing the penguins to find food relatively close to the rookeries.

Over the next few months we will be very busy analyzing the data and trying to figure out how these new pieces fit into our puzzle!

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