Journal of Robin Ross
Date: 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!
LTER PI Robin Ross monitors operations on board Polar Duke.
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!