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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" intowater.
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!
Robin Ross
Last Update: 1/1/97
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