TransAtlantic Studies of Calanus (TASC) Working Group
by Charles Miller
GLOBEC International now has offspring. The baby was born on the 7th of
April 1994 at Oslo, Norway. Its name is the TransAtlantic Study of
Calanus Working Group. In October it was recognized by ICES, which
included TASC activities as a function of the ICES Zooplankton
Productivity Working Group under Heine Rune Skjoldal. Attending the
birth in Oslo were 25 scientists from Norway, Sweden, Denmark, Germany,
Scotland, England, The Faroes Islands, Iceland, France, Canada and the
United States. We were hosted by Stein Kaartvedt of the University of
Oslo for a GLOBEC/ICES workshop designed to foster cooperation in the
study of Calanus finmarchicus all across its North Atlantic range from
New England to Northern Norway. Convenors were Kurt Tande of the
University of Tromso and myself. Funding for the workshop came from the
Norwegian Research Council, the European Union, the U.S. GLOBEC Office,
and from marine research programs of several nations. Everyone
attending is actively working on the biology of C. finmarchicus.
In preparation for the workshop, most of the participants wrote
manuscripts on a wide range of topics, including distribution, feeding,
growth, reproductive rates, genetics, the resting stage and methods for
mortality estimation. Everyone received those in advance so that we
arrived prepacked with relevant information, not to mention points to
argue with erring authors. Our first day was spent presenting and
discussing those papers, then celebrating our new (or renewed)
acquaintance in one of the world's most expensive restaurants (which
cluster in Oslo). Many of the papers have been revised after the
meeting and are in review for publication together as an issue of
Ophelia. The second day we spent on both plenary and working party
debates about the priorities for research on C. finmarchicus. An
amorphous mass of prose was produced which was later hammered into a
report to ICES by Kurt Tande. We divided the discussion and report into
four themes, which I list here with precis of the conclusions about
I. The Interplay between Generation Cycles and Large-Scale Circulation Patterns in Oceanic and Shelf Areas.
Calanus finmarchicus is a prominent component of shelf zooplankton during
late winter and spring in sites like the Northern North Sea and Georges
Bank. However, it seems to be entirely missing from those regions in
summer and autumn. Thus, the abundant stocks of winter-spring must be
imported by advection from oceanic areas where resting stocks at depth
maintain the species existence through the late summer and autumn. It
was recommended as a priority that we work out the population budgets
for several of these exchanges. This will allow us to distinguish
between several alternative population histories. Are the resting
stocks in oceanic sectors strongly dependent upon production over the
shelves? Or, are the resting stocks produced entirely in the oceanic
sector and simply "feeding" the shelf production with no strong return.
For the North Sea shelf an interaction between late winter inflow in the
Faroes-Shetland Channel and upward ontogenetic migration of maturing
Calanus have been suggested by Jan Backhaus, Mike Heath, Katherine
Richardson and others as a supply mechanism. That will be the subject
of an European Union Marine Science and Technology study during early
1995. The U.S. GLOBEC Georges Bank program is tackling a similar
problem on the west side of the Atlantic.
II. Strategies of Diapause and Reproduction
The control of entry to and emergence from diapause are not well
understood for any species of Calanidae. We produced several
recommendations aimmed at producing clues about the control mechanims:
Laboratory studies were also recommended. Reproduction in C.
finmarchicus has been a very active area of research recently. The TASC
recommendation was that this effort be sustained.
- TASC projects should select an indicator of diapause condition [gonad development, jaw facies, enzyme status] and trace its appearance in Calanus stocks as function of season, temperature history, depth and photoperiod.
- TASC projects should sample resting stocks for stage composition [which varies] over at least several years. Basic habitat data, particularly water column temperature patterns, should be recorded through the period prior to and during diapause phases.
III. Population Coherence and Latitudinal Impact on Growth Patterns
- We recommended evaluation of the diversity of the C. fimarchicus stock across its range by studies of its molecular genetics.
- A renewed study of the growth response to food, temperature and other habitat factors is needed. Sophisticated data are available for related species, but not C. finmarchicus.
IV. Trophic Interactions and Mortality
From a practical standpoint (support for our studies) we need to
establish whether interannual variability in fishery recruitment depends
directly upon variations of Calanus productivity. It may be hard to
believe that isn't established, but it's not.
Mortality rates are almost always unconstrained tuning variables in our
models of Calanus population processes. It was recommended that TASC
projects should invent and adopt strategies for determining the
partitioning of mortality among the developmental stages of C.
On our third and final day, we decided to appoint ourselves as a
long-term working group to continue communication about research on
Calanus finmarchicus all across its range. We also hope to promote
cooperative studies among laboratories and scientists so that knowledge
of Calanus biology can increase at the fastest possible rate. We warmly
invite anyone not at the workshop to join in this effort. We are the
TransAtlantic Studies of Calanus (TASC) Working Group. I am the initial
chair for interchange of information, principally through a newsletter.
Yes, another newsletter. Issues No. 1 and 2 have been distributed to
members. Copies can be obtained by writing (use email) to me. We also
have an internet mail list and internet reflector address so that
members can communicate rapidly with the entire group. We hope that
will be useful, not another source of electronic junk mail. (Charles
Miller is Professor of Oceanography at the College of Oceanic and
Atmospheric Sciences, Oregon State University, Corvallis, OR 97331-5503,