The TASC Annual Meeting

## The TASC Annual Meeting, 8-11 January 1997

by Charlie Miller

The second trans-Atlantic gathering of the faithful friends of Calanus finmarchicus was held in crisp, cool winter weather at the Dansk FolkFerie in Gileleje, Denmark, a fishing village at the north tip of Zeeland. FolkFerie was translated for us as "holiday center", and it appears the Danes have some good ideas about holidays. We occupied pleasant, spacious cabins and were fed gourmet food in a convivial dining hall. The view from the bluff near our meeting room was of the Kaategaat, and it was possible to imagine Petersen and Hensen sampling just at the horizon. The local arrangements for this "TASC-II" meeting were made by Keith Brander, our hero at ICES, and Katherine Richardson of Danish Sea Fisheries. Many of the communications and arrangements for equipment and transport were made by Tone Falkenhaug and Kurt Tande, and we attendees thank all of you cordially.

Our purpose at Gileleje was to review the progress of and plans for TASC studies as the European program hits full pace early this winter. We particularly wanted to compare European and North American studies. This was with an eye to insuring that, as our work progresses, we will get good data for valid comparisons from all along the range of C. finmarchicus. In fact, we identified a major gap, that we will not have much sampling from the great central region to the SW of Iceland, a population center for C. finmarchicus in which life history timing appears to be distinctive. Life history studies of this dominant, boreal copepod are clearly the unifying theme of TASC work, and many aspects of its phenology were presented at TASC-II. Much of the best work was presented by young scientists, and it was a pleasure to see the future of zooplankton studies in the North Atlantic region in such promising hands. There were many examples. Barbara Niehoff (who works with Han-Jürgen Hirche) gave her first professional talk in English without missing a beat. She presented fine data about egg production in mesocosms. Her poster presented a detailed study of the developmental sequence of egg clutches in the oviduct of Calanus. It was a small and fruitful intrusion of real biology (cells, nuclei, ducts) into an ecological session almost devoid of such basics. Perhaps we can learn more ecology by being more biological at times.

Benjamin Planque presented a fine new analysis of continuous plankton recorder data. Evidently, C. finmarchicus has distinct seasonality of its active development phase in three major subregions of the North Atlantic: in the far west the stock comes out of diapause very early, December-January, and subsequent generations are actively developing through late spring; in the Norwegian Sea and adjacent areas arousal peaks in mid-March, and the population is active well into summer; finally, in the middle region south of Greenland, arousal is even a little later (end of March) and active development is in progress into early autumn. All of the data presented from TASC studies agreed with this strong difference in life cycle timing across the range. For example, data presented by Erica Head from the eastern side of the Labrador Sea hinted at this distinctive timing, even distinctive development characteristics of this central substock. Planque also showed (see Fromentin and Planque, 1996, MEPS 134:111) that the stock of C. finmarchicus in the eastern Atlantic varies in detailed parallel with the strength of the North Atlantic oscillation (NAO). This measure of atmospheric pressure difference has dropped on average over the past three decades, and CPR abundance measures for C. finmarchicus dropped over the same interval by approximately 40%.

Two precise growth rate studies were presented by Robert Campbell and by Bengt Hygum and Catherine Rey which will provide much improved parameterization of Calanus numericus (introduced to science at the meeting by Francois Carlotti). Camilla Svensen (represented by Kurt Tande) showed experimental results implying that sex determination in C. finmarchicus is under partial environmental control. Heather Madden reminded us that C. finmarchicus almost always lives sympatrically with other Calanus species, and Thomas Torgerson reminded us that C. finmarchicus can fall victim to parasites and disease. Espen Bagoien, Trine Dale and Kjetil Eiane compared several fjords to show how predation may modify the vertical levels chosen by resting stages of C. finmarchicus. They made evident the power of interfjord comparisons to reveal aspects of marine plankton biology. Andy Bryant, Oyvind Fiksen, Alisdair, Ole-Petter Pedersen and Eddie McKenzie all showed insight-generating modelling results. Tone Falkenhaug showed the power of recurring anatomical evaluation to reveal seasonal patterns in reproduction and activity level. Melissa Wagner's poster showed an application of RNA/DNA ratios to evaluation of growth status.

Many older hands were also present at Gileleje, of course, and they also showed good signs of recent activity. However, those are not so exciting to report in detail, and summaries can be found in the abstract series for the TASC annual meeting at the TASC web site (http://calanus.nfh.uit.no/TASC.HTML).

The premiere goal of GLOBEC projects like the Georges Bank study and Euro-TASC is to show the couplings between physical processes in the sea (from general circulation to microturbulence) and the ecology of marine zooplankton. Success in reaching this goal was evident at TASC-II from studies on both sides of the Atlantic. In the Georges Bank area we are now able to explain the localization of cod spawning sites by coupling regional patterns of flow to the life history of C. finmarchicus. This understanding is embodied in models generated by Dan Lynch's group (results discussed at TASC-II by Peter Wiebe) that treat animals as Langrangian objects moving in flow fields generated by fundamentally Eulerian physical models, and it is well verified in Ted Durbin's sampling results from the Georges Bank Broad Scale Survey.

A very similar approach has resulted from a collaboration between groups headed by Jan Backhaus and Mike Heath. Their simulations show the importance of deep circulation to stocking the region southwest of the Faeroes-Iceland ridge with resting stage Calanus, and thus to the strength of the spring eruption of the stock. Heath and Katherine Richardson are strong advocates of the notion that the abundance of resting stocks south of the ridge determines abundance there and in the northern North Sea during the subsequent generation developing in spring. The Backhaus-Heath consortium argued convincingly that variation in deep flow from the Norwegian Sea should parallel the NAO, and that the Norwegian Sea is the source of a large fraction of deep resting stocks south of the ridge. Therefore, they think variation in seed stock numbers is the prinicipal explanation of the NAO-C. finmarchicus correlation seen by Planque and coworkers in northern reaches of the CPR study. Extended testing of these notions is part of Euro-TASC's work for the next two years, and a start was shown by Dagmar Hainbucher on field testing of physical aspects of the hypothesis.

Most of our field data are still to come, of course, but an awkward moment was produced by an apparent contradiction between multiple opening-closing net data from Astthor Gislason and Olafur Astthorsson and OPC data from Heath and Richardson at nearly the same site and date. The Icelandic team found large numbers of resting Calanus in a layer where the UK-Danish team found none. Fortunately, the UK sampler includes profiles of preserved plankton, and a resolution will surely emerge. Odd how productive a disagreement can be. Exciting time series will be generated by Euro-TASC. One is a study by Stig Skreslet in the coastal zone off central Norway. Another is the Faeroes time series in progress under the direction of Eilif Gaard. Another is the more oceanic time series at Station M to be gathered by a cooperative effort including Hans-Jürgen Hirche, Roger Harris and others. The meeting gave them a chance to sit together and plan.

Modelling of ecological aspects of C. finmarchicus biology is a central activity of TASC, which was reviewed by Dag Slagstad. Convergence of C. numericus Carlotti, 1997 with Calanus finmarchicus (Gunnerus, 1770) was evident in many talks and posters at TASC-II. We have very good egg production measures, like those of Jeff Runge, Katherine Richardson, Hans-Jurgen Hirche and Barbara Niehoff, and Fran¨ois Carlotti has modelled a reasonable physiology to explain their variation. Growth rates and development rates as a function of temperature at full nutrition have been very well measured in the past year, and some studies of nutritional effects are in progress. More modelling of 'reasonable internal processes' in this fashion was promised by Brad DeYoung and Geoff Evans of Canada GLOBEC. The roles of stored and active lipids are becoming evident in work like that of Sigrun Jonasdottir and can be included in individual-based models incorporating physiology. A little progress was evident on understanding life history decision points: to rest or mature, to arouse from rest or not, to be male or female. However, the real physiological controls of these decisions will probably evade us for the present round of TASC because (1) we do not have a sufficiently physiological orientation and (2) because the outcomes of decisions in laboratory containers are so evidently different from those in the field despite our best efforts to make our animals feel at home. Our examination of genetics, principally by Ann Bucklin to date, will show the degree to which C. finmarchicus is one adaptive system suited to circumstances throughout the range or has subregional specializations. Genes for general metabolic enzymes have shown mostly homogeneity. A search for genes controlling specific life history decision processes may or may not show this widespread similarity. The outcome will be important to validating models of population transport and exchange. Ann presented an argument based on her gene sequence data suggesting that the C. finmarchicus population passed through a very narrow population bottleneck in the geologically recent past, probably due to restriction to a very much smaller range in the last ice age. This certainly won first place among intellectual tours-de-force at TASC-II, and most of us will understand it only when we have a chance to study the details.

A glaring weak point in models to date is the huge freedom allowed in assigning mortality rates. In all systems where we are studying C. finmarchicus, the variations in TASC field abundance estimates are (or are certain to be) far too large to allow application of mortality estimators based on stage-to-stage abundance changes like those of Woods. Perhaps there are things we cannot simply choose to know by working hard enough. It was evident at the meeting that a large part of the ecology of C. finmarchicus is determined by interaction with predators. Some of this is fixed at the evolutionary time scale; some is variable behavior on time scales of days or less. An open task for TASC is to include in models this dependence of behavior variations on predators. Some of Oyvind Fiksen's work using optimality criteria and dynamic programming is a good start. More of Stein Kaartvedt and Dag Aksnes's extraordinary qualitative insights should help, too.

TASC-II included several sessions on Trans-Atlantic integration. Peter Wiebe and Kurt Tande (western and eastern head honchos) will cover those deliberations in a forthcoming article in the TASC newsletter.

Roger Harris, Kurt Tande and I were convenors for this meeting. We wish to thank all the participants for coming far, for preparing well and for sharing in the good times at Gileleje. Thanks to everyone involved in TASC who made our sharing of good new results and plans possible; the meeting showed showed what a fine adventure TASC has become. We're sorry that we could not get absolutely everybody to the meeting, but somebody had to be out on the boats. If somebody at the meeting was not included in this report; please write an essay for the TASC newsletter retelling your story.

Finally, at an evening business meeting, Katherine Richardson and Mike Heath volunteered to take over the newsletter for at least as long as I am in France. It has been a pleasure to produce the first issues, and I plan to contribute to more. I cannot easily do it from here, so many thanks to Mike and Katherine for taking over.

(Charlie Miller, Professor of Oceanography at Oregon State University, is currently on sabbatical at the Station Zoologique, Villefranche-sur-Mer, France.)