# NOTES FROM PROCESS CRUISE SUB-GROUP (25 MAY)

## First U.S. Southern Ocean GLOBEC Science Investigator Meeting
Arlington, VA
25-26 May 2000

## Moderator and rapporteur: Jose Torres

## Present: Jennifer Burns, Dan Costa, Bill Fraser, Chris Fritsen, Angela Gibson, Rodger Harvey, Doug Martinson, Don Perovich, Langdon Quetin, Robin Ross, Ray Smith, Meng Zhou

NB: These notes are reported from memory. Any errors of omission are exactly that and all viewpoints are reported in good faith. The order in which things were discussed may not be accurate and the moderator has offered his opinion where noted.

Discussion began late in the afternoon directly following the observation in plenary session that the process cruise was seriously oversubscribed (for the July-August time frame). Subjects that our group addressed were 1.) Locations or desirable characteristics of process study sites, and 2.) Typical sampling protocols within the process study sites. Before the process group broke out, it was clear that the ship for the process study was going to have to be the Gould for a variety of reasons, the most important of which was that the survey vessels' need for mobility in thick ice could not be accommodated by the Gould. Thus, the backdrop for the process group discussions was first, that we could expect heavy ice in the winter cruise based on historical satellite information, and second, that the boat we would be using has a very limited capability of breaking ice and therefore limited mobility.

The first topic of discussion was the location of process stations for the winter cruise. How do we decide what is a good site for a process study? It was a given that the process studies were to be nested within the survey grid, but remaining characteristics were to be determined. Several suggestions were made. One of the first, brought forward by Ray Smith, Chris Fritsen and Don Perovich was a selection based on ice type, e.g., newly forming ice, marginal ice zone, open pack ice, closed pack ice. Another selection criterion suggested was presence of multiple trophic levels. Yet another was hydrographic or topographic features underlying the ice cover. At about this juncture it became obvious that there were a couple of fundamental differences in programmatic needs that needed to be discussed so we moved to sampling protocols as our next topic without fully resolving the first issue.

The main issue at hand was whether, once a process location was chosen, the Gould would park at the site and remain there for approximately 5d as a functional ice camp, or if a general location, say a few square kilometers, was to be sampled intensively. The key here was movement of the boat. To be functional, the ice camp precluded any movement of the boat once is was parked to avoid disturbance to under ice communities and to a through-hole CTD setup. To complete their research as proposed, the ice camp was viewed as an absolute necessity by Angela Gibson, Doug Martinson, Don Perovich, Langdon Quetin, Robin Ross, and Ray Smith. It was viewed as highly desirable by Chris Fritsen. Rodger Harvey could go with either scenario. Jennifer Burns, Dan Costa, and Bill Fraser could live with the ice camp if there were animals to be sampled nearby . Jose Torres, Kendra Daly, and Meng Zhou could not function with the ice camp scenario due to trawling requirements.

A combination of two factors made it likely that the Daly/Torres/Zhou contingent would jump ship to join the survey vessel for the winter (July-August) cruise. First, it appeared that there was sufficient time to complete the survey (16.5 d) and still have enough time (15.5 d) to spare for diving within the survey grid to allow collection of animals for physiological experiments and diver surveys of under-ice krill distribution within the grid. In addition, large scale distribution information on fish (viz. daily or nearly daily 4m MOCNESS trawls) and ADCP backscatter data to characterize krill swarms could be accommodated as well. Second, it was considered very unlikely the Gould would be able to move effectively within the study area, so the idea of doing small scale net tows as part of a winter process cruise on the Gould was likely too optimistic for most site within the study area .

As humble moderator I would like to point out that the move by Daly/Torres/Zhou solves the dual problem of oversubscription of the process vessel (mostly) and the fundamental incompatibility of an ice camp vs small scale sampling strategy. It is thus a good outcome, but it will only work if the ice camps, once established, remain in place, or use the Gould for any limited local movement that is required. If the Palmer is called off the survey to service ice camp needs more often than at 5-7 d intervals, much of the extra time that would be used to accommodate the Daly/Torres/Zhou programmatic needs would be burned up and a different strategy for the two vessels would need to be employed. In the moderators opinion, it is not just the needs of the D/T/Z programs that are in jeopardy here, but the integrity of the program as a whole. This issue needs to be discussed and settled up front, not on site.

Other issues that arose partially at the process meeting and partially towards the very end of the plenary meeting on 26 May, but that I will report on here, concerned the relative roles of fall vs winter cruises and the mission of the process vessel in the fall (April/May) time period. It is likely that ice cover during the fall will be limited to areas well south of, or very deep into, Marguerite Bay. This once again brings up the issue of process site selection, since ice cover will be present in most of the study area in winter, and we need a baseline to work from. It makes the most sense from the moderator's perspective to select fall process sites based on the hydrographic/topographic features that drove our original hypotheses concerning krill abundance. Thus we would want to site a process study at each of two points along the axis of the cross-shelf canyon that feeds into Marguerite Bay, one at the mouth near the shelf break and one at the head deep within the bay. We would want one site within WAP gyre and yet another outside of both the gyre and the canyon that would serve as a control site for each. For a final two stations, we would want to sample at the perennial ice within Marguerite Bay and and at the ice well south of the original survey grid. This needs further discussion, but as a straw man it is a reasonable start.

The personnel participating on each of the process cruises is an important final consideration for the process studies and for the SO GLOBEC program as a whole. The number of participants (and the data sets they represent) in the winter process cruise greatly outnumber those participating in the fall cruise. The differences are occasioned by the PI's research as proposed, but nontheless pose a problem for both the consistency and types of data acquired from cruise to cruise and year to year. One the bright side, differences in personnel number lessen the problem of oversubscription on the process vessel. However, some basic data sets do need to be acquired on both cruises for the SO GLOBEC program to be competent in describing the overwintering strategies of krill. Those data sets will be addressed in the krill breakout group notes.

Personnel/cruise as of 26 May - tentative

    April - May                      July - August

    Costa - 4                        Costa - 4

    Zhou - 3                         Martinson - 4

    Torres - 4                       ODU - 2

    Daly - 4                         Gibson/Garrison - 2

    Martinson - 1                    Fraser - 2

    Fristen - 1                      Harvey - 2

    Fraser - 2                       Fanning - 1 (?)

    Vernet - 3                       Quetin/Ross - 8

    Fanning - 1                      Fritsen - 3

    TOTAL - 23                       TOTAL - 31