# KRILL WORKING GROUP REPORT

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

## Jose Torres and Peter Wiebe, Working Group Co-Chairs

## Participants: Carin Ashjian, Scott Gallager, Angela Gibson, Rodger Harvey, Langdon Quetin, Robin Ross, Jose Torres, Peter Wiebe, Meng Zhou

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

Our discussions centered on two main themes, first what holes exist in the krill program as it currently stands, and second, how can the needs be addressed. Jose had prepared a straw man original data set list based on the WinDSSOcK proposal and talks with Kendra Daly, Robin Ross and Langdon Quetin. This is reproduced below. It reflects, in part, the results of our discussions.

## Krill and Krill-related Data Sets: July-August

    I.  Krill, Zooplankton, Fish  Ecology

        A.  Distribution and abundance to include catch work-up

    	1.  Open water - survey

    	    A.  Nets - MOCNESS- Wiebe et al.

                B.  Acoustics - BIOMAPER : Wiebe et al.

                C.  Mesozooplankton - image analysis - Wiebe et al (unfunded)

    	    D.  MOCNESS (unfunded)- ADCP - Zhou

    	    E.  Fish - MOCNESS/Tucker/BMT - Torres

    	2.  Under-ice - survey

    	    A.  Broader-scale - ROV - Davis

    	    B.  Finer scale - Fish/krill - SCUBA (unfunded) - Torres

    	3.  Under-ice - process.

    	    A. Finer-scale SCUBA - Quetin/Ross

    II.  Physiological data sets

         A.  Metabolism (oxygen consumption rates) - all size classes - Torres

         B.  Excretion (NH3) - ditto - Torres

         C.  Feeding/experimental

    	 1.  Larvae - container - natural populations - Daly

    	 2.  Larvae - container - SIMCO communities - Ross/Quetin

    	 3.  Larvae - fecal pellet production - assimilation - Daly -

                 Ross/Quetin

             4.  Juveniles/adults - Huntley proposed -?? Zhou, Daly (unfunded)

             5.  Lipid biomarkers - Rodger Harvey

         D.  Feeding/in situ

    	 1.  Larvae -gut fluorescence - Daly

    	 2.  Larvae - gut contents - microscopic analysis - immunoassay???

             3.  Juveniles/adults - gut contents/gut fluorescence /assimilation

                 - Huntley proposed -???- Zhou - Daly (unfunded)

         E.  Growth

    	 1.  Larvae - IGR - Ross/Quetin - Daly

    	 2.  Juveniles and adults - ???- Huntley proposed- Daly/Zhou/Torres

                 - (unfunded)

     	 3.  Age - Rodger Harvey

         F.  Condition/metabolic proxies

     	 1.  Larvae - Ross/Quetin - ug C/l3

    	 2.  Larvae - Ross/Quetin - total lipid

    	 3.  Proximate/elemental composition all sizes - Torres

    	 4.  Lipid species - all sizes Hagen/Torres

    	 5.  CS - MDH - LDH - RNA/DNA - Torres

         G.  Development and reproduction

    	 1.  Reproductive status - Daly

    	 2.  Direct vs. indirect development - Daly

    III.  Ancillary data sets required for the success of the program

          A.  SIMCO composition and abundance - Fritsen, Gibson, Garrison

          B.  Microheterotroph water column abundance - ??? - Gallager - (unfunded)

          C.  Broad scale primary production measurements - Vernet - (unfunded)

As noted above, the group identified several holes in the program which needed filling for overall program competence. These are discussed in more detail below

### I. Krill ecology and ecosystem background

A. A glaring hole in the winter program is the absence of abundance data on microheterotrophs in the water column, an important potential food source for krill. This work was originally proposed by Lessard and Methot and will not be covered by the Garrison/Gibson program which has a fundamentally different (primarily under-ice) focus. Since Lessard and Methot were not funded, an interim solution may be to archive properly preserved samples from the rosette for later analysis in the event funding becomes available. In addition, time permitting, selected samples may be examined used Scott Gallager's video analysis system to get first order estimates of abundance. Whether Scott can handle the additional work without additional funding is unclear.

B. Primary production information on the survey grid is presently lacking and is an absolute must. We suggest augmenting Vernet's funding to allow her to cover this base.

C. MOCNESS sample enumeration for krill size frequency and mesozooplankton distribution originally proposed by Huntley for the process cruises is currently missing from the program, but since the main winter water column krill sampling effort has now shifted to the survey vessel, the combined efforts of Wiebe, Gallager, Davis, Daly, and Zhou should be able to cover this base. It is currently unclear what will happen with krill abundance on the April/May process cruise, a problem which will be discussed below.

D. Under-ice surveys for krill/fish abundance and for collection of live animals under the ice are lacking on the survey vessel for the winter cruise. Torres can cover this base with some additional salary funds.

### II. Krill physiology

A. Juvenile and adult feeding. Originally proposed by Huntley, data on juvenile and adult feeding are an absolute must if we are to be able to model krill overwintering strategies. At present, funded experimental research only includes feeding in larvae on both boats, leaving a data gap in the older size classes. The main problem with bootlegging experimental work on the older size classes is that it requires specialized equipment such as grazing wheels, and a lot of attention. It is unclear to the humble rapporteur at this time whether conducting feeding experiments on larger krill is even a possibility. Substitute data sets which give similar information include fecal pellet production from freshly captured and/or incubated animals, gut contents of preserved animals, and gut fluorescence, which can give a relative measure of feeding in field-caught animals. Zhou may be able to collect data on fecal pellet production; Torres and Daly will do what they can to help. This data set is still not completely resolved and needs to be. B. Juvenile and adult growth. This requires incubating animals for prolonged periods accompanied by constant checking for molts. A joint effort between the Daly/Torres/Zhou programs will cover this base.

### Krill and Krill-related Data Sets: April-May

    I.  Krill, Zooplankton, Fish  Ecology

        A.  Distribution and abundance to include catch work-up

    	1.  Open water - survey

    	    A.  Nets - MOCNESS- Wiebe et al.

                B.  Acoustics - BIOMAPER : Wiebe et al.

    	    C.  Mesozooplankton - image analysis - Wiebe et al (unfunded)

    	2.  Open water - process

                A.  MOCNESS (unfunded)- ADCP - Zhou

    	    B.  Fish - MOCNESS/Tucker/BMT - Torres

    	3.  Under-ice - survey

    	    A.  Broader-scale - ROV - Gallager/Davis

    	4.  Under-ice - process.

    	    B.  Finer scale - Fish/krill - SCUBA (unfunded) - Torres

    II.  Physiological data sets

    	A.  Metabolism (oxygen consumption rates) - all size classes - Torres

    	B.  Excretion (NH3) - ditto - Torres

    	C.  Feeding/experimental

    	    1.  Larvae - container - natural populations - Daly

    	    2.  Larvae - fecal pellet production - assimilation - Daly

                3.  Juveniles/adults - Huntley proposed -?? Zhou, Daly (unfunded)

    	    4.  Lipid biomarkers - Rodger Harvey

    	D.  Feeding/in situ

    	    1.  Larvae -gut fluorescence - Daly

                2.  Larvae - gut contents - microscopic analysis - immunoassay???

    	    3.  Juveniles/adults - gut contents/gut fluorescence/assimilation

                    - Huntley proposed -???- Zhou - Daly (unfunded)

    	E.  Growth

    	    1.  Larvae - IGR - Daly

    	    2.  Juveniles and adults - ???- Huntley proposed - Daly/Zhou/Torres

                    - (unfunded)

    	    3.  Age - Rodger Harvey

    	F.  Condition/metabolic proxies

    	    1.  Proximate/elemental composition all sizes - Torres

    	    2.  Lipid species - all sizes Hagen/Torres

    	    3.  CS - MDH - LDH - RNA/DNA - Torres

    	G.  Development and reproduction

    	    1.  Reproductive status - Daly

    	    2.  Direct vs. indirect development - Daly

    III.  Ancillary data sets required for the success of the program

    	A.  SIMCO composition and abundance - Fritsen ??

    	B.  Microheterotroph water column abundance - ??? - Gallager -

                (unfunded)

    	C.  Broad scale primary production measurements - Vernet - (unfunded)

The character of the program fundamentally changes between cruises. Many programs drop out of the picture, including a major krill program, or take on a greatly reduced role: e.g. Fritsen, Garrison/Gibson, Quetin/Ross, Perovich, Smith, Martinson. Much of the study area will likely be in open water, but data on krill distribution and abundance and physiological status for comparison with the winter months is an imperative for our program's goal of modeling krill life history and overwintering strategies. Holes that existed for the winter cruise exist for the fall cruise as well.

The process vessel will be mobile enough so that the original concept of a process cruise that occupies 5 to 6 sites nested within the survey grid for 5-7 d of intensive sampling of distribution, abundance, and physiological condition of krill is a real possibility and one that the rapporteur heartily endorses.

As a last note, it is imperative that our SO GLOBEC program finalizes the character of BOTH the fall and winter cruises to maximize the contribution of the program. We have come a long way toward melding several proposals with different goals into one program, but there is still work to be done.