U.S. GLOBEC Georges Bank Broad-scale Workshop October 31 - November 1, 2002 Woods Hole, MA

October 31, 2002

At 1:30 on Thursday October 31 Peter Wiebe called the meeting to order. The meeting was held in room 507 of the Clark Building on the WHOI Quissett Campus. The list of attendees is provided in Appendix 1. Because of scheduling conflicts a number of the PI’s on the main broad-scale proposal were unable to attend.

Peter reviewed the draft agenda (Appendix 2). The major topics identified were an update on the status of data and manuscripts, a discussion of gridding issues and then some presentations on results or issues from a few volunteers. On the second day the primary issue would be developing a chronology of biological events during the program.

The Gijon meeting:

Peter advised the group that a meeting on zooplankton production will take place next May in Gijon, Spain. Abstracts are due by November 15.

PI Presentations:

Lew Incze – Size selection of sampling gear (MOCNESS/PUMP) and zoo abundance.

To determine the abundance of zooplankton to be used in modeling studies, the difference in catch between the pump and the quarter meter MOCNESS needs to be resolved. The pump samples relatively small volumes of water, but with high resolution in the vertical. The MOCNESS samples much larger volumes, but as a result sometimes can become clogged. The pump is not vulnerable to clogging. Lew has compared a normalized index of catch by both gears for different stages of Calanus. The indication is that nauplii are undersampled by MOCNESS, but the copepidite abundances are pretty similar. The same type of comparison has been done for other species with basically the same result. The pump is more likely to miss the larger, more abundant organisms. A correction factor is being determined by length class. The comparisons between gear types doe exhibit a large variance.

Ted Durbin commented that his is doing similar comparisons between his pump and 1 meter MOCNESS data. For Calanus, the C1 stage is more efficiently sampled by the pump, while the larger stages are sampled more efficiently by MOCNESS. For Pseudocalanus only the adults were better sampled by the MOCNESS. For Orthona the MOCNESS again was better for the adults.

Ted Durbin – update on zooplankton analyses

The broad-scale zooplankton data is available from within the GLOBEC database system. In the coming months Ted will continue making comparisons between the catch-ability for the different gears. He also will continue improving the web-link to his data sets.

Greg Lough – Up date on cod and haddock feeding studies

The stomach contents of larval cod and haddock from process cruises are being analyzed. Greg is working with Lew Incze to develop the prey field for the larvae. In 1995 he had cruises in March, April and May with sampling of the prey field by the ¼ MOCNESS. In 1997 he had cruises in April and May with both the MOCNESS and pump. Greg is in the process of summarizing the larval feeding for those two seasons. In addition he has a time series of samples done in 1999 around the Tidal Mixing Front mooring line of Schlitz. The principle larval prey is various life stages of Pseudocalanus and Oithona. Whether the larvae are feeding on Calanus eggs has not been definitively determined.

Steve Bollens asked whether there are tintineds in the diet and could they be identified. Betsy Broughton indicated that they can be identified, but generally are not in the diet. She also made the point that late stage zooplankton eggs are digested, but early stage eggs get passed through the gut without being digested. Also, soft bodies animals, though they may be ingested, may not show up in the data.

John Steele asked what is the diet of the juvenile gadids, to estimate population-level prey requirements questions? Steven Bollins indicted that the MOC-10 juvenile catches were available and forwarded to the NMFS Narragansett Lab. However, the MOC-10 fish samples were stored in alcohol (for otoliths) and are not well suited for stomach analyses. NMFS may have some older data on cod and haddock juveniles. Betsy Broughton will check on the status of these data.

David Townsend – Timing of bloom conditions

In 1999 Townsend was on all 6 broad-scale cruises. In Jan the ‘spring’ bloom appeared to already be underway. By May it was ending, although in June production again increased. In the earlier years, Townsend did not have January or June data. In January, nitrate appeared to be available, while there was a silicate hole on the Bank. An earlier report on the annual cycle of nitriate on the Bank by Pastuszak et al. (using MARMAP data) indicated low values from May to August. The nitrate appeared to be restored pretty quickly in the fall-winter, and drawn down quickly between Feb and April. In summary, the fall may be an important time for setting up production during the subsequent seasons and we really don’t have much information from this period.

Larry Madin – Predator studies

All of the data on predators from the broad-scale survey cruises has been put into the GLOBEC database.

David Mountain – Larval Mortality

The 1998 haddock year class exhibited the highest level of recruitment since the 1970’s. Looking at preliminary estimates of the abundance of different life stages of haddock from the broad-scale surveys indicates that the number of eggs spawned in 1998 was not higher than other years, while the estimated number of eggs hatched was higher. This higher egg hatching would not account for all of the increase in recruitment. While the peak larval abundance was highest in 1998, the survival from that peak to recruitment actually was lower in 1998 than in 1995-1997, perhaps indicating some degree of density dependent mortality. The survivorship from estimated egg hatching to the period of peak larval abundance was very high in 1998 compared to the other years. The implication is that the high haddock recruitment in 1998 originated through low mortality during the egg and early larval stages.

Jack Green – Larval Growth

The growth rate of larval cod and haddock during the different years of the program was fairly consistent at about 0.02 mm/day. On a monthly basis, the growth in some months was as high as 0.07 mm/day.

Ann Bucklin and Dennis McGillicuddy (presented by Peter Wiebe)

Ann and Dennis plan to publish a mapping/modeling paper on the distributions of Psuedocalanus. The focus will be on 1997 and 1999. A movie was shown of the abundance through time during 1997 for both Psuedocalanus species. The distributions were determined by applying adjoint modeling to the monthly distributions.

Dicky Allison – GLOBEC Database

Dicky will be in touch with all those who have indicated they have data that is not yet in the GLOBEC database.

Bob Beardsley – PO Workshop

Bob summarized the activities at the PO workshop that preceded this workshop (see the report from the PO workshop). One overlapping issue for the two workshops is the development of a chronology for the physics and biology during the program period.

Jeff Runge – Estimation of Calanus and Psuedocalanus rates

Jeff is working with Barbara Niehoff is to compare a reproductive index with actual egg production rates determined from onboard experiments for Calanus and Psuedocalanus. A relationship between predicted egg production rate and observed egg production rate has been developed using data from 1997, 1998, and 1999. Using this relationship, distributions of egg production rate (EPR) have been generated for the broad-scale cruises. Comparing years: in April 1998 there were more females and greater EPR on Northeast Peak than in April 1995.

Jeff is also working with Mark Ohman and Ted Durbin on the mortality of Calanus and Pseudocalanus. They will want to compare these results with predator abundance from the data of Larry Madin and Steve Bollins.

Jeff hopes to determine the chlorophyll level that begins to limit for egg production. Initial indications are that around 1 microgram/liter egg production becomes less than maximal and becomes really bad by 0.5 microgram/liter.

Gridding of Broad-scale Data sets

Peter showed a set of points from the finite element modeling G2S grid that encompasses the broad-scale stations and could be used as a common grid for gridding the broad-scale data. He also showed the equivalent set for the finite volume model grid – which has about 5-10 times as many points. In discussion at the PO workshop, it was felt that interpolating the broad-scale data to such a dense grid would be unnecessary.

Peter showed the gridded/plotted plankton displacement volume data from Jack Green to show output of krigging to the G2S subset of points.

A discussion occurred about selection of a grid. If Dennis McGillicuddy is going to use the finite element model for his adjoint modeling, then using the subset of the G2S grid could make sense. Karen Fisher suggested that all actual observation points from the sampling should be included as grid points. John Quinlan pointed out that interpolating the original observations to grid points would involve an input from neighboring observations (in accord with the correlation length scales), so you really won’t preserve the original values, anyway. There was not a consensus about the best approach to use. Peter will talk to Dennis about his thoughts concerning the grid in relation to his modeling.

Karen Fisher – Analysis of along track high resolution data collected with Greene Bomber

Karen presented her work on wavelet modeling and her application of it to the Greene Bomber data. Wavelet analysis provides an efficient method of characterizing the variability of a parameter at a variety of length scales. It provides a spatial distribution of the amplitude of the different wavelets (length scales) used so that sharp features like fronts can be located. The wavelet analysis can be the basis for interpolating between observed data points, using a fractal interpolation scheme.

November 1, 2002 Day 2

The discussion of the gridding issue was continued. The EasyKrig software is available on line. It now includes the ability to do 3 dimensional krigging and also has the ability to put out values on the proposed broad-scale grid subset from the G2S grid. The data can be displayed with bathymetry and the location of the input points.

After a rolling discussion of the benefits and pitfalls of different methods and different application of the products, a way forward was suggested:

1) Examine methods to apply spatial variability to interpolated fields. Specifically, compare OAX plots with those from other interpolating schemes.

2) Determine what should be acceptable error levels? (for blanking out portions of a grid due to lack of confidence in the interpolated values).

3) Examine methods to determine areal estimates of parameters.

4) The idea of using a regular grid, rather than a subset of the finite element grid, seemed to gain momentum.

A group was formed to carry forth on this: Peter Wiebe., Lew Incze., John Quinlan., Dennis McGillicuddy., Jeff R., Ted Durbin, David Mountain, Karen Fisher. Mountain and McGillicuddy will act as co-chairs. The members of this committee who were present met at the end of the workshop.

JGR Special Issue

Bob Beardsley described the status of the special Issue of JGR on physics of Georges Bank, and highlighted the interest in getting the manuscripts available to the GLOBEC community at the earliest time, in advance of actual release of the volume.

Chronology

The physical oceanography component of the program has made a good start at developing a chronology of events during the program. It also is considering creating web access to figures and data that indicate conditions and events during the program. Jim Irish showed an example of a chronology from moored data.

What parameters are of interest or candidates for indicating a biological ‘event’ and what would determine an ‘event’?

Jim Bisagni suggested that since the cruises often took place at about the same time each year, we could develop a mean distribution for each month for a parameter of interest and then an anomaly distribution for each month in each year. A visual chronology of ‘events’ would result.

Steve Bollens showed an example of the occurrence of two species that are associated with Slope Water and were seen in high abundance in 1995 and 1999, but were not significantly present in the other years. These occurrences would constitute ‘events’. He also showed similar plot for Plurobrachia with very high numbers being observed in 1999.

 In relation to monthly distributions and anomalies, it was pointed out that several older data sets (e.g., MARMAP and Clarke-Bumpus) would be very useful to include. Effort to make these easily available should be undertaken. Lew Incze pointed out the Census of Marine Life has a project funded to work with NMFS to get the MARMAP data set more easily available.

A start to developing a chronology was made:

1995

            high salp abundance (Bollens)

            Calanus earlier peak, less abundant than 1996 (Durbin)

            Cod and haddock larvae showed chronic mortality

            Larval cohorts followed circulation around the bank

            Herring feeding on calanus patch (Green)

1996

            calanus a little later, and higher abundance than 1995 (Durbin)

            high growth rate for cod larvae (May) (than 1995) (Green)

            cod and haddock larvae showed chronic mortality

1997

            low larval abundance for cod and haddock (Mountain)

            herring feeding on calanus patch in May, and humpbacks feeding on herring (Durbin/Campbell)

            Food limitation event for calanus in April on southern flank (Runge)

1998

            high recruitment for haddock (Mountain)

            year of the pteropod (Wiebe)

            big year forall copepods in the spring (Durbin)

            low plurobrachia (Bollens)

1999

            high haddock recruitment (Mountain)

            high ctenophore abundance (Bollens)

            high salp abundance (Bollens)

            winter bloom and high production in GoM (Townsend)

            herring feeding on calanus patch and humpbacks feeding on the herring (Davis/Ledwell)

To be informative to others who are not so familiar with the biology, some background on the expected conditions or paradigm against which the noteworthy departures are identified would be helpful.

One suggestion is to expand this to a monthly table with columns for different parameters. The chronologies will, not doubt, evolve as investigators continue to analyze their data. The groups will need to be meeting more frequently than in earlier phases of the program and to keep updated on developments from the various analyses underway. There is an e-mail list for the broad-scale investigators: ggbbss@globec.whoi.edu.

Also a similar table will need to be developed showing the status of the various data sets. This table could be updated as progress is made.

To promote progress in creating the chronology a ‘chronology group’ was identified consisting of Jack Green, Ted Durbin and Peter Wiebe. It was noted that the process cruise biology was not all represented at either the PO or the broad-scale workshops. The chronology group will need to reach out to the process biology investigators to contribute to a biological chronology. The ExCo also may need to be involved to help this effort along.

In a related topic, it was noted that there are some cruise reports and workshop reports that are still outstanding.

Peter showed examples from the ICES CRR from the 1993 workshop comparing sampling gears, to illustrate the type of products we may want to consider for the broad-scale data sets.

Publication plans:

To help in the coordination of future activities, everyone was asked to submit a list of manuscripts recently published, submitted or nearing completion and a list of what they plan to accomplish over the next six months.

The Workshop was adjourned at 1:45 PM.

Rapporteur - David Mountain

Appendix 1. List of Attendees

Appendix 2. Meeting Agenda

Agenda - Phase IV Broad-Scale Workshop

Thursday 31 October 2002

1330: Introduction and review of Agenda

1345: Biological data status and manuscript status.

Gijon Meeting - Abstracts due 15 November

Lew Incze: Size selection of sampling gear (MOCNESS/Pump) and zooplankton abundance.

Ted Durbin: Up date on Zooplankton species analyses.

Greg Lough: Up date on cod and haddock feeding studies.

Others:

1530: Break

Jeff Runge, The estimation of Calanus and Pseudocalanus sp rates from broad-scale data and the use of broad-scale data to evaluate the sensitivity of growth rates of cod larvae to variations in prey abundance in 1995 and 1998: an update.

1615:Gridding of data sets:

Peter Wiebe: Common set of grid points and common methodology. Background and update

Karen Fisher: Application of wavelets and fractal interpolation to the gridding problem across multiple scales using along-track acoustics and fluorescence data collected on Georges Bank.

1730: Adjourn

Agenda - Phase IV Broad-Scale Workshop

Friday 1 November 2002

0830 Continued discussion of gridding and data products.

            What products should be produced/what products are needed?

0930: Chronology of biological events during the GLOBEC years (94-99)

1030: Break

1045:Chronology of biological events during the GLOBEC years (94-99)

1200: Lunch

1300: Other topics (See possible list below)

1500: Break

1515: Publication plans

1630 End of meeting.

Other topics:

Hydrography

Nutrients and Phytoplankton

Zooplankton Descriptive Analysis

Broad-Scale Distribution of Zooplankton on Georges Bank and Association

with Hydrography

Maintenance of Pseudocalanus spp. populations on Georges Bank

Zooplankton Production

Ichthyoplankton

Predators

Modeling