Items 1, 3, and 5. Support for Zooplankton Vital Rate Measurements During Phase II GLOBEC (prepared by T. Durbin).
The Phase II GLOBEC Program focuses on sources, retention and losses of the target species, with a heavy emphasis on advective inputs and losses of the target species at present. However, the importance of these advective processes can only be understood within the context of a study investigating all of the terms controlling the population dynamics of these species including birth, growth and mortality. During Phase I of GLOBEC, spatial and temporal differences in Calanus egg-laying rates, egg viability, and growth rates were observed, particularly differences between on-bank and off-bank populations of Calanus and spatial differences between different hydrographic areas on the Bank. Based on this initial knowledge, we are now in a position to look at specific questions which will greatly increase our understanding of the physical and biological processes controlling the dynamics of these species.
Modeling, which is essential in describing the interaction of physical and biological processes in controlling the population dynamics of the target species, requires a knowledge of their vital rates of birth, growth, and death. While measures of birth and growth rates of the zooplankton target species have been made during Phase I of GLOBEC, we have no information about mortality rates and no quantitative estimates are available for the Northwest Atlantic region. As presently funded, the next phase of the GLOBEC study does not attempt to measure this biological loss term comprehensively. The predation rate measurements of invertebrate predators by the Madin/Sullivan study can be used to estimate mortality, but there is no guarantee that the predators they are studying are the primary agents of mortality.
Birth Rates Measurements (Item 1): Present funding levels do not allow for the original egg laying and egg viability work plan. With additional support of $22K in year 1 and $12.5K in year 2, the following changes were made to the Durbin/Runge work plan in order to retain a viable copepod birth rate program: (1) Egg-laying measurements during the process cruises will be done by E. Durbin assisted by a graduate student, with J. Runge participating in one of the process cruises. (2) The reproductive index will be measured by the URI sorting group for process and Broad-scale stations. However, we may only be able to analyze the priority stations and there will be no bank-wide contour maps of females and water column egg production rates for the 1997 Broad-scale surveys. (3) Egg viability will be measured during the process cruises as a part of the egg laying rate measurements. Additional funding would support analyses of the phytoplankton samples associated with these experiments. (4) J. Runge will continue analysis and writeup of the 1995 egg-laying and viability data, and contribute to analysis of growth and data on abundance and distribution as needed. He would also contribute in the analysis of data collected in 1997.
Mortality Rate Estimation (Item 3): Present funding levels provide no support for this work. With an additional $50K and $53K in years 1 and 2, a pilot study will be carried out on the Southern Flank on G. Lough's larval fish cruises during April and May. This is the period and location where recruitment of Calanus declined to very low levels in 1995, despite continuing high population egg production rates. High egg and naupliar mortality is a likely cause. By combining the drifters Durbin's group presently has with Lough's, we would have an adequate number of drifters to tag the water for several days where the mortality-rate measurements were being made. This pilot study would provide the first direct measurements of zooplankton mortality on Georges Bank.
Growth Rate Measurements (Item 5): Reallocation of funds within the recommended award will permit measurement of growth rates of the target zooplankton species on the process cruises by E. Durbin's associate, R. Campbell. Additionally, D. Gifford and M. Sieracki will add treatments to their ingestion experiments to measure growth rates of Calanus and Pseudocalanus nauplii in selected experiments.
Item 2: Need for Vertically Discrete Ichthyoplankton Sampling on Broad-Scale Surveys (prepared by D. Mountain)
With the support identified for the NMFS Broad-Scale components, the only ichthyoplankton work that can be accomplished is determining the distribution, abundance, and age of eggs and larvae from vertically integrated hauls either from a bongo net or a single net of a MOCNESS system on some, but not all surveys. In particular, no vertically discrete sampling of larvae can be done, due to the cost of sorting and processing the additional samples. However, the vertically stratified sampling is needed to determine the vertical distribution of the larval population in relation to prey distribution and water column conditions. GLOBEC modeling results have shown that vertical position is critical in determining retention on the Bank by recirculation and removal from the Bank by wind driven advection. The focused process studies will identify the larval vertical distribution, but only in a narrow window of time and space. This information is needed on a bank-wide basis for understanding the dynamics of the larval populations, through the full range of conditions encountered by the cohort, from hatching to metamorphosis.
In order to hindcast the development of the population using the models and information gained in the process studies, we need to know the characteristics of the organisms that are important to the critical physical and biological processes. The vertical distribution of the larvae by age in relation to time, space, prey, and water column conditions is a fundamental characteristic. Only with the confirmation of the hindcasting ability can the program say it is taking the science in the direction of prediction.
The collection, processing and analysis of the samples for vertical resolution could be accomplished with an additional $70k for sorting and support for an additional technician ($29k) for each field year.
Item 4: Moored Array Design for 1997 Field Program (prepared by R. Beardsley and J. Irish)
Due to reduced funding, the Long-term Mooring Component Group initially decided to maintain the full instrumentation normally deployed at the southern flank (SF) mooring site from November 1996 to September 1997 and deploy a more lightly instrumented mooring at the crest (CR) site during spring 1997. After discussion of concerns raised by the biologists about the lack of physical oceanographic time series on the Northeast Peak during late winter and spring 1997, K. Brink, R. Beardsley and J. Irish decided to shift the crest mooring to the Northeast Peak (NEP) long-term mooring site, and contract with P. Smith (BIO) to deploy two guard buoys at the NEP site to protect the WHOI scientific mooring. In addition, a second scientific mooring with guard buoys will be deployed at a shelfbreak (SB) site south of the NEP mooring to serve as a monitor for the flow of Scotian Shelf water directly across the Northeast Channel onto Georges Bank. These additional moorings will be deployed in September 1996 by Smith and recovered in July 1997. The instrumentation at the NEP and SB sites on the eastern end of the Bank will provide important time series of current and water properties during the late winter period (JanuaryMarch) when the target species tend to be concentrated in this area. The most cost-effective approach to obtaining this information is for NSF to shift a modest amount of money ($21K in year 1) from the WHOI Long-term Mooring Grant to the Dartmouth subcontract to BIO for Smith's mooring work. Consequently, the budgets for these two grants have been revised.
Item 6: Prey Selectivity on Broad-Scale Surveys (prepared by D. Mountain).
Preliminary results from the 1995 and 1996 field season show that significant changes in the distribution of larval fishes and their prey occur both within a season and inter-annually. Knowledge of larval prey selectivity and feeding success is needed to understand the connection between variations in the zooplankton prey field and its influence on the growth and survival of the developing larval fish populations. While detailed information on larval feeding rates and prey selectivity will be obtained by the focused process studies in a relatively narrow spatial and temporal window, larvae and their prey are broadly distributed and larval development is not synchronous across the entire Bank. Information is needed over the whole range of conditions encountered by the larval cohort. This information can be provided only by analysis of the samples collected on the Broad-scale surveys.
The larval samples will already have been collected and sorted. The only additional support needed to accomplish this task is support for a technician in the NOAA Broad-scale Component to assist in analyzing the gut contents at a cost of about $29K/yr.
Item 7: Support For A Biological Modeler Postdoc to Work with the Dartmouth Finite-Element Coupled Model (prepared by C. Davis)
The zooplankton dynamics modeling project is designed to bring together the various components of the GLOBEC Georges Bank Program in order to understand the biological and physical processes controlling the distribution of target zooplankton species on the Bank. The bulk of the proposed modeling work was to be conducted by a postdoctoral scientist working with D. Lynch at Dartmouth College. Due to the funding shortfall in the Dartmouth budget, the postdoctoral position cannot be supported. The loss of this position will cause a major negative impact on the modeling project, and we will not be able to achieve our main goal of modeling population dynamics. About $65K/year is needed to support a post-doctoral investigatorship at Dartmouth.
Item 8: Need for Additional Support for Scientific Analysis of Satellite Data (prepared by J. Bisagni and P. Cornillon).
This project is designed to provide a retrospective analysis of over a decade (13 years) of satellite-derived sea surface temperature frontal locations for comparison with various types of frontal information collected by Sea-Soar (Brink), drifter (Beardsley and Limeburner), VPR (Davis), acoustic (Wiebe and Greene), optical (Wishner), and satellite data (Bisagni) from the 1997 field year. In addition, this project will provide real-time satellite imagery both prior to and during 1997 cruises which will enable these same investigators to accurately locate and sample various hydrographic features which are central to their research.
The URI/GSO-side of our budget was reduced by an amount which represents the approximate two-year cost of a post-doctoral scholar. This reduction would relegate our project to a "service-only" role, eliminating nearly all of the "science" from our proposed retrospective study, which is designed around analysis of a 13-year time series of satellite-derived SST data (19851997). Understandably, we are reluctant to perform solely a service role in the program, despite the fact that a large number of other projects funded under Phase II depend directly on this service (Brink, Beardsley, Davis, Wiebe, Wishner and Greene). In addition, the information on frontal position and strength during both 1995 and 1997 field years will be extremely useful in interpreting existing field data and testing model hindcasts to be done by the Lynch modeling group.
More specifically, this reduction:
(1) eliminates calculations of climatological-mean sea surface temperature (SST) frontal positions and strengths which were to be used for comparison with 1997 field year measurements from satellites (Bisagni) and ships (Beardsley, Brink, Davis, Wiebe, Wishner and Greene);
(2) eliminates calculation of interannual variability regarding SST frontal locations and strengths, and;
(3) eliminates linking SST frontal positions with hydrographic and drifter data to determine persistent versus intermittent pathways of water/biota onto and off Georges Bank.
A net reduction in our original request, coupled with movement of funds from the NOAA/NMFS budget to the URI/GSO budget could accomplish all the scientific goals given above through restoration of the two-year cost of the post-doctoral scholar, while retaining the "service" role of the project as outlined below under two different options. (Note: two-year cost of the post-doc salary/fringe/overhead is $96.6K).
Option 1: Convert $25K of permanent
equipment money from NOAA/NMFS for purchase of a faster computer to
~50% of the post-doc's salary/fringe/overhead for the first of two
years. Computer processing will require more time but all "service"
roles are retained. This will require $71.6K of additional funds
above the amount recommended by the program managers over two years
to provide the remainder of the postdoc's
Option 2: Convert $25K of permanent
equipment money from NOAA/NMFS for purchase of a faster computer,
together with $23.3K from URI/GSO for technician to 100% of the
postdoc's salary/fringe/overhead for the first of two years.
Computer processing will require more time, however, all "service"
roles are NOT retained, i.e., production of
optimally-interpolated SST fields for the 1997 field year would be
eliminated. This will require $48.3K of additional funds above the
amount recommended by the program managers over two years to provide
the remainder of the postdoc's salary/fringe/overhead.
Item 9: Target Copepods Life History Characteristics. (Prepared by P. Wiebe).
The "Calanus paradigm" of over-wintering diapause, spring wake-up, and summer reproduction was disproved during Phase I of the Georges Bank study. Several Phase I projects contributed to new understanding of C. finmarchicus' life history, including flexibility in the timing and frequency of diapause inception. The funded Phase II projects do not include continued examination of the physiological and morphological accompaniments of diapause nor of the role of environmental cues. Continued scrutiny of target copepod life histories is an essential component of the Georges Bank study.
Item 10: Need for Examination of Ring-Induced Entrainment Over the Southern Flank of Georges Bank (prepared by J. Churchill and J. Manning).
Entrainment into Gulf Stream
warm-core rings has been shown to be a dominant agent acting to
remove water from the southern flank of Georges Bank and from
the shelf of the Middle Atlantic Bight. However, present
evidence is inconclusive regarding the geographic scope over
which water is drawn into warm-core rings or the type of water
which is typically entrained into rings [Churchill et al.
(1993); Schlitz (1996)]. Defining the scope of warm-core
ring entrainment and understanding the mechanisms involved is
clearly critical to the study of retention and loss of larvae
over Georges Bank. Currently planned Phase II research does
not include direct measurements of transport to a ring.
Studies in which measurements near a ring are considered (most
notably the SeaSoar surveying of Brink et al.) will be
limited to one or two scheduled cruises which may or may not
coincide with the presence of a ring.
In view of the potential impact of ring entrainment to larval populations, we contend that the Phase II program should include a study specifically targeting warm-core ring entrainment. Our proposed addition to the project is a drifter-CTD-ADCP study of the transport of shelf water initially onshore of a warm-core ring. To ensure that the study can be done whenever a ring is present, field work will be carried out from a local fishing vessel. The effort will include multiple deployments of drifters along lines onshore of the rings, coupled with ADCP-CTD surveys within the region of these lines. Ideally, this work would be done as part of one of the major sampling efforts on the bank (given the appearance of a ring). In such case, the plan is to coordinate the drifter deployment and CTD-ADCP surveying with other sampling. A separate vessel is needed due to the requirements of the drifter tracking and to focus the CTD-ADCP surveying in the region of the drifters. In the event that scheduled cruise times are ring-free, the proposed work will be carried out anytime (within a minimum 18-month window) when a ring appears in the SST imagery. The results will be used to define the scope of warm-core ring entrainment, focusing on the types of water masses drawn into the ring (e.g., frontal water vs. cold-band water) and their larval/plankton content (either measured or determined from historical data). The results will also be useful to the modelling groups, in particular to Lynch and Haidvogel whose models will include merged shelf and open-ocean modules incorporating Gulf Stream rings. Direct measurements of ring interactions and entrainment are needed to validate their test cases. This would be a new program component and require an additional $42K in year 1 and $22K in year 2.
Item #11: Need for Processing Shipboard MET and Other Underway Data(prepared by R. Beardsley)
During the GLOBEC Phase II 1995 field effort, a full suite of shipboard MET, navigation, surface temperature and salinity, and other underway data (except ADCP data) were routinely collected on the process oriented cruises. Editing this data set (especially combining the ship's absolute speed and heading over ground with the ship's relative wind measurements to compute the true wind velocity) required a skilled technician, so we hired R. Payne (WHOI) to process much of this data for the 1995 field effort and make it available through the program data office for use by all PIs. Support for this unanticipated but important effort was taken from the WHOI Stratification Experiment grant to Beardsley and co-PIs.
Support to continue this effort for the Phase II intensive 1997 and 1999 field efforts was requested in the Candela, Flagg, and Payne proposal. While partial support was recommended for the collection and archiving of ADCP data by Flagg and Candela, funding for Payne and the processing of the shipboard MET and other data was omitted. We note that many PIs want to know in detail the meteorological conditions (including insolation, heat flux, and wind stress) during their shipboard experiments, so that having the shipboard MET and other data processed correctly by Payne (who is our resident technical specialist in shipboard met measurements) makes good programmatic sense. We also note that the shipboard MET measurements will help define the atmospheric forcing used in numerical model hindcasting of the intensive field years by D. Lynch (Dartmouth) and co-PIs.
We estimate that for about $25K/year for three years, Payne can improve the editing software and process and archive the data collected during the Phase II process-oriented cruises. Since this editing and archiving is a service to the entire program, its funding should be added to the Wiebe and Groman Program Office grant.
Item 12: Need for Additional Support for Scientific Analysis of ADCP Data (prepared by J. Irish and R. Beardsley)
to reduced funding, the shipboard ADCP collection and
processing proposal was not funded as a separate proposal, but
incorporated at a reduced level into the Long-Term Moored and
Drifter proposal. This level of funding will allow the
shipboard ADCP data to be collected and archived, but little or
no scientific analysis can be done. As this data is of use to
many components of the GLOBEC program, it would be useful to
have the data fully processed and served as part of the GLOBEC
data base. This processing would include (1) biomass estimates
by C. Flagg (BNL) and (2) de-tiding by J. Candela (through
WHOI). The biomass estimation effort would involve improving
the acoustic backscattering to biomass algorithm utilizing
available GLOBEC MOCNESS, Sea-Soar, VPR, etc. data and then
applying the new algorithm to the shipboard acoustic
backscattering observations to estimate the spatial and
temporal biomass structure. The de-tiding effort would involve
analysis of historical current meter data and improvements in
the predictive tidal model to include additional constituents
and more realistic data fitting algorithms. Then the improved
predictive model would be applied to the shipboard data to
remove the tidal component, and the results included in the
GLOBEC data base. To include both components of processing and
serving the data would require an additional $100K in funding
per year to be split between WHOI and BNL.