4. Reports of Working Groups

4.1 Population Dynamics and Physical Variability: Zooplankton Working Group

Chair: M. Huntley

Rapporteur: A. Clarke

Members: B. Battaglia

S. Kim

J. Stromberg

``To understand the effects of physical processes in predator-prey interactions and population dynamics of zooplankton, and their relation to ocean ecosystems in the context of the global climate system and anthropogenic changes.''

The aims for the Southern Ocean as decided at the La Jolla GLOBEC workshop (U.S. GLOBEC Report No. 5) were re-examined and agreed to be:

1. regional differences in overwintering strategies of the Antarctic krill (Euphausia superba) in relation to physical environment;

2. a detailed study of population dynamics of related zooplankton species, both sea-ice related and planktonic species;

3. population dynamics of major krill predators, ice-based (such as Adelie Penguins, crabeater seals) and more pelagic species (e.g. chinstrap penguins, Antarctic fur seals and the fish, Pleurogramma) (Efforts should also be made to include the much neglected squids.); and

4. studies of the effects of UV-B radiation on zooplankton dynamics.

1. By what means do Southern Ocean zooplankton survive the winter, and how does this vary geographically?

2. What is the seasonal and geographical variation in the distribution of key Southern Ocean zooplankton species, particularly in relation to the physics of the environment?

3. What factors influence successful reproduction in Southern Ocean zooplankton?

4. What physical processes influence the subsequent survival of larvae and recruitment to the adult population?

5. How is the distribution of Southern Ocean zooplankton related to the distribution of food biomass and reproduction?

These questions do not specifically address the subject of global change. The subject is nevertheless important and is referred to specifically in the overall GLOBEC aim, but it was felt that this aspect was best studied through remote sensing and suitable monitoring studies.

It was recognised that to gain a full understanding of the population dynamics of zooplankton, it is absolutely critical to obtain winter data. This requires ship-board work in winter, but shore bases can make an important input through year-round studies of suitable coastal zooplankton.

The role of physics in influencing biology was deemed to include regional circulation, mesoscale structures and dynamics and the role of sea--ice. Although it is desirable to tackle complex biological questions in an area where the physics is simple, it was recognised that in many areas of the Southern Ocean, the physics is insufficiently understood to decide whether the area is simple or complex.

Work on spawning, larval survival and recruitment to the adult population is at the heart of population dynamics. To resolve these questions will require a close collaboration between modelling, experimental and observational work.

Tackling these questions will require a range of techniques and approaches, including time-series surveys, process studies at sea and experimental studies in laboratories.

4.1.3 Key Species

Euphausia superba (a key prey species in the Southern Ocean)

Calanoides acutus (an important herbivorous copepod with a typical overwintering strategy, and one with a substantial body of previous research

Metridia gerlachei (an important predatory copepod with reproduction throughout the year)

Euphausia crystallorophias

Thysanoessa macrura

Salpa thompsoni

Calanus propinquus

Rhincalanus gigas

Themisto gaudichaudii

Sagitta gazellae

Chair: J. Croxall

Rapporteur: J. Bengtson

Members: D. Costa

S. Jacobs (part)

G. Laurence (part)

Y. Naito

P. Penhale (part)

We reviewed the nature and content of potential studies of birds, mammals and fish in relation to the aims of SO GLOBEC. (Fish and squid were considered in general terms but no specialists were present. Subsequent comments from Dr. I. Everson and Dr. P. Rodhouse are incorporated but further elaboration of research approaches and priorities for these groups are required.) We took particular account of: a) the increasing focus of the overall study onto species and processes intimately associated with the pack-ice zone; b) the need to concentrate on Antarctic krill because of its unique role amongst zooplankton as a key prey for a wide range of predator species; c) the need to ensure that the various predator studies are conducted at spatial and temporal scales congruent with the research into the physical and biological environment; d) the requirement that many of the key process studies must be conducted simultaneously on predators and prey; e) the requirement that both process and survey studies need to be underpinned by the continuation and enhancement of existing studies monitoring trends and variation in population parameters and in aspects of foraging and reproductive performance of predators; f) the need to conduct SO GLOBEC studies over several years, at all seasons of the year and especially to include work in the sea-ice zone in winter.

4.2.1 Target Species

Primary

Crabeater seal

Adelie penguin

Snow petrel

Antarctic petrel

Fish

Squid

Psychroteuthis glacialis

Moroteuthis knipoviitchi

Secondary

Leopard seal

Chinstrap penguin

Cape petrel

Antarctic fulmar

Fish

Squid

Kondakovia longimana

Alluroteuthis antarcticus

The questions below were formulated to try to focus attention on some of these issues and to aid the development of appropriate field and laboratory research, linked to relevant numerical modelling initiatives.

1. How do changes in the physical environment (e.g. ice cover) and biological environment (e.g. food availability) influence top predator species':
   1. distribution and abundance;
   2. reproductive performance and breeding success;
   3. juvenile survival;
   4. adult survival; and
   5. foraging strategies and tactics?

2. How do the presence and characteristics of ice affect foraging performance, reproductive success and survival of top predators?

3. How do changes in krill availability affect allocation of krill among different dependent species?

4. How and to what extent do the presence and foraging activities of predators induce changes in the behaviour, abundance and distribution of krill (e.g. through avoidance behaviour and removal via predation)?

5. What is the nature of the functional relationships between krill availability and the performance and survival of its predators:
   1. what is the relationship between the distribution (vertical and horizontal) and abundance of krill and its availability to different predators;
   2. how do fluctuations in krill availability affect foraging performance, reproductive success and survival of dependent species; and
   3. which life history stages of predators are most sensitive to changes in prey availability or in the physical environment?

Particularly for this reason the development of outline research programme elements to address each of the key questions will require substantial work by appropriate krill and top predator scientists working together.

Information on the status of current research activities in the fields below are presented in Table 4.2.1. This is a draft version and the group recommended that WG-CEMP, the SCAR Group of Specialists on Seals and the SCAR Bird Biology Subcommittee be asked to review and amend them as soon as possible.

4.2.3.1 Definable Populations

1. Definition of Unit Populations

This requires studies, using newly developed molecular techniques, of genetic variation within and between breeding units of target species. Definition of population units for crabeater seals and fish are particularly important.

2. Surveys of Population Distribution and Abundance

Some target species, especially seabirds, can be surveyed, at least locally, by land-based surveys from shore stations. There are quite extensive existing studies of this kind. For other species, ship, aircraft and satellite based work will be essential. Remotely-operated vehicles, especially airborne platforms, could provide invaluable assistance for studies of seals (and possibly seabirds) also.

4.2.3.2 Population Dynamics

For ice breeding seals, age structure and vital rates are determined by examination of teeth and reproductive tracts taken from samples of the population. For commercial fish, regular surveys to estimate stock size, population structure, reproductive status and diet are undertaken in support of CCAMLR. Studies on squid are restricted to determining distribution and trophic relationships. In general for fish and squid, age structure and vital rates are determined by examination of otoliths/statoliths and maturity status of the reproductive system taken from samples of the population.

Long-term marking of individuals is not as straightforward in most top predators as it is for flying birds. The use of passive induction transponders offers very significant advantages over flipper tags for penguins but further technological development is required, particularly of recognition systems to detect tagged individuals, to make maximum effective use of this new technology.

4.2.3.3 Processes and Mechanisms

1. Diet composition--including seasonal, interannual and geographical variations in the nature of the prey, including their size, sex and age, where feasible. Diet research is chiefly based on analysis of stomach (and sometimes faecal) samples (increasingly involving lavage methods for seabirds and seals). Serological techniques have provided important confirmation of visual diet observations in squid. Determination of age, size and sex of prey relies extensively on relationships between structures relatively resistant to digestion (e.g. otoliths, statoliths, beaks, mandibles, eyeballs, carapaces) and whole animals. Better, and standardised, relationships are needed for many taxa. Diet studies other than during the summer months are rare and need to be a particular focus of future work.

2. Foraging habitat and area--the physical structure and physical and biological characteristics of the location selected by top predators for feeding activities and how these vary at temporal scales ranging from diel to annual. Once almost entirely dependent either on direct visual observations (seabirds, seals) or net-haul samples with concurrent oceanographic data (fish, squid), the use of satellite telemetry is nowadays revolutionising data acquisition in this field, especially for seabirds and seals. Acquisition of congruent data on the nature of the ice and water habitats is essential and, using conventional methods, more difficult for seabirds and seals than for fish and squid.

3. Foraging behaviour--this comprises all aspects of a) how predators catch prey, including defining the functional morphology of feeding structures (e.g. squid), the methods used, the conditions and circumstances involved (e.g. in terms of the physical (including optical) properties of their environment); b) when predators catch prey (time of day, etc.); c) how often and how much prey is caught. For all except flighted seabirds, relevant quantitative data have only been acquired with the very recent development of archival and satellite-linked instruments on and inside free ranging animals. A range of sensors recording continuously or intermittently data on pressure (= depth), temperature (external and internal), velocity, and light levels, (and often linked to location and physiological data) are permitting unique insights into foraging behaviours, patterns and performance. Requirements for further developing this type of research include smaller and better instruments (i.e. more efficient with respect to power utilisation), better data compression and storage, more accurate sensors to record existing variables (e.g. to collect data on ambient temperature and conductivity in order to determine water body characteristics) and especially better data transfer to satellite. The complementary data on prey distribution and environmental characteristics need to be collected on equivalently fine scales. Laboratory research on sensory abilities of predators is also required.

4.2.3.3.2 Energetics and Physiology

For seabirds and seals the most widely used measures of condition are still those of mass, or size-corrected mass. Use of electronic weighing platforms is greatly enhancing: a) the range and quality of such data; b) the ability to make regular records from individuals with minimum disturbance; c) the feasibility of estimating body energy stores/reserves; and d) linking such data to simultaneous studies of reproductive performance and survival of both adults and/or offspring.

Sampling populations via collected samples offers a range of additional physiological indices and condition (e.g. blubber thickness, fat and protein reserves, chemical composition, nucleic acid ratios, gonadosomatic and hepatosomatic indices (fish), etc.). Almost none of these techniques have been used successfully on a routine basis on animals captured and released alive. Considerable development, both in laboratory and field, in acquisition and interpretation of data using ultrasound, biological impedance and blood chemistry techniques will be required before these techniques can have widespread use.

4.2.3.3.3 Growth

1. Existing electronic systems deployed on and/or in predators need: a) further miniaturisation; b) better sensors, especially those collecting oceanographic data; c) better data compression and storage; and d) better data transmission systems to satellite. It is likely that further rapid progress will only be achieved via a workshop involving current manufacturers and relevant sensor developers from both predator and oceanographic communities.

2. In the longer term, research relying on satellites will be fully effective only with the availability of satellites dedicated to biological applications.

3. The development of systems to record the frequency, amount and nature of prey ingested is essential to thorough understanding of predator-prey interactions. Relatively simple devices and techniques are in use currently; development of more sophisticated systems is a high priority.

4. The use of remotely-operated vehicles, whether aerial or submersible, is a high priority in this type of research.

Chair: A. Clarke

Rapporteur: A. Clarke

Members: J. Bengtson

J. Croxall

M. Huntley

It was recognised in plenary discussion that a major difficulty was posed by the requirement to study different organisms on a single cruise. A sampling protocol designed solely around, for example, the population dynamics of a fast-growing copepod would not provide any meaningful data on, again for example, adult Euphausia superba or predatory behaviour by Cape Petrels, Daption capense.

The detailed planning of cruises would need to be undertaken by a separate implementation workshop. Nevertheless the major types of study could be clearly identified. These were:

Time-Series Surveys

Process Surveys

Process Studies

Laboratory Experimental Studies

Modelling

This type of cruise was seen as essential to tackle the following questions:

1. seasonal and geographical variation in zooplankton in response to physical forcing;

2. factors influencing reproduction in zooplankton;

3. the impact of physics on recruitment; and

4. the effect of sea-ice on krill predators.

In each matrix the abbreviations representing types of study are:

TSS: Time-series Survey

PSV: Process Survey

Proc: Process Study

Lab: Laboratory work (either on ship or shore-based)

Mod: Modelling

4.4 Historical Data and Data Management Working Group

Chair: I. Everson

Rapporteur: S. Nicol

Members: R. Holt

S. Jacobs

J. Klinck

1. A large range of historical scientific data exists for the Antarctic region. The task is to define which of these data are relevant to GLOBEC, where they are to be found and how they can be accessed. These historical data are important for GLOBEC for a number of reasons.
   1. They can be influential in the planning process for GLOBEC studies.
   2. Older data can be re-analyzed using modern techniques and used to extend time-series. It should be noted that a recent change in sampling technology does not necessarily make older observations obsolete.
   3. Some older samples and records have never been analyzed. In some cases, it may well be more cost-effective to locate and analyze these than to collect new data.

2. Data and samples exist in a variety of formats and in many cases, it appears that there is not any concerted national or international effort to catalog these data and samples, particularly in the biological field. In many cases, the only way of judging whether data and samples of a particular type exist for a particular area may be to contact the SCAR representative in those countries working in those areas. This group recommends that SCAR be requested to prepare a catalog of national archived biological data and samples.

3. The data and samples that exist will be of different quality and will often have been obtained by different devices using different sampling techniques. Some sources of scientific data and samples are listed in Table 4.4.1. This table is not meant to be exhaustive but merely illustrates the diversity of forms in which the information is available.

4. Future data and samples that are collected under GLOBEC should be collected using standard protocols and should be presented together with the information necessary for their interpretation. The group recommends that GLOBEC develop protocols of standard methods.

   4.4.1 Data Management

5. The report from the U.S. GLOBEC Southern Ocean Workshop (GLOBEC Report No. 5, 1991) presented the arguments in favor of timely exchange and use of data. Other international bodies such as JGOFS and WOCE have protocols for the submission and exchange of data and a protocol should also be developed for SO GLOBEC. This should recognize the inherent differences between the different sorts of data that will come out of SO GLOBEC, e.g. hydrographic data vs. biological data, surveys vs. process studies. It should also take into account different national stipulations on the use and submission of data. A decision should be made on whether data would be submitted and stored centrally or whether data would be made available in a specified format and lists of available data would be published. The WG recommends that a group be formally tasked by GLOBEC.INT with developing the necessary protocols and with making detailed suggestions for methods of data submission and handling.

Chair: E. Hofmann

Rapporteur: E. Hofmann

Members: C. Lascara

B. Rothschild

The recommendations for modelling studies that arose from the U.S. GLOBEC Southern Ocean Workshop that was held in 1991 focused on the need for modelling prior to a field programme, the need for sea-ice models, and the need for models of aggregation behavior. Our modelling group endorsed these recommendations and took the next step in making more specific recommendations for a Southern Ocean modelling programme. These are discussed in the following sections.

4.5.2 Modelling Issues

Circulation models of the Southern Ocean will be affected by inclusion of sea-ice processes, mixed layer dynamics and buoyancy-driven flows. In particular, models of sea-ice processes were considered to be critically important since many of the components of the Antarctic marine food web depend on sea-ice during all or part of their life history.

Two unique aspects of the Antarctic ecosystem which will influence biological modelling studies are the aggregation (swarming) behavior of Antarctic krill (Euphausia superba) and the importance of top predators, such as penguins and seals. The working group felt that the understanding and modelling of krill swarming behavior was critical to the understanding of krill population dynamics as well as understanding the population dynamics of the top predators. The working group also discussed the need for resource modelling studies that could be used to determine how krill is allocated among its many predators.

4.5.3 Conceptual Model

Within each module of the conceptual model are submodules that consider specific processes, for example:

1. Physical Environment

   circulation model (including three-dimensional flow fields and hydrographic structure), sea-ice model (including dynamic and thermodynamic processes), mixed layer model

2. Food Resources

   bio-optical models for pelagic phytoplankton production and sea-ice algal production

   heterotrophic production models, including pelagic and sea-ice components

3. Top Predators

   energy requirements to support steady state populations

   foraging behavior, impact on krill processes

4. Krill (separate into early life stages and older stages that swarm)

   individual processes--energetics

   swarming--mechanisms of formation and maintenance, spatial, and temporal variability

   population dynamics

1. a conceptual model of the Antarctic physical environment and marine food web sufficient to provide a framework for a field programme be constructed;

2. the International GLOBEC programme sponsor a workshop on observation, theory and modelling of krill swarms to be held within eighteen months; the product of the workshop would be a book; and

3. existing circulation, ice and biological models of the Southern Ocean be evaluated within the context of the needs for the development of GLOBEC Southern Ocean modelling studies;

4. GLOBEC modelling programmes maintain close contact with the sampling and observation components of Southern Ocean GLOBEC. This is especially important if data assimilative models are to be developed;

5. models of krill allocation among various predator species be developed; and

6. sea-ice and circulation models that can be interfaced with biological models of the Antarctic marine food web be developed.

Chair: V. Marin

Rapporteur: D. Costa

Members: J. Comiso

L. Guglielmo

G. Laurence

D. Manahan

1. Sea Surface topography-from TOPEX and the ERS-1 Altimeter

   Ocean currents from large-scale dynamic topography, and from instrumented drifters

   Quantification of ice-melt fresh water production

   However, for some of these satellites, there is a significant delay in data availability.

2. Sea-ice coverage and sea surface temperature can be obtained as:

   Global scale ice cover-

   DMSP (SSMI) passive microwave

   resolution 30 km, daily maps of globe

   Mesoscale-

   ERS-1 SAR Ice coverage

   5 degree coverage (100 km) every 3 days (planned coverage)

   Cloud independent, resolution 30 m.

   AVHRR ice cover and sea surface temperature variations and current movements can be obtained from time-series analysis of these images.

   Interference by cloud coverage

   1 km temperature and sea-ice resolution, at 1500 km coverage

   Possibility of sensing aggregations of birds and seals?

   Landsat 6 visible image of sea-ice cover

   (rookeries?), etc. at 35 m resolution every 15 days, 800 km coverage. Expensive

   SPOT visible-15 m every 15 days, swath width 800 km

3. Ocean Color Scanner-Pigment concentrations can be obtained from:

   MOS1B Japanese system launched, but data availability unknown

   SeaWiFS-April 1994, 8 channels likely, data availability-3 days after satellite pass

   4 km resolution available with receiver anywhere in world.

   1 km resolution available only when receiver is in quadrant of interest

   Need to calibrate pigment concentrations for Southern Ocean. GLOBEC could provide major contribution here.

   ADEOS-High resolution OCS with high resolution data acquisition accessible anywhere in the world. Has memory capability and 12 channels.

There is a significant potential for the application of small remotely piloted, or programmed aircraft to carry sensors or cameras over specific areas of interest. These aircraft have been used by the military for pilotless reconnaissance. These could be used for mammal and bird population surveys, determination of fine scale oceanographic features, and sea-ice characteristics.

4.6.3 Problems That Need Attention

Currently studies of the behavior of mammal and bird behavior while at sea is limited by the data bandwidth of the ARGOS satellite system. The potential exists to acquire data on the diving behavior (swim velocity, depth and feeding rate) that can be correlated with physical features (location, depth, salinity, and temperature). This limitation is based on the limited time available for data uplinks to ARGOS and the small bandwidth available (8 bytes).

4.6.4 Local Level Data and Sample Acquisition Needs

1. Zooplankton Development issues:

   Same as other GLOBEC.INT programmes except:

   Develop the capability to use newly developed sampling schemes in ice.

2. Zooplankton and Higher Trophic Levels:

   Apply genetic techniques to Southern Ocean systems. State-of-the art approaches have yet to be implemented for population genetic studies with higher trophic levels.

3. Higher Trophic Levels:

   Population dynamics-

   Need further refinement and/or development of PIT tags (transponder identification tags) that can incorporate greater ranges and can be coupled with automatic weighing and counting devices.

   Development of data loggers with sensors capable of collecting data (pressure, temperature, salinity) valuable to oceanographers.

   Develop data loggers and/or satellite tags that can measure:

   swim velocity

   animal location

   feeding rates (stomach temp, pH, jaw movements, etc.)

   Use R.O.V.'s to observe behavior of predator-prey interactions.

   Develop capability to place cameras on predators to observe their behavior in relation to prey.

   Develop acoustic and/or optical sensing methods to correlate prey abundance with predator behavior.

   Develop ability to telemeter behavioral data on top predators by acoustic transmission to moorings coupled to ARGOS satellites or directly to ship. (This includes fish, mammals, and birds.)

1. Develop new satellite dedicated to wildlife telemetry to enable greater data throughout.

2. Incorporate state-of-the-art data compression algorithms designed for other information processing systems.

3. Develop data loggers that can be deployed on mammals and birds that incorporate GPS technology and use LEOS (low earth orbiting satellites) that use hand bandwidth data transmission.