Minutes of the Fourth SO GLOBEC Science Investigator Meeting

9-11 December 2002

Arlington, VA

WEDNESDAY, 11 DECEMBER 2002

Hofmann began by indicating that this meeting is the last of the SO GLOBEC meetings that will be supported by Raytheon. She said that additional meetings were likely needed as the program moves into the synthesis and modeling phase. Submission of a proposal to NSF Office of Polar Programs is one possible mechanism for funding additional large group meetings and workshops. This could be done by the SO GLOBEC Planning Office. Hofmann also said that some funds are available from the Planning Office to hold small workshops (8-10 people) and that many of the individual investigator proposals should have funding to support participation in small meetings.

Hofmann said that there is possibility of a special announcement for SO GLOBEC synthesis and modeling activities and that more information on this would be forthcoming. She said that it will not be before the 1 June 2003 core program proposal deadline. She said that proposals submitted for synthesis and modeling should integrated studies that include historical data and international collaborations as well as the SO GLOBEC data sets. The proposed analyses need to be an integrated approach to look at data sets. There is no need to maintain the original science investigator groupings for the synthesis and modeling phase. Hofmann said that she would check into obtaining supplemental funding for a large group meeting and for subsequent DSR special topics volumes dedicated to SO GLOBEC.

The meeting then started with a presentation by Bill Fraser in which he gave results from satellite tagging of Adélie penguins during the fall 2002 process cruise. He said that two of the Adélie penguins tagged in Marguerite Bay ended up at breeding sites at Palmer Station. This is evidence that that the satellite tagging instruments are not affecting penguin weight or breeding ability. He said that overall 76 instruments have been deployed over four sites. He said that Adélies do not forage under low-light conditions, nor at night and that they need regions of dependable prey supply. He noted that there are five sites along the Antarctic Peninsula, Paulette Island, King George Island, Anvers Island, Renaud Island, and Avian Island, where Adélies breed and that these sites support 300,000 breeding pairs of birds. Each day 300-600 g krill are being removed by each bird. He noted that the common element among the breeding sites is the presence of deep bathymetry that comes close to the land margin. Most of the Adélies are foraging within 15-20 km of the Anvers Island site, which coincides with a deep depression. Also, areas of open water (polynyas) were key foraging areas during winter 2001 and some of the penguins were found along the sea ice edge in winter 2001. In winter 2002 the Adélies were found in areas of coastal polynyas and not so much along the ice edge. Fraser said that a breeding colony for Adélies has been discovered on Charcot Island, in Marguerite Bay, and on Renaud Island in 2002. He said that the tagging data show that Adélie females foraged more northward and that the males foraged relatively close to the breeding sites, near the deep bathymetry. Future plans for the Adélie penguin work include participation in the 2003 LTER summer cruise to deploy more satellite tags. He said that Anvers, Renaud, and Avian Islands are biological hot spots and are deserving of more study. Fraser also said that there is the suggestion that the Amundsen Sea region contains unidentified predator populations. Fraser suggested that sea ice facilitates access to the hot spots along the Antarctic Peninsula and female Adélies may need sea ice more than the males. The tagging and stomach content data sets show males Adélies feeding on krill and diving to 125 m; whereas, female Adélies feed on fish and dive to 75 m.

Erik Chapman gave an overview of the seabird observations that were made on the 2001 and 2002 fall and winter survey cruises. He said that most of the flying seabirds are surface-feeders; whereas, the Adélies and seals are sub-surface feeders. He said that the seabird observations are made using continuous survey methodology and that 155 transects were made in fall 2001 and 131 transects were made in winter 2001. An objective of the seabird research component is to explain the distribution of the seabirds on the basis of physical variables, such as water mass structure, sea ice, bottom topography, sea surface temperature and salinity, and distance to land or sea ice edge. These relationships will then be used with modeling studies of seabird distribution. Chapman noted that the analyses done to date show a strong association of some seabird species with certain water mass types (particularly with inner shelf water). In the winter the timing of development and extent of sea ice are important in explaining the observed seabird distributions. The analyses also give a strong indication that something biologically important is going in the inner shelf waters near Alexander Island. Overall sea ice has a strong influence on seabird distribution and abundance. Also, sea ice appears to modify species assemblage and abundance of top predators and the winter sea ice extent and timing of development may impact predation patterns. Chapman indicated that the next level of analysis will include comparing the seabird results with those from the cetacean surveys, and the Adélie penguin and crabeater seal tagging studies.

Costa focused his presentation on the seal work in SO GLOBEC on the use of seals to obtain environmental data, such as temperature. He showed results from elephant seal studies in the north Pacific in which environmental sensors that measure temperature and salinity were attached to the seals. The environmental data were then transmitted to satellites at specified intervals. Thus the seals were used as sensors of the environment to provide oceanographic data. He indicated that the elephant seal program had worked well. Costa then presented video of the capture of a seal during the 2002 winter process cruise and the attachment of a satellite transmitter to the seal. He also showed temperature profile obtained from temperature sensors attached to crabeater seals during SO GLOBEC. He said that the next step is to compare the seal-derived temperature data to that obtained from CTD data.

Jenn Burns next gave an overview of the SO GLOBEC seal program which has as an objective determining the foraging ecology of crabeater seals during winter. In total 46 seals were handled and 35 satellite tags deployed in the 2001 and 2002 field studies. In 2001 the seal distribution was mostly inside the shelf break, but in 2002 the seals were using the shelf break area and seal hot spots were in Crystal Sound and around Alexander Island. Burns noted that the areas of penguin hot spots correlated with the seal hot spots. Also the regions of high seal abundance were correlated with areas of high krill abundance. Other predators, such as whales, were also more common in these areas. In general predator biomass was higher nearshore than offshore and was higher in areas with widely varying bathymetry. Burns noted that a large data set on seal diving characteristics has been obtained. The deepest dive recorded was 712 m and the average dive over the whole data set was about 92 m. She noted that seals dive deeper during the day, following a vertically migrating food source. The vertical distribution of seals seems to suggest that they are using specific depth strata to access prey resources. The seals dove deep and long during mid-day when adult krill were aggregated at depth.

John Hildebrand next showed results from the passive acoustic moorings, which provided a continuous record from March 2001 to March 2002. He said that the benefit of the acoustic moorings is that they work day and night, are independent of water motion, can monitor broad areas over long periods and can provide population information. The acoustic recording package (ARP) samples at 500 Hz and is a seafloor mooring with a floating hydrophone. Seven of the eight ARPs were recovered and then re-deployed in February-March 2002. The final recovery will be on the mooring cruise scheduled for February-March 2003. He said that the acoustic records from the first year of the moorings showed calls from fin, minke and humpback whales and a surprising number of calls from blue whales, which are rarely seen. The moorings also recorded crabeater seal vocalizations. The blue whales appear to be present year-round call from the northern locations in the autumn and from the southern locations in summer. Peak calling is in January and February. This is a spatial change in calling for blue whales with season. Hildebrand said that there is evidence of circumpolar blue whale song. Fin whales are seasonal and are present in the austral fall but disappear as the winter sea ice develops. The peak in calling for these whales in fall and the highest number of calls was at the northern mooring sites. The whales appear to come in from the south.

Deb Thiele gave an overview of the International Whaling Commission (IWC) efforts on the SO GLOBEC cruises. She said that biopsy samples had been obtained from 5 minke and 18 humpback whales. Also individual photo identification (photo matching) had been done for many individuals. The visual surveying effort has been a success with humpbacks and minkes most commonly sighted. She said that no humpbacks were sighted in winter. The areas with high abundances of whales correlate with the hot spots for seals, penguins, and krill. She noted that a group of humpbacks was seen off Alexander Island and suggested that this may be a response to isolated patches of krill, bathymetry or water mass structure. The sighting surveys indicate that minke whales show seasonal changes in distribution and interannual variability in density. She said that there are many implications that could result from climate change in the western Antarctic Peninsula (warming/less ice cover) and in other parts of Antarctica for cetacean distributions. For example, killer whales (top predator) use sea ice as a habitat and for overwintering. A reduction in sea ice would have severe consequences for these animals. Thiele said that she is using historical and other time series records (e.g., IWC commercial catch data from 1920-1980s, anecdotal historical whaling records, and the IDCR circumpolar whale survey data from 1978-present) to explore regional variability in Antarctic cetacean populations. She said that the effort is focused on the circum-Antarctic scale and that an acoustic mooring program at this scale is now in the planning stages.

Ari Friedlaender next gave a review of the objectives of the IWC and SO GLOBEC collaboration. He said that a goal of the collaboration was to model the effect of climate change on cetacean distribution. He next gave an overview of a GIS that can be used to investigate linkages between biological processes and physical processes and their effect on cetacean distribution. He showed the application of the GIS to whale sighting data and discussed how it can be used to develop empirical models for whale habitat. He also noted that the SO GLOBEC whale, seal, seabird data are tightly correlated.

The presentation by Friedlaender marked the end of the formal presentations and a brief general discussion occurred prior to adjournment for lunch.

Wiebe started the discussion by saying that there is a need for a common grid to intercompare the different SO GLOBEC data sets. Ashjian commented that there is also a need for common definition of the region, water masses (similar to what Erik Chapman is now using), and sea ice conditions. Wiebe agreed that the definitions of the sea ice edge need to agree. Hofmann suggested that these issues might provide the topic for a smaller workshop. Daly asked if a base map with the revised bathymetry was available for the study area. Ashjian said that Tom Bolmer had made this available on the GLOBEC data management web site and on a website dedicated to the bathymetry.

Thiele said that the Australians have a standard ice edge definition. Wiebe said that the Danish remote sensing sea ice images could also be used to define the sea ice edge. Hofmann said that she will check with Joey Comiso for a definition of the sea ice edge. Wiebe said that the trick to defining the ice edge is to get daily images.

Allison reminded everyone to submit their data to the GLOBEC management office. The meeting was then adjourned for lunch.

Following lunch the meeting participants who remained reconvened for an informal discussion session.

Following from the discussion prior to lunch, the suggestion was made to have a small data workshop (about 10 people) during the third or fourth week of January 2003. Hofmann offered to host this meeting at the Center for Coastal Physical Oceanography at Old Dominion University in Norfolk, VA. She also said that there are limited funds available from the SO GLOBEC Planning Office to support travel to this workshop. Several people indicated a willingness to attend such a data workshop.

The issue is what data products should be common to the entire program. One start would be to put Erik Chapman's water mass scheme on the SO GLOBEC data website. Hofmann said that this might need modification because it does not differentiate between Upper and Lower Circumpolar Deep Water and may not include what others need. The question was then raised as to the availability of standard temperature-salinity plots. Hofmann said that this could be done.

The need to talk with Joey Comiso about an ice edge definition was raised again. Limeburner suggested have a plain x,y file with the ice edge latitudes and longitudes. The need for access to SeaWiFS ocean color data was raised. These data are generally available now. Beardsley said that the AWS meteorological data is on University of Wisconsin site (the AWS numbers are #8930 and 8932).

The issue of ice concentration analysis was again raised and such products as an estimation of leads were indicated as being useful. Hofmann asked for an indication of which ice products would be most useful so that a coherent request could be made to Joey Comiso.

The consensus was that the data products needed in the short term are: hydrography, sea ice maps, bathymetry, meteorology, and SeaWiFS ocean color data.

Hofmann asked for suggestions of figures the DSR special topics volume cover. The individual cruise tracks can go on the CD to be included in the volume.

Hofmann said that data reports with the SO GLOBEC CTD data at standard depths will be available soon.

Hofmann said that Julie Morgan will send an electronic mail message in the next few days about participation in a data workshop in January. This message will ask for input on data products, and gridding for data set compatibility.

Gallager gave a brief discussion in which he suggested the possibility of establishing a long-term data observatory off Palmer Station (cable observatory). He said that this would need to be done through something like a National Ocean Partnership Program (NOPP arrangement with NSF and NASA. He mentioned this because it might be something to pursue in programs that follow SO GLOBEC. He also suggested that such an autonomous mooring might be part of the proposal for the Southern Ocean initiative that is being proposed as part of the IGBP-SCOR OCEANS program.

There being no further business, the meeting was adjourned.