1. INTRODUCTION

The Meridional Overturning Circulation (the global oceanic thermohaline circulation) is an important part of the global transport of heat from the tropics to the higher latitudes. The nature of water mass exchange between ocean basins, affects the physical layout of this circulation belt and its effectiveness in controlling climate (Gordon, 1986; Rintoul, 1991; Speich et al. 2001). The Antarctic Circumpolar Current (ACC) is the largest location for this exchange, it is unhindered around Antarctica, it is the main means for heat, salt and water are exchanged between the different ocean basins.

1) The Antarctic Circumpolar Current (ACC) is the only current connecting all three main ocean basins, thus vital fresh water and heat route.

2) Within the Subantarctic belt, the Southern Ocean supports a strong coupling between the atmosphere and ocean, through the formation of Antarctic Intermediate Water and Subantarctic Mode water, has a polar-extrapolar linkage of freshwater, heat and CO2. These water masses move north, injecting low salinity cool water into and along the foot of the main thermocline.

3) South of the Antarctic Circumpolar Current, Circumpolar Deep Water upwelled, provides a transport route of heat from greater than 2000m to the atmosphere and cryosphere.

4) The formation of very dense, cold Antarctic Bottom Water.

5) The Antarctic sea ice fields are mobile and changeable surfaces, whose expanse and characteristics possible affect the global radiative budget and therefore the global climate.

6) The large-scale coherent changeability of atmospheric circulation in the Southern Ocean and these variations mechanisms and geographic linkage, are directly involved in the anomaly propagation over the different climate zones.

Figure 1: Schematic diagram indicating the average location of the subsurface temperatures indicators of the STC (10ºC), SAF (6ºC), and APF (2ºC), south of South Africa. The 1ºC isotherm is representative of the SACCF, which is located below the Tmin.

The formation of Southern Ocean water masses and their circulation paths require an understanding for the interpretation of temperature and salinity variability noted in the ocean interior. Deep ocean may supply changes in heat, affecting the atmosphere directly or through sea ice changes. Regular hydrographic observations are vital to describe and improve the dynamic and physical processes, which are responsible for the ACC variability since these exchanges have a vital role in regulating the mean global climate (Budillon and Rintoul, 2003). The majority of the flow linked with the ACC is centered at various circumpolar fronts, acting as boundaries separating areas of uniform water masses (Whitworth, 1980) (Figure 1). From the north to the south, the fronts and associated areas of the Southern Ocean are: Subtropical Convergence (STC), Subantarctic Zone (SAZ), Subantarctic Front (SAF), Polar Frontal Zone (PFZ), Antarctic Polar Front (APF), Antarctic Zone (AAZ) and the Antarctic Divergence (AAD).

The Southern Ocean, south of Africa, has a special role in providing a source of heat moved equatorward into the South Atlantic. It has been suggested by Speich et al. (2001, 2002) that the differences in water masses between the Atlantic and South Indian Oceans would be by far, more notable were it not for various smaller inter-ocean links. In the South of Africa, water masses originally from the Indian Ocean are injected to the South Atlantic from both filaments of the Agulhas Current Water (Lutjeharms and Cooper, 1996) and anticylonic ring shedding processes in the region of the Agulhas Retroflection region (Lutjheharms and van Ballegooyen, 1988). Suggestions from recent modeling studies of the global ocean circulation, are that Indo-Atlantic interocean exchanges through the Agulhas Current system are by far, more important than direct water input from the Drake Passage for the thermohaline circulation (Speich et al., 2001, 2002). Estimates of mode and intermediate water percentages entering via the Agulhas region to the Atlantic are highly variable, ranging from 0% (Rintoul, 1991) to 50% (Gordon et al., 1992). It is vital the inflow of Indian waters into the Atlantic Ocean is properly quantified and monitored to understand the role of the key component of the MOC on global ocean circulation and its possible role in the climate.

The objective of the GoodHope Programme is to set up an intensive monitoring platform, providing detailed information on volume flux and physical structure of interbasin exchanged water, south of South Africa. To implement a high-density XBT line is a key section of this programme. The GoodHope programme has 4 advantages:

1) It is approximately located with the TOPEX/POSEIDON – JASON 1 altimeter ground-tracks, serving to ground-truth the data of altimetry-derived sea height anomaly;

2) South of 50ºS (Southern part of the line) is currently monitored by moorings investigating deep and bottom water formation in the Weddell Sea, and deployed in the WECCON project of the Alfred Wegener Institute for Polar and Marine Research;

3) There is overlap in the northern section of the GoodHope programme with the USA – ASTTEX program, linking observations in the Southern Ocean with data collected in the Benguela region and the west coast of Southern Africa. ASTTEX analyses fluxes of heat, salt and volume entering the South Atlantic Ocean from the Agulhas Retroflection, hence providing quantitative and Eulerian measurement of the characteristic and strength scales of the mass and volume transport of the Agulhas Current into the South Atlantic. Altimetry observations illustrate that Agulhas rings are shed intermittently with no ring formations of up

to several months, requiring confirmation from a single consistent in-situ and

hydrographic observations (Byrne, 2000). GoodHope will provide extra support

while examining the scale and nature of the Indian Ocean water injection into the

southeastern South Atlantic via the Agulhas Retroflection; 4) GoodHope will assist in the data collected by the two Pressure inverted Echo Sounder (PIES) moorings already located along this line.

Ongoing observations for example repeat transects along AX25 will provide the only way to analyze the vertical structure and investigate the front variability in the area. Year-to-year and longer period variability in the fluxed will be analised for example those linked to the Antarctic Circumpolar Wave. Since the 1970’s, intense and regular monitoring has been undertaken in the Drake Passage (Sprintall et al., 1997) and south of Tasmania (Budillon and Rintoul, 2003). The third Southern Ocean “choke point” between South Africa and Antarctica, was only initialized during the first GoodHope cruise in 2004.

Figure 2: An illustration of the three major ‘chokepoints’ of the ACC. The GoodHope transect (the solid yellow line) objective is to obtain detailed information on physical, biological and chemical structures of the waters south of Africa.

Pelagic fauna species are highly mobile and are quick to utilize any available food source. The distribution of predatory pelagic species is therefore not random through the southern ocean but is dependant on the type and quantities of the available food resource. In the Southern Ocean krill (Euphausia superba) is the keystone species which drives the entire food chain. Certain species of birds, fish, seals and whales all specialize in utilizing this resource. Fish and cephalopods are also very important food resources for Antarctic bird species. In comparison to the pelagic fish and mammal species, birds are easy to identify and count from a moving vessel. It is for these reasons that birds are the preferred visual indicator of the productivity of any particular piece of open ocean. Due to the lack of historical sampling the foraging and dispersal ranges of many pelagic bird species are incompletely known. The data collected on this voyage will therefore assist in obtaining a clearer understanding of the dispersal ranges of oceanic bird species. Another major objective was also to correlate bird species and densities with the physical data collected by the oceanographers. On both the GoodHope lines the oceanographers deployed XBT’s which capture temperature profiles to a depth of approximately 900m. These results indicate the precise locality of the oceanic fronts. It has long been recognized that these oceanic fronts are hotspots for biological productivity and it is speculated that these areas harbour a higher faunal biomass than the surrounding ocean. These fronts are also regarded as biogeographical barriers to the distribution of plankton.

Pelagic bird species are primarily surface feeders with most species such as Antarctic Petrel (Thalassoica antarctica), Kerguelen Petrel (Aphrodroma brevirostris) & Pintado Petrel (Daption capense) utilizing surface-seizing and surface-plunging to acquire their food. Some pelagic species, such as Sooty Shearwater (Puffinus griseus) and White-chinned Petrel (Procellaria aequinoctialis) are capable of pursuit-plunging and surface-diving to a maximum of 13 meters. The penguin species, however, are specialized for foraging at far greater depths with Emperor Penguin (Aptenotytes forsteri) being recorded to depths in excess of 500 meters.

Food resources are undoubtedly the major factor influencing bird distribution in the open ocean but it is important to consider other factors such as:

1) The proximity to breeding islands.

During the austral summer the pelagic birds return to Antarctic and Sub-Antarctic islands or ice free areas of the continent itself. During this time the breeding birds have to make regular visits to their nests to feed chicks or to take over incubating duties. This will effectively limit the foraging range of many species during the breeding season.

2) Inter-specific competition

Several species share similar distribution ranges and will compete directly for food recourses. No two species will occupy the same ecological niche and would have physiological and behavioral adaptations in order to minimize direct competition. It is however likely that where one species is particularly dominant it could potentially exclude another species.

3) Range of tolerance

Many species are most abundant within a certain range of latitude. A ‘sister’ species may however occupy a very similar niche but be more abundant within a different range of latitudes. Such species minimize inter specific competition by being adapted to different environmental pressures. For example, Light-mantled Sooty Albatross (Phoebetria palpebrata) generally occurs at more southerly latitudes than Dark-mantled Sooty Albatrosses (Phoebetria fusca). Individuals will venture from their preferred range of tolerance but these individuals can be regarded as vagrants.

Oceanic birds are vulnerable to human induced threats. This has resulted in the decline in the populations of many species. Some species have declined to critical levels and extinction will result if causal factors continue. The major threats are:

- Disturbance of breeding sites primarily through the introduction of exotic fauna and flora. Most problematic are rats, mice and cats.

- Bycatch from the long-line fishing industry has become a major threat in recent years.

- Reduction in prey species through human harvesting and more seriously through climate change.

- Competition for nesting sites with seals on breeding islands

- Pollution; the ingestion of plastics is a serious problem to certain species. Prions and Storm-petrels are particularly adversely affected.

Chlorophyll A

The primary producers of the ocean are phytoplankton, which form the base of the open ocean food chain. The presence and abundance of phytoplankton are influenced largely by the availability of nutrients, carbon dioxide and sunlight. The luminescent shrimps (Euphausiacea) are the most important primary consumers dependant on these phytoplankton blooms. The most important of these is the 3 – 6 cm long Antarctic Krill (Euphausia superba). Krill is consumed by Cetaceans, Seals, Fish, cephalopods and forms an important food source all Antarctic bird species. The abundance of phytoplankton in a particular area is a reflection of the productivity of that area. It is important to note that these phytoplankton blooms usually occur in isolated patches for a limited time and are dependent on the abiotic conditions. The quantities of phytoplankton can be crudely assessed by sampling the amount of Chlorophyll A in the water. Once this data is processed it can be compared to the abiotic data and to the bird data. It is also important to note that birds do not feed directly on phytoplankton but mainly on large zooplankton (Krill) and nektic organisms such as fish and cephalopods which are at a higher trophic level. There therefore may not be a direct correlation between bird numbers and diversity and the Chlorophyll A results.

2. STANDARD PROCEDURES: OCEANOGRAPHIC

2.1. XBT

High-density observations are required when effectively measuring oceanic variability of heat fluxes, notable across areas of interbasin exchange. Measurements of change in heat content and SST of the upper ocean both seasonally and inter-annually are provided by repeated XBT’s on the ‘chokepoint’. XBT’s may also be used to infer velocities, including in the Southern Ocean, where salinity variability is import, by manipulating the relationship between dynamic height and upper ocean temperatures (Rintoul and Sokolov, 2001; Legeais et al., 2006). Therefore, XBT sections are important method to measure variability in the interocean heat exchange.

For GoodHope VII and GoodHope VIII, XBT’s were funded by the NOAA’s Office of Global Programs as part of their High Density XBT project at NOAA/AOML. For GoodHope VII, A total of 183 Sippican Deep Blue XBT’s were deployed between 33.85º S, 17.61º E and 69.94º S and 3.76º W (Figure 3). Deployment occurred at approximately 15 nautical mile intervals, increasing to every 10 nm approximately over the main frontal regions. Positions of XBT deployment is given in Appendix 1. In total, 8 XBT’s (~4%) failed, mainly resulting from strong winds combined with sea swell pushing the copper signal wire against the ship’s hull, resulting in the stretching of the XBT wire, therefore insulation leakages. For GoodHope VIII, a total of 171 Sippican Deep Blue XBT’s were deployed (Figure 4), of which 5 (~3%) failed. These XBT deployment positions are given in Appendix 2.

Data related to the GoodHope VII and GoodHope VIII XBT transects may be obtained from:

http://www.aoml.noaa.gov/phod/hdenxbt/high_density_home.html

Figure 3: Position of all XBT stations (red dots) and all Argo Float deployments (green diamonds) during GoodHope VII.

Figure 4: Position of all XBT stations (blue dots) deployed during GoodHope VIII.

3. RESULTS

3.1. FRONTAL LOCATIONS

The main characteristic of the Southern Ocean is the strong zonal nature of the main frontal bands with the spatial structure highly determined by the flow regime and position of multiple frontal systems indicating different ACC Zones (Belkin and Gordon, 1996). In the last 30 years, extensive measurements have been made in the South Indian and South Atlantic sections of the Southern Ocean (Lutjeharms and Valentine, 1984; Lutjeharms, 1985; Lutjeharms and McQuaid, 1986; Lutjeharms, 1990). During AJAX (Whitworth and Nowlin, 1987), SR2 WOCE (Roman, 2003) and opportunistic basis enroute to the ice edge, full depth CTD measurements were made. The frontal characteristics of the Greenwich Meridian line area are less variable and intense, as inferred from altimetry and historic hydrographic data (Lutjharms et al., 1993). This is dissimilar to other areas of the Southern Ocean, including Drake Passage and South Georgia (White and Peterson, 1996), the South-West Indian Ridge (Park et al., 2001; Pollard and Read, 2001; Ansorge and Lutjeharms, 2003) and south of Australia (Sokolov and Rintoul, 2002; Budillon and Rintoul, 2003), where frontal systems illustrate bands of high variability including enhanced eddy activity.

To track the upper level circulation linked with baroclinic shear, the identification of the main ACC fronts is vital. However, accurate identification of the fronts is not always easy, notable in areas where they are joined (Park et al., 2001). One notable difficulty is the numerous definitions given for characterizing the fronts bordering the ACC (Belkin and Gordon, 1996). These definitions are based on surface or subsurface property values, while others are based on phenomenological definitions, depending on the author. Table 3 is based on definitions set by Belkin and Gordon (1996), including surface and subsurface ranges. The location of the ACC fronts for GoodHope VII and GoodHope VIII is given in Table 4.

Table 3: Fronts definitions bordering the Antarctic Circumpolar Current

FRONT	SURFACE	SUBSURFACE
STC	10.6 – 17.9ºC: 34.3 – 35.5	8.0 – 11.3ºC: 34.42 – 35.18 Axial Value: 10ºC, 34.8
SAF	6.8 – 10.3ºC: 33.88 – 34.36	4.8 – 8.4ºC: 34.11 – 34.47 Axial Value: 6ºC, 34.3
APF	2.5 – 4.1ºC	Axial Value: 2ºC

The definition of the subsurface expression of the APF, the definition determined by Orsi et al. (1995) where the axial value marking the intersection of the 2ºC isotherm at 200m, is used. Intensive analysis by Belkin and Gordon (1996) indicate the subsurface APF and SAF axial values to remain fairly constant between 0º and 150ºE.

Figure 5: XBT data producing a temperature section along GoodHope VII. The dashed isotherms indicate the subsurface axis of the STC (blue - 10ºC), SAF (orange - 6ºC), APF (green - 2ºC) and SACCF (red - 0ºC).

Figure 6: XBT data producing a temperature section along GoodHope VIII. The dashed isotherms indicate the subsurface axis of the STC (blue - 10ºC), SAF (orange - 6ºC), APF (green - 2ºC) and SACCF (red - 0ºC).

3.1.1. SUBTROPICAL CONVERGENCE

The boundary between salty, warm subtropical surface water and fresher, cooler Subantarctic Surface Water (SASW), in the south, is separated by the Subtropical Convergence (STC). This is the extreme northern front of the ACC (Figure 1) and is the most indicative surface thermal front. It is indicated from over 70 XBT data collections from crossing the STC in the South Atlantic, the STC has an average location at 41º40´S (Lutjeharms, 1985).

The 10ºC isotherm at 200m is the subsurface expression of the STC. In GoodHope VII, the subsurface indicator of 10ºC at 200m of the STC is located at 40ºS, further north than in previous years while in GoodHope VIII it was found at 40.2°S. Two different fronts linked with the Northern (NSTC) and Southern (SSTC) of the STC have been noted in previous studies of the South East Atlantic section of the Southern Ocean (Smythe-Wright et al., 1998). These observations have been the result of more than 10 datasets ranging from the South Atlantic from the Brazil Current (located at 42ºW) to the Agulhas – Benguela area (at 11ºE).

3.1.2. SUBANTARCTIC FRONT

The Polar Frontal Zone (PFZ) has the Subantarctic Front (SAF) as the northern boundary, a transitional zone between the SASW and AASW. Compared to the STC (noted as sharp and consistent gradient in both surface and subsurface expressions, hence identification remarkably easy) (Lutjeharms and Valentine, 1984, Lutjeharms, 1985), the SAF is less clear in the surface expression. As a result of the weak nature of the PFZ, the precise boundaries may be difficult in identifying. While the SAF is notably a subsurface front (defined from the most vertically orientated isotherm of temperature gradient between 3ºC and 5ºC), its surface expression is between 8ºC and 4ºC (Lutjeharms 1985). While Lutjeharms and Valentine (1984) identify the SAF with an average position of 46º23’S of Africa, Belkin and Gordon (1996) note the criteria where the temperature range subsurface is 4.8 – 8.4ºC and 34.11 – 34.47 at 200m, with axial values of 6ºC and 34.3. In GoodHope VII, the subsurface criteria show the SAF to lie at 44.6ºS. In GoodHope VIII, the subsurface expression of the SAF is found at 44.5°S. The SAF seems to be substantially wider compared to other areas in the Southern Ocean (Belkin and Gordon, 1996). Recently, investigations (Smythe-Wright, 1998) indicate the SAF in the South Atlantic, is often a wide frontal band extending over 250km.

3.2. AVIFAUNAL DISTRIBUTIONS

3.2.1. GOODHOPE VII

The ship departed from Cape Town on 7 December 2006 and arrived at the Antarctic shelf on 20 December 2006. The ship encountered heavy pack ice at 70° 23.8’ latitude and had to reduce speed drastically and was forced to regularly change direction in order to navigate through the ice. The counts were therefore discontinued on 17 December 2006. The course followed was the predetermined GoodHope line. This was the GoodHope VII line and entailed the ship steaming west-south-west from Cape Town until it reached the Greenwich Meridian at about 52° 30.0’ South. From this point it headed due south. As such the ship passed 129 NM west of Bouvet island which is an important breeding locality for numerous species including, Macaroni Penguin (Eudyptes chrysolophus), Pintado Petrel (Daption capense), Southern Fulmar (Fulmarus glacialoides). As it is in the peak breeding season for pelagic bird species it can be expected that birds breeding on Bouvet would be more numerous in the vicinity of the island.

A total of 83 hours of counts were conducted on this leg. See Appendix 1.

Figure 8: Total number of birds encountered along the GoodHope VII transect.

The highest six data points (above a total number of 60) were excluded from Figure 8 in order to allow more detail on the graph. The peak in the number of birds (a value of 532) was at 49º 41’S.

3.2.2. GOODHOPE VIII

The route of the South Sandwich buoy run proceeds in close proximity to numerous breeding islands that are important for pelagic bird species. This includes the 13 island SS archipelago and the island of South Georgia. The route goes to the South Thule Islands and then to 35°W. The ship steamed along this latitude to 50°S where a buoy was deployed. The ship deviated from 35°W in order to steam past the island of South Georgia. The ship returned to RSA Bukta via Zavodovski, Candlemas and Montagu Islands. Montagu was in the process of erupting and it was requested that we obtain some photographs of this event. Unfortunately the island was in heavy mist and we were only able to see the base of the island. Mist was a constant factor of this leg and often rendered bird observation impossible. This was particularly the case north west of South Georgia.

A total of 141 hours of counting was conducted on this leg. An evening count of birds returning to South Georgia was conducted and while waiting for the mist to lift at Montagu another count was conducted of birds near the island. See Tables 5 and 6.

Table 5: Bird counts conducted along south-east coast of South Georgia on 12 January 2007^♦

SPECIES	TOTAL	NOTES
Wandering Albatross	2	Adults.
Black-browed Albatross	30
Light-mantled Sooty Albatross	4	Adults.
Giant Petrel sp.	25
White-chinned Petrel	>240	2 Rafts on water. 40 & 80 individuals respectively.
Snow Petrel	2
Diving Petrel sp.	28	Probable that both P. urinatrix & P. georgicus present.
Antarctic Prion	>10000	Abundant. 1000’s continually streaming past the ship

		towards Island.
Wilson’s Storm-petrel	>500
Black-bellied Stormpetrel	2
Sub-Antarctic Skua	2
Gentoo Penguin	>125
Macaroni Penguin	>100
South Georgian Shag	10
Antarctic Tern	2

♦

Distance from Island: 4 NM, Ship speed: 6 knots, Surface Temperature: 3.7 ºC, Starting Position: 54º 54.0’ S 35º 54.5’ W, End Position: 54 º 46.2’ S 35 º 38.0’ W, Starting Time: 20h00 GMT, End Time: 22h00 GMT.

Table 6: Bird counts conducted along the Northern coast of Montagu on 17 January 2007^■

SPECIES	TOTAL	NOTES
Pintado Petrel	36
Southern Fulmar	88
Southern Giant Petrel	2
Kerguelen Petrel	2
Snow Petrel	7
Black-bellied Stormpetrel	1
Sub-Antarctic Skua	1
Chinstrap Penguin	43

■

Distance from Island: 3 NM, Ship speed: 4.1 knots, Surface Temperature: 0.3 ºC, Starting Position: 58º 22.2’ S 26º 24.4’ W, End Position: 58 º 21.9’ S 26 º 32.1’ W, Starting Time: 09h00 GMT, End Time: 09h35 GMT, Wind Speed: 34 knots, Wind Direction: 79º.

3.2.3. SOUTH SANDWICH ISLANDS

A total of 6608 individual birds comprising 29 species were encountered within the transect during the GoodHope VII leg. Antarctic Prion were the most commonly encountered species in the transect, with 2776 individuals being recorded. This amounts to 42.01% of all the birds recorded on this leg. The second most numerous species recorded was Chinstrap Penguin (Pygoscelis antarctica). These records refer to birds seen at the surface of the water and less regularly, roosting on ice within the transect. The high numbers of Chinstrap Penguins along this route can be expected due to the estimated 1.5 million pairs on the South Sandwich Islands. Due to their flightless nature and exceptional diving abilities it is highly likely that penguins are largely undercounted compared to other bird species.

Kerguelen Petrels (Aphrodroma brevirostris) outnumbered Soft-plumaged Petrels (Pterodroma mollis), with 350 and 317 individuals being recorded respectively. This can be explained by the fact that Soft-plumaged Petrels prefer lower latitudes than Kerguelen Petrels and this leg was limited to latitudes above 50ºS. It is of interest to note that the closest that both these species breed to the South West Atlantic is Gough Island 1310 NM to the north-east. The presence of so many individuals of these species is an indication that they have very large foraging ranges while breeding. There is also the possibility that there may be undiscovered breeding localities closer to these foraging areas.

Landfall was made on SouthThule, the south-west island in the South Sandwich archipelago. The time on the island was limited to 30 minutes due to descending fog. This limited time frame did not allow time for counts of the Chinstrap Penguin (Pygoscelis antarctica) and Adelie Penguin (P. adeliae) breeding colonies. At suitable sites photographs were taken and the exact position recorded with the use of a GPS. This will allow subsequent visitors to the island to take similar pictures allowing for comparisons. This method will enable visitors to the islands with no ecological training to contribute to the project by taking photos or videos from fixed points.

The ship deviated from the 35ºW line of longitude in order to pass close by South Georgia. On the evening of 12 January 2007 an estimate of all the birds seen between 58º 22.2’ S 26º 24.4’ W and 58 º 21.9’ S 26 º 32.1’ W was conducted. The results of this are expressed in Table 5. The most abundant species off the south-east coastline of the island, where the count was conducted, was Antarctic Prion with thousands of Prions continually streaming past the ship towards the island. Wilson’s Storm-petrel numbered over 500 and vastly outnumbered the Black-bellied Storm-petrels (Fregetta tropica) of which only two individuals were seen. Both Macaroni and Gentoo Penguin (Pygoscelis papua) were observed returning to the island, the latter being more numerous.

In the hope that the mist may lift off Montagu to allow photographs to be taken of the volcanic activity, the ship steamed slowly 2.8 NM off the northern shore. The ship was going too slowly to conduct regular counts so all the birds seen on the portside of the vessel were counted. The results are expressed in Table 6. The three most numerous species recorded, namely, Southern Fulmar, Chinstrap Penguin and Pintado Petrel, were the three most abundant breeding species on the South Sandwich Islands. Both Kerguelen Petrel (2 individuals) and Black-bellied Storm-petrel (1 individual) were recorded in close proximity to the island but are not known to breed on Montagu. Kerguelen Petrel is not recorded as nesting anywhere in the archipelago while small numbers of Black-bellied Storm-petrel have been recorded as nesting only on Candlemas in the group.

4. CONCLUSIONS

The Antarctic Circumpolar Current (ACC) is important as a link in the overturning of the global thermohaline circulation. The characteristics of water masses associated with the ACC and the modifications there of thus forms a crucial function in the maintenance of both the global heat and salinity budgets. An observational goal for many years has been the determination of the transport flux of the ACC south of Africa. During the World Ocean Circulation Experiment (WOCE) in the 1990’s, such observations were conducted, where by repeat transects across the ACC were restricted to 3 chokepoints. In both the Drake Passage and south of Tasmania intense and periodic monitoring have continued since WOCE, however only very recently has a monitoring line between South Africa and Antarctica been established.

Due to a severe lack of observations, the understanding of how and why the ACC transport varies inter-annually and seasonally is relatively poor. Thus the sources, pathways and characteristics of the heat and salinity exchanges are not recognized enough to quantify their influence on the climate system south of Africa. It is therefore the aim of GoodHope to establish an intensive monitoring line, providing new information of the volume flux in this region, particularly the Indo-Atlantic exchange. The empirical relationship between upper ocean temperature and the baroclinic transport stream from these repeat hydrographic sections across the ACC, south of Africa, is currently being investigated. This empirical relationship could then be applied to all past and future observations to monitor the variations and variability of the ACC south of Africa. It will thus be possible in the future to extrapolate the behavior of the ACC, particularly its seasonality and inter-annual variability, by defining a second empirical relationship between surface dynamic height and cumulative transport and (Rintoul and Sokolov, 2001).

The comparison between the eight GoodHope cruises also shows the effects of seasonality on the position and strength of the main frontal cores. It is thus hoped that another outcome of the GoodHope project is the establishment of a long time monitoring line to establish a clearer understanding of the seasonal behavior of the frontal regions.

The start of a new and exciting multinational and inter-disciplinary endeavor has thus begun, aimed at integrating high-resolution physical, biological, and atmospheric observations with along-track satellite and model data. A clearer understanding of the Indo-Atlantic inter-ocean exchange in this region of the Southern Ocean, as well as its impact on both regional and global climate change is anticipated to be the end result of the GoodHope project.

5. RECOMMENDATIONS

It is strongly recommended that an effort be made to include a bird observer on similar cruises. Repeating the methods used and obtaining comparable data for different regions of the Southern Ocean would be invaluable in contributing to the knowledge of at-sea distributions of seabirds. This would contribute to monitoring, for example, the effect of direct human impact (long-line fishing etc.) and global warming on various species, their breeding success and the pelagic distribution patterns. The correlation between the Avifaunal data collected and the Antarctic Circumpolar Current Fronts should be subject to further statistical analysis in order to determine the exact associations between these two components, if any.

In future if no bird observers are present on voyages the Meteorologists or other scientists landing on any island should be requested to photograph the penguin colonies from predetermined points.

6. LIST OF PARTICIPANTS AND AFFILIATIONS

INSTITUTE ADRESSES

UCT (Oceanography)

UCT (P. Fitzpatric Institute)

Ocean Climatology Research Group Department of Oceanography University of Cape Town Rondebosch 7701 South Africa sswart@ocean.uct.ac.za

Percy Fitzpatric Avian Institute Department of Zoology University of Cape Town Rondebosch 7701 South Africa pryan@botzoo.uct.ac.za

7. ACKNOWELEDGEMENTS

The survey would not have been a success without the invaluable assistance of Captain Jonathon Wanliss, the officers and crew of the S.A. Agulhas. We would like to extend our gratitude to Robert Roddy, Jim Farrington and all the rest at NOAA and OPG/NOAA for their support and incredible generosity towards the cruise. We would like to thank Henry Valentine, and Sam Oosthuizen of the South African National Antarctic Program for the help they give us in dealing with the administration and planning procedures for GoodHope VII and VIII.

8. REFERENCES

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Byrne, D.A. (2000). From the Agulhas to the South Atlantic: Measuring Interocean Fluxes, Ph. D. thesis. 181 pp., Columbia Univ., New York.

Gordon A.L. (1986). Interocean exchange of thermocline water. J. Geophys. Res. 91, 5037 -5046.

Gordon, A.L., Weiss R.F., Smethie W.M. and Warner J. (1992). Thermocline and intermediate water communication between the South Atlantic and Indian Oceans.

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9. APPENDIX Appendix 1: Positions of all XBT underway stations occupied during GoodHope VII

Appendix 2: Positions of all XBT underway stations occupied during GoodHope VIII (between Antarctica and Cape Town).