About the Ross Sea
The Ross Sea lies 3500 km south of New Zealand next to the Antarctic continent. It is one of two areas around Antarctica with a wide continental shelf (the other being the Weddell Sea on the opposite side of Antarctica).
Where is the Ross Sea?
This image of the Ross Sea is coloured to show the average concentration of chlorophyll-a (proxy for phytoplankton abundance) in the summer. High concentrations are shown in red, and low concentrations in blue and purple. Data are used courtesy of NASA, USA.
The area covered by the food-web model
The Ross Sea region chosen by NIWA scientists for the trophic model covers the continental shelf and slope. The model region has a total area of 637 000 km2, almost two and a half times the land area of New Zealand. It is bounded:
- to the north by the 3000 m depth contour and by 69° S line of latitude
- to the south by the permanent ice shelf
- to the east and west by land, and the 160°W and 170°E meridians.
How deep is the Ross Sea?
The bathymetry (undersea contours) in the region shows that:
- 30% of the study region is shallower than 500 m
- 40% of the region has depths 500–1000 m
- 30% is deeper than 1000 m.
To the north and east of the Ross Sea, the depth quickly reaches more than 3000 m.
Why choose this study region?
The study region was chosen because:
- The 3000 m bathymetric contour approximates the location of the Antarctic Slope Front which in part hydrodynamically separates the study region from the rest of the Southern Ocean.
- It covers the main fishing grounds for adult Antarctic toothfish comprising Small-Scale Research Units (SSRU) 88.1H–88.1L, and some of SSRU 88.2A.
- It is thought to include the main nursery grounds for juvenile and sub-adult toothfish.
- It encompasses the intense localised burst of primary production associated with the Ross Sea polynya (summer openings in the ice) adjacent to the permanent ice shelf.
- It is similar to regions used in previous research, allowing us to use published information when other data are limited. McMurdo Sound is located in the southwest corner of the Ross Sea. It has been extensively studied, partly because it is home to the long-term Antarctic research stations of New Zealand (Scott Base) and the United States (McMurdo Station).
Below the permanent ice shelf
We exclude the ecosystem below the permanent Ross Ice Shelf, as we assume that it plays a small role in the ecosystem of the larger Ross Sea region – an assumption to be tested in the future.