Deep Sea Minerals - Vol 3 - Cobalt-rich Ferromanganese Crusts

2.1

Habitats and biodiversity associated with cobalt-rich ferromanganese crusts

3.1.1 Geographic context In the Southwest Pacific region, crusts form on the summits and flanks of seamounts, especially large flat-topped guyot features (isolated volcanic mountains), at depths of about 400 metres down to 4 000 metres. There are several thousand seamounts

Cobalt-rich ferromanganese crusts (Fe-Mn crusts) are found throughout the global oceans on the summits and flanks of seamounts, ridges, and plateaux. They form only on bare rock surfaces, and are therefore distributed where oceanic currents keep the seamounts free of sediment. The process is very slow, taking millions of years for development of thick crusts.

Biogeography: mapping the distribution of species

Biogeography examines the geographic distribution of fauna and flora, generally at the larger scale of similar faunal communities.

Much of the open ocean has never been sampled, especially the deep sea. Even in the case of seamounts, which have been the focus of international efforts, only a few hundred have been stud- ied, out of hundreds of thousands worldwide. However, we know that the distribution of animals varies considerably between areas.

A biogeographic classification puts together information on biological composition, species distributions, and physical

GOODS Bioregions bathyal

1

2

3

4

14

12

7

11

13

5

6

8

10

9

1. Arctic 2. Northern North Atlantic 3. Northern North Pacific

4. North Atlantic 5. SE Pacific Ridges 6. New Zealand Kermandec

7. Cocos Plate 8. Nazca Plate 9. Antarctic

10. Subantarctic 11. Indian 12. West Pacific

13. South Atlantic 14. North Pacific

Figure 6 Lower bathyal provinces. Depth range 800 to 3000 metres (UNESCO, 2009).

COBALT-RICH FERROMANGANESE CRUSTS 16