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

3.4

Defining characteristics of biodiversity of cobalt-rich ferromanganese crusts

The faunal communities associated with ferromanganese crusts have been described in detail in the preceding section on habitats and ecosystems. There are some key characteris- tics that need to be considered specifically for this environ- ment when assessing potential impacts: • The dominant benthic fauna on seamounts are often ses- sile corals and sponges. These may include species with a wide distribution as well as those that are endemic or only occur in a small region. Their slow growth rates and high longevity make recovery from disturbance either unlikely or very long-term. • It is uncertain whether seamounts with ferromanganese crusts have different fauna from non-ferromanganese-crust features. This uncertainty needs to be addressed. If there is

no difference, then mining sites and protected sites should be relatively easy to select. If there are distinct communities specific to seamounts with ferromanganese crusts, then con- servation strategies will need more detailed evaluation. • Faunal composition changes with water depth, and sea- mounts have a large depth range. As the species compo- sition and abundance change, so too do the vulnerability/ resilience of benthic communities. Therefore, the depth of an extractive activity must be considered when developing management plans or designing for conservation. • Knowledge of the biodiversity associated with ferromanga- nese crusts is poor, and considerable basic data need to be collected during the exploration phase of any mineral development.

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