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distribution will require more careful management to assure maintenance of
biodiversity.
iv) Dose-response characteristics of plume fallout – many vent species are sessile or
capable of little locomotion. Some feed by filtering particles from surrounding
seawater. In both cases, the presence of particulate plumes or sediment fallout
from adjacent mining could have adverse affects on their survival even if they
are not directly disturbed by mineral extraction machinery. There is no
published information on dose-response characteristics of vent organisms in
relation to particulate plumes. Test or pilot mining operations would provide
opportunities to conduct this type of study prior to full-scale mining operations.
Such studies need not be site specific since much useful general information can
be derived from monitoring burial of vent organisms or their food supply and
particulate fouling of suspension feeders.
Development of management plans for individual mining sites will require
baseline information on their biological characteristics. These include:
i) Distribution of habitat within the affected area – Hydrothermal emissions are often
correlated with seafloor relief features. Sidescan or pencil-beam sonars provide
detailed topographic information that can be used to develop a basemap.
Submersible video surveys or digital photography can then be used for “ground
truthing” sonar maps to relate relief and textural information to hydrothermal
activity, occurrence of mineral deposits and presence/absence of visually distinct
faunal assemblages.
ii) Species composition and community structure – complete information on species
composition can only come from sampling. This information is vital to questions
regarding the geographic range of the affected species. Since extensive sampling
is costly and time-consuming, an approach that combines synoptic habitat
mapping (see above) with targeted sampling will likely be the best strategy.
iii) Basic biology of species – key here is information concerning the feeding mode of
individual species (i.e. how they will be affected by particulate plumes) and an
understanding of their ability to recolonise a disturbed site (reproductive cycles,
recolonisation potential).
There is no imminent threat to the entire global vent fauna from mining or any
other human activity. Concentration of mining activities in areas such as the southwest
Pacific back arc spreading centres will, however, produce local and even regional effects
on vent organism abundance, to the point where the survival of some species could
become an issue. The challenge to regulators, vent biologists and miners will be to use
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