A Community Consensus on Designating Vulnerable Marine Ecosystems from Imagery
An initial assessment showed a lack of consistency between FAO regions regarding what is considered a VME species. Another challenge was determining how many images were needed. In certain cases, from a single image, experts agreed that the site should be designated a VME, most often in areas of scleractinian reefs, dense octocoral beds, multiple VME species present together, and chemosynthetic ecosystems. In cases where VME taxa were present but a VME designation could not be made easily from a single image, other factors were considered, with a specific focus on density. We compiled natural density data for indicator taxa from images from 3 oceans to assess whether there was a similar threshold among scientists. Densities varied considerably by taxon, but were not correlated to depth. The mean density of all megafaunal taxa in an image was ~2.5 individuals per m2, but for most individual taxa, densities higher than 1 individual per m2 were rare. In terms of VME designation, values as low as 0.1 colonies per m2 for octocorals and antipatharians were commonly considered to be a VME, with higher values for sponges. These findings are discussed in light of current fisheries management practices and cobalt-rich Mn crust mining.