Davidson Seamount - Ecology

Ecology

Grenadier fish (Coryphaenoides sp.) in front of bubblegum coral (Paragorgia arborea) on the crest of Davidson Seamount, at 1,255 m (4,117 ft) deep. Paragorgia grow to over 2.5 m (8 ft) tall on Davidson; they also grow in Monterey Canyon, but are generally smaller and less abundant.

Studies have indicated that a seamount functions as an "oasis of life," with a higher species count and more biodiversity then the surrounding seafloor. Although previous analysis has stressed the exceptionally of the seamount habitat, recent biological analysis, much of it centered on Davidson Seamount, has indicated that this does not necessarily translate into a higher endemic percentage. However, it is believed that they provide a refuge for rare species that have difficulty surviving elsewhere.

There are reasons that seamounts are biologically important. They rise high in the water column, creating complex current patterns that support life on, around, and above the seamount. The surface of the seamount also provides a substrate upon which organisms can attach themselves and grow. This in turn supports the species that feed on them, in turn supporting the whole ecological food web. Scientists have found that seamounts often provide a habitat for endemic species that are not found anywhere else.

Davidson Seamount is among the best biologically described seamounts worldwide. Six major expeditions to the volcano have yielded over 60,000 species observations. As of 2009 scientists have observed and recorded 168 species of megafauna on the seamount. Of these, about 7% of the species at Davidson are endemic, meaning they live only at Davidson. 71% of the species can be confidently classified as cosmopolitan (widespread), and sufficient data exists for 22% of the observed species to strongly suggest that their range is not limited to seamounts. The remaining 7% have only been seen in video footage. Interestingly, 13 species have been identified in other areas, but never in other seamounts.

The seamount is populated by a large variety of deep-sea corals, most of which in turn provide a habitat for other species. It has in the past been called "An Oasis in the Deep", hosting a vast coral forest, large sponge field, crabs, deep-sea fish, basket stars, and a number of rare benthic species, some of which have yet to be studied properly or even named. These are all cold-water species, as the temperature even at the top of the seamount is just above freezing—around 2 °C (36 °F), as compared to 14 °C (57 °F) at the ocean's surface.

Despite its size, the top of Davidson Seamount remains over 4,500 ft (1,372 m) below the ocean's surface. This great depth means that the habitats that the seamount supports have not been significantly disturbed by human activity; anchoring and trawling typically does not occur below a depth of 1,500 ft (457 m), and waste disposal and discharge occurs much closer to shore.

In comparisons drawn to the nearby Monterey Bay National Marine Sanctuary, the two were shown to be very different biologically. Species that are rare in Monterey Bay are common on Davidson, and vice versa.