Underwater mountains obstruct ocean currents, forcing deep, nutrient-bearing water upward. So seamount ecosystems are fertile compared with the surrounding ocean, and they support unique organisms. Many of them have adapted to the cold, dark conditions with slow growth and long lives. Orange roughy, which reach sexual maturity at between 20 and 30 years of age, can live to be 150.
Some deep-sea corals have been dated to 4,000 years old. They were growing when Moses led the Israelites out of Egypt, says Mr. Norse.
Scientists think that many seamount species are endemic, existing only there. One survey near Tasmania found that perhaps one-third of the invertebrates were endemic. Between 24 and 43 percent were new to science. Researchers have also found that seamounts closed to trawling had double the biomass and nearly half again as many species compared with those that were trawled. The high rate of unique species, plus the ecosystem’s sensitivity to disturbance, leads many to conclude that seamount trawling will lead to extinctions.