Are seamounts threatened biodiversity hotspots?
Seamounts are ubiqitous features in the world oceans. They have commonly been regarded as locations of enhanced productivity and biodiversity and thought to support high levels of endemism. Recent studies question these generalizations and stress the high diversity of seamount types and environmental settings, which may result in very different ecological features.
In this respect, some seamounts may be »hotspots of biodiversity«, whereas others do not differ in species richness from their surrounding. Regardless of whether their biodiversity is enhanced or not, seamount species and communities are affected by several human activities and, due to the low resilience and regeneration potential of seamount and deep-sea fauna, a recovery from disturbances is highly unlikely or will take a very long time.
Currently the industrial fishery is the main threat to seamount ecosystems, with bottom trawls removing not only target species, but also high amounts of bycatch and destroying coral and sponge communities and their associated fauna. Similarly, a possible future mining for ferromanganese crusts at seamounts will result in large-scale destruction of communities and habitats.
The impact of climate change on seamount communities may include an expansion of warm-water species and the displacement of cold water species to higher latitudes or deeper layers in a warming ocean.
Ocean acidification due to rising CO2 levels may particularly affect corals with calcified skeletons and result in substantial changes of the benthic communities at seamounts. Both, pelagic and benthic communities, may be impacted by the expansion of oxygen minimum zones in the tropical oceans. Potential effects of changes in the ocean circulation system can currently not be predicted.