Seamounts: Biological Richness and Mineral Wealth

**Statement of Problem**:

Seamounts are submerged extinct volcanic edifices that form individual
or composite cones and ridges. It is estimated that 50,000 seamounts
more than 1 km high occur in the Pacific Ocean, thousands within the EEZ
of the U.S. These seamounts support fisheries, unique biological
communities, and rich mineral deposits. However, little is known about
the distribution of these biogeo-resources on seamounts, the
environmental interactions that promote their biological richness and
mineral wealth, or the external forces that influence seamount surface
processes.

Seamounts are unique in that they obstruct the flow of bottom-water
masses, thereby generating a wide array of seamount-specific currents.
The result of these interactions is turbulent mixing along seamount
flanks and upwelling of nutrient-rich waters. This latter process
supplies nutrients that support fisheries above seamounts, even if the
seamount summit lies at great depth. Another consequent of the
impingement of bottom-water flow is the creation of circular gyres
around the edifices, which may effectively inhibit the dispersal of
larvae away from individual seamounts. If true, this would produce
distinct biological communities even on adjacent seamounts and may
produce a high degree of endemism. These currents also keep parts of
many seamounts sweep clean of sediment for millions of years, which
allows for the accumulation of thick iron/manganese oxide deposits.
These deposits acquire vast amounts of other metals from seawater
because of incredibly slow growth rates (1-6 mm/Ma) and huge specific
surface area (320 m^2^/g). Seamounts support unique environments where
distinct interactions of geological, chemical, biological, and
oceanographic processes produce fisheries, unique biological
communities, and seabed metal deposits.

**Objectives**:

It is essential that we understand the seafloor processes that promote
and maintain fisheries, the unique biological communities, and the
mineral resources on seamounts. It is also necessary to determine the
contributions that seamounts make to biological and mineral resources in
the overall complement of assets found in the U.S. EEZ, so that informed
decisions can be made by policymakers.

**Work Strategy**:

Monitor currents, mixing, and upwelling on selected seamounts within the
U.S. EEZ. Detailed swath bathymetric mapping is essential in
understanding the relationships of topography, habitats, and mineral
resources. Research cruises are needed to determine the complex
interaction of currents with geological, geochemical, and biological
processes on seamounts that promote biological health, endemism, and
high-grade mineral resources.

**Relevance**:

Seamounts are unique deep-ocean features in that they provide benthic
habitats in an otherwise pelagic environment. They support forests of
octocorals and sponges, deep-water coral reefs, and associated diverse
invertebrate communities. They create obstructional upwelling thereby
creating fisheries above their summits. They support the formation of a
unique type of mineral deposit that is a potential resource for an
amazingly wide variety of metals that are critical to our national
welfare. Fewer than 100 of the 100,000 seamounts that occur globally
have been studied in any detail and only a few of those have been mapped
in sufficient detail to understand the relationships of topography,
substrate types, biohabitats, and mineral resources. The physical
oceanographic processes that promote upwelling and fisheries are poorly
known and with the vast decline in fisheries worldwide these processes
must be understood.

**Impact**:

See sections on Statement of Problem and Relevance. Understanding
processes on seamounts is viewed as a priority project for the Census of
Marine Life, and studies of seamount mineral deposits are priority
programs being undertaken by the governments of Russia, China, Japan,
Korea, and India. These resources are viewed as essential to supporting
the rapidly developing economies of China and India. The seamounts
within the U.S. EEZ must be surveyed for their biological richness and
mineral wealth so that informed environmental and resource decisions can
be made by U.S. policymakers.

**Partnerships**:

Partnerships should be developed with NOAA, university scientists, and
international and national organizations dedicated to seamount
biogeosciences, such as the Census of Marine Life (CoML)
([www.coml.org](http://www.coml.org/)); Global Census of Marine Life on
Seamounts (CenSeam)
([http://censeam.niwa.co.nz](http://censeam.niwa.co.nz/)), and the
Biogeosciences Network (SBN)
(<http://earthref.org/events/SBN/2006/index.html>).