They challenge the mountain ranges of the Alps, the Andes and the Himalayas in size yet surprisingly little is known about seamounts, the vast mountains hidden under the world's oceans. Now in a special issue of Marine Ecology scientists uncover the mystery of life on these submerged mountain ranges and reveal why these under studied ecosystems are under threat.
The bathymetry of our oceans is now resolved at a scale and detail unimaginable by early pioneers and recent estimates suggest that, globally, there may be up to 100,000 seamounts, yet less than 300 have been well studied. Recognising this scarcity of knowledge provided the motivation for CenSeam, a seamount-focused field research project within the Census of Marine Life which commenced in 2005.
"The field of seamount ecology is rife with ecological paradigms, many of which have already become cemented in the scientific literature and in the minds of advocates for seamount protection," said Dr Ashley Rowden, one of the principal investigators of CenSeam. "Together, these paradigms have created a widely held view of seamounts as unique environments, hotspots of biodiversity with fragile ecosystems of exceptional ecological worth."
The special issue puts major paradigms in seamount ecology under the microscope to assess their status against the weight of existing evidence to date, and against the backdrop of the latest findings.
Researchers challenged the theory that seamounts act as hotspots of species richness, the weight of evidence now suggests that seamounts may have comparable levels of diversity and endemism to continental margins. However, it appears that their ecological communities are distinct in structure, and are of higher biomass than neighbouring continental margins.
The geographical differences between seamount communities have suggested limited larval dispersal, local speciation, geographic isolation, or a combination of all these processes. New genetic research presented in the special issue addresses these themes, documenting complex patterns of connectivity among species populations that depend on spatial scale, physical barriers, and life history characteristics.
Much seamount research has been born out of the need to better manage these potentially vulnerable ecosystems. Globally, seamount ecosystems are under pressure from bottom-contact fishing and other human-related impacts. Researchers detail the footprint of trawling and a risk assessment confirms what has long been suspected: seamount communities are highly vulnerable to disturbance by bottom trawling and recovery from fishing impacts is a lengthy process, likely requiring decades at a minimum.
It is also predicted that shallowing of the aragonite saturation horizon caused by ocean acidification is expected to place deepwater corals at risk, but researchers pose that the summits and upper flanks of seamounts may yet provide a spatial refuge from these impacts.
"It is hoped" says Thomas Schlacher, lead editor of the volume "that the papers in this special issue will challenge some of the previously held concepts about seamount ecosystems, and hopefully stimulate and help guide future research endeavours both on seamounts, and across the wider deep-sea realm."
Research papers from the Census of Marine life have been published in two special issues of the Marine Ecology, published by Wiley-Blackwell. The Census of Marine Life's latest title Life in the World's Oceans: Diversity, Distribution and Abundance, also published by Wiley-Blackwell, which includes the research of CenSeam, will be available in October.
About the Census of Marine Life
The Census of Marine Life is a global network of researchers in more than 80 nations engaged in a 10-year scientific initiative to assess and explain the diversity, distribution, and abundance of life in the oceans. The Census of Marine Life is an unprecedented undertaking that is significantly contributing to understanding of the marine environment and life in the global ocean. Census researchers are discovering new life forms, finding life in unexpected places, advancing technology to create windows into what was an opaque ocean, and building global partnerships to advance what is known about life below the surface. For more information about the Census of Marine Life visit: http://www.coml.org
About the Journal
Marine Ecology is published on behalf of Stazione Zoologica di Napoli and publishes original contributions on the structure and dynamics of marine benthic and pelagic ecosystems, and on the critical links between ecology and evolution of marine organisms. Visit the journal on Wiley-Online Library here: http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-0485
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