Nav: Home

Hawaiian submarine canyons are hotspots of biodiversity and biomass for seafloor animal communities

April 07, 2010

Underwater canyons have long been considered important habitats for marine life, but until recently, only canyons on continental margins had been intensively studied. Researchers from Hawaii Pacific University (HPU) and the Universtiy of Hawaii at Manoa (UHM) have now conducted the first extensive study of canyons in the oceanic Hawaiian Archipelago and found that these submarine canyons support especially abundant and unique communities of megafauna (large animals such as fish, shrimp, crabs, sea cucumbers, and sea urchins) including 41 species not observed in other habitats in the Hawaiian Islands The research is published in the the March issue of the journal Marine Ecology.

The researchers used both visual and video surveys from 36 submersible dives (using UHM's Hawaii Undersea Research Laboratory submersibles Pisces IV and Pisces V) to characterize slope and canyon communities of animals at depths of 350-1500 meters along the margins of four islands of the Hawaiian Archipelago. The coastlines of Oahu and Molokai were selected as examples of high, mountainous islands with large supplies of terrestrial and marine organic matter which can be exported down slopes and canyons to provide food to deep-sea communities. Nihoa Island and Maro Reef were chosen to represent low islands and atolls that are likely to export less organic matter to feed the deep-sea fauna.

Eric Vetter, the lead author of this paper and a Professor of Marine Biology from HPU, had previously studied four canyon systems off the coast of California and found that the productive waters along southern California had resulted in the delivery and accumulation of substantial amounts of organic material. "Craig Smith (Professor of Oceanography at UHM and co-author of this study) and I wondered if the same dramatic contrast in benthic food resources between canyon and non-canyon settings seen in continental margins would also occur on tropical oceanic islands," says Vetter. "We reasoned that the low productivity in tropical regions would result in reduced source material for organic enrichment in canyons and that steep bathymetry combined with curving coastlines would limit the area over which material could be transported to individual canyons. On the other hand we thought that any amount of organic enrichment might have a measureable effect given the very low background productivity."

Canyon systems can enhance abundance and diversity of marine life by providing more varied and complex physical habitats, and by concentrating organic detritus moving along shore and downslope. On most continental margins, the continental shelf and slope are dominated by soft, low-relief sediments; in contrast, canyons crossing these margins often have steep slopes, rocky outcrops, and faster currents that can support fauna with diverse habitat requirements. The margins of oceanic islands generally are steeper than continental margins, making the physical contrast between canyon and non-canyon habitats potentially less dramatic than along continents. "We wanted to learn, given all of these differences, if tropical oceanic islands would be regions of special biological significance, particularly in terms of productivity and biodiversity," says Vetter.

To conduct the research off Oahu, Molokai, and Maro Reef, Vetter, Smith and UHM Doctoral student Fabio De Leo took turns in the submersibles counting marine life on the ocean bottom using visual transects and recording results into a voice recorder. The survey off of Nihoa Island was conducted using a video recorder attached to the submersible. The results of the 36 surveys showed that the highly mobile megafauna (like fish, sharks, shrimp and squid) were much more abundant in the canyons than on the open slopes at all depths studied. This suggests that canyons provide an especially good habitat for mobile species that are able to feed on accumulated organic matter but can escape the physical disturbances in canyons resulting from high currents and mobile sediments (e.g., migrating sand ripples).

"Perhaps the biggest surprise of this study was the large number of species, 41, that we found only in canyon habitats", says Smith. "This suggests that canyons support a substantial specialized fauna that would not exist in the Hawaiian archipelago in the absence of canyons. Thus, submarine canyons are contributing uniquely to biodiversity in the islands and merit careful attention for environmental protection and management."

The elevated abundance and biodiversity of megafauna (especially highly mobile species of fish and crustaceans) in canyons suggests that those environments experience greater food availability, and may provide critical habitat for commercially important bottom fish and invertebrate stocks. "From a conservation standpoint, these regions would be ideal candidates to become Marine Protected Areas (MPAs), especially due to the higher turnover of species diversity when compared to regular slopes", says De Leo. "If we prove that the animals are using the canyons as a feeding ground because the organic debris accumulates there and nowhere else outside the canyons, that's another argument for an MPA". Adds Smith, "if we allow the Hawaiian canyons to be overexploited or impacted by human activities such as dredge-spoil dumping, there is likely to be a significant drop in biodiversity in the deep waters of Hawaii. Clearly, canyon habitats merit special attention for inclusion in Hawaiian MPAs."

Future studies by the team of the Hawaiian canyon fauna include analyses of the stable carbon and nitrogen isotopes in shrimp, urchins and other bottom feeders to identify their main food sources. Because different potential food sources, such as land plants, seafloor algae and phytoplankton, often have different stable isotope "signatures", these analyses will help the researchers to understand what exactly is fueling the rich animal assemblages in the canyons. "We need biochemical proof that the canyons are really channeling this type of material," says DeLeo. "Carbon and nitrogen isotopic signatures could tell the difference between the detrital plant material and the phytoplankton material pools, so you can see if the animal in the canyon is eating phytoplankton cells coming from pelagic production or macroalgae coming from the coast."

Vetter says that their current research is also formulating conceptual models that will allow the researchers to predict which features associated with different canyon systems act to influence biological patterns including animal abundance and diversity. "DeLeo's PhD research will include data on megafauna and macrofauna (smaller animals living in the sediments) patterns in canyons along the U.S. West Coast, Hawaii, and New Zealand, which should make important strides here."
-end-
This research was supported by the National Oceanic and Atmospheric Administration (NOAA) Ocean Exploration Office, by the Hawaii Undersea Research Laboratory in the School of Ocean and Earth Science and Technology at UHM, and by the Census of Diversity of Abyssal Marine Life (CeDAMar). We also thank Capes-Fulbright for a fellowship for DeLeo.

Paper Information: Hawaiian hotspots: enhanced megafaunal abundance and diversity in submarine canyons on the oceanic islands of Hawaii, Marine Ecology, Eric W. Vetter, Craig R. Smith & Fabio C. De Leo http://www3.interscience.wiley.com/journal/123243773/abstract
Volume 31 Issue 1 (March 2010)
Special Issue: Special Issue: The roles of habitat heterogeneity in generating and maintaining biodiversity on continental margins A Contribution to the Census of Marine Life

Video and Images available: http://www.soest.hawaii.edu/soest_web/2010_news_PDFs/Canyon/

Researcher Contact:
Eric W. Vetter, Marine Science Program, Hawaii Pacific University, (808) 236-5832, evetter@hpu.edu
Craig Smith, Professor, Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa. (808) 956-7776, craigsmi@hawaii.edu
Fabio De Leo, Doctoral Student, Department of Oceanography, School of Ocean and Earth Science and Technology, University of Hawaii at Manoa. (808) 956-5372, fdeleo@hawaii.edu

SOEST Media Contact: Tara Hicks Johnson, (808) 956-3151, hickst@hawaii.edu
HPU Media Contact: Crystale Lopez, (808) 544-0879, clopez@hpu.edu

The School of Ocean and Earth Science and Technology at the University of Hawaii at Manoa was established by the Board of Regents of the University of Hawai'i in 1988 in recognition of the need to realign and further strengthen the excellent education and research resources available within the University. SOEST brings together four academic departments, three research institutes, several federal cooperative programs, and support facilities of the highest quality in the nation to meet challenges in the ocean, earth and planetary sciences and technologies.

University of Hawaii at Manoa

Related Biodiversity Articles:

Biodiversity is 3-D
The species-area relationship (SAC) is a long-time considered pattern in ecology and is discussed in most of academic Ecology books.
Thought Antarctica's biodiversity was doing well? Think again
Antarctica and the Southern Ocean are not in better environmental shape than the rest of the world.
Antarctica's biodiversity is under threat
A unique international study has debunked the popular view that Antarctica and the Southern Ocean are in much better ecological shape than the rest of the world.
Poor outlook for biodiversity in Antarctica
The popular view that Antarctica and the Southern Ocean are in a much better environmental shape than the rest of the world has been brought into question in a study publishing on March 28 in the open access journal PLOS Biology, by an international team lead by Steven L.
Temperature drives biodiversity
Why is the diversity of animals and plants so unevenly distributed on our planet?
Biodiversity needs citizen scientists
Could birdwatching or monitoring tree blossoms in your community make a difference in global environmental research?
Biodiversity loss in forests will be pricey
A new global assessment of forests -- perhaps the largest terrestrial repositories of biodiversity -- suggests that, on average, a 10 percent loss in biodiversity leads to a 2 to 3 percent loss in the productivity, including biomass, that forests can offer.
Biodiversity falls below 'safe levels' globally
Levels of global biodiversity loss may negatively impact on ecosystem function and the sustainability of human societies, according to UCL-led research.
Unravelling the costs of rubber agriculture on biodiversity
A striking decline in ant biodiversity found on land converted to a rubber plantation in China.
Nitrogen is a neglected threat to biodiversity
Nitrogen pollution is a recognized threat to sensitive species and ecosystems.

Related Biodiversity Reading:

Biodiversity: An Introduction
by Kevin J. Gaston (Author), John I. Spicer (Author)

CLICK HERE TO DOWNLOAD ARTWORK

This concise introductory text provides a complete overview of biodiversity - what it is, how it arose, its distribution, why it is important, human impact upon it, and what should be done to maintain it.

Timely overview of the serious attempts made to quantify and describe biodiversity in a scientific way Acts as an easy entry point into the primary literature Provides real-world examples of key issues, including illustrations of major temporal and spatial patterns in biodiversity Designed primarily with undergraduate... View Details


Tree of Life: The Incredible Biodiversity of Life on Earth (CitizenKid)
by Rochelle Strauss (Author), Margot Thompson (Illustrator)

If every known species on Earth were a leaf on a tree, that tree would have 1 750 000 leaves. Since humans count for just one leaf on the tree, we have a lot to learn about the millions of other forms of life with which we share the world. A dazzlingly illustrated and child-friendly introduction to biodiversity, Tree of Life shows how living things are classified into five kingdoms -- and how each has much to tell us about all aspects of life on our planet. Tree of Life is part of CitizenKid: A collection of books that inform children about the world and inspire them to be better global... View Details


The Sixth Extinction: An Unnatural History
by Elizabeth Kolbert (Author)

WINNER OF THE PULITZER PRIZE
ONE OF THE NEW YORK TIMES BOOK REVIEW'S 10 BEST BOOKS OF THE YEAR
A NEW YORK TIMES BESTSELLER
A NATIONAL BOOK CRITICS CIRCLE AWARD FINALIST

A major book about the future of the world, blending intellectual and natural history and field reporting into a powerful account of the mass extinction unfolding before our eyes

Over the last half-billion years, there have been Five mass extinctions, when the diversity of life on earth suddenly and dramatically contracted. Scientists... View Details


Sustaining Life: How Human Health Depends on Biodiversity
by Eric Chivian (Editor), Aaron Bernstein (Editor)

The Earth's biodiversity-the rich variety of life on our planet-is disappearing at an alarming rate. And while many books have focused on the expected ecological consequences, or on the aesthetic, ethical, sociological, or economic dimensions of this loss, Sustaining Life is the first book to examine the full range of potential threats that diminishing biodiversity poses to human health.

Edited and written by Harvard Medical School physicians Eric Chivian and Aaron Bernstein, along with more than 100 leading scientists who contributed to writing and reviewing the book,... View Details


Biodiversity: Exploring Values and Priorities in Conservation
by D. J. Perlman (Author), G. Adelson (Author)

Biodiversity has become a buzzword in the environmental movement and in science, and is increasingly being taught in university degree courses. This new text is designed as a primer, giving non-specialists an introduction to the historical context, current debates, and ongoing research in this subject. View Details


Complexity: The Evolution of Earth's Biodiversity and the Future of Humanity
by William C. Burger (Author)

This very readable overview of natural history explores the dynamics that have made our planet so rich in biodiversity over time and supported the rise and dominance of our own species.

Tracing the arc of evolutionary history, biologist William C. Burger shows that cooperation and symbiosis have played a critical role in the ever increasing complexity of life on earth. Life may have started from the evolution of cooperating organic molecules, which outpaced their noncooperating neighbors. A prime example of symbiosis was the early incorporation of mitochondria into the eukaryotic... View Details


Insect Biodiversity: Science and Society, Volume 1
by Robert G. Foottit (Editor), Peter H. Adler (Editor)

Volume One of the thoroughly revised and updated guide to the study of biodiversity in insects

The second edition of Insect Biodiversity: Science and Society brings together in one comprehensive text contributions from leading scientific experts to assess the influence insects have on humankind and the earth’s fragile ecosystems. Revised and updated, this new edition includes information on the number of substantial changes to entomology and the study of biodiversity. It includes current research on insect groups, classification, regional diversity, and a wide range... View Details


Precious Heritage: The Status of Biodiversity in the United States
by Bruce A. Stein (Editor), Lynn S. Kutner (Editor), Jonathan S. Adams (Editor)

From the lush forests of Appalachia to the frozen tundra of Alaska, and from the tallgrass prairies of the Midwest to the subtropical rainforests of Hawaii, the United States harbors a remarkable array of ecosystems. These ecosystems in turn sustain an exceptional variety of plant and animal life. For species such as salamanders and freshwater turtles, the United States ranks as the global center of diversity. Among the nation's other unique biological features are California's coast redwoods, the world's tallest trees, and Nevada's Devils Hole pupfish, which survives in a single... View Details


The Diversity of Life: With a New Preface (Questions of Science)
by Edward O. Wilson (Author)

View a collection of videos on Professor Wilson entitled "On the Relation of Science and the Humanities"

"In the Amazon Basin the greatest violence sometimes begins as a flicker of light beyond the horizon. There in the perfect bowl of the night sky, untouched by light from any human source, a thunderstorm sends its premonitory signal and begins a slow journey to the observer, who thinks: the world is about to change." Watching from the edge of the Brazilian rain forest, witness to the sort of violence nature visits upon its creatures, Edward O. Wilson reflects on the crucible of... View Details


Breakfast Of Biodiversity: The Political Ecology of Rain Forest Destruction
by John Vandermeer (Author), Ivette Perfecto (Author), Vandana Shiva (Foreword)

In Breakfast of Biodiversity, John Vandermeer and Ivette Perfecto insightfully describe the ways in which such disparate factors as the international banking system, modern agricultural techniques, rain forest ecology, and the struggles of the poor interact to bring down the forest. They weave an alternative vision in which democracy, sustainable agriculture, and land security for the poor are at the center of the movement to save the tropical environment.

This new, fully updated edition of Breakfast of Biodiversity discusses important new developments in our understanding of rain... View Details

Best Science Podcasts 2017

We have hand picked the best science podcasts for 2017. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Simple Solutions
Sometimes, the best solutions to complex problems are simple. But simple doesn't always mean easy. This hour, TED speakers describe the innovation and hard work that goes into achieving simplicity. Guests include designer Mileha Soneji, chef Sam Kass, sleep researcher Wendy Troxel, public health advocate Myriam Sidibe, and engineer Amos Winter.
Now Playing: Science for the People

#448 Pavlov (Rebroadcast)
This week, we're learning about the life and work of a groundbreaking physiologist whose work on learning and instinct is familiar worldwide, and almost universally misunderstood. We'll spend the hour with Daniel Todes, Ph.D, Professor of History of Medicine at The Johns Hopkins University, discussing his book "Ivan Pavlov: A Russian Life in Science."