"Coastal oceans are under intense pressure due to overfishing, coastal development and land-based pollution. Lack of understanding of the dynamics of coastal ecosystems has seriously impeded management and policy efforts. Our new findings will greatly aid ocean protection, restoration, and sustainable use," says principal investigator Jane Lubchenco of Oregon State University. "Coastal zones are not only home to over 50% of Americans they are also home to a great majority of commercial and non-commercial marine species, as well as pivotal for industrial and recreational activities. The grand challenge is to use coastal oceans without misusing them."
"It's ironic that we've known so little about this critical area," says Steve Palumbi of Stanford's Hopkins Marine Station. "We know more about the productivity of the open ocean 1000 miles off Hawaii, than we do 100 yards off the west coast."
This near-shore zone, extending approximately 10 kilometers (about 6 miles) out from shore, is often called "the bad zone" because its three dimensional nature, complex currents, shallow water and high wave energy have stymied oceanographers and their large vessels. Now, scientists from PISCO (the Partnership for Interdisciplinary Studies of Coastal Oceans) which includes Oregon State University, Universities of California at Santa Barbara and Santa Cruz and Stanford University's Hopkins Marine Station, are comprehensively exploring the coastal zone along the US West coast for the first time --integrating genetics, microchemistry, oceanography and computer based mapping to solve the mysteries of how near-shore currents link populations, habitats and ecosystems on the regional scale.
A major stumbling block to ocean management has been understanding cause and effect. "We really haven't understood how coastal ecosystems are put together - which makes it difficult to reconstruct them," says Bob Warner of UC Santa Barbara. "It's a very complicated place."
The researchers are not only finding areas of special productivity where fishes and invertebrates concentrate and grow more quickly, they are also beginning to understand why--providing new insights applicable to coastal management worldwide.
Historic approaches to managing oceans focused on individual species or suites of similar species such as salmon or groundfish because they were prime targets for fishing. "There is strong consensus that the 'target species' approach is insufficient and there is emerging recognition of the need to switch to ecosystem-based management, yet there is precious little understanding of what that actually means," says Lubchenco.
Ecosystem-based management will require taking into account the movements of larvae, the importance of preserving individuals and habitats, interactions among species, and how all of those change with larger scale ocean processes such as El Niños, regime shifts and climate change. PISCO scientists are beginning to "visualize" the 3-D spatial and temporal variability of coastal life and to tease apart the differences between human impacts and natural fluctuations.
The PISCO team's new discoveries include the following:
Like on land, location matters and the most desirable districts - where food is abundant and where new animals are swept in by currents - are closely linked to physical structures and oceanographic processes. Animals in these hotspot areas produce abundant marine larvae for export and show faster growth rates. They can show distinct genetic signatures that set them apart from neighboring areas. Especially interesting is that the physical characteristics of hotspots are consistent. The scientists are examining satellite imagery to identify reliable features that lead to these highly productive areas. "We have been testing these predictions in New Zealand, Chile, and soon we hope in South Africa - other major upwelling areas around the world," says Lubchenco.
Most marine animals produce tiny larvae that drift with the plankton for weeks or months until the survivors settle into bottom habitats. Managing ecosystems requires knowing where new individuals in marine populations come from, how they got there, and where their babies go. "One of the greatest challenges in managing fisheries is to know what the larvae are doing and where they are going," says Warner. A major scientific breakthrough is the new ability to track the previously invisible movements of larvae. The ear bones or otoliths of many marine fish show distinct chemical signatures reflecting their movements through the water. Acting like mini-flight recorders, the bones offer the potential of tracing the pathways of individual larvae as they move from spawning sites to adult settling sites. "Microchemistry is allowing us to track larvae for the first time and that can help us determine what areas are necessary and dependable sources of young for other areas," says Warner. Given the current global dialogues about zoning the oceans and establishing networks of marine reserves to protect and restore marine ecosystems and replenish depleted fisheries, this new knowledge is critical.
Predicting Effects of El Niño Effects of El Niño and La Niña on fish populations have been much debated. Much like a whale "sees" by bouncing sound waves off its surroundings, new acoustic tools can detect thin layers of larvae in the water. This novel oceanographic technology reveals that larval fish such as rockfish, may be clustered in thin layers in the near-shore environment. Particularly during periods of La Niña, the larvae of some fish may be retained near-shore, rather than being carried out into the open oceans with the currents. The larvae of certain species of rockfish return to shore in greater numbers during La Niña periods. "These new discoveries can help resource managers tease apart when fish populations are changing due to human impacts such as fishing or pollution, or due to natural changes in the environment," says Margaret McManus of the University of Santa Cruz. This is important knowledge for understanding why the numbers of rockfish (also known as snapper) and other economically important species have plummeted in recent years.
Oceans Have Neighborhoods
New genetic mapping work, using barnacles as proxies for other presumed long distance dispersers shows that, "instead of being citizens of a global ocean, many marine species seem to live in ocean neighborhoods whose borders are surprisingly small," says Palumbi. "The borders of these populations are linked to ocean currents that form gyres, sweeping the marine larvae back near their birth places. We used to think that these larvae settled 100's or 1000's of kilometers from home, but now we are finding that ocean neighborhoods are defined by distances as small as 10's of kilometers."
The concentration of local effects is good news for coastal management, especially as the trend continues towards spatial management and coastal zoning. "One of the biggest fears about marine reserves is that they would close local areas but the benefits of this protection would travel," says Warner. "These new insights imply that conservation efforts may yield their greatest results closer to home than previously realized."
While the new science brings new hope for our eventual ability to know how to restore damaged ecosystems, Lubchenco cautions that one thing is clear. "We need to acknowledge the reality of uncertainty. Even though we are making great headway in understanding the causes of variability in ocean populations, the complexity and inherent uncertainty of the coastal ecosystem points towards the need to build in buffers. An example might be designing networks of reserves that can take advantage of variability - protecting a variety of habitats and oceanographic features so that we will be more likely to sustain populations in the long term, through the ups and downs of natural fluctuations - some reserves might be good one year, others next year, some during El Niño years."
In order to restore ecosystems, managers will have to consider all scales, from larvae to the entire ecosystem. But the good news is, that the black box of these complex ecosystems is opening at last. "And now there is real hope that there can be local benefits from local conservation efforts," says Palumbi. "The adage 'think globally act locally' has never been applied to the ocean because we thought the ocean would quickly dilute local conservation efforts. But now we can begin to see how to use this powerful approach in the ocean realm."
PISCO is funded by a grant from the David and Lucile Packard Foundation. Supplemental funding for PISCO-related research has been provided by the Andrew W. Mellon Foundation, the National Science Foundation, the Office of Naval Research and the National Oceanographic Partnership Program.
MEDIA NOTE: The scientists will discuss their findings at a news briefing at the AAAS Annual Meeting in Denver on Saturday, February 15th at12 noon Mountain Time. Detailed findings will be presented at 2:30 Mountain Time.
For assistance contacting the speakers during AAAS please call Jessica Brown at 202-497-8375
Oregon State University
University of California, Santa Cruz
University of California, Santa Barbara