jackson 01 discussion presentation
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Paper disTRANSCRIPT
What was natural in the coastal oceans?
Jeremy Jackson
2001
PNAS
Who is the author?
Dr. Jeremy Jackson
Professor and Researcher, Scripps Institute of Oceanography, UCSD and Smithsonian Tropical Research Institute, Balboa, Panama
Expert in paleoecology, macroevolution, coral reef ecology
Collaborator and husband to renowned scientist Nancy Knowlton
Main goals of paper
1. Demonstrate the magnitude of ecological changes that have occurred over the past few centuries as a result of human exploitation and pollution
2. Show how awareness of these changes can benefit efforts for conservation and restoration of coastal ecosystems
Coastal Systems Studied
• Caribbean Coral Reefs
• Caribbean Seagrass Meadows
• Chesapeake Bay
• Kelps and Codfish, Gulf of Maine
• Benthic Communities on Continental Shelves
Caribbean Coral Reefs
overfishing has shifted composition and abundance
Caribbean Seagrass Meadows
Loss of large grazers impacts susceptibility to disease
Current turtle population < 200,000 [was 16 million+]
Chesapeake Bay
Overfishing = profound shift to bacterially-dominated community
Keystone of bay: Oysters
Kelps and Codfish, Gulf of Maine
Once kelp dominated, now urchin barrens
Kelps and Codfish, Gulf of Maine
Once cod was numerous and LARGE in size – now almost extinct and stunted in size
Kelps and Codfish, Gulf of Maine
Georges BankOverfishing = profound shift in community structure urchin barrens
Benthic Communities on Continental Shelves
More recently altered but can’t reconstruct the extent (poor documentation)
Raja laevis
Patterns observed
• Vulnerability of Large Vertebrates
• Collapse of Sessile Ecosystem Engineers
• Time Lags Between Effects of Overfishing and Collapse of Ecosystem Engineers
• Fishing Down Food Webs
• Rise of Microbes
Model of collapseFig. 2. Model of the collapse of Western Atlantic coastal ecosystems caused by overfishing. Arrows indicate the three major ecological transitions discussed in the text.
“Shifting Baselines”
http://www.shiftingbaselines.org/
Summary
“It is time scientists began an aggressive series of experiments involving large keystone species on the largest possible spatial and temporal scales. The alternative is absolute microbial domination of coastal ecosystems in 20 to 30 years.
Is that the future of evolution in the oceans?”
Current studiesJackson, Jeremy B. C. 2008.
Ecological extinction and evolution in the brave new ocean
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 105: 11458-11465 Suppl.
The great mass extinctions of the fossil record were a major creative force that provided entirely new kinds of opportunities for the subsequent explosive evolution and diversification of surviving clades. Today, the synergistic effects of human impacts are laying the groundwork for a comparably great Anthropocene mass extinction in the oceans with unknown ecological and evolutionary consequences. … We can only guess at the kinds of organisms that will benefit from this mayhem that is radically altering the selective seascape far beyond the consequences of fishing or warming alone. The prospects are especially bleak for animals and plants compared with metabolically flexible microbes and algae.
Discussionhttp://www.shiftingbaselines.org/
• This paper is a call to scientists to put studies into an evolutionary context and not settle for what once was 50 or 100 years ago. Coral reefs flourished for millions of years before human activities began to wipe them out.
• It also is a call to think in the large global scale, not just the local. Certainly the problems in Chesapeake Bay are enormous but those studies shed light on a rising global problem as well.
• Good example of a study using existing data.