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 paper1. Demonstrate the magnitude of ecological changes that have occurred over the past few centuries as a result of human exploitation and pollution2. 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 Reefsoverfishing 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 BayOverfishing = profound shift to Keystone of bay: Oystersbacterially-dominated community
Kelps and Codfish, Gulf of MaineOnce 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 MaineOverfishing = profound shift in Georges Bank community structure urchin barrens
Benthic Communities on Continental ShelvesMore 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 collapse Fig. 2. Model of the collapse of Western Atlantic coastal ecosystems caused by overﬁshing. Arrows indicate the three major ecological transitions dis-cussed 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 oceanPROCEEDINGS 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.
Discussion http://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.