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.