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Adverse Eco-Feedbacks

PI: Dr. Andrew Bakun, Pew Institute for Ocean Science

The term “adverse eco-feedbacks” refers to mechanisms operating within marine ecosystems that, when stressed beyond a range within which inherent feedbacks promote restoration of a prior less disturbed state, may unleash a self-amplifying progression of greater and greater disturbance leading to a new, less desirable state in which the feedback mechanisms then act to oppose reversion of the system to the more desirable earlier state. For example, in the Baltic Sea, cod are predators of adult sprat and herring, but sprat and herring consume the eggs and larvae of cod. The cod population was depleted in the 1990s due to a combination of poor environmental conditions and overfishing. The depletion of cod allowed large populations of sprat and herring to build up, which increased predation on cod eggs. Thus, when environmental conditions improved and fishing pressure was reduced, the cod failed to recover (Bakun 2004).

Better scientific understanding of the nature of the adverse eco-feedbacks might point the way to reversing their operation, and thus reveal how to conceive direct constructive actions toward repairing the function of marine ecosystems that currently may be operating in a degraded manner due to durable human-caused distortions in their function.

This project is evaluating adverse eco-feedbacks in a range of ecosystems, with project components including:

  1. Attributes and plasticity of sites of coral reef fish spawning aggregations.
  2. Global statistical test to demonstrate operation of life cycle length-dependent rapidly-evolving adaptive response mechanisms.
  3. Collaborative demonstration of possible operation of adverse eco-feedbacks in the 1980s collapse of the Japanese sardine population.
  4. Inventory of accessible information relevant to investigation of a potentially dangerous instability in the oceanic predator--prey system supporting tuna resource productivity and sustainability.
  5. Examination of plume patterns in the intense coastal “core” zones of the world’s main coastal upwelling ecosystems to determine potential for shifts to degraded “Lüderitz”-type ecosystem configurations.

The first publication from this project is a demonstration that intact sardine stocks might slow damage to coastal upwelling ecosystems due to climate change.

More information

Dr. Andrew Bakun is Professor of Marine Biology and Fisheries at the University of Miami Rosenstiel School of Marine and Atmospheric Science. He has more than forty years of experience in marine resource ecology. He is recognized as a leading expert in the environmental effects on the population dynamics of exploited fish populations and in the role of small pelagic fishes in "wasp waist" ecosystems. He has served on numerous international and national scientific advisory panels and has written extensively on fisheries and marine ecosystems.

Dr. Bakun's faculty page

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