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:
- Attributes and plasticity of sites of coral reef fish
spawning aggregations.
- Global statistical test to demonstrate operation of life
cycle length-dependent rapidly-evolving adaptive response
mechanisms.
- Collaborative demonstration of possible operation of
adverse eco-feedbacks in the 1980s collapse of the Japanese
sardine population.
- Inventory of accessible information relevant to investigation
of a potentially dangerous instability in the oceanic predator--prey
system supporting tuna resource productivity and sustainability.
- 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.
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