Transcript The “Known” Projections of human drivers

The “Known”
Projections of human drivers
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Human population density will increase, especially in developing countries and on the coast
In developing countries this will increase most human impacts on coastal ecosystems:
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Where human drivers intensify their ecological impact will depend largely on management
practices, technology transfer, education
Developed countries will see leveling off in most impacts
Land use changes:
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Habitat loss and degradation
Shoreline development
Physical disturbance (humans, tourism, …)
Degradation in water quality
Nutrient loading
Chemical pollution
Oxygen depletion
Freshwater conversion / changes in hydrograph
Species invasions
Deforestation is leveling off
Agriculture will intensify especially in developing countries
Projected large increases in protein demand (aquaculture, life-stock production) will
increase nutrient loading
Accelerated sea level rise will increase loss of shallow estuarine and coastal habitat (e.g.
wetlands, oysters, seagrasses)
The “Known”
Projections of impacts on biodiversity
• Large shifts in species compositions resulting in new mixes of species
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simplification and homogenization
extinctions and extirpations
Accelerated invasions
Increase in small, fast-growing, opportunistic species
Decline in specialists
Recovery of some protected taxa
Range contractions and expansions
• Loss of habitat diversity and complexity
• Increase in variability , surprises, extreme events
• This increases possibility of exceeding thresholds and increase likelihood of
catastrophic and possibly irreversible events (e.g. 1998 global bleaching
event)
• Increasingly stressed and degraded ecosystems will be less resilient, more
susceptible to change, disease, HAB, especially when cumulative human
impacts occur.
• We know stressors will increase in tropical zones where there is lot of
biodiversity but lack of data
The Unknown of human drivers
• Human population:
– Trends of human migration (more or less in the coastal zone in developing
countries)
– Increasing urbanization having net benefits or harm on coastal environment.
• Will technology transfer between developed countries and developing
countries allow them to skip or speed through the same destruction the
developed countries already have experienced?
• Effectiveness of best management practices in controlling human
impacts.
• Complex interactions among human drivers:
– synergistic effects, surprises, feed backs
– thresholds
• Identity of introduced species, diseases, HAB.
• Link between human health and ecosystem “health”?
The Unknown impacts on diversity
• Broad trends are known, but regional predictions are difficult (e.g.
climate change)
• How new mixes of species will interact
• Evolutionary responses of species to change
• Synergistic effects of increased variability and decreased resilience
• Lag times of human impacts on species / ecosystems (i.e. nitrogen
storage, pollutants in sediments)
• Predictions of recovery vs. non-recovery, lots of surprises: e.g. slower
than expected (Atlantic cod) or faster than expected (rockweed in the
Baltic) some species recover from very reduced numbers (e.g. elephant
seals) others don’t (Northern right whale)
• Baselines as feasible goals for restoration and conservation?
• Effects on cryptic species diversity
The Unknowable,
and the significance of not knowing
• Abrupt changes in people’s attitude and
behavior towards the environment
• Precise prediction of catastrophic events in
space and time (storms, floods, disease,
HAB, social disruption, economic
disruption, …)
• Significance: we have to live with dynamic
ecosystems and uncertainties
Gaps in knowledge:
what do we need to know and why
• Cumulative effects of diverse drivers
• Threshold and feedback effects
Is it possible to reverse the trajectory of
degradation?
• Cleanup of Baltic Sea
• Recovery of sea otters, elephant seals in CA
• Restoration of Swedish wetlands and
saltmarshes