Lotze_et_al_2006

Lotze_et_al_2006 - REPORTS Depletion, Degradation, and...

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Depletion, Degradation, and Recovery Potential of Estuaries and Coastal Seas Heike K. Lotze, 1 * Hunter S. Lenihan, 2 Bruce J. Bourque, 3 Roger H. Bradbury, 4 Richard G. Cooke, 5 Matthew C. Kay, 2 Susan M. Kidwell, 6 Michael X. Kirby, 7 Charles H. Peterson, 8 Jeremy B. C. Jackson 5,9 Estuarine and coastal transformation is as old as civilization yet has dramatically accelerated over the past 150 to 300 years. Reconstructed time lines, causes, and consequences of change in 12 once diverse and productive estuaries and coastal seas worldwide show similar patterns: Human impacts have depleted 9 90% of formerly important species, destroyed 9 65% of seagrass and wetland habitat, degraded water quality, and accelerated species invasions. Twentieth-century conservation efforts achieved partial recovery of upper trophic levels but have so far failed to restore former ecosystem structure and function. Our results provide detailed historical baselines and quantitative targets for ecosystem-based management and marine conservation. E stuaries and coastal seas have been focal points of human settlement and marine resource use throughout history. Centuries of overexploitation, habitat transformation, and pollution have obscured the total magnitude of estuarine degradation and biodiversity loss and have undermined their ecological resilience ( 1–5 ). This poses potential for disaster, as demonstrated in numerous fisheries collapses ( 1–3 )a n dt h e recent impacts of the 2004 Asian tsunami and 2005 Hurricane Katrina that were exacerbated by historical losses of mangroves and wetlands ( 5–7 ). With recognition of their essential role for human and marine life, estuaries and coastal zones have become the focus of efforts to develop ecosystem- based management and large-scale restoration strategies. To be successful, these approaches re- quire historical reference points and assessments of the degree and drivers of degradation in an eco- system context ( 8 , 9 ). We reconstructed historical baselines and quantified the magnitude and causes of change in 12 temperate estuarine and coastal ecosystems in Europe, North America, and Australia from the onset of human settlement until today (Table 1). We used paleontologic, archaeological, historical, and ecological records (table S1) to quantify changes in 30 to 80 species per system standard- ized into 22 guilds and six taxonomic and seven functional groups, as well as seven water-quality parameters and species invasions ( 10 ). Species were selected for their economic, structural, or functional significance throughout history. We estimated relative abundance of each species over
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This note was uploaded on 08/06/2008 for the course ESM 260 taught by Professor Lenihan during the Spring '08 term at UCSB.

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Lotze_et_al_2006 - REPORTS Depletion, Degradation, and...

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