Cover Image

HARDBACK
$59.00



View/Hide Left Panel

TABLE 1.3 Status and Trends of Major Ocean Ecosystems Defined by Principal Symptoms and Drivers of Degradation in the >99% of the Global Ocean That Is Unprotected from Exploitation

Coral reefs: Critically endangered

Symptoms: Live coral reduced 50–93%; fish populations reduced 90%; apex predators virtually absent; other megafauna reduced by 90–100%; population explosions of seaweeds; loss of complex habitat; mass mortality of corals from disease and coral bleaching

Drivers: Overfishing, warming and acidification due to increasing CO2, runoff of nutrients and toxins, invasive species

Estuaries and coastal seas: Critically endangered

Symptoms: Marshlands, mangroves, seagrasses, and oyster reefs reduced 67–91%; fish and other shellfish populations reduced 50–80%; eutrophication and hypoxia, sometimes of entire estuaries, with mass mortality of fishes and invertebrates; loss of native species; toxic algal blooms; outbreaks of disease; contamination and infection of fish and shellfish; human disease

Drivers: Overfishing; runoff of nutrients and toxins; warming due to rise of CO2; invasive species; coastal land use

Continental shelves: Endangered

Symptoms: Loss of complex benthic habitat; fishes and sharks reduced 50–99%; eutrophication and hypoxia in “dead zones” near river mouths; toxic algal blooms; contamination and infection of fish and shellfish; decreased upwelling of nutrients; changes in plankton communities

Drivers: Overfishing; trophic cascades; trawling; runoff of nutrients and toxins; warming and acidification due to rise of CO2; introduced species; escape of aquaculture species

Open ocean pelagic: Threatened

Symptoms: Targeted fishes reduced 50–90%; increase in nontargeted fish; increased stratification; changes in plankton communities

Drivers: Overfishing; trophic cascades; warming and acidification due to rise of CO2

Coastal ecosystems are endangered to critically endangered on a global scale. The lesser endangerment of pelagic ecosystems reflects their remoteness from all factors except fishing and climate change, although there are no real baselines for comparison to critically evaluate changes in plankton communities. This grim assessment begs the question, What are the projected long-term consequences for the ecological condition of the ocean if we continue with business as usual?

Predicting the future is, at best, a highly uncertain enterprise. Nevertheless, I believe we have a sufficient basic understanding of the ecological



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement