Decline of world's estuaries and coastal seas

June 22, 2006

(Washington, D.C.) -- Human activity over the centuries has depleted 90% of marine species, eliminated 65% of seagrass and wetland habitat, degraded water quality 10-1,000 fold, and accelerated species invasions in 12 major estuaries and coastal seas around the world, according to a study published in Science Magazine on Friday, June 23d, and supported in part by the Lenfest Ocean Program. However, in areas where conservation efforts have been implemented in the 20th century, signs of recovery are apparent.

Entitled "Depletion, Degradation, and Recovery Potential of Estuaries and Coastal Seas," the study is the most comprehensive quantitative assessment of the state of estuaries and coastal ecosystems ever conducted. Initiated by the National Center for Ecological Analysis and Synthesis and co-authored by ten international experts, it shows that human impact on estuaries and coastal waters dates back to ancient times (e.g. Roman Empire in the Adriatic Sea). However, damage to marine ecosystems has accelerated over the past 150-300 years as populations have grown, demands for resources have increased, luxury markets have developed, and industrialization has expanded.

"Throughout history, estuaries and coastal seas have played a critical role in human development as a source of ocean life, habitat for most of our commercial fish catch, a resource for our economy, and a buffer against natural disasters," stated Dr. Heike K. Lotze, a marine biologist at Dalhousie University in Halifax, Canada and lead author of the study. "Yet, these once rich and diverse areas are a forgotten resource. Compared to other ocean ecosystems such as coral reefs, they have received little attention in the press and are not on the national policy agenda. Sadly, we have simply accepted their slow degradation."

Most mammals, birds and reptiles in estuaries were depleted by 1900 and declined further by 1950 as the demand for food, oil, and luxury items (such as furs, feathers and ivory) grew. Among fish, the highly desirable and easily accessible salmon and sturgeon were depleted first, followed by tuna and sharks, cod and halibut, and herring and sardines. Oysters were the first invertebrate resource to degrade because of their value and accessibility as well as destructive harvesting methods.

The primary cause of estuarine damage is human exploitation, which is responsible for 95% of species depletions and 96% of extinctions, often in combination with habitat destruction. In the coming years, however, invasive species and climate change may play a larger role in stressing estuarine resources.

According to the study, the fastest path to recovery has been through mitigating the cumulative impacts of human activity. Seventy-eight percent of recoveries have happened by reducing at least two human activities, including resource exploitation, habitat destruction, and pollution.

"Our study documents severe, long-term degradation of nearshore marine ecosystems worldwide which, as human impacts spread, may well forecast future changes in the entire ocean," said Hunter Lenihan, a marine ecologist at UC Santa Barbara's Bren School of Environmental Science and Management. "But we have also shown that the causes and consequences of this damage are common to all areas, and so we now have the necessary reference points and targets to develop effective management and restoration plans. Because over-exploitation and habitat destruction are responsible for the large majority of historical changes, reducing these destructive impacts should be a priority in these plans."

Despite severe degradation in these 12 very different estuarine and coastal water environments, there is good news. "Only 7% of species went regionally extinct, and some are rebounding (birds and seals in particular). Clearly, recovery is achievable. As we expand our conservation efforts, we will see more evidence of healthier, abundant marine ecosystems." said Roger Bradbury, a resource management scientist at Australian National University.

In developed countries, trends suggest that estuaries may have passed the low point and are on the path to recovery, according to the study. In developing countries, however, population growth, which puts pressure on coastal areas, may further increase degradation.

"The 2004 Asian Tsunami and 2005 Hurricane Katrina helped us recognize how important healthy estuaries are in our lives," stated Jeremy Jackson, a paleontologist at Scripps Institution of Oceanography. "Thanks to this study, we can now see much more clearly what coastal ecosystems looked like before humans interfered with them, which has given us a historical baseline and a vision for how to regenerate diverse, resilient ecosystems that can thrive in the centuries to come."

The study quantifies the magnitude and causes of ecological change in 12 estuaries and coastal seas in Europe, North America, and Australia from the onset of human settlement to the present day. They are Massachusetts Bay, Delaware Bay, Chesapeake Bay, Pamlico Sound, Galveston Bay, Francisco Bay, Western Baltic Sea, Wadden Sea, Northern Adriatic Sea, Southern Gulf of St. Lawrence, Outer Bay of Fundy, and Moreton Bay. The researchers combined palaeontological, archaeological, historical, and ecological records to trace changes in important species, habitats, water quality parameters and species invasions.
-end-
About Lenfest Ocean Program: A portion of this analysis was supported by the Lenfest Ocean Program. The Program was established in July 2004 by the Lenfest Foundation and is managed by The Pew Charitable Trusts. It brings the best scientific research to bear on identifying the causes, consequences and solutions to problems facing the global marine environment. The Program currently supports research on the ecological, social and economic impacts of current and proposed fishing regimes, and options for sustainable fisheries management.

Other funders: Other supporters of this work include the National Center for Ecological Analysis and Synthesis (funded by the National Science Foundation, University of California, and University of California Santa Barbara), the German Alfred-Wegener Institute for Polar and Marine Research, and the Census of Marine Life's History of Marine Animal Populations Program. Author contact information:


Lead author: Heike K. Lotze
Biology Department, Dalhousie University, Halifax, NS B3H 4J1, Canada
Email: hlotze@dal.ca
Phone: 902-494-2478 (wk) or 902-346-2112 (hm)
Fax: 902-494-3736
Web: http://myweb.dal.ca/hlotze/


Hunter S. Lenihan
Bren School of Environmental Science and Management, University of California, Santa Barbara, CA 93106-5131, USA
Email: lenihan@bren.ucsb.edu
Phone: 805-893-8629
Fax: 805-893-7612


Roger H. Bradbury
Centre for Resource and Environmental Studies, Australian National University, Canberra, ACT 0200, Australia
Email: roger@tjurunga.com
Phone: 61-2-6295-2839
Fax: 61-2-6232-7463


Jeremy B. C. Jackson
Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, La Jolla, CA 92093-0244, USA
Email: jbjackson@ucsd.edu
Phone: 858-822-2432
Fax: 858-822-3310


Bruce J. Bourque
Department of Anthropology, 155 Pettengill Hall, Bates College, Lewiston, ME 04240, USA
Email: bbourque@bates.edu
Phone: 207-287-6604
Fax: 207-287-6633


Lenfest Ocean Program

Related Marine Ecosystems Articles from Brightsurf:

Ninety years of data shows global warming impacts on foundation of marine ecosystems
Phytoplankton are microscopic plants that underpin ocean productivity and provide 50% of the world's oxygen via photosynthesis.

Radical changes in ecosystems
Earth and all the living organisms on it are constantly changing.

Saving marine life: Novel method quantifies the effects of plastic on marine wildlife
Scientists at Tokyo Institute of Technology together with their international collaborators developed a novel quantitative method to quantify the effects of plastic on marine animals.

Effects of nutrient pollution in marine ecosystems are compounded by human activity
Nutrient pollution in the oceans caused by human activity can significantly impact marine life.

Traces of ancient life tell story of early diversity in marine ecosystems
If you could dive down to the ocean floor nearly 540 million years ago just past the point where waves begin to break, you would find an explosion of life--scores of worm-like animals and other sea creatures tunneling complex holes and structures in the mud and sand--where before the environment had been mostly barren.

Tierra del Fuego: marine ecosystems from 6,000 to 5000 years ago
Global warming will modify the distribution and abundance of fish worldwide, with effects on the structure and dynamics of food networks.

Marine energy devices likely pose minimal impacts to marine life, report shows
On World Oceans Day, an international team of marine scientists reports that the potential impact of marine renewable energy to marine life is likely small or undetectable.

Marine waste management: Recycling efficiency by marine microbes
It was only relatively recently that tiny, single-celled thaumarchaea were discovered to exist and thrive in the pelagic ocean, where their population size of roughly 1028 (10 billion quintillion) cells makes them one of the most abundant organisms on our planet.

From deep water to the surface: the nexus between climate, upwelling and marine ecosystems
It is critical for the foundation of the aquatic food web, for the condition of the environment and the biodiversity of the ocean, for fisheries and many activities at sea.

Re-thinking 'tipping points' in ecosystems and beyond
Abrupt environmental changes, known as regime shifts, are the subject of new research in which shows how small environmental changes trigger slow evolutionary processes that eventually precipitate collapse.

Read More: Marine Ecosystems News and Marine Ecosystems Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.