According to researchers at the University of California, Santa Barbara (UCSB), a number of coastal marine ecosystems are increasingly threatened by human activity. UC Santa Barbara says the authors have performed the first integrated, or comprehensive, analysis of all coastal areas in the world.
Benjamin Halpern, the lead author, National Center for Ecological Analysis and Synthesis (NCEAS), UCSB, argues that pollution is coming from a variety of sources. “Resource management and conservation in coastal waters must address a litany of impacts from human activities, from the land, such as urban runoff and other types of pollution, and from the sea.” Furthermore, deciding where to focus anti-pollution efforts can be challenging. Research can provide direction on how to invest strategically in conservation and restoration: “One of the great challenges is to decide where and how much to allocate limited resources to tackling these problems. Our results identify where it is absolutely imperative that land-based threats are addressed –– so-called hotspots of land-based impact –– and where these land-based sources of impact are minimal or can be ignored.”
Halpern and his co-authors list what they view as the top 10″hotspots” where the greatest conservation efforts are needed. The ”hottest hotspot,” or most polluted marine ecosystem, is found at the mouth of the Mississippi River. The authors note in the report: “the nutrient runoff from upstream farms that flows down the Mississippi River to the Gulf of Mexico is responsible for the most tainted coastal ecosystem in the world. These nutrients have led to a persistent dead zone in the Gulf of Mexico caused by an overgrowth of algae that feeds on the nutrients and takes up most of the oxygen in the water, depriving other marine organisms of the oxygen they need to survive.”
The other top 10 coastal marine ecosystems most affected by people are in Asia and the Mediterranean. “The second most threatened marine coastal ecosystem is where the Ganges River drains into the Sunderbans delta in the Bay of Bengal near Dhaka, Bangladesh. The third most imperiled coastal ecosystem is where the Mekong River empties into the South China Sea near Saigon, Vietnam. Next are China’s Pearl River where it meets the South China Sea near Hong Kong, Italy’s Po River where it drains into the Adriatice Sea near Venice, followed by the Rhine and Meuse rivers that empty into the North Sea near Rotterdam in the Netherlands.”
The authors surveyed four “key land-based drivers of ecological change” to determine their ranking:
- nutrient input from agriculture in urban settings
- organic pollutants derived from pesticides
- inorganic pollutants from urban runoff
- direct impact of human populations on coastal marine habitats
Halpern explained that just a few coastlines are hit hard by pollution because most pollution drains into just a few major rivers. “This is because a vast majority of the planet’s landscape drains into relatively few very large rivers, that in turn affect a small amount of coastal area.” The authors conclude: “these are areas where conservation efforts will almost certainly fail if they don’t directly address what people are doing on land upstream from these locations.”
Read the press release and research. Also, see TreeHugger’s photos of the world’s dirtiest lakes and rivers
Image credit: Mississippi River, via: TreeHugger / Getty Images – Internetwork Media
