In recent years, serious proposals have been made to intentionally fertilize the ocean as a way to fight global warming or increase world fish catches. According to Jonathan Sharp, professor of oceanography at the University of Delaware’s Graduate College of Marine Studies, these are interesting, but dangerous ideas.
“We have inadvertently fertilized most of the estuarine and coastal waters of the developed world through nutrient enrichment from agricultural, human sewage, and industrial inputs,” says Sharp. “Near-shore nutrient enrichment is a serious global problem. If open ocean fertilization did not yield the planned effects, it could cause a major global disaster.”
On Thursday, May 15, at 7:00 p.m., at UD’s College of Marine Studies in Lewes, Sharp will discuss the pros and cons of ocean fertilization in “Fertilizing the Oceans — Can Mistakes in our Estuaries Prevent Disasters in the Open Ocean?” Sharp’s presentation is part of the Ocean Currents Lecture Series, held monthly at the Lewes campus through September.
In his presentation, Sharp will first discuss some of the issues facing estuaries and coastal waters as a result of nutrient enrichment. Probably the best known of these issues is the process of “eutrophication,” where excess nutrients encourage the growth of algae in the water, gradually depleting the water of oxygen. Eventually, the plants and animals that live in the water cannot survive these low oxygen levels.
“Nutrient enrichment is a very complex issue to solve,” says Sharp. “It may be possible to reduce inputs from a single source such as a wastewater pipe, but others, like atmospheric sources, are more difficult. In addition, loss of habitat coupled with overfishing has decreased the consumption of algae by fish and other marine life. Therefore, even if excess nutrients were removed from the ecosystem, there could still be a problem from buildup of algae.”
In the case of ocean fertilization, some scientists believe that nutrient or iron enrichment can be a way to remove excess carbon dioxide from the atmosphere — a greenhouse gas that is thought to play a primary role in global warming. Because this process also will stimulate the production of phytoplankton, the tiny microscopic plants at the base of the food chain, some scientists also propose that ocean fertilization will enhance fish production and increase total world fish catches.
“Although these ideas look good on paper, we do not know enough about ecosystem dynamics to predict the outcome of large-scale ocean fertilization,” says Sharp. “We must learn from the problems of near-shore fertilization so that similar problems are not created in the open ocean, where remediation would be even more difficult.”
A member of UD’s faculty since 1973, Sharp earned his doctorate in oceanography from Dalhousie University in Halifax, Nova Scotia, and did postdoctoral research at Scripps Institution of Oceanography in California.
The lecture will begin at 7:00 p.m. in Room 104, Cannon Laboratory, at the Hugh R. Sharp Campus, 700 Pilottown Road, Lewes. The hour-long talk will be followed by light refreshments.
While the lecture is free and open to the public, seating is limited and reservations are required. To reserve your seat, please contact the college at (302) 645-4279.