Jul/Aug 2007Marine Plants: Commanding the Coastlineby Marc Rapport
Beaches bring to mind relaxation and serenity, but salty chlorophyllic invaders may be lurking along the South Carolina shoreline.
"Marine and estuarine invasive species are difficult to control," says David Knott, a marine biologist with the S.C. Department of Natural Resources, noting that he has never heard of a successful aquatic invasive species (AIS) eradication in U.S. oceans. "Plus, South Carolina has no program to manage or control these species."
One of the most conspicuous exotic beach-dwellers is beach vitex, a woody shrub from the Pacific Rim that inhabits dunes. It was intentionally imported to minimize erosion in the 1980s, but its tendency to spread rapidly while crowding out native plants began to raise concerns in the mid 1990s.
"The unanticipated characteristic of this fast-growing species is that it is actually less effective at stabilizing sand dunes than the native species it replaces," says Knott.
Problems like the beach vitex infestation raise questions about introducing new biological organisms to regulate unwanted biological organisms. It would be impossible to predict every ramification of these biological controls, but scientists minimize threats by following standard practices, conducting new research and using sterile animals like triploid grass carp whenever possible.
"We investigate problems in public waters and provide remedies based on prior experiences, research and currently accepted management techniques," says Chris Page, program coordinator for the DNR's Aquatic Nuisance Species Program. "We also do our own research to determine if we can improve our techniques to increase control efficacy."
The beach vitex's aquatic classification may be debatable, but its impact on local ecosystems is readily apparent. Sprawling up to 12 feet in diameter and four feet in height, the hearty vitex threatens endangered loggerhead turtle nesting sites.
To combat the vine, state and federal agencies, industries, non-government agencies and concerned private citizens have banded together to form the Carolinas Beach Vitex Task Force. Working together to map the infestation, limit its spread, restore affected areas and assess the overall impact, the task force is seen as a shining example of conservation partnership.
"A number of federal and state agencies have regulatory and management responsibilities regarding AIS," says Steve de Kozlowski, assistant deputy director for the DNR's Land, Water and Conservation Division and chairman of the S.C. Aquatic Plant Management Council.
"We also need the support of the private sector. Good coordination among partners is essential for managing aquatic invasive species throughout the state."
The newly formed Aquatic Invasive Species Task Force, which consists of 35 representatives from interested agencies and the private sector, is a positive step in that direction.
Individual organizations such as Charleston's South Carolina Aquarium are also fighting unwanted marine infestations. For instance, the aquarium is helping to protect native marine life through the international Ocean Project, which provides members with consistent, research-based conservation messages, programs and activities.
"In the marine realm, educating the public to refrain from releasing aquarium fish and plants could really reduce aquatic invasive species rates," says Knott. "Enlisting citizens to help us monitor non-native plants would also help considerably. Early detection is critical for our rapid response containment methods."
Knowledge will be crucial to warding off invasive marine plants, especially as a global economy and higher temperatures increase their scope and viability. A major 1999 survey conducted by Northeastern University, the MIT Sea Grant and Williams College-Mystic Seaport showed that most companies and organizations importing live marine plants are at risk of introducing invasive species into local waters.
The choppy soup of ocean currents makes complete eradication of any unwanted species nearly impossible. Regaining control of key areas overrun by dense plant populations in large marine bodies is a more realistic goal.
"Working in a marine environment places unique social, political and technical constraints on options for pest control," wrote Ronald E. Thresher and Armand M. Kuris in an article titled "Options for Managing Invasive Marine Species" for the journal Biological Invasions. Their research suggests that current low-risk efforts to regulate non-native oceanic species have a low probability of success against established invaders.
"Because of the viability of these aquatic invasive species, we need to remind the public that our native populations are here for a reason, and introducing new species can cause problems," says de Kozlowski. "First of all, it's against the law. But it's also a very bad idea if we want to preserve our natural heritage."
To limit marine plant contamination, the DNR recommends removing any visible mud and plants before transporting equipment among bodies of water, eliminating water from equipment before transportation, cleaning and drying anything that comes into contact with water (including boats, trailers, clothing and even dogs), and never releasing bait or aquarium plants and animals back into lakes or oceans.
"It's like eating food," says de Kozlowski. "When in doubt, throw it out. Dispose of your bait, aquarium plants and animals, or any hitchhiking plants in a dumpster, but don't put them back into the water."
The DNR also asks citizens to help report aquatic weed problems in public waters by con-tacting the Aquatic Nuisance Species Program at (803) 755-2836.
For More Information
- SCDNR Aquatic Nuisance Species Program
- South Carolina Aquatic Invasive Species Task Force
- Stop Aquatic Hitchhikers
- University of Florida Center for Aquatic and Invasive Plants
- National Exotic Marine and Estuarine Species Information System
- Smithsonian Institution - Marine Invasions Research