- Author: Leigh Taylor Johnson
- Author: Michelle D. Lande
Quagga mussels (Dreissena bugensis) have invaded Southern California, infesting two dozen lakes, reservoirs and Colorado River stations! San Justo Reservoir in Central California is closed to public use because it is infested with their cousins, the zebra mussels (D. polymorpha). The mussels proliferate rapidly via swimming “veliger” larvae that settle on every available surface and grow into adults that typically reach the size of fingernails. They can pile up layer upon layer until they clog pipes up to 2 feet in diameter. To sustain this growth, mussels strip plankton from the water, denying food to other species and causing fisheries to collapse.
Quaggas were introduced into Lake Mead on the Colorado River a few years ago, spreading down the river, into the Colorado Aqueduct and eventually to lakes and reservoirs. The Metropolitan Water District of Southern California spends $10 million/year to clean adults from their water delivery systems and reduce the amount of veliger larvae in the water.
Mussels can also be spread by boats, clinging to underwater surfaces and in pockets of water in cooling systems, bilges, etc. The California Department of Fish and Game and California Department of Boating and Waterways are providing educational resources for boat owners and many lake managers are operating boat inspection and decontamination stations with an eye to preventing them from spreading to new area.
On February 1st and 2nd of this year, the UC Division of Agriculture and Natural Resources and the UC Sea Grant program convened a workshop in San Diego on control and eradication strategies for quagga and zebra mussels. Water managers, agency staff and research scientists from California to Virginia and Canada met to learn about 8 control and eradication strategies. The strategies included: hand removal, covering with tarps to expose mussels to chemicals in a contained situation, types of chemicals used for mussel control, molluscicide derived from a micro-organism, fish bio-control, UV light and seismic technologies, pH manipulation, and integrated pest management.
The participants also met in discussion groups to identify information, equipment, supplies, staff, etc. that they would need to use each method. A second round of discussion groups focused on sharing information and considering how they could collaborate within geographic regions of California, as well as working with partners from Arizona and Nevada. During visits to lightly and heavily infested reservoirs, workshop attendees learned how to find mussels by touch and visual cues.
We will be developing new research and education programs to assist in efforts to control and eradicate invasive mussels. One research project in which we are collaborating is to test how to enhance the ability of resident fish to clean mussels off water facilities in lakes. Future blogs will report on our new program in invasive mussel control.
- Posted By: Leigh Taylor Johnson
- Written by: Michelle Lande, Leigh Johnson and Carrie Culver
A growing body of science is finding that many fouling species can tolerate copper antifouling paints. Although many boat owners know they must clean copper hull paints, the extent of copper tolerance reported by scientists is surprising.
Some invasive fouling species, and even some native species, can attach directly onto copper antifouling paint and can also dominate in copper polluted environments. This has implications for the effectiveness of copper antifouling paints, but also for the importance of having a clean harbor or bay.
Copper-tolerant species also provide an opportunity for other, less-tolerant species to hitchhike on a hull coated with copper antifouling paint. The science shows that copper-sensitive species can attach, grow and be carried within the folds and crevices of more tolerant species.
Copper-based paint is the dominant antifouling strategy. Yet, copper tolerance studies make it clear that antifouling paint, or “chemical control,” may not be able to do the job, alone. They support the need for an integrated approach (see May 23, 2011 blog post “Integrating Hull Fouling Controls – IPM for Boats!”).
An in-depth discussion of the science behind copper tolerance can be found in our fact sheet “Hull Fouling and Copper Tolerance – 2011 Scientific Review.” You can access it on the Nontoxic Antifouling Strategies page of our website.
The photo below shows 12 months growth on copper antifouling paint in San Diego Bay - from our field research.
Copper antifouling paints "dipped their toes" into US west coast legislative waters this year. California Senate Bill 623 was last amended on June 21, 2011 and was referred to the Appropriations Committee on June 29, 2011. Washington Senate Bill 5436 was passed by the Legislature on April 18, 2011 and signed by the Governor on May 3, 2011; it is now Chapter 248, Laws of 2011. Both bills would increase restrictions on using copper antifouling paints on recreational boats.
Use the Internet links provided above to access exact language and status of each bill. Here is a quick comparison as of June 29, 2011, provided for educational purposes, only:
The WA bill will be fully effective by 2020, apply to recreational boats up to 65' and restrict copper content to 0.5% of antifouling paints.
The latest version of the CA bill is more complicated. It includes provisions for determining whether water quality in marinas and harbors, where low-leach rate copper antifouling paints are used, is moving toward meeting the standard for dissolved copper. It also addresses transient vessels, best management practices for in-water hull cleaning, and the importance of maintaining boating in the economic and social fabric of California. Depending on whether certain conditions are met, copper antifouling paint could be prohibited for recreational boats as early as 2015.
The CA bill states that the Legislature intends to promote the use of nonbiocide paints in order to balance control of aquatic organisms on vessel hulls and the requirements of the federal Clean Water Act.
Both bills exempt boats subject to US Coast Guard inspection and that are engaged in commercial use or carrying paying passengers.
In 2002 and 2003 we conducted a field demonstration to see how well fouling could be controlled with nontoxic hull coatings and in-water hull cleaning. We found that fouling could be controlled on nontoxic epoxy and ceramic-epoxy coatings if they were cleaned more often than typical copper antifouling paints. These durable hull coatings could also withstand vigorous cleaning.
Three of the boats in our demo kept their durable nontoxic coatings for 7-8 years. Our 2002 survey of 200 San Diego Bay boat owners found that copper antifouling paints were replaced on average after 2 and a half years. Thus, the nontoxic coatings lasted about 3 times as long as copper paints. In other words, the owners saved the cost of two haul-outs for repainting by using durable nontoxic hull coatings instead of copper antifouling paints. We are conducting an economic analysis of these long-term results and will report findings when it is complete.
For links to more information on our field demo, performance of the nontoxic hull coatings in our demo for the first 5 years, an in-depth economic forecast for costs to use copper versus nontoxic hull coatings, and a sampler of nontoxic hull coatings, visit the Nontoxic Antifouling Strategies page of our website.
Boaters paint a boat hull with copper antifouling paint and expect it to prevent fouling organisms from growing on the surface. Evidence is growing that some invasive, and even some native, hull fouling species have developed the ability to tolerate copper. Further, copper paints have come under regulatory scrutiny.
Boaters are asking for effective alternatives. This leads me to ask, “What does ‘effective’ mean?” I propose that it means the ability to keep fouling under control in a manner that is technically feasible, environmentally friendly and in line with costs for using copper antifouling paints. How do we do that?
Integrated Pest Management, or IPM, may help us to set a new course. According to the manual, IPM In Practice (by University of California Agriculture and Natural Resources), the general approach is to suppress pests over the long term in the least disruptive way that is possible. It often combines biological, cultural, mechanical, physical, and chemical methods and considers the risk that pests will develop resistance to pesticides. I’d like to suggest that we start talking about IPM for Boats!
How can we apply IPM to hull fouling control? In-water hull cleaning is an example of mechanical control. Slip liners and boat lifts are examples of physical control. Antifouling paint is an example of chemical control. Less toxic and nontoxic hull coatings are environmentally friendly.
Cultural control could use the ecology of hull fouling species to guide application of other methods. We’ll be including this IPM approach in future publications and blog posts about our research on fouling control ecology.
Cost effectiveness is an issue for boaters who need to replace copper antifouling paints and want to avoid using another toxic product. We are compiling long-term costs for using durable, nontoxic epoxy hull coatings from boats that participated in our 2002-2003 field demonstration. We expect to be able to report results later this year.
Meanwhile, you can read about our 2007 check-in with boat owners from our field demo to see how the nontoxic coatings were doing five years after they were applied. Visit the Nontoxic Antifouling Strategies page of our website and click on Nontoxic Hull Coating Field Demonstration: Long-Term Performance 2007 Update.
My thanks to Cheryl Wilen, Area Integrated Pest Management Advisor in Southern California, for assistance in learning about the principles of IPM and how we can apply them to hull fouling control!
Who ya gonna call?! Although about half of boats rarely leave home, there is a lot of traffic on the coastline of the Californias. What resources are available for boaters to control invasive hull fouling species as they travel this long coast? To find out we surveyed nearly 200 providers of fouling control supplies and services on the coasts of California, the Sacramento-San Joaquin Delta, and three major boating areas of Baja California.
We found widespread capacity to provide and maintain copper-based antifouling paints. Supplies and services for zinc-based, nontoxic epoxy and nontoxic slick hull coatings are uncommon to rare. In-water hull cleaning, slip liners and boat lifts complement hull coatings in controlling fouling growth. Hull cleaning services are available all along the coasts of the Californias. Slip liners and boat lifts are uncommon to rare.
For information on policy relevant findings and cost summaries for supplies and services, take a look at the two new, supply-side fact sheets on the Aquatic Invasive Species page of our website at http://ucanr.org/sites/coast/Aquatic_Invasive_Species/