Week of May 11, 2008

Invasive algae found in Maryland

Annapolis, Md. — The Maryland Department of Natural Resources (DNR) announced that a new invasive, non-native algae has been found in Maryland for the first time. The algae, commonly known as Didymo, was found by anglers in Gunpowder Falls in Baltimore County.

Didymo mats, also called “rock snot,” look slimy, but feel like wet cotton or wool, and can be white, yellow or brown. “This alga has the potential to disrupt ecosystems in waters it invades by choking out bottom-dwellers and removing food organisms for game fish and other aquatic species,” said Don Cosden, Assistant Director of DNR’s Fisheries Service.

DNR is developing an aggressive plan of attack to deal with this invader, and asks anglers and outdoor enthusiasts who enjoy Maryland’s waters to use extra precautions when moving from one stream or lake to another.

Once Didymo is established, it can cover and suffocate a stream bottom, and movement of a single cell can contaminate a new waterway. Felt bottom boots and waders commonly used by anglers are the worst culprits in the spread of aquatic invaders. Anglers are strongly encouraged to replace these boots with non-porous materials. New boots made of a sticky rubber material are safer for the aquatic environment and are much easier to clean.

Anglers and other recreational users of Gunpowder Falls and surrounding waters are especially urged to make sure they don’t contribute to the spread of Didymo or any other aquatic invasive species. The public is asked to clean anything that comes into contact with stream water by scrubbing away all dirt and debris before leaving a stream. At home, disinfect equipment by soaking in a 5% salt solution (1 lb/ 5 gal) for several minutes, or scrub well with dish detergent and rinse well. If disinfection is not possible, let equipment dry completely for at least 48 hours. Anglers may want to consider having two sets of equipment in order to move safely from one spot to another.

Didymo is an algal diatom that forms long stalks which combine to form heavy, thick mats that can smother a stream bottom. The stalks can persist for two or more months after the diatoms die, causing habitat damage for an extended period of time. Originally found in Scotland and extreme northern Europe and Asia, Didymo has been transported worldwide. Recently, the species has been found in the northeast and mid-Atlantic regions of the United States. In many cases, anglers have unknowingly transported the diatom on their fishing gear. DNR urges anyone who observes Didymo to contact Don Cosden at 410-260-8287 as soon as possible. Article

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Microwave zapping kills invasive species before the invasion

Scientists in Louisiana are reporting development and successful testing of a new cost-effective system to kill unwanted plants and animals that hitch a ride to the United States in the ballast water of merchant ships.

These so-called “invasive species,” such as the notorious zebra mussel, devastate native organisms and infrastructure and cost taxpayers billions of dollars annually. The study is scheduled for the June 1 issue of ACS’ Environmental Science & Technology.

In the study, Dorin Boldor and colleagues point out that invasive species often travel in ballast tanks of international cargo ships. Ships pump sea water into these tanks for stability when a vessel leaves port with little or no cargo. They dump the water at their destination — along with zebra mussels, Asian clams and other organisms that may pose environmental risks.

The new study describes development and laboratory-scale tests of a continuous microwave system which, much like a kitchen microwave oven, used heat to inactivate zooplankton, algae, and oyster larvae in salt water.

Researchers found that a 30-second zap, followed by a 200-second holding period, removed all marine life. Boldor noted that the high heating rates, low operating costs, and effectiveness in hazy water distinguish it from conventional heating methods. Article