Environment DEC
From the August 2008 issue
Additional Discoveries of Didymo in Famed NYS Fishing Rivers
DEC recently announced the presence of the invasive algae didymo (Didymosphenia geminata) in the West Branch of the Delaware River downstream from the Cannonsville Reservoir, indicating that the main stem of the Delaware River is now infested as well. This is the latest recorded incident of this aquatic nuisance species-also called "rock snot"-in New York State.
Six Waters Now Infested
Didymo has now been verified in the Batten Kill, the East Branch of the Delaware River downstream from the Pepacton Reservoir and the West Branch of the Delaware River downstream of the Cannonsville Reservoir. The main stem of the Delaware River is now also considered to be infested due to exposure from its East and West Branch tributaries. Currently, didymo is not known to be present in any other New York waterway.
Didymo forms thick mats on stream bottoms that choke out organisms that live there
The Delaware tailwaters are one of the premier trout fisheries on the East Coast, and are a popular destination for large numbers of anglers. The discovery of didymo in these waters is particularly troubling given their proximity to other famous trout streams, notably the Beaver Kill and Willowemoc Creek, and the tendency of anglers to fish multiple streams over the course of a day or weekend. The microscopic algae-an invasive species in New York-can survive for many days in cool, damp conditions. Porous materials such as neoprene waders and felt soles used by wading anglers are prime suspects in the spread of didymo among streams.
Didymo cells can produce large amounts of stalk material that forms thick mats on stream bottoms. The appearance of these mats has been compared to brown shag carpet, fiberglass insulation, or tissue paper. During blooms these mats may completely cover long stretches of stream beds and persist for months. The stalk material produced by didymo is slow to break down and may persist for up to two months following its peak growth.
Alters Stream Conditions
While didymo does not pose a threat to human health, it can alter stream conditions, choking out many of the organisms that live on the stream bottom, potentially causing a ripple effect up the food chain affecting trout and other fish. Didymo has historically been limited to cold, nutrient-poor, northern waters, but in recent decades has been expanding its range and its tolerance to warmer and more productive streams.
Once introduced to an area, didymo can rapidly spread to nearby streams. Anglers, kayakers, swimmers, canoeists, boaters and jet skiers can all unknowingly spread didymo by transporting the cells on boats, bodies and other gear. There are currently no known methods for controlling or eradicating didymo once it infests a water body. Anglers, canoeists, kayakers, boaters, or others who witness and suspect the presence of didymo in state waters are advised to contact DEC with the location so that samples can be taken to document and monitor the algae's spread.
Check, Clean and Dry
DEC continues to urge anglers and other water recreationists to Check, Clean and Dry to prevent the introduction and spread of didymo and other potentially invasive organisms from one water to another:
Clumps of algae can be transported on motors, equipment and clothing. Be careful to clean off all gear thoroughly
Check -- Before leaving a river or stream, remove all obvious clumps of algae and look for hidden clumps. Leave them at the affected site. If you find any later, do not wash them down drains; dispose of all material in the trash.
Clean -- Treatment varies depending on what needs to be cleaned. Be sure that the cleaning solution completely penetrates thick absorbent items such as felt-soled waders and wading boots.
For non-absorbent items:
- Detergent or salt: soak or spray all surfaces for at least one minute in a five-percent solution (by volume) of dishwashing detergent or salt (seven ounces of detergent or salt added to water to make one gallon); or
- Bleach: soak or spray all surfaces for at least one minute in a two-percent solution (by volume) of household bleach (three ounces of bleach added to water to make one gallon); or
- Hot water: soak for at least one minute in very hot water kept above 140° F (hotter than most tap water), or for at least 20 minutes or in hot water kept above 115° F (uncomfortable to the touch).
Absorbent items require longer soaking times. For example, felt-soled waders require:
- Hot water: soak for at least 40 minutes in hot water kept above 115° F; or
- Hot water plus detergent: soak for 30 minutes in hot water kept above 115° F containing five-percent dishwashing detergent.
Dry -- If cleaning is not practical, after the item is completely dry to the touch, wait an additional 48 hours before contact or use in any other waterway. Check thick absorbent items closely to assure that they are dry throughout. Equipment and gear can also be placed in a freezer until all moisture is frozen solid.
Note: If cleaning, drying or freezing is not practical, restrict equipment to a single water body. While DEC recommends anglers always take these precautions, it is especially important that any gear used out of state be treated before use in New York waters.
