New Hampshire correspondent John Tilton is reporting from his home state of Vermont for the summer.
Curly-leaf pondweed, or potamogeton crispus, is an aquatic invasive plant in nearly all of the lower 48 states. Originally from Eurasia, Africa and Australia, this invasive was most likely introduced to the United States as an aquarium plant that was released into the Great Lakes area during the late 1800s. Since that time it has found its way into so many lakes and ponds across the country that few people even realize that it is an exotic plant.
Curly-leaf pondweed begins to form new plants during the winter while the water is still covered with sheets of ice and snow. It is this tolerance for low light and water temperatures that allows curly-leaf pondweed to get a head start on its native counterparts that don't begin to grow until the early spring. This early rising weed can then block the sun to other plants and begin to choke out all of its competitors.
The problem continues when this invasive begins to die off in mid summer while most aquatic plants are still growing. These early die-offs can consume oxygen and alter nutrient levels in the water as the plant decomposes. This can effect aquatic life and lead to algal blooms, which can shut down beaches and pose a threat to public health.
The most likely cause for curly-leaf pondweed's rapid spread across the continent since the late 1800s is human transportation. Plant fragments can get tangled in fishing equipment or boat motors, and it can get snagged on the trailer. The plant produces turions, or vegetative propagules commonly referred to as "winter buds," that can find their way into bilge water or bait buckets and start new plants. The best way to prevent this is to wash and dry your boat and to make sure that live wells, bait buckets and any bilge water is all drained.
While recently working on an invasive species survey for the Lake Champlain Basin Program, I came across a fisherman who put it best: "Not washing your boat is like not wearing a condom," he said, "enter at your own risk." Perhaps he was being blunt, but the point certainly comes across. Moving from one water body to the next without the "protection" of washing your boat and equipment certainly poses the threat of moving invasive species and aquatic diseases, like VHS, around to unaffected areas.
Since curly-leaf pondweed's growing season starts early, it is one few aquatic plants that can be easily found at this time of the year. Like all pondweeds, curly-leaf has a long dark green stem that emerges from the floor of shallow water with leaves that are arranged in an alternating pattern. However, its distinctive feature is its curly, lasagna noodle-like leaves that are about three inches long and a half an inch wide with serrated edges. Even though this invasive plant is widespread, it is important keep it from spreading further. So, inspect and wash your boat and try to enjoy the water.