by Sara Grady, PhD

Aquatic invasive species, particularly invasive pond weeds, are a concern for many lake and pond groups. Given the size and recreational popularity of Great Herring Pond, as well as the presence of a state boat ramp that attracts boats from outside the pond, documenting the presence of any potential invasives is important to do early.

The pond has been monitored for invasive pond weeds in 2011 and then every year 2016-2023 – none of these surveys has found any invasives. However, these surveys happen once a year, while the residents and users of the pond are on the water far more often and can act as spotters for potential invaders before they spread. The most important defense that everyone can participate in is education and vigilance. There is a lot of boat activity in the pond, and any boat coming from another water body could bring a piece of invasive weed that could colonize the pond. Below are images and descriptions of three invaders of greatest concern/likelihood – there are more. Please keep your eye out for anything that seems like it doesn’t belong!

• Hydrilla (Hydrilla verticillata): 6-petaled small white flowers, leaves have serrated edges and a distinctive midrib, leaves are arranged in 4-8 (can be confused with native Elodea that is present in the ponds and has 3 leaves per whorl).
• Variable milfoil (Myriophyllum heterophyllum): Feathery leaves with rounded tips in dense whorls of 4-6. Has a “raccoon tail” appearance, and is often confused with Coontail, which has divided leaves instead.
• Water chestnut (Trapa natans): Triangular floating leaves arranged in rosettes. Leaves are shiny and waxy above and slightly hairy below, with an air bladder at the base and wavy edges. Distinctive nuts are dark brown with four sharp barbs.

For boaters, you/they should keep their boat clean by checking it before and after boating and not transporting organisms from one pond to another. The basic guidelines are CLEAN, DRAIN, and DRY. Please note that these guidelines apply not only to motorboats but also to jetskis, non-motorized craft like kayaks and canoes, and trailers for transporting them.

CLEAN

• Remove any plants or animals from all parts of your boat, paying special attention to places where plant fragments might get tangled (like your propeller) or any rough spots that could be microscopic settled mussel larvae. Dispose of anything you find in the trash.
• Do not transport bait from one pond to the next. Dispose of unused bait in the trash.

DRAIN

• If you’ve been fishing, dispose of live well water away from any water body. Even if you can’t see anything in the water, there could still be fragments of plant or planktonic larvae of animals like mussels present.
• Drain all water from your boat away from any water body.

DRY

• Wash your boat, preferably with hot water. Allow it to completely dry before bringing it to another pond.

If you find something that concerns you, take a good photo of it (2 photos at least – close up of leaves and growth pattern) and email it to sgrady@massaudubon.org  Keep a sample in your freezer in case it needs to be examined.