Invasive species are defined, by law, as species that are not native to the ecosystem and are likely to cause economic harm, environmental harm, or harm to human health. Once introduced, invasive species can spread easily because the new environment lacks the predators, pathogens, or competing species that limit the growth of the species in their original locations. Invasive species often are larger and have more reproductive success in their new locations – a phenomenon that ecologists call “competitive release”. Scientists predict that invasive species will become an even larger threat as native species are stressed by habitat loss or by changed temperature and precipitation regimens.
In the Three Lakes, we worry most about aquatic invasive species (AIS), although with the acquisition of Long Pond Preserve, more terrestrial invasives are also on our radar.
Our most frequently observed aquatic invasive species is Eurasian watermilfoil, which was found in one spot in one lake in 1970 and is now at about 80% of our plant sampling locations. Eurasian watermilfoil is the dominant rooted plant in our lakes, and the example of its spread has made us more vigilant and concerned about other newly introduced invasive plants.
Our most “famous” aquatic invasive species is Brazilian elodea, Egeria densa. Our effort to eradicate this invasive after it was found in 2008 is described on our Brazilian elodea eradication program (BEEP) page.
And the invasive introductions we fear the most are probably invasive zebra or quagga mussels – because of their impact, their proximity, their ease of transport, and because they have never been successfully eradicated. But many other threats exist in nearby waterbodies as well. For just one scary example, hydrilla, which is the worst invasive plant in the US today, is in the Croton Reservoir and Croton River.
Our effort to keep out invasive species revolves around trying to keep out transient boats and fishing gear. See the boat sticker and how to clean your boat pages to learn more. Don’t release bait into our lakes. Another important source of invasives species can be aquarium releases. Put unwanted aquarium plants, fish, and snails into the trash. Invasive species can also come from water features like koi ponds. Use only native species so that overflows in big storms don’t carry non-native species into our lakes.