Invasive Species on Horn Pond
Currently, Horn Pond is effected by relatively few invasive species. However, the species that do infect our lake pose a threat to the integrity of our ecosystem and the threat of further infestation from invasive species that may infect our lake in the future continues to loom.
Removal of Invasive Species
Invasive Species That May Threaten Horn Pond in the Future
Eurasian Watermilfoil is a species of submerged plant that is native to Europe, Asian, and North Africa. Eurasian Milfoil can grow up to over 8 feet long , with 12-21 pairs of leaves covering the entire stem of the plant. This species was first introduced to North America by the 1940s, where it quickly became an invasive species and spread across the US and Canada. It was likely introduced through the water aquarium trade or through the transportation of watercraft. Once the species enters an aqautic habitat, it spreads quickly and crowds out native plant species. It forms large, dense mats that interfere with boating and swimming. The plant also disrupts the environment in which juvenile and adult fish, as well as crustaceans live, reducing their populations.
Milfoil
Eurasian Watermilfiol
Variable Milfoil
Variable Milfoil is another species of milfoil that is native to the Southeast and Midwest US. This particular variant of milfoil can grow up to 15 feet long, and has 6 inch spike-like flowers that bloom above the lakes surface during the months of June and July. It was introduced to Maine and New Hampshire in the 1960s through the transportation of out-of-state watercraft. This species of milfoil spreads through fragmentation, meaning when one bit is broken off, it settles on the waterbed and grows roots. It, too, forms large mats that interfere with residential use, kill off native plants, and interfere with local fish and crustacean populations.
While there are several species of milfoil that are native to both Maine and New Hampshire, all of these species possess native predators and do not overwhelm ecosystems. Eurasian and Variable Milfoil, however, posses no natural predators in New Hampshire and Maine and thus their growth is unregulated. Under optimum conditions, Milfoil can grow up to an inch per day. Variable Milfoil is much more common in New Hampshire and Maine, as lakes in these areas typically do not have a pH that can support Eurasian Milfiol. These plants spreads quickly across lakes through seeds and fragmentation, engulfing entire aquatic ecosystems rapidly. Once a population of Milfoil is established, it becomes incredibly quickly difficult to remove. It is an incredibly tenacious species that recovers quickly from large population depletion.
If Horn Pond is infected by Eurasian or Variable Milfoil, it is likely that the infection would never be totally removed. However, the population could be managed and kept to a relative minimum through the use of chemicals, dredging, and the potential introduction of predator species of Milfoil.
Invasive Crustaceans
Zebra Mussels
Zebra Mussels are a form of mussel with alternating dark and light stripes. They are native to the Black, Caspian, and Aral Seas of Asia and Europe. The species was brought to the US via European transport ships, but was not identified until 1988. As of yet, there are no reported Zebra mussel infestations in Maine or New Hampshire. However, the threat they pose is enormous. One Zebra Mussel can create up to a million offspring in a single year, allowing for their population to expand extremely rapidly. Zebra Mussels filter zooplankton, which are vital to the food web of Horn Pond, out of the water at a very high rate. They also attach themselves to boat hulls, boat motors, and fishing equipment, which can reduce the usability of these items or destroy them completely.
Asian Clam
The Asian Clam is a freshwater clam native to the waters of Asia, Australia, and Africa. It was first intoduced to the US in the 1900s as a food source. It first reached New Hampshire in 2007, however there are no documented infestations of the clam in Maine yet. The species is incredibly resilient, surviving in an incredibly wide range of temperature and pH. Asian Clams can reduce the water quality by increasing the cycling of nutrients into the waterbody and polluting the water. They can also foul beaches when dead clams wash up on shorelines. Their sharp shell shape possess a threat to swimmers who may injure themselves by unknowingly stepping on them. Finally, like the Zebra Mussel, they eat vital planktons that sustain the fooweb.
Other Aquatic Plants
Considered the most problematic invasive plant in North America, this weed species is native to Africa. The plant, which can grow up to 30 feet long, has a high tolerance for a variety of conditions, a high level of adaptability, and a fast reproduction rate. It is known to spread much more rapidly than Variable Milfoil, which is the most common invasive plant species in Maine and New Hampshire. The species high rate of photosynthesis removes large quantities of carbon dioxide from the water and starves out all other native plants. With no natural predators, Hydrilla destroys food chains eliminating local plants, which intern removes the food that may other species rely on. Once a Hydrilla infestation has occurred, it does not take long before it is the only species in the water.
Hydrilla
Dubbed the most difficult invasive plant species to control by the Maine Lakes Association, this plant originates from Europe, Asia, and North Africa. It was first introduced to the US through the aquarium trade in the early 1900s. The plant produces a large quantity of tiny seeds, which spread easily via water currents, wind, and watercraft. It can also reproduce through fragmentation, similar to milfoil. Once established, this aquatic invader grows leaves up to 8 feet long that block out the sun in many shallower areas of waterbodies. Infestations can by so thick in shallow waters that it recreational activities such as swimming, boating, and fishing are made impossible.
European Naiad
Fanwort
Fanwort is an aquatic plant invader that is native to the Southern US, Central America, and South America. It is a bright green submerged plant that produces lilies and small white flowers in the summer. It was first found in New Hampshire in the 1960s. Like other invasive species, this plant spreads quickly. It can reach lengths of up to 12 feet long and primarily lives on coastlines. Like the European Naiad, it’s infestations can impair boating, fishing, and swimming.
How can we stop these threats from becoming reality
Being a relatively small lake, Horn Pond does not have nearly the resources of other larger lakes in Maine and New Hampshire. These Lakes can afford to spend large quantities of money on checking for invasive species on boats, around their water bodies, and flowing in from other lakes and rivers. They can also afford mass removal and control measures when their lakes become affected. Horn Pond is not afforded such luxuries. To combat this, the HPA does its best to organize Plant Paddles, or trips around the lake lead by experts to scan the local wildlife.
However, being a small lake has its advantages. We have less outside boat traffic, reducing the risk of invasion via watercraft. We also have less area to patrol and, if need be, remove invasive species from. That does not mean that the risk becomes eliminated, however.
There are several things you can do to protect our lake. If you see a plant or animal that you think is invasive or looks suspicious, take a picture and a sample of the species and send it to Julie Callum, Horn Pond Association President. She will consult the state governing bodies to confirm if the species is invasive or not. To help those bodies, and other non-profit groups that fight to control invasive species across Maine and New Hampshire, visit the sites linked below under “Learn More”.
