Understanding and Addressing Invasive Species

Photo from: New York State Department of Environmental Conservation, water chestnut bed at Beacon

Spring is officially here! Tulips will soon be emerging from the ground, buds blossoming on trees and, unfortunately, invasive plant species will begin their annual growing cycle. No type of habitat or region of the globe is immune to the threat of invasive species (“invasives”). Invasives create major impacts on ecosystems throughout the world, and freshwater ecosystems and estuaries are especially vulnerable because the establishment of such species in these habitats is difficult to contain and reverse.

This blog provides an introduction to invasive aquatic species, including information that will help you prevent the spread of invasives in the waterways of your community.

Defining Invasive Species

Invasive species can be defined as non-native occurring in an ecosystem that is outside its actual natural or native distributional range. Although the colonization of an ecosystem by non-native species can occur naturally, it is more often a function of human intervention, both deliberate and accidental. For aquatic ecosystems some species have become established as a result of the aquarium trade, fish culture practices and/or transport of plants and animals in the bilge and ballast water of trans-oceanic shipping vessels.

One of the primary reasons invasives are able to thrive, spread rapidly, and outcompete native species is that the environmental checks and predators that control these species in their natural settings are lacking in the ecosystems and habitat in which they become introduced. The subsequent damages they cause occur on many ecological levels including competition for food or habitat (feeding, refuge and/or spawning), direct predation and consumption of native species, introduction of disease or parasites, and other forms of disruption that lead to the replacement of the native species with the invasive species. As a result, invasives very often cause serious harm to the environment, the economy, and even human health. A prominent example is the Emerald Ash Borer, a non-native, invasive beetle that is responsible for the widespread death of ash trees.

As noted above, there are a large number of aquatic invasive species. Some of the more commonly occurring non-native aquatic plant species that impact East Coast lakes, ponds and reservoirs include:

Understanding How Invasives Spread

Either intentionally or unintentionally, people have helped spread invasives around the globe. This is not a recent phenomenon but rather something that has been occurring for centuries. “Intentional introductions,” the deliberate transfer of nuisance species into a new environment, can involve a person pouring their home aquarium into a lake or deliberate actions intended to improve the conditions for various human activities, for example, in agriculture, or to achieve aesthetics not naturally available.

Photo by: Tom Britt/CC Flickr, zebra Mussels adhered to a boat propeller“Unintentional introductions” involve the accidental transfer of invasives, which can happen in many ways, including aquatic species attached to the hull of boats or contained in bilge and ballast water. A high-profile example is the introduction of zebra mussels to North America. Native to Central Asia and parts of Europe, zebra mussels accidentally arrived in the Great Lakes and Hudson River via cargo ships traveling between the regions. The occurrence, density, and distribution of Zebra mussels occurred at an alarming rate, with the species spreading to 20 states in the United States and to Ontario and Quebec in Canada. Due to their reproductive fecundity and filter-feeding ability, they are considered the most devastating aquatic invasive species to invade North American fresh waters. They alter and diminish the plankton communities of the lakes that they colonize leading to a number of cascading trophic impacts that have especially negative consequences on fisheries. Zebra mussel infestations have also been linked to increased cyanobacteria (bluegreen algae) blooms and the occurrence of harmful algae blooms (HABs) that impact drinking water quality, recreational use, and the health of humans, pets, and livestock.

Additionally, higher than average temperatures and changes in rain and snow patterns caused by climate change further enable some invasive plant species to move into new areas. This is exemplified by the increased northly spread of hydrilla (Hydrilla verticillate), a tropical invasive plant species that has migrated since its introduction in Florida in the 1950s to lakes, rivers, and reservoirs throughout the U.S.

Regardless of how any of these invasive species first became established, the thousands of terrestrial and aquatic invasive species introduced into the U.S. have caused major ecological, recreational and economic impacts.

Measuring the Impacts of Invasives

After habitat loss, invasive, non-native species are the second largest threat to biodiversity. According to The Nature Conservancy, “Invasive species have contributed directly to the decline of 42% of the threatened and endangered species in the United States. The annual cost to the nation’s economy is estimated at $120 billion a year, with over 100 million acres (an area roughly the size of California) suffering from invasive plant infestations. Invasive species are a global problem — with the annual cost of impacts and control efforts equaling 5% of the world’s economy.”

Of the $120 billion, about $100 million per year is spent on aquatic invasive plant control to address such deleterious issues as:

  • Human health (West Nile Virus, Zika Virus)
  • Water quality impacts (Canada geese)
  • Potable water supplies (Zebra mussel)
  • Commercial fisheries (Snake head, lamprey, Eurasian ruffe, round goby)
  • Recreational activities (Eurasian watermilfoil, water chestnut, hydrilla)
  • Biodiversity (Purple loosestrife, common reed, Japanese knotweed)

Invasive species can change the food web in an ecosystem by destroying or replacing native food sources. As the National Wildlife Federation explains, “The invasive species may provide little to no food value for native wildlife. Invasive species can also alter the abundance or diversity of species that are important habitat for native wildlife. Additionally, some invasive species are capable of changing the conditions in an ecosystem, such as changing soil chemistry…”

Addressing Invasives

Our native biodiversity is an irreplaceable and valuable treasure. Through a combination of prevention, early detection, eradication, restoration, research and outreach, we can help protect our native heritage from damage by invasive species.

What Can We Do?

  • Reduce the spread
  • Routinely monitor
  • Document and report
  • Spread the word

Reducing the Spread:
The best way to fight invasive species is to prevent them from occurring in the first place. There are a variety of simple things each of us can do to help stop the introduction and spread of invasives.

  • Plant native plants on your property and remove any invasive plants. Before you plant anything, verify with your local nursery and check out this online resource for help in identifying invasive plants.
  • Thoroughly wash your gear and watercraft before and after your trip. Invasives come in many forms – plants, fungi and animals – and even those of microscopic size can cause major damage.
  • Don’t release aquarium fish and plants, live bait or other exotic animals into the wild. If you plan to own an exotic pet, do your research to make sure you can commit to looking after it. Look into alternatives to live bait.

Monitoring:
The Lake Hopatcong Foundation Water Chestnut prevention brochureInvasive plant monitoring is one of the most valuable site­-level activities people can support. Contact your local watershed organizations to inquire about watershed monitoring volunteer opportunities. For example, the Lake Hopatcong “Water Scouts” program was established to seek out and remove any instances of the invasive water chestnut species.

If you are a lake or watershed manager, the best way to begin an invasive plant monitoring project is with an expert invasive plant survey to determine which invasives are most likely to be problematic in your watershed and identify the watershed’s most vulnerable areas. Contact us to learn more.

 

Documenting and Reporting:
It’s important to learn to identify invasive species in your area and report any sightings to your county extension agent or local land manager. For example, in New Jersey there is the Invasive Species Strike Team that tracks the spread of terrestrial and aquatic invasives and works with local communities in the management of these species. Additionally, consider developing a stewardship plan for your community to help preserve its natural resources. Princeton Hydro’s team of natural resource scientists can help you get the ball rolling by preparing stewardship plans focused on controlling invasive species and protecting the long-term health of open spaces, forests habitats, wetlands, and water-quality in your community.

Spreading the word:
Many people still don’t understand the serious implications of invasive species. Education is a crucial step in stopping the spread of invasives, which is why it’s so important to talk with your neighbors, friends and family about the hazards and ecological/economic impacts of invasive species.

Also consider talking with your community lake or watershed manager about hosting an educational workshop where experts can share their knowledge about invasives specific to your area and how best to address them. Princeton Hydro’s Director of Aquatic Programs Dr. Fred Lubnow recently gave a presentation to the Lake Hopatcong Foundation titled, “Invasive Species in Watershed Management.” View it here.

 

We encourage you to share this article and spread your invasive species knowledge so that together we can help stop the introduction and spread of invasive species.

Lake Management and Restoration in the Hudson River Valley

Lake Management Planning in Action
at Sleepy Hollow Lake and Truesdale Lake

The Hudson River Valley encompasses 7,228 square miles along the eastern edge of New York State. It comprises 3 million residents, 133 communities and 553 significant freshwater lakes, ponds and reservoirs. Princeton Hydro has worked with municipalities and organizations in the Hudson River Valley for over 18 years actively restoring, protecting and managing waterbodies throughout the area.

Princeton Hydro is currently implementing customized Lake Management Plans at two waterbodies in the Hudson River Valley: Sleepy Hollow Lake, a 324-acre drinking water reservoir/recreational lake located in Green County, NY and Truesdale Lake, an 83-acre lake in Northern Westchester County, NY.

Sleepy Hollow Lake

Stretching over two and a half miles long and reaching depths of approximately 70 feet, Sleepy Hollow Lake is a NYSDEC Class “A” drinking water reservoir that provides potable water for the Sleepy Hollow community. The lake is also extensively used by residents for swimming, boating and water-skiing. And, it is recognized as an outstanding large-mouth bass and white crappie (current New York State record holder) fishery!

Princeton Hydro was hired by the Association of Property Owners (APO) at Sleepy Hollow Lake to develop a comprehensive lake management plan. The first step involved an in-depth analysis of the biological, chemical and physical attributes of the lake, with the goal being to generate a database that can be used to better understand the interactions defining the Sleepy Hollow Lake ecosystem.

The data collection and investigation phase includes:

  • Watershed Investigation: an in-depth assessment of the major and minor tributaries and road network in order to identify areas of stream bank and ditch erosion; sources of both sediment and nutrient loading to the lake
  • Bathymetric Survey: the accurate mapping of water depths and the quantification of the amount of accumulated, unconsolidated sediment present in the lake
  • Fisheries & Food Web Study: the collection of fish and plankton data for the purpose of creating a comprehensive fisheries management program focused on managing the lake’s outstanding fishery, further promoting the ecological balance of the lake, and enhancing lake water quality
  • Aquatic Plant Mapping: the development of detailed maps identifying the plant species present in the lake along with their relative abundance and distribution throughout the lake, but especially within the shallower coves
  • Hydrologic & Pollutant Budget: the computation of the lake’s hydrologic budget and pollutant loading budget. The hydrologic budget represents the water balance of the lake and is an estimate of all of the inputs and losses of water. The pollutant budget represents an estimate of the amount of nitrogen and phosphorus entering the lake from various sources. These data are used to evaluate the effectiveness of lake management options, enabling us to determine the best, most ecologically sound and most cost-effective approach to protect and improve the lake’s water quality now and into the future.

Princeton Hydro is now in the process of utilizing all of the data developed during the investigation phase of the project to create a comprehensive Lake Management Plan that will be used to guide the APO’s future lake restoration and protection initiatives. The Lake Management Plan and supporting data will also be used by Princeton Hydro on behalf of the APO to seek grant funding for various lake and watershed restoration projects.

Princeton Hydro is also overseeing the aquatic plant management program at Sleepy Hollow Lake, the focus of which is to control invasive plant species in a manner consistent with and complimentary of the lake’s overall ecological enhancement.

Truesdale Lake

At Truesdale Lake, Princeton Hydro is working with the Truesdale Lake Property Owners Association (TLPOA) to develop a comprehensive Lake Management Plan. The Plan provides a detailed project implementation roadmap for TLPOA, including recommendations for priority ranking of particular activities and restoration measures. A key element of the Plan are the short-term (1-year) and long-term (5-year) water quality and problematic algae and invasive aquatic plant control goals. Another highlight of the Plan is the review of Federal, State, County and local grants, programs and initiatives that may provide funding for identified lake and watershed projects.

During the Plan’s development, Princeton Hydro has provided the TLPOA with lake management consultation services such as community education initiatives, the coordination of NYSDEC permitting activities associated with the implementation of lake restoration measures, and the oversight and administration of an aquatic weed management program at the lake.

Earlier this year, Truesdale Lake experienced excessive aquatic weed growth, which significantly reduced the water quality, recreational use and aesthetics of the lake. Princeton Hydro utilized its Truxor, an eco-friendly, amphibious machine, to cut and remove the nuisance weed growth from the lake. This program helped reduce the negative impacts to the lake and lake users caused by the dense weed growth. Future use of the Truxor to remove invasive weeds is already part of the long-term Lake Management Plan for TLPOA. The Truxor will be used in concert with other measures to control invasive weed growth and restore a more balanced native aquatic plant community.

For more information about Princeton Hydro’s work in the Hudson River Valley or to discuss your project goals, please contact us.