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.

Preventing Zika Virus & Other Mosquito-Borne Diseases

The start of mosquito season is right around the corner. Princeton Hydro offers simple solutions to reduce mosquito exposure and eliminate mosquito breeding.

Concerns about Zika virus (transmitted by the Aedes aegypti mosquito) arose in Brazil last May and have since quickly escalated. With cases confirmed in over 20 countries across Central and South America, the World Health Organization (WHO) recently declared the virus an international public health emergency. WHO reported that Zika could infect as many as 4 million people by the end of 2016. Additionally, West Nile virus remains a concern throughout the U.S. along with other mosquito-borne illnesses that affect humans, pets and livestock.

With spring rains and warmer temperatures on the horizon, mosquitos of all types will soon be buzzing. As predicted by the National Center for Atmospheric Research, by June we can expect mosquitos carrying the Zika virus to arrive in the Mid-Atlantic States. There are many simple measures that public and private pond and land owners can take in advance of mosquito season to reduce mosquito breeding and lessen the spread of mosquito-borne illnesses without resorting to the use of chemicals.

Here are three simple mosquito-prevention tips for ponds:

  • Eliminate stagnant water by installing a sub-surface aeration system. This will keep the pond thoroughly mixed and properly circulated. Subsurface aeration systems are the most cost-effective and energy-efficient way to maintain proper pond circulation and mixing. DSC02027Agitating the water’s surface interferes with the female mosquito’s ability to lay eggs and the success of mosquito larvae.
  • Along the shoreline of the pond, maintain or create an aquascaped edge dominated by native, non-invasive vegetation. As opposed to a sterile lawn edge, an aquascaped edge provides habitat for mosquito-eating amphibians, fish, birds, and beneficial insects.
  • Prevent grass clippings and lawn fertilizer from entering the pond. Doing so decreases the chance of an algae bloom which could create the still water conditions that favor mosquito breeding.

Additionally, you may want to consider hiring a certified professional to assess your pond and develop a customized management plan. Having your pond inspected by an expert helps you stay informed about your pond’s ecological status and implement measures to prevent/remedy conditions that could create mosquito breeding habitat and promote mosquito related problems.

But that’s not all!

Here are seven things you can do around your home or business property to prevent mosquito breeding:

  • Stagnant water is the perfect habitat for mosquito breeding. IMG_0695Check your property for areas where water easily collects: empty flower pots, buckets, old tires, tire ruts, low spots in lawns and trash cans.
  • Clear clogged rain gutters and storm drains, and keep them free of debris.
  • Regularly change the water in bird baths and pet dishes.
  • Store canoes and small boats upside-down.
  • Check tarps and grill covers for pooled water, and shake them out after a rain storm.
  • Repair leaky outside faucets, pipes and hoses to prevent puddles from forming.

Simply put, if you want to limit mosquito breeding in your pond or on your property, take the time to implement long-term management measures that integrate natural solutions, thereby creating an inhospitable environment for mosquitos. As noted above, this can be accomplished without resorting to chemicals! In addition to keeping your pond properly circulated, employ preventative practices that eliminate potential mosquito-breeding areas around your property, and regularly inspect areas to help quickly identify and resolve developing mosquito populations.

Princeton Hydro offers a full complement of services, including detailed water quality analysis, adaptive management plans and field services covering all areas of pond maintenance. Our team of certified lake and pond managers, wetland scientists, and water resource engineers can provide you with the expertise needed to diagnose the cause of pond problems and develop solutions that are environmentally sound and cost-effective. Contact Princeton Hydro to discuss how we can help you!

Read an interesting article about the origins of Zika here.