Watershed – Page 6

Beavers Beyond the Dam

June 22, 2022 By Watershed Protection Team

By Watershed Protection Program Co-Op Catherine Quinn

Beavers are known and loved as one of North America’s favorite stream architects. With historic removals of these lovely creatures, we are only just now grasping how important they are in shaping our freshwater ecosystems, which encompasses all streams, rivers, lakes, and ponds, as well as the surrounding land. In food chains, removing any level will alter populations of other levels. For instance, if a species of fish is removed from a stream, populations of macro-invertebrates (which are aquatic, typically early development forms of insects) will grow as there are fewer predators to keep their populations in check. In turn, with large numbers of macro-invertebrates, algae will decrease in population size as there is a higher demand for them as food.

With beavers, their impact extends beyond these food chain alterations when they are introduced to a new stream ecosystem. As ecosystem engineers, beavers actively change the physical features of freshwater environments by building their dams. Even failed or abandoned dams continue to affect the environment. Dams are incredibly capable of storing nutrients and groundwater. They affect water flow to varying degrees and can alter water temperatures. These alterations of physical qualities change the quality of life for other organisms. For example, certain organisms rely on food flowing straight into their mouth, habitat, or home and therefore thrive in fast-flowing areas of water. If that water slows down, they may not be able to survive!

In terms of understanding our streams, we already have a considerable grasp of the macro-invertebrates that inhabit them. Freshwater macro-invertebrates typically live on rocks in fast-flowing environments, like streams. They play an integral role in food chains as they consume much of the plant matter in streams and are an excellent food source for predators, both in water and on land. With the introduction of a significant change to an ecosystem, such as a beaver dam, the conditions macro-invertebrates are used to may be impacted, which will either improve or worsen their ability to survive and reproduce in the environment.

Beaver Dam by WCT Watershed Protection Program

Macro-invertebrates play an important role in regulating nutrients as they enter and leave the water. They are also incredible bioindicators, meaning their presence alone can tell us about the health of the water they are living in. Each macro-invertebrate lies on a scale of pollution tolerance, from sensitive to tolerant. In healthy freshwater systems, we see sensitive groups and a variety of species. This biodiversity tells us that the ecosystem is healthy enough to keep the maximum number of organisms happy. With this application of macro-invertebrates, we can use them to understand how beaver dams are affecting freshwater systems entirely.

The jury is still out on how beaver dams impact the existence of macro-invertebrates, but one thing is certain: beaver dams are indeed affecting them. One study by Clifford et al. (1983), found that in an Alberta, Canada stream, macro-invertebrates increased in both abundance (the number of species) and biodiversity (the variety of species) after the introduction of beavers. The study concluded that sections of the stream flowing from the beaver dam are healthier than sections flowing into the dam. On the other hand, in Utah, Washko et al. (2019) found that beaver ponds (areas completely blocked by beaver dams, creating a pond-like environment) showed lower levels of biodiversity and significantly lower populations of macro-invertebrates. The effects of beaver activity on macro-invertebrates likely depend on a variety of factors. Further research will help us better understand the overall impact beavers have on our waters.

— By Watershed Protection Program Co-Op Catherine Quinn

[1]

Sources:

Clifford, H. F., Wiley, G. M., & Casey, R. J. (1993). Macroinvertebrates of a beaver-altered

boreal stream of Alberta, Canada, with special reference to the fauna on the dams.

Canadian Journal of Zoology, 71(7), 1439–1447. https://doi.org/10.1139/z93-199

Hood, G. A., McIntosh, A. C. S., & Hvenegaard, G. T. (2021). Ecological Compromise: Can

Alternative Beaver Management Maintain Aquatic Macroinvertebrate Biodiversity?

Wetlands, 41(8), 112. https://doi.org/10.1007/s13157-021-01494-7

Robinson, C. T., Schweizer, P., Larsen, A., Schubert, C. J., & Siebers, A. R. (2020). Beaver

effects on macroinvertebrate assemblages in two streams with contrasting morphology.

Science of The Total Environment, 722, 137899.

Shampain, A. (2017, December). The impact of beaver dams on aquatic macroinvertebrate

communities | WALPA.

macroinvertebrate-communities/

Washko, S., Roper, B., & Atwood, T. B. (2020). Beavers alter stream macroinvertebrate

communities in north-eastern Utah. Freshwater Biology, 65(3), 579–591.

Wetlands & Bogs: Aquatic Ecosystems Undercover

June 21, 2022 By Watershed Protection Team

By Watershed Protection Program Co-Op Catherine Quinn

Wetlands are a critical ecosystem in the protection of our watersheds. But what are wetlands exactly? They are just as they sound — land that is wet. How are they critical? In the realm of watersheds, they have many beneficial roles. For instance, the watershed areas protected by the Willistown Conservation Trust make up the headwaters of the Darby, Crum, and Ridley creeks. Their role as headwaters means they have a significant impact on downstream areas of these creeks.

The wetlands surrounding these headwaters help filter the water feeding into them, which in turn helps reduce flooding and pollution. Sphagnum moss, a characteristic plant of bogs, is unique compared to other land plants because it works like a sponge. When precipitation occurs, vegetation normally acts as a barrier from much of the water reaching the ground. However, sphagnum moss, with its sponge-like abilities, will absorb water from precipitation and release it into the ground below, helping maintain that wetland habitat.

Now, how do wetland ecosystems come to be in the first place? Most can be explained by groundwater! Groundwater is also exactly as it sounds — water that exists in the ground. Groundwater can be explained in more detail by the water table, which is a term used to describe the boundary between soil that is completely wet (below the water table), and soil that can hold more water (above the water table). When the ground’s surface is below the water table boundary, or when the surface-level ground is consistently saturated with water (which can also occur with persistent rain), a wetland ecosystem occurs. It is important to distinguish ecosystems like wetlands versus woodlands from one another, particularly in conservation, because of their varying functions, populations, and dynamics. Within wetlands, there is a further multitude of habitat types.

Wetland at Rushton Woods Preserve by Catherine Quinn

A common subset of a wetland is a bog. You have likely heard of bogs before, particularly in relation to where cranberries come from. Bogs are characterized by the makeup of their soil. These wetlands have had at least hundreds of years to develop by means of decaying plant matter. Bogs form from plant matter decaying into what we call peat, which is known for its significant amounts of stored carbon, otherwise known as a carbon sink. Carbon sinks are hugely important ecosystems in terms of the global climate. Human-caused climate change is primarily attributed to the amount of carbon dioxide in the atmosphere. The deterioration of carbon sinks is a contributor to this problem; a common example of this is deforestation.

Many wetlands in our region likely contained bogs, which is a discovery made through finding layers of peat. In our conservation efforts, it is incredibly beneficial to understand the ecosystems we are working in as well as we can. For example, bog turtles are the smallest turtle in North America and are critically endangered due to poaching and habitat loss. Being able to identify their habitat is critical to their protection as an individual will know to look out for them.

The Watershed Protection Program had the opportunity to shadow George Gress, a bog turtle pro from the Nature Conservancy, on a bog turtle habitat assessment. We discovered that while many wetlands do not contain the habitat that bog turtles look for, that does not necessarily mean they are not there. In ecology, it is quite difficult, and sometimes impossible, to prove the complete absence of a species, especially when it comes to our smaller friends. In addition to bog turtles and sphagnum moss, bog habitats have several other characterizing species. Another common type of bog plant is sedges. Sedges are grass-like plants that grow in clumps and help provide ideal habitat to bog turtles by allowing for muddy, particularly wetter depressions in the ground.

— By Watershed Protection Program Co-Op Catherine Quinn

Sources:

https://education.nationalgeographic.org/resource/bog
https://www.epa.gov/wetlands/what-wetland
https://www.nature.org/en-us/get-involved/how-to-help/animals-we-protect/bog-turtle/
https://en.wikipedia.org/wiki/Peat
https://en.wikipedia.org/wiki/Sphagnum

Welcome to Willistown Conservation Trust’s 2022 Creek Week Sponsored by Aqua!

June 20, 2022 By Lauren McGrath

Established in 2017 through a generous grant from the William Penn Foundation, the Watershed Protection Program Team has been working to monitor the health of the Ridley, Crum, and Darby Creek Watersheds. One of the main goals of the Watershed Program is to study and understand how human activities on the landscape are connected to the function of local streams.

For this year’s Creek Week, we will be sharing information about bogs and wetlands; beavers and stream insects; dragonflies, freshwater mussels, and a case study of water chemistry in Ridley Creek. Each of these topics is inspired by what we have observed during our time in these beautiful watersheds, and highlight the intricate relationships between our soil, air, and water systems.

Kirkwood Crum Creek | Photo by Jennifer Mathes

This Creek Week is not just online! The Watershed Team will be at Ashbridge Preserve on Thursday, June 23 and Saturday, June 25. We welcome volunteers of all ages and abilities to join us as we work to maintain the Ashbridge Tree Planting area! This planting was generously funded by the PA DCNR, and since 2019, we have planted over 1,200 trees along Ridley Creek within the preserve.

The trees along Ridley Creek help keep the water cool, slow and filter stormwater, keep the banks of the stream stable and provide important food resources to power the base of the stream food chain, which extends far beyond the waterway. The insects that rely on the leaves and branches from the banks go on to feed fish, mammals, and birds. Insects that emerge from waterways over the course of the spring fuel migratory and hatchling songbirds! With insect populations declining across the country, it is critical to understand where these insects live and how we can make sure they have the habitat and food they need to thrive.

As caretakers of the origin, or headwaters, of the Ridley, Crum, and Darby Creek stream systems, we have an opportunity to provide healthy water for everyone downstream of us — humans and wildlife alike! Both Ridley and Crum Creeks are potential drinking water sources for thousands of residents in Delaware County, and we are thrilled to have Aqua, an Essential Utilities Company, as a sponsor for this year’s Creek Week! We hope to see you on Friday, June 24, at our Community Supper Series, where you can learn more about the amazing water resources in our region.

Please enjoy this week-long sampling of lessons from the streams. The aquatic environment is a dramatic, wonderful, and ancient world full of resilience and hope. Each of us in the Watershed Program is thankful for the opportunity to share what we have been learning, and we welcome your curiosity and questions!

The Trust Teams up with Project Plastic at Ashbridge Preserve to Clean Up Microplastics Using Innovative Device: The Plastic Hunter

February 1, 2022 By CommIntern

Last year we learned that Microplastic Pollution is No Small Problem, after our Watershed Protection Program discovered the dangerous presence of these minute plastics within the headwaters of our focus area: Crum, Darby and Ridley Creeks. Our Watershed Team continues to document and monitor their presence, but now with the help of Project Plastic.

Based in Princeton, New Jersey, Project Plastic is made up of Princeton students and postdoctoral researchers working to design, develop and implement natural systems that can be used to remove plastic pollutants from rivers. Founder Yidian Liu was inspired to find a solution to plastic pollution after observing an increase in the presence of plastics and microplastics gathering in the waterways following large storms in her hometown in China. Now, with Project Plastic, it is her goal to create the first portable microplastic collection device that is both easily portable and environmentally friendly.

Enter the “Plastic Hunter,” an “affordable floating wetland unit that collects and removes microplastic debris from rivers via plant root biofilters.” Resembling an elongated hexagon, this device consists of a fiberglass frame that holds a net-like pad that is both compostable and consisting of a planting membrane. This is where the magic happens – once deployed on the surface of a polluted river, the plant membrane grows downward, and over time, its dangling roots catch microplastic fragments. Once saturated, the removable planting membrane is carefully lifted from the water with a net, and the contaminated plant matter can be taken back to the lab for analysis. A new pad replaces the old one, and the microplastic-trapping cycle continues.

Plastic Hunter’s natural fibers and root system catch microplastics

Conceived and developed by Yidian Liu and Nathaniel Banks, this device and Project Plastic have already received attention after winning multiple awards, including a $10,000 prize for top startup at the Princeton Startup Bootcamp. They have since added to their team, refined their idea, filed a patent, and made multiple design improvements using 3D print prototypes. And then this past December and January, Project Plastic officially launched the very first Project Hunter prototype at Ashbridge Preserve with the help of our Watershed Protection Team.

Thanks to the continual monitoring of our watersheds, Watershed Protection Program Director Lauren McGrath identified a test site known to be highly contaminated with microplastics at Ashbridge Preserve. Plastic Hunter lived here for one month, where it was anchored to stakes located on either side of the stream, covering the majority of the stream’s width. And in place of a true plant membrane, an artificial root system comprised of coconut fiber brushes was used to entrap microplastics, essentially acting as a filtration device.

Project Plastic and WCT at Ashbridge Preserve

Throughout Plastic Hunter’s stay at Ashbridge, Lauren McGrath and Watershed Conservation Associate Anna Willig collected water samples around Plastic Hunter on a weekly basis to determine if the device had reduced microplastic quantities within the stream. Once Plastic Hunter was removed from the stream, its fibers were taken by to Project Plastic’s lab for analysis, and there, the team found that their prototype was mostly effective in capturing microplastics.

Says Yidian Liu, “The Ashbridge Preserve field test marks a prospective start to the development and continued refinement of the Plastic Hunter, as well as an auspicious confirmation of the device’s technical feasibility and efficacy. We are looking forward to continuing to improve this device with the help of the Trust’s Watershed Team.” The group hopes to make Plastic Hunter more buoyant with increased connectivity between those fibers and the device’s frame.

The vision for this group is to deploy future generations of Plastic Hunter across rivers, ponds, and other bodies of water, where their hexagonal frames can connect to one another to create larger filtration devices. Yidian and Nathaniel aim to keep costs as low as possible, so that their product can be affordable and reach a variety of customers across the world. And by focusing on using compostable, natural materials, they hope to also reduce the cost to our planet.

Says the Trust’s Watershed Protection Program Director Lauren McGrath, “Globally, microplastic contamination is a major concern for public and environmental health, and identifying meaningful solutions for the reduction and removal of plastic from stream and ocean systems has been a serious challenge. We have enjoyed partnering with the Project Plastic Team and are inspired by their creative and innovative approach to this increasingly complex issue. We hope that through regular monitoring and creative problem solving, we can continue to better understand how to reduce microplastic pollution in our waterways.”

Visit Project Plastic to learn more about their plastic-free vision for the future!

Beaver Business

January 4, 2022 By Anna Willig

Please Note: The Watershed Protection Team is excited to welcome our newest team member and encourages all visitors to keep an eye out for beavers at Ashbridge but please do not go searching for them. The health of our waterways will benefit from the presence of Castor canadensis, so please be respectful of their space.

In the middle of the 2021 spring tree planting, the Watershed Protection Team had quite the surprise when we spotted evidence of beaver activity in Ashbridge Preserve. A single tree was knocked down along Ridley Creek, with distinctive teeth marks that indicated a beaver had found itself a tasty meal. In October, the first lodge was located, and it was clear that the beavers had settled in the center of 1,000 freshly planted trees. But more than concern was a feeling of validation; the hard work of every staff member, volunteer and student has resulted in the creation of suitable habitat for one of nature’s most effective ecosystem engineers.

A beaver caught on the Trust’s wildlife cam

Beavers (Castor canadensis) are the largest rodent found in North America, reaching 3 feet in length and weighing between 30 and 60 pounds. They have small faces, stocky brown bodies, and a distinctively hairless, paddle-shaped tail. Their tail allows beavers to be distinguished from groundhogs, which have short, furry tails, and muskrats, which have long, hairless tails. Beavers are well-adapted for an aquatic lifestyle: when they dive underwater, their eyes are protected by a set of transparent eyelids and their ears and nose are protected by watertight membranes. They even have a second set of lips that close behind their teeth, which allows them to chew while underwater and not drown. They can remain underwater for 15 minutes, and their oily, waterproof fur helps them stay dry. Their webbed feet and rudder-like tail allows beavers to swim at speeds of 5 miles per hour.

Chompy the beaver was donated to Willistown Conservation Trust and currently lodges in the Rushton Conservation Center. Note its glossy fur and hairless, paddle-shaped tail. Photo by author.

Beavers were once abundant throughout North America, from northern Mexico all the way up to the southern Arctic. However, they were heavily hunted for their waterproof pelts by European colonizers, and their numbers dropped rapidly. In Pennsylvania, beavers were wiped out by the beginning of the 20th century. Reintroduction efforts in the 1920s proved successful, and beaver populations have been stable in Pennsylvania since the 1930s, though they likely are not as abundant as they were before European colonization. There are a few known beaver colonies near Willistown in Ridley and Darby creeks, and evidence of beaver activity is occasionally spotted in Willistown, most recently at Ashbridge Preserve.

Beavers are perhaps nature’s most effective engineers, changing entire ecosystems to fit their needs. They build their homes, called lodges, almost exclusively in the middle of slow-moving ponds, where the surrounding water acts as a moat that protects them from terrestrial predators. If no such pond can be found, beavers dam streams and rivers to create the perfect pond. To create their dams, beavers cut down trees with their chisel-like teeth, which constantly grow and self-sharpen. They generally prefer trees with diameters of less than 3 inches, but will cut down larger trees if small trees are not readily available. They construct their dam with logs, branches, twigs, and grasses and seal everything into place with mud.

Once the dam backs up enough water, beavers build wood and mud lodges in the middle of the pond that can be 6 feet high and up to 40 feet wide. These lodges have 1 or 2 underwater entrances, a ‘living area’ above the water line, and a small air hole in the top to provide ventilation. A lodge houses a colony made of a breeding pair — believed to mate for life — the current years’ kits, and the surviving offspring from the year before. Before the kits are born, the female drives out the second year young. After the young are driven out from the den, they disperse to find new habitat and form their own colonies.

Beaver settlement causes widespread changes to an ecosystem. The first noticeable change is the clearing of several trees, usually small, that the beaver will use to build its dam. After the dam is built, the creek will start to back up, flooding the adjacent land and forming a small pond. More trees may be felled to build the beaver’s lodge. What was once a wooded valley with a small stream becomes an open pond bordered by wetland vegetation. This new pond supports a host of wetland species that would not otherwise be found in the area — ducks, geese, herons, turtles, fish, frogs, salamanders, and more. Even beaver lodges create habitat: the underwater base of the lodge provides shelter for young fish and the top of the lodge can be a nesting area for birds.

A beaver captured on the Trust’s game cam

Beyond supporting a biodiverse ecosystem, beavers and their dams improve local water quality. Beaver ponds trap and slow down water, reducing downstream flooding during major storm events. By slowing down the flow of water, beaver dams also allow more water to seep through the soil and replenish groundwater resources. As water passes through a beaver pond, fine sediment and pollutants are filtered out, resulting in cleaner water downstream of the dam.

Beavers inhabitat a pond until they deplete all nearby food sources, usually after 20 to 30 years. At this point, they abandon their pond and lodge and move on to new habitat. Without constant maintenance, the dam slowly breaks down and eventually breaches. The pond drains, and the previously-submerged seed bank begins to germinate. Shrubs and trees re-establish in the area and, eventually, the open land turns back into a wooded valley.

If you want to learn more about the history, biology and benefits of having beaver living in local streams, join us for our upcoming virtual Beaver Talk on February 2!

References

Beaver. (n.d.). Pennsylvania Game Commission. Retrieved May 27, 2021, from https://www.pgc.pa.gov:443/Education/WildlifeNotesIndex/Pages/Beaver.aspx

Beaver. (2016, April 25). Smithsonian’s National Zoo. https://nationalzoo.si.edu/animals/beaver

Beaver | National Geographic. (n.d.). Retrieved May 27, 2021, from https://www.nationalgeographic.com/animals/mammals/facts/beaver

Wohl, E. (2021). Legacy effects of loss of beavers in the continental United States. Environmental Research Letters, 16(2), 025010. https://doi.org/10.1088/1748-9326/abd34e