Headwaters throughout the United States constantly face many pressures that threaten their integrity. New housing developments, new roads, yards and agricultural systems all introduce different forms of contamination into freshwater systems. One prominent streamside pressure throughout the country is agricultural grazing. Roaming livestock feeds on, or grazes, vegetation in fields and streams. This process can lead to rapid declines in stream health if not properly managed.

In the United States, agriculture is a multi-billion-dollar industry that sees universal demand from consumers. This incredibly high demand directly leads to extensive changes to our watersheds to account for the presence of livestock.

To meet this demand, open space is converted into farmland suitable for species like cows to roam and consume vegetation on land or in water, if lakes or streams are present. This shift to intensive use from meadow or forest systems introduces stresses to the riparian areas and waters that did not exist before. After conversion, our waters may experience increased sediment deposition from nearby land, increased nutrient loads that come from improperly managed pastures, and streambank damage from increased use from livestock. These stresses and pollutants come from non-point sources, making it hard to pinpoint exactly where they originate. Finding a universal solution is even harder, as a system wide approach should be taken to ensure water quality is preserved. Recommendations to minimize damage exist, but sometimes they can fall short.

There are many solutions available for pasture and livestock owners that not only benefit the environment but can also benefit farmers by decreasing the amount of time and money invested. One of the simplest solutions is to ensure that pasture vegetation maintains a minimum height of 4 inches. When the vegetation is kept near this height, root systems are given the opportunity to grow deeper and hold soil and excess nutrients in place.

Rotational grazing is another solution available to farmers that benefits people, water, livestock, and birds alike when enough space is available. Rotational grazing requires pasture managers to divide their land into different sections, or paddocks. When land is divided, livestock is kept to graze in one section while the vegetation in other paddocks grows out. When growth is depleted in one section and lush in another means livestock can be moved based on plant growth ensuring food and ground cover is sufficient for both the animals and the environment. The ungrazed plant growth serves as an important habitat for ground nesting birds like meadowlarks and an important nutrient barrier for our waters.

When improper practices and bare minimum efforts are applied, sediment from cattle walking paths and fields can be washed into the waterways, potentially smothering algae, fish and aquatic insects that call these waters home. Additionally, if streams are small enough, grazing can occur directly in the streambed or on the riparian buffer that is directly protecting the stream. This can cause foliage to die back and expose the streambanks to new conditions where they can cause erosion downstream, impacting other landowners.

Dust is dangerous in the water, but so are fertilizers, pesticides and nutrients from livestock waste that can leach into waters when riparian areas are damaged in heavily grazed systems. Roots from trees and riparian vegetation hold these compounds in the soil column where they are essentially inert. Without sufficient buffers along waterways, widespread death of fish and other stream wildlife is bound to happen when algae growth can inhibit proper levels of vital chemicals like oxygen.

In areas where it is possible, adding fencing around streams to reduce the impact of grazing animals ensures riparian vegetation can grow and root systems can remain intact. Fencing in grazing heavy habitats can also increase activity of pollinators and birds by ensuring specific habitats and conditions needed to host these groups are present.

Grazing comes in many forms. Large swaths of land can be used by cattle ranchers for habitat and feed or smaller plots can be used. Regardless, unless proper measures are taken to ensure sediment loss and nutrient retention are kept at appropriate levels to maintain healthy waters, this non-point pollution source can impact millions of downstream neighbors when managed improperly.

By Zack Smith

Resources:

Agouridis, C. T., Workman, S. R., Warner, R. C., & Jennings, G. D. (2005). Livestock grazing

management impacts on stream water quality: a review 1. JAWRA Journal of the American Water Resources Association, 41(3), 591-606.

Cole, L. J., Brocklehurst, S., Robertson, D., Harrison, W., & McCracken, D. I. (2015). Riparian

buffer strips: Their role in the conservation of insect pollinators in intensive grassland systems. Agriculture, Ecosystems & Environment, 211, 207-220.

DeYoung, J., & Leep, R. (n.d.). Grazing Streamside Pastures.

https://forage.msu.edu/extension/grazing-streamside-pastures/.

Undersander, D., Albert, B., Cosgrove, D., Johnson, D., & Peterson, P. (2002). Pastures for Profit: A Guide to Rotational Grazing. National Resources Conservation Service: USDA. https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1097378.pdf.

Ecosystem engineers are species that change the habitats in which they live. In the Trust’s program area, one ecosystem engineer that many would first think of is a beaver. However, there is another ecosystem engineer in our waters that is changing the way our streams and rivers flow: the Caddisfly.

While small, these small insects are incredibly important in their systems. Caddisflies are sensitive to pollution and other environmental changes, and by assessing their presence, stream scientists are able to get a good understanding of a stream’s health. If caddisflies are present and disappear, that may indicate stream conditions have changed enough to a point where caddisflies cannot live there anymore. Alternatively, if caddisflies have not historically been in a stream and appear, that could point to positive changes in a stream’s quality.

Perhaps one of the most important steps to using caddisflies to assess stream quality is knowing how to identify them. With many different types of aquatic insects living in our streams, being able to distinguish a caddisfly from another species ensures that we can be fully sure that we understand the communities in our waters.

Caddisflies have life stages in both the water and on land, but for our purposes we’ll be focusing on the aquatic stage of their life when they are larvae. To identify if an insect is a caddisfly, first look at the shape of its body. These macroinvertebrates, or animals without backbones, have long bodies that are usually smaller than 45 millimeters or about the size of a paperclip. Their heads have hard skin compared to the rest of their bodies and no antennae. They have 3 pairs (or 6 total) legs extending from their middle body segment which is called the thorax. Their abdomen, which is the segment farthest from the head, will be soft and fleshy with branched gills. The most notable feature of many caddisflies is a case that they make out of aquatic debris like branches, rocks and dead plants.

Caddisflies are in the taxonomic order Trichoptera and are very closely related to butterflies and moths, and use silk to build their unique cases! Found on rocks, logs, and other objects on streambeds, some caddisflies use silk to spin nets to construct their homes.  When found in large numbers, their silk nets have been known to improve the stability of streambeds around the world. In multiple studies looking at caddisfly larvae’s impact on the stability of the stream bed (also called substrate) during floods, it was found that the presence of certain caddisflies can hold substrate in place in many floods. This is very important because as our waters face more intense flooding caused by climate change, habitat stability for aquatic species is put at risk. Net spinning caddisflies decrease the chances of streambed removal by increasing the stress or pressure needed to push the sand, pebbles, gravel and larger rocks downstream. A stable refuge from stormwater is created in the process, and other species like small fish, crayfish, other aquatic insects and vegetation are less likely to wash away when high velocity flood waters come through.

Though small, the abundance of caddisfly larvae in our headwaters is important because of their importance in identifying and maintaining a healthy stream habitat. When spinning nets, these larvae are inadvertently benefitting other organisms in their system and ensuring downstream species are not disturbed by excess inflow of sediments. Despite the caddisfly’s small size, the importance of this ecosystem engineer in our local watersheds is very large! While it may take thousands of caddisflies to make an impact, their presence is felt by many stream residents.

By Zack Smith

Resources:

Cardinale, B. J., Gelmann, E. R., & Palmer, M. A. (2004). Net spinning caddisflies as stream ecosystem engineers: the influence of Hydropsyche on benthic substrate stability. Functional Ecology, 18(3), 381-387.

Johnson, M. F., Reid, I., Rice, S. P., & Wood, P. J. (2009). Stabilization of fine gravels by net‐spinning caddisfly larvae. Earth Surface Processes and Landforms, 34(3), 413-423.

Voshell, J. R. (2003). A Guide to Common Freshwater Invertebrates of North America.    McDonald & Woodward Pub.

Chester County is home to some of the most beautiful landscapes on the east coast with its rolling hills, beautiful open grasslands and bubbling brooks. The county is home to headwaters, the groundwater source, of many streams that will eventually lead to the Schuylkill and Delaware Rivers, which will flow into the Atlantic Ocean. There is one interesting creature that is frequently overlooked when thinking about our creeks and streams: the crayfish.

Crayfish are small crustaceans that can grow to 7 inches in length, they look like “mini” lobsters with colorations that vary from dark brown to a brilliant blue (USDA, 2021). There are over 500 species in the United States and 12 are native to Pennsylvania. While they are amazing creatures, certain invasive crayfish present many threats to our local waterways.

These fascinating arthropods are found in small creeks, usually burrowed under large rocks or under fallen trees. Their lives begin as eggs which the mother carries under her tail for seven weeks. Once they hatch, the larvae will remain attached under her abdomen for another few weeks. When they are on their own, their main food source is tadpoles, insects and worms. Crayfish are commonly nocturnal, and will hunt at night while remaining in their burrows during the day. In under a year, they will be ready to mate in the fall and lay eggs in spring. One crayfish can lay up to 100 eggs and restart the life cycle again (Britannica, 2019).

The rusty crayfish, Orconectes rusticus, named for the rust colored spots on their backs and the virile crayfish, Orconectes virilis, are the most common invasive crayfish affecting our local waterways in Pennsylvania. The rusty crayfish is native to the Ohio river basin while the virile crayfish is native to the Missouri river, Mississippi river and Great Lakes (USGS, 2019). They are particularly harmful to our local environment because they have different adaptations that are better suited to displace the native species of Pennsylvania. They are bigger, stronger, and mature faster, creating a combination that out-competes the native species for resources. They also can live close to each other at about 20 per square foot in comparison to the native crayfish that can only have about 1 comfortably living per square foot. The invasive rusty crayfish competes with native species of crayfish for aquatic plant life that provides valuable shelter, nesting ground and food. Once the rusty crayfish is introduced, 60% of the aquatic plant life can decrease, causing a domino effect of damage to the ecosystem (Schneck, 2013). Frogs and salamander eggs are the most at risk of population decline, as their eggs are a favorite snack of the invasive species. Both the invasive crayfish and native amphibians feed on similar diets of macroinvertebrates, organisms with no internal spine that can be seen with the naked eye. This caused populations to decrease as much as 70% in areas where non-native crayfish have been found.

When it comes to the invasive species of crayfish, their introduction has been difficult to contain, leading to new regulations at the state and federal level. The species were commonly introduced to the local watersheds in a few ways; the most common being distribution to be used in restaurants. The crayfish would fall out of trucks or get loose and walk to suitable water sources that allow them to survive and reproduce (McGinnis, 2019). Another means of introduction into the natural environment is the release from tanks by owners that no longer want them, mixing imported exotic crayfish with the native population. This has been curbed by legislation that prohibits the commercial moving of crayfish without the removal of their heads first (Reed-Harry, 2014). For local anglers, the heads must be removed as soon as they leave the water or be used as live bait in the same water from which they came.

While native crayfish are great indicators of water health and important parts of aquatic ecosystems, the invasive species are major disturbances that must be carefully managed and controlled to allow waterways to return to their original balance. The best thing that can be done at the personal level is to fish responsibly and not return any caught crayfish to the water in which they were found. Up to 50 non-native crayfish can be removed by anglers after removal of their head, and may be used as live bait in the same water source they were caught in (Reed-Harry, 2014). Additionally, be sure to do research on any crayfish that may be owned as pets, not allowing non-native species to be released into local waterways.

By Gloria Avila

Resources:

Virile Crayfish, Northern Crayfish (Faxonius Virilis) – Species Profile. Virile Crayfish, Northern Crayfish (Faxonius virilis) – Species Profile. (n.d.). https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=215.

McGinnis, J. (2019, August 6). ‘Aggressive, delicious’ crayfish invading Bristol Township. Bucks County Courier Times. https://www.buckscountycouriertimes.com/news/20190806/aggressive-delicious-crayfish-invading-bristol-township/2.

Britannica, T. Editors of Encyclopaedia (2019, March 20). Crayfish. Encyclopedia Britannica. https://www.britannica.com/animal/crayfish

Reed-Harry, J. (2014, October 1). PDF. Harrisburg, PA; Pennsylvania Aquaculture Advisory Committee.

In the middle of our 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. While it is too soon to tell if the beaver will make a home at Ashbridge, we wanted to take this opportunity to share the history of beavers in the area and the special role they play in stream ecosystems.

Beavers 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, as well as 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 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.

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 twentieth 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 can occasionally be spotted in Willistown, and 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 (which 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 — typically 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.

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 inhabit 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.

By Anna Willig

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