By: Sarah Barker

Parasites have a pretty bad reputation, which is well-deserved in most cases, but did you know that they can actually tell us a lot about ecosystem health? Parasites are creatures that rely on another organism in order to complete their life cycle. An example of a common parasite are mosquitos; these insects require blood from a host animal in order to reproduce. In fact, only female mosquitoes suck up blood, males rely solely on plant nectar for their food source. In aquatic ecosystems parasites are incredibly diverse and abundant; they are also often specific about which host species they will infect. These traits mean that parasites can be used to measure biodiversity in a habitat since the more parasite species are present, the more host species are required to support their populations. It is estimated that for every one “free-living” species on earth there are approximately four parasite species that may use it as a host.

Many parasites actually need multiple different host species in order to complete their life cycle (heteroxenous parasites) and oftentimes they use hosts which live in different habitats, connecting aquatic and terrestrial ecosystems as they mature and reproduce. For example Alaria americana, a type of flatworm which hatches in freshwater, requires three to four different hosts in order to successfully reproduce: a snail, a frog, sometimes a transport host like a snake or a small mammal, and a larger predator mammal like a fox or a dog. This means that the presence of this species or other heteroxenous parasites in a watershed indicates the presence of all of their hosts in the same area; making these multi-host parasites a wonderful barometer for ecosystem diversity. 

Adult Alaria flatworms. (Photo Credit: https://wcvm.usask.ca/learnaboutparasites/parasites/alaria-species.php)

Parasites are also essential in maintaining healthy and well-adapted host species populations. There is evidence to suggest that some parasites like intestinal worms may actually benefit infected hosts by removing toxins from their body and taking them up into their own. But, only strong individuals can withstand the stress of a parasite infection and successfully reproduce. Over time, this leads to a stronger community as weaker individuals are weeded out. Additionally, parasites can modify the physical appearance, behavior, energy levels, and even the gut microbiome of their hosts, creating more differences in the host population for natural selection to act upon and more opportunities for parasites to infect new hosts. Most of these modifications serve multiple functions. For example, when mice are infected with toxoplasmosis, a parasitic microorganism, they no longer show a fear response to cats. As a result, these mice are eaten by cats, which are then consequently infected by toxoplasmosis. Since the mice that are vulnerable to toxoplasmosis are eaten and do not reproduce; only mice that are not as vulnerable or more resilient to infection survive and reproduce. Overall this system drives evolution in the host species, increasing the adaptive fitness of populations undergoing parasitic infections.

Mussel larvae, called glochidia, attached to a fish’s gills. (photo credit: Rachel Mair https://usfwsnortheast.wordpress.com/2017/08/21/mussels-making-moves-for-water-quality/8-freshwater-mussel-glochidia-attached-to-gills-of-a-host-fish-credit-rachel-mair/)

In aquatic systems, freshwater mussels start their lives as parasites. The mussel larvae, called glochidia, are expelled in large clusters by female mussels either into the current or directly into a host fish’s face or gills. These glochidia then hitch a ride by attaching to the gills of their host fish and eventually releasing themselves into the water once the host reaches an ideal location. Freshwater mussels perform many vital functions in an ecosystem including filtering out nutrients from the water and anchoring sediment in place using fibers they produce called byssal threads. Finding a healthy population of freshwater mussels in a water body means that their host fish must also be present in significant enough numbers for glochidia to travel with them. 

Parasites may not be the prettiest or most charismatic critters, but they sure do tell us a lot about the health of our aquatic environments. They can also provide some surprising benefits for individual hosts and the ecosystem as a whole. These anti-heroes serve to remind us that every creature has an important job in their environment, even the worms and micro-organisms we wish we could forget!

By: Daniel Price

Plants are an interesting metric to assess environmental health. The common thought that “green is good” when observing non-developed spaces is natural as the alternative is no green in these hyper-developed areas. However, green is not created equal. Some of the green found in Pennsylvania and throughout the U.S. are known to be invasive. Invasive plants are non-native (not from the region) and well-adapted to outcompete the native plants. These plants are great at spreading rapidly and taking or making more efficient use of the resources plants need (think sunlight, water, nutrients). The presence of invasive plants can negatively affect the living organisms that share the same space, putting more stress on an ecosystem. 

One area greatly affected by invasive plants is the watershed. A watershed encompasses the land in which all the rainfall and snowmelt make its way into smaller waterways, like streams and creeks, to eventually flow into a larger body like a lake or ocean. Simply, it’s where a drop of rain will go after it falls. The drop of rain will eventually evaporate or transpire before once again becoming a drop of rain, completing the water cycle. As an organism that needs water to survive, plants are often found in abundance surrounding streams and rivers. A key area plants inhabit is called the riparian zone. The riparian zone is the land directly next to a body of water. Being next to each other, the riparian zone and the waterway have a unique relationship where the contents of one influence the other. Invasive riparian plants can disrupt the normal relationship between the riparian zone and the waterway. One method invasive plants can disrupt this relationship is by releasing toxins to suppress the growth of other plants or changing the pH of the soil to become too basic or acidic for native species to survive. These plants are known as allelopathic. A common allelopathic plant seen throughout Pennsylvania is garlic mustard (Alliaria petiolata). Garlic mustard is not exclusive to the riparian zone but can often be found inhabiting that space. 

Garlic mustard (Alliaria petiolata)

Other invasives like the Japanese knotweed (Reynoutria japonica) which grows very densely, can alter the amount of sunlight the stream and other plants receive, negatively affecting their health. Invasive plants can often take up and retain water differently than native plants. This can lead to discrepancies in the natural relationship between water and waterways. For example, an invasive plant may not require as much water as a native plant, leading to a greater chance that nutrients enter a waterway via runoff, rather than being absorbed by a plant.  

Japanese knotweed (Reynoutria japonica)

Image from Oklahoma State University

A watershed is a highly connected system where slight changes can largely affect the organisms that inhabit it, including humans. Humans are very much a part of the watershed and need to better understand that the actions taken or not taken, greatly affect the health of that ecosystem. A simple way to help combat the spread of invasive riparian plants is to plant native. Regardless of where you plant invasives, they often find ways to spread to more sensitive areas like the riparian zone. The PA Department of Environmental Protection has released a field guide of common invasive plants, detailing how to identify and potentially control these plants in your local area (see link at bottom). Here at Willistown Conservation Trust, the Stewardship Program holds Stewardship Thursdays, where you can volunteer to help reduce the spread of invasive riparian plants, care for newly planted native trees and shrubs, and help establish healthy habitats in public spaces. With a little bit of work and awareness, the spread of invasive riparian plants can be combated. 

Link for PADEP Field Guide – https://www.dep.state.pa.us/dep/deputate/watermgt/wc/subjects/streamreleaf/Docs/Invasive%20Plants.pdf

By: Ryan Ferguson

It was a dark and stormy night. You just bought a cozy lawn chair to relax in the next day, but when you look outside, you see it getting washed away by the flooding in your backyard! All you can do now is sit in the wet grass, yell at the sky, and wonder how you can fix this flooding issue. Excess stormwater runoff comes from numerous surfaces that block water from passing through them, such as roofs, driveways, sidewalks, and parking lots. In addition to flooding, runoff can lead to various issues such as erosion and the transportation of pollutants like fertilizer, oil, and road salt, which ultimately reach our waterways. 

Luckily, you have come to the right spot to learn about a potential solution! Bioretention basins are a fantastic treatment option for stormwater management. These basins, also known as rain gardens, are depressions in the ground that absorb excess stormwater runoff. Bioretention basins typically consist of native plants on top of a combined soil/sand bed, topped with a layer of mulch. The runoff water will flow into the basin, where it goes through two main scenarios. When runoff water flows into the basin, it first passes through the mulch, which traps larger debris. It then filters through the soil/sand bed, where finer particles and pollutants are captured, and beneficial microorganisms break down contaminants. Some of this filtered water infiltrates into the groundwater. Meanwhile, native plants absorb a portion of the water through their roots, which is crucial for photosynthesis, cooling, and nutrient transport. This process not only supports plant growth but also enhances the basin’s filtration capacity by stabilizing the soil. Thus, bioretention basins effectively filter runoff water while supporting plant life, creating a sustainable system for water management and the local ecosystem. It’s a win-win scenario for everything involved! In addition to reducing stormwater runoff, these basins provide numerous other benefits, including:

        Improving water quality: Bioretention basins offer a variety of pollutant-removal mechanisms. This can include filtration through the vegetation, evaporation, transpiration, and infiltration into the soil. The best basins can remove suspended solids, metals, and nutrients.  Studies show that bioretention areas can remove 75% of phosphorus and nitrogen, 95% of metals, and 90% of organics, bacteria, and sediment. When large amounts of these contaminants enter waterways,  they can produce toxins that harm people, animals, and aquatic life. 

       Improving water quantity: Soaking up the stormwater runoff allows the water to infiltrate into the ground and become groundwater. This keeps our streams and rivers flowing and fills up the groundwater that we eventually clean and drink.  Groundwater is also cleaner and colder than storm water, which strongly benefits stream life.

       Habitat improvement: Using native trees and flowers creates habitats for animals such as birds and insects, especially pollinators. If you build multiple bioretention basins together, the benefits only get better for the inhabitants, and if you do not have space to build a basin, planting even a small space with native plants can benefit local wildlife and waterways! Here are other ways to reduce stormwater runoff and stormwater pollution on your property.     

Appearance: Bioretention basins are very pleasant to look at, like outside the Rushton Conservation Center!

Bioretention basins offer versatile applications across diverse environments, including right here at Rushton Woods Preserve! WCT staff are currently working with ThinkGreen and Meliora to design and install a new basin this year. This project is possible through generous funding from the Pennsylvania Department of Environmental Protection and the Department of Conservation and Natural Resources. This new construction will join the rain garden outside of the Rushton Conservation Center, which works to reduce the stormwater impact from the building and parking lot on the preserve. 

Check out Rushton Woods Preserve when the basin and deck are complete, any day of the week from dusk to dawn!

Interested in making your own rain garden? Check out this website to learn how to make a simple rain garden in your own yard: https://www.bhg.com/gardening/landscaping-projects/landscape-basics/make-a-rain-garden/

Sources

https://www.epa.gov/system/files/documents/2021-11/bmp-bioretention-rain-gardens.pdf

https://www.hamiltontn.gov/pdf/WaterQuality/bmps/9.1rag.pdf

https://www.lakesuperiorstreams.org/stormwater/toolkit/bioretention.html#:~:text=An%20engineered%20soil%20bed%20containing,of%20six%20to%20nine%20inches.

Fact Sheet: Bioretention Areas

https://www.epa.gov/soakuptherain/soak-rain-whats-problem

By: Rhys Hals 

Erosion of streambeds is a major threat to the health of our ecosystems. Some erosion over time is natural, but too much too quickly results in soil getting washed away and deposited elsewhere, greatly altering the state of the stream, the biodiversity in it, and the overall aquatic habitat. During intense rain events, water washes over impervious surfaces such as parking lots and driveways and picks up speed as it heads toward a stream. As it makes its way across the land, this water cuts down and through the soil. When the water reaches the stream and has a lot of velocity from heavy rain, it can widen the streambed, or cause erosion near the headwaters of the water body. A deep crevice caused by this kind of erosion near the headwaters of a stream is called a headcut.

Headwaters are the source or origin of a stream or creek, the furthest point from where the steam empties. Headwaters are vital in ecological health¹. Yet, despite the importance of these waters, they are disproportionately unmonitored. As runoff from highly developed or agricultural areas empties into headwaters, the stability of the stream is thrown off. The water can become overrun with chemicals and synthetic fertilizers, decreasing water quality and sometimes resulting in algal blooms. Changes in headwaters can go undetected but result in big downstream ecological issues.

• ¹ https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14516
• ² https://soils.org.uk/news/soil-the-elephant-in-the-room/

By: Lauren McGrath

Welcome to Creek Week, our annual week-long celebration of Ridley, Crum, and Darby Creeks. 

Since its inception in 2017, the goal of the Watershed Protection Program has been to study relationships between land conservation and water quality in the headwaters of Ridley, Crum, and Darby Creeks. We have worked to accomplish this goal through monthly water quality sampling and annual aquatic macroinvertebrate sampling. To date, we have collected over 11,500 water quality measurements and sorted and identified over 12,000 aquatic macroinvertebrates. We published the State of our Streams Report in 2022, summarizing our findings, and plan to publish an updated edition next year.

In 2021, we launched the Darby & Cobbs Creek Community Science program in partnership with Darby Creek Valley Association and with support from Stroud Water Research Center. This program, which started with the humble goal of recruiting five volunteers to collect water quality samples in Darby Creek, has grown wildly, with 40 volunteers sampling at 31 sites throughout the Darby Creek and its tributaries, including Cobbs Creek.

Our watershed research has led to exciting discoveries. In 2022, we partnered with the Academy of Natural Sciences to formally document two previously undocumented populations of freshwater mussels in Ridley and Crum Creeks. We were thrilled by the results – both streams had over 70 mussels in a 500 meter stretch. When a volunteer reported finding freshwater mussels near her sample sites in Darby Creek, we were eager to conduct another survey. In May, we partnered with Delaware Riverkeeper Network and found 853 mussels in less than 500 meters of stream and evidence of breeding. Freshwater mussels are one of the most imperiled groups of organisms on the planet, and finding a population as robust as the one in Darby Creek is astonishing. 

No less astonishing than the discovery of our beloved bivalves thriving in Darby Creek was documenting the first sighting of an animal that has not been seen in Ridley Creek in over 100 years – the River Otter! In December, we set up wildlife cameras to monitor a local beaver. We captured many photos of the beaver and, to our shock and joy, a River Otter checking out the camera. River Otters were hunted to near extinction in Pennsylvania and have made a comeback through conservation and reintroduction efforts. Their presence in Ridley Creek is a testament to the long history of land conservation in the region.

To improve habitat for wildlife in Ridley Creek, from mussels to River Otters, we planted nearly 1,500 native trees and shrubs at Ashbridge Preserve from 2019 to 2023. These plants – comprising 53 different species – stabilize the stream bank, reduce erosion, and provide habitat for a myriad of species. Join us for a volunteer day this Thursday, June 27, to maintain this tree planting and ensure it continues to thrive. Sign up here.

From water chemistry to River Otters, one message is clear: everything that happens on the land impacts the water. Open space benefits water quality, development degrades it. We hope you take some time this Creek Week to explore your local stream – you never know what you might find!

Every day this week, we will post a blog about something going on in our local waterways:

• Monday – Soils and Water Quality
• Tuesday – Bioretention Basins
• Wednesday – Riparian Buffers
• Thursday – Aquatic Parasites
• Friday – Invasive Fish
• Saturday – Case Study: Little Crum Creek