WILLISTOWN CONSERVATION TRUST

  • Facebook
  • Instagram
  • LinkedIn
  • YouTube
DONATE
  • About
    • HOW WE WORK
    • WHERE WE WORK
    • OUR STAFF AND TRUSTEES
    • JOBS & INTERNSHIPS
    • VOLUNTEER
    • RUSHTON CONSERVATION CENTER
    • STRATEGIC PLAN
    • DIVERSITY, EQUITY & INCLUSION STATEMENT
    • FAQs
  • LATEST
    • BLOG
    • IN THE NEWS
    • PUBLICATIONS
    • PHOTOS
  • PROGRAMS
    • BIRD CONSERVATION
    • COMMUNITY FARM
    • EDUCATION
    • LAND PROTECTION
    • STEWARDSHIP
    • WATERSHED PROTECTION
  • NATURE PRESERVES
    • ASHBRIDGE PRESERVE
    • HARTMAN MEADOW
    • KESTREL HILL PRESERVE
    • KIRKWOOD PRESERVE
    • RUSHTON WOODS PRESERVE
  • EVENTS
    • EVENT CALENDAR
    • BARNS & BBQ
    • RUN-A-MUCK
    • WILDFLOWER WEEK
    • ECOCENTRIC EXPERIENCE
    • RUSHTON NATURE KEEPERS (RNK)
    • ACCESS Program
  • Support
    • WAYS TO GIVE
    • SPONSOR THE TRUST
    • CORPORATE PARTNERSHIP PROGRAM
    • JOIN THE SYCAMORE SOCIETY
    • LEGACY SOCIETY & PLANNED GIVING
  • CAMPAIGN FOR KESTREL HILL PRESERVE

A Microcosm of Macroinvertebrates

June 25, 2023 By Anna Willig

By Watershed Conservation Research and Data Specialist Anna Willig

Aquatic macroinvertebrates — animals without a backbone that are visible to the naked eye — are some of the most fascinating creatures found in streams. We tend to lump all macroinvertebrates into one category, but there is tremendous diversity found underwater. 

Some macroinvertebrates live for a few weeks, others for a few years. Some stay burrowed in the streambed their entire lives, others emerge as flying adults and migrate across the country. Some scrape algae off of rocks, others are voracious hunters. To illustrate this diversity, we are highlighting three sample orders from the class Insecta (the insects) that have vastly different life histories. While there are generalities that are shared between all species of each order, this is akin to generalizing the life history of all passerine birds (order Passeriformes, which includes most songbirds). 

Odonata Spotlight | The Dragonflies

Larval Dragonfly by Anna Willig

First up is the order Odonata, which includes dragonflies and damselflies. Dragonflies and damselflies are similar, but we focus on dragonflies, which are unique among aquatic macroinvertebrates for their large size, long lifespan, and hunting prowess. Dragonflies start their lives as eggs laid near the surface of the water. Eggs hatch within a few weeks, but some dragonflies can delay hatching for a year if they sense stream conditions are suboptimal. Once they hatch, they typically spend less than a year underwater in the larval (juvenile) stage, though some species spend up to six years developing in streams. Larval dragonflies are fearsome hunters that eat anything they can catch, including other insects, small fish, and tadpoles. 

In their final days as larvae, dragonflies stop eating! During their metamorphosis from larvae to adult, their mouthparts change and, for a few days, are not functional. They crawl onto land at the end of their metamorphosis and climb out of their larval skin, emerging as adults. Once their wings dry and harden, adults take to the air, where they are as ferocious as they are underwater. They have remarkable vision and can predict where their prey will go, a feat not seen in other insects. Males establish territories over water, keeping other males out and luring females in. 

Adult dragonflies live for several months to a year, and a few species, including the Common Green Darner (Anax junius), migrate across the country. Much remains unknown about the migration of Common Green Darners, but, like Monarch Butterflies, a migratory cycle likely lasts a few generations. The first generation emerges in the late winter in southern states and flies north to mate and lay eggs. The second generation hatches in late spring and migrates in late summer, making their way south to a place they have never been. They mate and lay eggs in the south, and the final generation emerges in the fall. This generation overwinters in the south, mating and laying eggs for the next migratory generation.

Ephemeroptera Spotlight | The Mayflies

Larval Mayfly Under Microscope by Anna Willig
Adult Mayfly by Anna Willig

Our next order is Ephemeroptera, the mayflies. Like dragonflies, mayflies have an aquatic larval stage and a terrestrial adult stage, but they share few other similarities. Mayflies are the only insect with an extra phase of metamorphosis called the subimago life stage. They are short-lived as adults and, in ideal conditions, can form massive swarms. Mayfly eggs often hatch within a few weeks, though some species hatch immediately and others delay hatching for a year in suboptimal stream conditions. Mayflies spend up to two years as aquatic larvae, shedding their skin dozens of times before adulthood. While most larval mayflies eat algae, leaves, and other plant matter, a few are predators (though not nearly as efficient as dragonflies).

At the end of their larval stage, mayflies crawl out the stream and shed their larval skin. However, they are not yet adults. This post-emergent, pre-adult form is a life stage unique to mayflies called a subimago. Subimagos have a hairy covering over their wings and must molt one more time to remove this covering, after which point they are adults. Adults only live for a few hours to days. During this ephemeral time, they have one task: reproduce. They lose the ability to eat during their metamorphosis into adults, forcing them to focus all their energy on finding a mate instead of finding food. Males form massive swarms, sometimes large enough to be detectable by weather radar, twirling and dancing to attract females. Females fly into the swarm, find a mate, and speed off to the nearest body of water, where their final act is laying eggs. 

Coleoptera Spotlight | The Water Beetles

Larval Water Beetle Under Microscope
Adult Water Beetle Under Microscope by Anna Willig

Another unique order is Coleoptera, the beetles, which is the largest order in the animal kingdom, containing an estimated 25% of all animal species. Unlike Odonata and Ephemeroptera, which include exclusively insects with an aquatic life stage, only a small fraction of Coleopterans have an aquatic life stage. Common water beetles include water pennies, diving beetles, and riffle beetles. Water beetles are aquatic for their larval and adult stages, only emerging for a few weeks to pupate. They hatch from eggs laid in the water, typically within two weeks, as most cannot delay hatching. Larval water beetles have diverse diets; some scrape algae off of rocks, some shred leaves, and some are predatory. They spend anywhere from a few months to a year in their larval stage and crawl onto the banks to metamorphose.

On the banks, larvae burrow into soft sand and mud to metamorphose, emerging as adults several weeks later. They fly briefly until they find a suitable place to enter the water. Once they re-enter the water, many water beetles never return to the surface. Some even lose their wings. Adults do not have gills and carry an air bubble to breathe, maintaining an equilibrium with the oxygen in the water that constantly replenishes their air. Some adults are short-lived and may not have mouthparts, while others can live for up to three years and have a variety of feeding strategies. Adults mate and lay their eggs underwater, setting the stage for the next generation.

Each of these orders contains multiple families, each family contains multiple genera, and each genus contains multiple species, each with a unique life history. Each stream contains its own community of macroinvertebrates, an unknown diversity hiding just beneath the waters.  And these insects are not exclusive to local streams —  there are thousands of species of dragonflies, mayflies, and water beetles found on all continents except Antarctica. Since 2018, the Watershed Team has collected annual macroinvertebrate samples from the headwaters of Ridley, Crum, and Darby Creeks. We are busy sorting and identifying our samples and are looking forward to sharing what these unique creatures can tell us about local stream health.

References and Resources

Voshell, J. R. (2002). A guide to common freshwater invertebrates of North America. McDonald & Woodward Pub.

Interested in learning more about macroinvertebrates? Check out macroinvertebrates.org for information about and pictures of many of our local macroinvertebrates.  

Filed Under: Watershed

Taking the Temperature of Local Streams

June 24, 2023 By Anna Willig

By Watershed Conservation Research and Data Specialist Anna Willig

One of the most basic, yet most critical, aspects of stream health is temperature. Temperature sits behind the scenes, governing nearly everything that happens in a stream. Make a stream too warm or too cold, and the wildlife will disappear. 

While measuring the temperature of a stream seems straightforward — just stick a thermometer in the water — the reality is much more complicated. In small streams, such as the headwaters of Ridley, Crum, and Darby Creeks, temperature is incredibly variable. At the same spot in a stream, temperature can change by several degrees depending on the time of day, current weather, and time of year. Each day, water temperature rises and falls with the sun. Weather matters — a hot, sunny day will warm a stream more than a cool, cloudy day. Temperature also changes with the seasons, rising throughout the spring and summer and dropping in the fall and winter. 

Location in a stream is important as well. In shady areas, streams will be cooler than in sunny areas. Slow-moving stretches tend to be warmer than fast-moving areas. Muddy water gets warmer than clear water. Shallow areas can warm more than deep sections. The variation of water temperature over time and across space in streams makes it crucial to measure temperature many times at many places in a stream in order to understand temperature trends.

Changes in land use further alter water temperature. When forests are leveled and replaced with strip malls and subdivisions, streams heat up. In undeveloped areas, rainfall soaks into the ground and cools as it flows underground towards streams. In developed areas, rainfall instead runs off of (often hot) parking lots, roads, houses, and sidewalks right into streams. This water cannot cool off and can make streams hotter. Removing streamside trees, building dams, and creating ponds all expose water to more sunlight, ultimately heating the stream.

Add in climate change, which will warm our region drastically in the next few decades, and it is clear that our streams are heating up. But why is this a problem? What does temperature have to do with the animals that live in our streams?

The danger of warm water temperature starts at the molecular level. Temperature governs the rate of chemical reactions and, in water, the amount of oxygen available. As a stream warms, chemical reactions occur faster and the water holds less oxygen. Most animals that live in streams — insects, mussels, fish, frogs, turtles — are cold-blooded, meaning their body temperatures change with the stream temperature. If a stream warms up, so will body temperature, speeding up respiration, metabolic reactions, and all other internal chemical processes that keep the animal alive. However, since warm water holds less oxygen, there will be less oxygen to support these processes, causing stress. 

This thermal stress affects how fast organisms grow, how big they get, and how well they reproduce. Researchers from Stroud Water Research Center tested the impacts of water temperature on aquatic insects, which form the base of the food chain in streams. While there was a threshold above which all insects died, there were concerning effects even before temperature reached lethal levels. As temperatures warmed, insects developed and matured faster, but they did not become as large and consequently struggled to reproduce. If streams become too hot for aquatic insects to survive and reproduce, they will disappear, with catastrophic consequences for the entire ecosystem. 

Fish are also sensitive to changes in stream temperature. Brook trout, Pennsylvania’s only native trout, currently cannot reproduce in local streams because temperatures are too warm. Even though trout are stocked by anglers every spring in local streams, the thermal stress forces these fish to devote so much energy to survival that they have no energy left for reproduction. Even less sensitive types of fish, like bass and sunfish, will show signs of stress when temperatures get too high.

If we want to keep our streams healthy, if we want to protect all the animals that depend upon them, we need to keep them cool. Limiting deforestation, especially along stream banks, will protect shady areas that cool streams. Establishing and expanding forested streamside buffers will create new shade and cool streams. Limiting new development will prevent the expansion of hot pavement. Shifting from stormwater management strategies that hold water, such as retention basins, to strategies that encourage infiltration, such as rain gardens, will force more water into the soil, where it can cool before reaching a stream.

You can make a difference at home by replacing lawns with gardens or meadows full of native plants, which will allow more water to enter the soil. Adding rain barrels will reduce the amount of hot runoff flowing off rooftops into streams. Planting trees, even if you are far from a stream, will also cool water down. Climate change means that rising temperatures will remain a constant threat, but making stream-conscious decisions can help ensure our streams remain healthy and full of life. 

References and Resources

Check out this lecture on temperature from Dr. John Jackson of Stroud Water Research Center (lecture starts at 18:20): https://youtu.be/8Y1ey45053Q?t=1100.

Check out this research article about the impacts of temperature on mayflies from Stroud Water Research Center.

To see a streamside buffer restoration in progress, visit the Watershed Team’s Tree Planting at Ashbridge Preserve! Since 2019, we have put in nearly 1,500 trees with the goal of lowering water temperature in Ridley Creek.

Filed Under: Watershed

Welcome to Creek Week 2023!

June 23, 2023 By Lauren McGrath

By Watershed Protection Program Director Lauren McGrath

Welcome to Willistown Conservation Trust’s 2023 Creek Week! We are so excited to have you join us on a meandering exploration of stream ecosystems — from the tiniest single-celled member of the biofilm to one of the largest rodents on the planet — there is so much to learn about in the Watershed Program’s favorite ecosystem. 

This year’s Watershed Protection Program Co-ops Sarah Barker (front) and Sally Ehlers (back). Photo by Anna Willig

This year, we begin with one of the most critical pieces of determining a stream’s health and function: water temperature. Water temperature dictates the ability of stream life to survive and thrive, and as stream temperatures increase, so does the stress level of sensitive species, like brook trout and macroinvertebrates; a perfect segue to day two of Creek Week, where we will be learning more about the life cycles of different stream insects! Dragonflies, mayflies, and riffle beetles all play an important role in ecosystem health in all of their life stages.  

On day three, we look at what powers the insect base of the food chain: Biofilms! These microscopic ecosystems are all around us and play important roles in transforming light and chemicals into energy, often without much celebration. Learn more about how biofilms are present all around the world — even within your own body.

While we love to celebrate the diversity of endemic, or native, macroinvertebrates, we would be remiss if we did not dedicate a day to learn about one of the newest arrivals to local streams: the New Zealand mudsnail. Join us on day four to take a deep dive into a potentially disruptive new arrival, which has been documented around southeastern Pennsylvania in the last several years. These little snails can form populations so dense that they remove the biofilm from a stream completely! 

While invasive species can be very small like the New Zealand mudsnail, invasive species can also be quite large. Day five brings us face to face with the infamous Northern snakehead, an Asian fish that was first discovered in 2004. Learn more about this frightful predator’s unique adaptations that make it difficult to fully remove from a waterway. 

Finally, we end with the colorful Tale of Charlie Woodscomb: a True Beaver Pioneer. Learn more about the behaviors of beaver through the eyes of Charlie, known fondly as Chompy, as he explores his environment looking for a healthy ecosystem to build a life.

We hope to see you out in the stream, and we invite you to join us for our Watershed Volunteer Day on June 24 and our Streams Learning Evening on June 26!

Filed Under: Watershed

Insights from Two Years of Community Science Monitoring in Darby Creek

March 27, 2023 By Anna Willig

By Anna Willig, Watershed Conservation Research and Data Specialist

This March, the Darby Creek Community Science Monitoring Program (DCCS) — a collaboration between Willistown Conservation Trust, Darby Creek Valley Association, and Stroud Water Research Center — celebrated its second birthday! We officially launched the DCCS in March 2021 with two stalwart volunteers sampling at two sites in Berwyn. Today, 28 volunteers actively monitor 21 sample sites throughout the watershed, extending past Folcroft (Figure 1). The goals of the DCCS are to learn about the health of Darby Creek and its tributaries and identify key restoration sites through monthly water quality monitoring visits.

Figure 1

Water temperature is a key indicator of stream health. As water warms, it holds less oxygen and becomes inhospitable to aquatic wildlife. Trout fishes are one of the most sensitive groups to high water temperature and are a benchmark for healthy streams. If streams are too warm for trout, they are likely too warm for a host of other aquatic species, including mussels and macroinvertebrates. Water temperatures in Darby Creek are often too warm to support the reproduction and survival of trout species (Figure 2). The removal of trees along a stream, increases in development, and stormwater runoff can all contribute to warming streams. The best way to cool streams down is by reforesting stream banks, planting native plants, and designing stormwater management that allows rain to soak into the soil.

Another indicator of stream health is chloride concentration. Chloride is an ion that reflects the amount of salt in streams. Road salt is the main source of salt in streams and is increasingly recognized as a major pollutant. Chloride concentration varies widely between sites in Darby Creek (Figure 3). Generally, chloride concentrations are below the chronic exposure threshold set by the EPA, but are above levels that researchers have found harmful to aquatic organisms. While road salt is necessary for safe winter travel, limiting use and sweeping salt up after storms can reduce salt pollution in streams.

While temperature and chloride concentration reflect a host of threats to the health of Darby Creek, our volunteers have found good news in Darby Creek. One volunteer found a small population of freshwater mussels — which are uncommon in Darby Creek — at one sample site. Freshwater mussels are one of the most imperiled groups globally, and finding them in Darby Creek is a clear indicator that, despite development and pollution, the creek is still a critical resource deserving of protection. We are working with research groups to document and protect this precious group of mussels.

Figure 2. Water temperature in Darby Creek. Each dot represents a measurement taken by a volunteer. Each site is individually colored. The black line represents the maximum water temperature that supports the reproduction of trout.
Figure 3. Chloride concentration in Darby Creek. Each dot represents a measurement taken by a volunteer. Each site is individually colored.

We are incredibly grateful to all the fantastic volunteers who participate in this program. Through their dedication and enthusiasm, the DCCS has exceeded all expectations! The heart of this program is partnership, and we are thankful for support from Stroud Water Research Center and Darby Creek Valley Association. As the DCCS enters its third year, we are excited to build on partnerships, gain new insights, and leverage our volunteers’ data to improve the health of Darby Creek.

To learn more about the Darby Creek Community Science Monitoring Program, please visit their website or email Lauren McGrath (lbm@wctrust.org).

Filed Under: Volunteers, Watershed

Introducing WCT’s Strategic Plan

February 14, 2023 By Communications Team

STRATEGIC PLAN | 2023-2025
Saving, Studying, and Sharing Land, Water, and Habitat


WHERE HAVE WE BEEN?

Land conservation efforts have been underway in the Willistown area for over 40 years. A satellite program of Brandywine Conservancy, formed in 1979, was known as the Willistown Area Conservation Program. With the encouragement of the community and key local conservation leaders, Willistown Conservation Trust (WCT) became an independent, community based land trust in 1996 with a committed and active Board of Trustees.

Using the Crum, Ridley, and Darby Creek watersheds as a boundary guide, WCT’s traditional program area encompasses 28,000 acres in Chester County and portions of Delaware County, and is located approximately 20 miles west of Philadelphia. Despite tremendous growth pressures that have converted many neighboring communities into vast tracts of sprawl development, the WCT program area still remains largely an oasis of green space.

Successful land conservation and stewardship paved the way for major growth within the organization. Since its founding, WCT has grown to include a suite of activities focused on science, stewardship, education, and community engagement. In addition to Land Conservation and Land Stewardship, these core activities include Bird Conservation, Community Farm, Watershed Protection, and Outreach and Education. This holistic approach to conservation explores the connections among land, birds, habitat, agriculture, and water, and educates the public on these connections.

Our land protection and stewardship efforts have been focused on the Willistown area; however, our work has a regional and national impact on conservation.

WHERE ARE WE GOING?

Over the next three years, as our land protection efforts thrive and new opportunities in our traditional program area diminish, we anticipate a growing emphasis on habitat conservation and restoration, education and community outreach. Within these conserved lands, we will use our growing body of research in bird, water, and agro-ecology to inform best practices and engage with the community to educate and inspire an ethos of conservation and care of our land, waters, and habitat where wildlife thrives. In addition, we will identify and consider land protection and conservation opportunities outside of our traditional program area that fulfill service gaps in surrounding communities and meet vital conservation needs, as we interact and collaborate with new communities and organizations.

We will continue to be a robust organization that is well established, broadly supported, and attracts leaders at the forefront of the conservation field. Our science-based programs will contribute research to inform conservation priorities and best practices on a regional, national and international scale. We will attract a diverse group of staff, Trustees, and volunteers who are deeply committed to the mission of WCT and bring a variety of perspectives, skills, and experiences to our work. We will offer robust community and educational programs that attract a wide swath of participants. We will use our established expertise and connections for the conservation benefit of communities outside our traditional area of focus.

To read our Strategic Plan in full, click the cover below:

Filed Under: Bird Conservation, Education, Farm, General, Land Protection, Staff, Stewardship, Watershed

  • « Previous Page
  • 1
  • 2
  • 3
  • 4
  • 5
  • …
  • 14
  • Next Page »

CONTACT

925 Providence Road
Newtown Square, PA 19073
(610) 353-2562
land@wctrust.org

JOIN OUR MAILING LIST

Copyright © 2025 · WCTRUST.ORG