Figure 1. Members of the Valley Forge Crayfish Corps remove invasive rusty crayfish from Valley Creek, a state-designated “Exceptional Value Waterway.”
The Crayfish Corps is one of three re source stewardship activities that make up Valley Forge’s Stewards of Native Diversity program, a natural resource initiative that focuses on the preservation and restoration of native biodiversity. These programs are designed to engage youth in meaningful stewardship activities and promote hands-on learning to achieve resource management goals. Under the direction of National Park Service staff, Crayfish Corps participants systematically search sections of Valley Creek, removing rusty crayfish while counting and releasing native crayfish. They learn proper search and capture techniques, how to minimize habitat disturbance, species identification, and the impact of rusty crayfish on native diversity. In addition to hands-on learning in the field, the park created lesson plans to link field activities back to the class room, making the program increasingly popular with local schools. Promotional brochures, buttons, and T-shirts featuring the Crayfish Corps logo (see start of article) help promote the program with park visitors and families and encourage long-term engagement. During the last four years, more than 6,000 volunteer hours have resulted in the removal of more than 11,000 rusty crayfish and achievement of the park’s goal of suppressing the invasive species’ population so that it remains at initial invasion levels. Focused on the creation of future park stewards and management of park biodiversity, the Crayfish Corps is now the park’s most popular volunteer program and the only one in which the majority of participants are under age 18.
In addition to contributions from volunteers, hundreds of staff hours are spent each summer supervising participants, catching crayfish, and collecting, managing, and analyzing data. To inform the resource management strategy and pro mote science-based decision making, park staff collect data on stream temperature, species captured, location, sex, reproductive status, volunteer efforts, and size. Subsequent analysis enables staff to evaluate changes in the relative abundance of crayfish species, determine trends, understand changes in population structure, and assess the overall efficiency and effective ness of the program. The analysis indicates that through the Crayfish Corps the park has managed to maintain a native–to–rusty crayfish ratio of 4:1, preventing the loss of native crayfish species and helping to maintain biodiversity in the aquatic ecosystem. Additionally, the average total body length of rusty crayfish is decreasing, which indicates that the Crayfish Corps is effectively removing most of the large reproductive individuals. Interestingly, data also indicate that stream sections with cooler average water temperatures (coincidently the sections with the most well-established riparian buffers) have fewer rusty crayfish than warmer sections, and that an old dam near Valley Creek’s confluence with the Schuylkill River may be slowing the movement of rustys into the watershed. We presented these results at the 2011 George Wright Society meeting and the Schuylkill Watershed Congress.
To help prevent the continued spread of the species, the park incorporated a “no live bait” policy into its superintendent’s compendium and regularly provides literature and educational materials about invasive species to park visitors. In 2012 a park internship project investigating the relative abundance and distribution of the three crayfish species in the Valley Creek watershed found, unfortunately, that the rusty crayfish has continued to advance up Valley Creek beyond the park boundary. Valley Forge National Historical Park is working with partners at Valley Forge Trout Unlimited, Stroud Water Research Center, and Cabrini College to develop a Crayfish Corps that extends into stream sections outside the park to help suppress the invasion as it moves farther up the watershed.
Valley Forge National Historical Park translated an urgent need for invasive species control into the most popular multiage volunteer program at the park. Through volunteer help and community support, a small natural resource staff are able to effectively control an immediate threat to biodiversity while engaging thousands of volunteers in hands-on lessons in the importance of stewardship. As parks face limited budgets and staff, this program can serve as a model for achieving invasive species control, citizen engagement, and biodiversity management.
Butler, R. S., R. J. DiStefano, and G. A. Schuster. 2003. Crayfish: An overlooked fauna. Endangered Species Bulletin 28:10–11.
Garvey, J. E., R. A. Stein, and H. M. Thomas. 1994. Assessing how fish predation and interspecific competition influence a crayfish assemblage. Ecology 75:532–542.
Huryn, A. D., and J. B. Wallace. 1987. Production and litter processing by crayfish in an Appalachian mountain stream. Freshwater Biology 18:277–286.
Lieb, D. A., and R. F. Carline. 1999. The effects of urban runoff from a detention pond on the macroinvertebrate community of a headwater stream in central Pennsylvania. Journal of the Pennsylvania Academy of Science 73:99–105.
———. 2000. Effects of urban runoff from a detention pond on water quality, temperature, and caged Gammarus minus (Say) (Amphipoda) in a headwater stream. Hydrobiologia 441:107–116.
Lieb, D. A., R. F. Carline, and H. M.ingram. 2007a. Status of native and invasive crayfish in ten National Park Service properties in Pennsylvania. Technical Report NPS/NER/ NRTR–2007/085. National Park Service, Philadelphia, Pennsylvania, USA.
Lieb, D. A., R. F. Carline, and V. M. Mengel. 2007b. Crayfish survey and discovery of a member of the Cambartus acuminatus complex (Decapoda: Cambraridae) at Valley Forge National Historical Park in southeastern Pennsylvania. Technical Report NPS/NER/ NRTR–2007/084. National Park Service, Northeast Region, Philadelphia, Pennsylvania, USA.
Momot, W. T. 1995. Redefining the role of crayfish in aquatic ecosystems. Reviews in Fisheries Science 3:33–63.
About the author
Amy Ruhe (email@example.com) is a biologist at Valley Forge National Historical Park in Pennsylvania.
Pollinators in peril? A multipark approach to evaluating bee communities in habitats vulnerable to effects from climate change
By Jessica Rykken, Ann Rodman, Sam Droege, and Ralph Grundel
Can you name five bees in your park? Ten? Twenty? Will they all be there 50 years from now? We know that pollinators are key to maintaining healthy ecosystems—from managed almond orchards to wild mountain meadows—and we have heard about dramatic population declines of the agricultural workhorse, the honey bee, yet what do we really know about the remarkable diversity and resilience of native bees in our national parks?
A large proportion of flowering plants in most parks rely on insect pollinators for successful reproduction, and native bees are almost always the most efficient and diverse of these insects, with 3,604 described species in North America north of Mexico, and what are thought to be another 400 undescribed ones. Bees are known to be at risk from various human-mediated threats, such as habitat loss and alteration, pesticides, introduced parasites, and invasive plant and insect species. Climate change also poses a significant risk to native bees, with potential consequences including range shifts (especially upslope or northward), population declines, and mismatches in the phenology of plant-pollinator relationships.
At particular risk are bee communities (including rare and endemic species) in habitats most vulnerable to effects from warming temperatures, altered climates, and rising seas. These include high-elevation meadows, inland arid areas, and coastal dunes—in other words, many of the iconic landscapes protected in our national parks. In fact, the geographically and ecologically diverse landscapes preserved and protected by the National Park Service provide an ideal natural laboratory in which to investigate large-scale patterns of bee distribution in sensitive habitats and to model how strongly climate change may affect these patterns.
In 2010, collaborators from the National Park Service (Ann Rodman, Yellowstone National Park), USGS (Sam Droege and Ralph Grundel), and Harvard University (Jessica Rykken) were awarded funding from the NPS Climate Change Response Program to launch just such an investigation in almost 50 units of the National Park System (fig. 1). The main objectives of this multiyear project were to:
1. Compare bee communities in three “vulnerable” habitats (high elevation, inland arid, coastal) and paired “common” habitats, representative of the landscape matrix, in order to determine whether vulnerable habitats have a distinctive bee fauna that may be at higher risk under climate change scenarios.
2. Inform natural resource managers at each park about the bee fauna at their paired sites, including the presence of rare and endemic species, and make suggestions for active management strategies to promote native bee habitat if warranted.
3. Increase awareness among park natural resource staffs, interpreters, and visitors of native bee diversity and natural history, the essential role of bees in maintaining healthy ecosystems, and potential threats from climate change to pollinator-dependent ecosystems.
[Map of the United States showing the location of the 46 national park areas that have taken part in the inventory research: Acadia NP, Apostle Islands NL, Assateague Island NS, Big Thicket NPres, Biscayne NP, Blue Ridge Parkway, Boston Harbor Islands NRA, Bryce Canyon NP, Buck Island Reef NM, Canaveral NS, Cape Cod NS, Cape Krusenstern NM, Channel Islands NP, Colorado NM, Cumberland Island NS, Death Valley NP, Denali NP & Pres, Fire Island NS, Fort Matanzas NM, Fossil Butte NM, Gateway NRA, George Washington Birthplace NM, Glacier NP, Grand Teton NP, Great Basin NP, Great Smoky Mountains NP, Indiana Dunes NL, Isle Royale NP, Kenai Fjords NP, Lake Clark NP & Pres, Mojave NPres, North Cascades NP, Organ Pipe Cactus NM, Petrified Forest NP, Pictured Rocks NL, Point Reyes NS, Redwood NP, Rocky Mountain NP, San Juan Island NHP, Santa Monica Mountains NRA, Sleeping Bear Dunes NL, Timpanogos Cave NM, Timucuan EHP, Wrangell-St. Elias NP & Pres, Yellowstone NP, Zion NP]
Figure 1. Forty-six parks in the National Park System participated in the bee inventory research.
The challenge of a multipark approach
The project was designed so that the cost and effort of sampling for each park would be minimal, while the information provided by uniformly collected bee data from dozens of parks across the continent would be of unprecedented scope and power. Each park was responsible for selecting a pair of vulnerable and common sites and then sampling both sites five times between the earliest spring flowering and the end of the blooming period in the fall. Sampling procedures were designed to be simple, repeatable, and volunteer-friendly. At each of the two sites, 30 “bee bowls” were set out along a transect, spaced 5 m (16 ft) apart. The cups were painted blue, yellow, and white to resemble flowers and attract bees (fig. 2). Once inside the “flower,” bees were trapped in soapy water. Ideally, bowls were left out for 24 hours when conditions were calm and sunny. Bees were then collected, labeled, bagged, and sent off for identification. To facilitate communication between project organizers and participating parks, a “bees in parks” e-mail list was set up early on. This was useful for discussions about where and when to sample (which varied greatly depending on park location, habitat, and local climate) and, later, to pass along interesting bee discoveries directly from bee biologists to parks.
[A researcher pours the contents of a bee collection bowl through a strainer. Credit: NPS Photo]
Figure 2. Collecting bees involves pouring the contents from one of the painted “bee bowls” through a strainer. Contents from all 30 bowls of a transect were combined, transferred to a plastic bag, and shipped to the bee lab in Maryland.
As is commonly the case with insect biodiversity studies, collecting is the easy part. One of the largest challenges for a project of this scale is preparing, identifying, and databasing the tens of thousands of specimens that can be sampled in a relatively short period of time. With bees coming in from Alaska to Maine, southern California to Florida, and everywhere in between (fig. 1), the potential number of specimens and the pool of possible species (several thousand) were somewhere between thrilling and completely overwhelming. USGS biologist Sam Droege took on the herculean task of processing all the bees at his Bee Inventory and Monitoring Lab at the Patuxent Wildlife Research Center in Beltsville, Maryland, where his efficiency rating (“bees per minute”) rises ever higher in the nimble hands of high school and college students. Identification of the bulk of the eastern bees and some of the western bees was also completed within his lab; however, most of the western bees were sent to the USDA Bee Biology and Systematics Lab in Logan, Utah.
Preliminary results: Many cool bees!
A total of 46 national park units participated in the study (fig. 1). These included 30 national parks, preserves, and monuments; 10 national lakeshores and seashores; and six national recreation areas, historical parks, and parkways. All NPS regions in the lower 48 states (with the exception of the National Capital Region) were well represented, as were Alaska and the Virgin Islands. Several parks without any of the target vulnerable habitats also participated in order to enhance their knowledge of local bees in other sensitive habitats. In Alaskan parks, all habitats were considered potentially vulnerable to climate change because of their northern location. Many parks also placed a transect near a visitor center for interpretive value, and some parks added transects in additional habitats. Among them, the 46 parks ran an impressive 809 bee bowl transects, sampling more than 43,000 bees from 2010 to 2013.
Full sets of results have been completed for some parks and regions (mostly in the eastern and midwestern United States), but the enormous task of identifying all the western bees has fallen to a very few western taxonomists, and many of these identifications are still pending. Addition ally, there are some taxa that are so diverse and difficult to separate (e.g., the diabolical subgenus Dialictus, with almost 100 species in eastern North America alone) that some or all of these bees have been passed on to individual specialists around the country (see acknowledgments). As is also often the case with insect biodiversity studies, taxonomists are in short supply and in high demand. To date, more than 25,000 specimens have been identified, representing 43 genera and approximately 685 species. Among these are many interesting discoveries.
Some bee species are noteworthy because they are so abundant or widespread. Not surprisingly, the nonnative honey bee (Apis mellifera) showed up in relatively large numbers in half the parks surveyed, all across the continent. Other cosmopolitan “weedy” (but native) species included the two sweat bees Halictus confusus and H. rubicundus, both found in 17 parks, the latter from Redwood (Calif.) to Glacier (Mont.) to Assateague Island (Md.). The most commonly collected bee overall, with 2,012 individuals (4.6% of the bee total), was Augochlorella aurata, a brilliant green sweat bee found in 17 parks, from Big Thicket (Tex.) eastward (fig. 3). In a previous study at Indiana Dunes (Grundel et al. 2011), this species was also the most frequently captured bee, making up 16% of all bees surveyed, and was observed on more than 60 plant species, suggesting that this generalist forager is a pollination workhorse in the eastern parks.
[Eastern sweat bee (purple variety). Credit: USGS Bee Inventory and Monitoring Lab]
Figure 3. The eastern sweat bee, Augochlorella aurata, one of the most common bees in eastern North America, and the most abundant bee in the study. Color varies from metallic deep purple (above left) (Cumberland Island, Ga.) to green (above right) (Md.), depending on the region.
Of greater interest to this project were the habitat specialists, some of which were also very abundant across parks. For instance, more than 1,000 individuals of Lasioglossum marinum, a coastal dune specialist, were found in seven parks down the Atlantic coast, from Boston Harbor Islands (Mass.) to Biscayne (Fla.) (fig. 4). In contrast, the polyester bee Colletes brevicornis, found only in the dune site at Assateague Island (Md.), is a much rarer dune specialist restricted to the Atlantic coastal plain. The mason bees Dianthidium simile (fig. 5) and Osmia michiganensis are also rare dune specialists, but are found on the shores of the Great Lakes. These and other species that depend on deep sand for nesting suggest that dune habitats of lakeshores and seashores do have a distinctive fauna, including rare and endemic species (see sidebar, page 88). If sea and lake levels change with warming climates, or extreme weather events like Hurricane Sandy reshape coastlines, these bee com munities are at risk of losing habitat.
[A sweat bee. Credit: USGS Bee Inventory and Monitoring Lab]
Figure 4. A dorsal shot of a sweat bee, Lasioglossum marinum, from Fort Matanzas (Fla.). As its name suggests, this bee is a coastal dune specialist and builds its nest in deep sand.
[Mason bee. Credit: USGS Bee Inventory and Monitoring Lab]
Figure 5. The mason bee, Dianthidium simile, is a rare dune specialist, found on the shores of the Great Lakes (this one is from Sleeping Bear Dunes, Mich.). Females build nests at the base of grass clumps; cells are constructed of conifer resin and sand grains.
As the two other focal habitats (inland arid and high elevation, figs. 6 and 7) are concentrated in the western United States, we are still awaiting species data, and thus patterns of bee diversity across these landscapes are not yet clear. However, interesting discoveries have already been made. For instance, the digger bee, Habropoda pallida, found at Mojave (Calif.), is a dune specialist from the desert Southwest, thought to be a specialist on creosote bush. The tiny desert-dwelling mining bee, Perdita albihirta, collected at Petrified Forest (Ariz.), is not well-known, but is probably a pollen specialist like many of its relatives (fig. 8). Michael Orr from the Logan bee lab, who has been working with many of the western bees, has emphasized the importance of collecting in undersampled areas (i.e., most of our national parks), and illustrates this point with two specimens from Santa Monica Mountains (near Malibu, Calif.) that look very much like the cactus bee, Diadasia australis, but are likely a new undescribed species.
[Arid dune pollinator habitat at Mojave National Preserve. Credit: NPS photo]
Figure 6 (top). Arid dune pollinator habitat at Mojave National Preserve. Interns setting up a transect of bee bowls at a high-elevation meadow site in Yellowstone National Park, Wyoming.
Credit: NPS photo
Figure 7. Interns set up a transect of bee bowls at a high-elevation meadow site at Yellowstone National Park.
[Mining bee. Credit: USGS Bee Inventory and Monitoring Lab]
Figure 8. This tiny mining bee, Perdita albihirta geraeae, collected at Petrified Forest (Ariz.), measures just a few millimeters long. Polyester bee.
Credit: USGS Bee Inventory and Monitoring Lab
Figure 9. Prior to being collected at Canaveral National Seashore (Fla.) in 2013, there had been no collection records for the southeastern endemic polyester bee, Colletes titusensis, since 1938.
Bumble bees are another group of bees of great conservation interest, as several species have shown precipitous declines in all or parts of their ranges during the last two decades. These hardy bees make up a large component of high-elevation and northern-latitude bee faunas, so as results come in from western mountain and Alaska parks, we hope to contribute important range information that will help us assess the status of bumble bees in these regions.
In the deep South, many rare and unusual discoveries are being made in Florida parks, including sand specialists, such as the metallic sweat bee Augochloropsis anonyma from Biscayne and Canaveral, and the rarely collected southeastern endemic, Dianthidium floridiense. Another exciting find at Canaveral was the polyester bee Colletes titusensis, named after the town nearest to Canaveral, Titusville (fig. 9). The last recorded specimen of this rare endemic was collected in 1938.
Next steps: Discerning patterns and making links to climate change
Once the 43,000+ bee records for all 46 parks are complete and ready for analysis, the resulting database will represent the largest replicated survey of native pollinators anywhere in the world. The study design allows analysis of bee diversity and distribution patterns at multiple scales. For instance, we can compare bee communities between vulnerable and common habitats within individual parks to determine whether vulnerable habitats have more rare and endemic species or are distinctive in other parameters (e.g., species richness, diversity, nesting guilds, proportions of floral specialists or parasitic bees). This already seems to be the case with coastal and lakeshore dune habitats, where we have found many dune specialists (see sidebar).
We can also make these comparisons across regions to determine whether, for example, bee communities in coastal dune sites across the Atlantic coastal plain are more similar to each other than bee communities in paired vulnerable-common sites within parks are to each other. If so, this indicates a strong regional “dune signal” (versus a “park signal”) and suggests that we can assess the threats of climate change to these more vulnerable habitats at a regional scale, and perhaps also develop regional management guidelines and conservation partnerships. Similarly, we will make these comparisons for dune versus inland communities on the Great Lakes and the Pacific coast, for sand-dominated areas versus other open habitats in southwestern deserts, for subalpine/ alpine versus lower-elevation meadows in the western mountains and in subarctic regions of Alaska, and so on. Ordination and regression analyses will help us decipher what the dominant environmental (e.g., elevation, latitude, aspect, soil type) and climatic (e.g., mean air temperature, precipitation) drivers are for any patterns we see within and across habitats.
We are developing climate summaries for each sampling location that compare historical and current conditions with future predictions from the latest downscaled climate models. Climate changes are already evident, but the change is not uniform across the country. Rates of change in temperature and precipitation patterns, especially the timing during the growing season, will likely have profound effects on the future makeup of a park’s native bee populations. With these climate data we can begin to make predictions about the fate of bee communities. By examining species distributions across the environmental and climatic gradients surveyed, we can comment on the likelihood that a particular species will persist under new regimes of these gradients, such as a new combination of mean temperature and different soil type. Predictions for individual species can be combined and scaled up into estimates of effects of climate change on entire bee communities.
Long-term monitoring of bee communities from sensitive and common habitats in any of the 46 parks will also be possible now that we have established a baseline against which we can measure change. The sampling protocols are simple to repeat and can be replicated in many other habitats of interest. Monitoring to assess the trajectories of bee abundance, richness, and other parameters in climate-sensitive habitats may be especially informative on a regional scale.