The Lizard Log

The Langkilde Lab in Action


Leave a comment

Vernal Pool Macro-invertebrates in a Burnt Landscape

My name is Richard Novak and I am finishing up my freshman year. I am in the Schreyer Honors College and I am studying Wildlife and Fisheries Science, with the Fisheries option. This is my second semester working in the Langkilde Lab. In fall 2017, I began working under Dr. Chris Howey as a research assistant helping with rattlesnake gestation site video monitoring. Currently, Dr. Howey and I are working on a study with macroinvertebrate communities in vernal pools and how they are impacted by prescribed fire. I was fortunate to receive an Erickson Discovery Grant which will allow me to continue working on this project into the summer. So far, I have developed my research questions and data collection methods, and I have been gathering data throughout spring semester. This research experience has been valuable to me for several reasons. First, I have been able to get a first-hand look at the entire experimental design and execution process, something I can only read about in classes. Additionally, interacting with graduate students and other faculty has been very influential when thinking about my future ambitions and career path potentials.

Vernal Pool within a previously burnt landscape

Vernal Pool within a previously burnt landscape

The purpose of this study is to compare macroinvertebrates communities in vernal pools with varying fire histories.  Fire is being used as a forest management tool, which will create a more open landscape that some wildlife species may prefer.  Additionally, these prescribed fires may promote the growth of new vegetation and increase food for wildlife within the forest.  I am looking at water samples from 12 vernal pools; three that were burnt over once (in 2016), three were burnt and mowed over (in 2016; this is an additional disturbance to the landscape), three pools burnt over twice (in 2014 and 2016), and three vernal pools from a control group with no recent fire or disturbance history.  Specifically, I would like to answer the question, “do prescribed fire practices alter the macroinvertebrate communities of vernal pools?” This question has been relatively unexplored in previous research.  But preliminary data collected by Chris suggests that physiochemical (physical and chemical) characteristics of these pools are different, which could lead to differences in what macroinvertebrates are able to survive in these pools.  I will analyze water samples collected from these vernal pools for macro-invertebrates, identify all macroinvertebrates found to family, and determine abundance of each family. The water samples that I have been going through now were collected in 2016, and additional samples will be analyzed from 2017 that are currently being collected.  I look forward to getting out in the field this summer and assisting with measurements and collections.

Macroinv lab bench set up

This is what my lab bench typically looks like while I’m collecting data. My sorting tray with a sample spread out to the left, a hand-held magnifying glass, dissecting microscope, and the computer with my spreadsheet in the background. Note, there are also plenty of macroinvertebrate books to help me identify everything I find.

 

When I first began this project, I had to learn how to identify the macroinvertebrates to family. One of the reasons I am interested in macroinvertebrates is because of my interest in fly fishing, which requires basic knowledge of aquatic entomology, so I had some ID skills to bring to the table. I practiced using dichotomous keys to identify the specimens, a task I found time consuming but very learnable with practice. Now, I am very familiar with the families that I encounter most often. As of right now, I have identified the presence of over 20 families of macroinvertebrates among the vernal pools in the study. I find a lot of mosquito larvae (Culicidae), phantom midges (Chaoboridae), cased caddisflies (Limnephilidae and Odontoceridae), as well as several families of dragonfly and damselfly. To me, the coolest creatures that I find are fairy shrimp (Chirocephilidae) and water-boatmen (Corixidae) although I don’t come across either of those frequently.

Culicidae Pupae

Culicidae pupae. These will grow up to become the dreaded mosquito!

Chaoboridae Larvae

Chaoboridae larva. These are also known as phantom midges.

Chaoboridae Larvae

Limnephilidae larva. This is a type of caddisfly.  Caddisflies are known to build these ‘houses’ out of sticks, leaves, and rocks within their environment.  The actual larva is within this house made of sticks and you can see its head sticking out of the top.  Different species of caddisflies will use different substrates to build their houses, so you can tell species apart based on the house materials.

Limnephilidae

Odontoceridae larvae. These are another species of caddisfly. You can see that they use a different substrate material for their houses.

Chirocephilidae Larva

Chirocephilidae larva. This is also known as a fairy shrimp and can be very common in many of Pennsylvania’s vernal pools.

Corixidae

Corixidae adult. These are also known as water-boatmen. They are typically seen swimming across the surface of a vernal pool, but can dive to the bottom when foraging or escaping a would-be predator.

 

So far, I am finding more mosquito larvae (Culicidae) in unburned pools.  But among the burned pools, I am observing more mosquito larvae and caddisflies (Limnephilidae) in pools that were more disturbed (burned and mowed).  This trend among the vernal pools is interesting, because that mow was an extra disturbance on top of the burn, yet these two families appear to be doing better in these pools.  Please note though, these data are still being collected and these results may not accurately represent our final findings once we have analyzed all water samples.

Macroinv prelim data

Preliminary data for our macroinvertebrate communities within the four different treatments. In the future we will compare species diversity and richness among vernal pools. We will also see if there are any correlations between species presence/absence from vernal pools and the physiochemical characteristics of those pools.

Working on this project has been useful to me for many reasons. I have had a lot of fun sorting through samples and looking at the macroinvertebrates; it really never gets old to me which is good because I’ll be staring at trays a lot more this summer. It has been very satisfying to see my very own data begin to build on the spreadsheet as I work. Also, being around other lab members has given me a look into what school is like for graduate students. My freshman year is coming to a close, and I hope to take on new and exciting projects throughout the rest of my undergraduate career. When I came to college last fall, I did not expect to become involved in research right away, but I am very glad I took that step early and I have been fortunate in the opportunities presented to me. After graduating, I plan to pursue at least a master’s degree in a biology related field. I am interested in working for a natural resource management agency, although this experience has opened my eyes to the possibility of university research as a career. Whatever happens, my goal is to continue exploring more about biology and the organisms that fascinate me so much.

Richard Novak

Me looking hard at work keying out macroinvertebrates!

Advertisements


1 Comment

Uncovering the Effects of Prescribed Fire on Vernal Pool Amphibians

Fire is landscape disturbance that can do great things for resident organisms. Certain plants and animals are adapted to cope with or even thrive in the earlier successional habitat created by this blistering disturbance. Serotinous pine cones that open following a fire, oak trees with thick bark protecting them from the heat of the fire, or grasses taking advantage of the nitrogen released in the post-fire soil. Small rodents like mice and chipmunks dive into burrows to protect themselves from the direct effects of a burn, only to re-emerge in a scorched world that will be filled with food, grasses and acorns, within a year. Other species like snakes and lizards may survive the fire and find a new forest with more sunlight reaching the forest floor and greater basking opportunities. Forestry managers have begun to reintroduce this natural disturbance back onto the landscape in the form of a controlled burn. And whereas some species may benefit from this disturbance, other species may not fare so well to the disturbance itself or the post-fire landscape. For many species, it is unclear how they will respond to prescribed fire.

 

The effects of prescribed fire on vernal pools and vernal pool amphibians remains largely understudied.  Some amphibian species like Spotted Salamanders, Jefferson Salamanders, and Wood Frogs rely on vernal pools as an essential habitat where their eggs can be deposited and larvae can develop in the presence of a plethora of food and absence of fishy predators.  These pools disappear each summer only to refill with winter rain and snow melt, just in time for spring migrating salamanders and frogs which lay their eggs among their submerged branches and vegetation.  The eggs and larvae of amphibians can be highly sensitive to changes in water chemistry and temperature.  As fire changes the landscape around a vernal pool, it may also influence characteristics of a vernal pool. Reductions in forest canopy may allow more light to reach the vernal pool and increase amphibian larvae growth rates.  Run-off from the burnt forest floor may also increase alkalinity within the vernal pool.  Following a series of prescribed burns in Florida, Clay Noss and Betsie Rothermel found a slight increase in vernal pool water pH; however, this change did not affect their focal species, the Oak Toad.  So, would a similar change be expected from prescribed fires in the forests of Pennsylvania?  Would amphibians native to our vernal pools respond in similar ways to the Oak Toad?

 

OLYMPUS DIGITAL CAMERA

Jefferson Salamander eggs attached to a submerged branch.

OLYMPUS DIGITAL CAMERA

Wood Frogs mating within a vernal pool. Large swollen eggs are present in the background as well as a freshly laid egg mass to the right.

These are just a few of the questions that I am looking to answer with a couple research projects I began this spring.  Luckily, I have the assistance of a fantastic undergraduate, Michaleia Mead, who will stay on after she graduates this spring and turn some of these projects into her Masters thesis.  For our first project, we began sampling the water chemistry (pH, dissolved oxygen, conductivity), temperature, and physical characteristics of a series of vernal pools with differing burn histories.  We are also measuring the canopy cover over the vernal pools and the amount of UV-B radiation that may reach the water surface.  UV-B is known to cause detrimental effects on amphibians in high enough doses. We want to see if vernal pools in an oak dominated forest respond to prescribed fires in similar ways to the vernal pools of Florida.  We will sample invertebrate and amphibian abundance and diversity within these vernal pools.  Do we see a change in community composition of a vernal pool as characteristics are altered by prescribed fire?

 

OLYMPUS DIGITAL CAMERA

Vernal pool located in a post-burn landscape. This tract of land was burned in 2014. Note the charred trees in the background and reduction in understory vegetation.

To accompany the field projects, we began to raise Wood Frog tadpoles in the lab under different pH and UV-B conditions.  We will determine if these changes affect tadpole development and survival.  Additionally, we will compare corticosterone levels among tadpoles from different treatments to determine if certain treatments lead to more stressed tadpoles.  Even if tadpoles survive and develop under certain conditions, developing under stressful conditions can result in increased energy expenditures and decreased fitness.  This could have implications beyond the vernal pool if recently metamorphed Wood Frogs have lower energy reserves.

OLYMPUS DIGITAL CAMERA

50 tadpoles are placed in each tank with varying amounts of pH and UV-B.

OLYMPUS DIGITAL CAMERA

Our experimental set-up manipulates water pH and amount of UV-B exposure, while controlling room temperature.

So stay tuned as Michaleia and I update everyone on the progress of our studies!


1 Comment

Rattlesnakes and Vernal Pools

Image 2Another field season is underway and things are getting crazy!  This summer, I will be conducting three big projects, but luckily I will have the assistance of a small army of technicians.  The first project will focus on the habitat use and thermal biology of the timber rattlesnake and how prescribed fire may affect the availability of these preferred habitat characteristics.  This summer we will radio-track rattlesnakes to determine thermal and habitat preferences.  Next year, the study sites will be burned, and I will determine if these post-burn landscapes provide more or less habitat fitting these preferences.  So far we are off to a great start! We have captured 21 rattlesnakes and we are radio tracking 5 males and 4 females (we hope to get a few more females).  Next week we will begin to characterize the available habitat surrounding the rattlesnakes as we will begin vegetation surveys, measuring operative temperatures, and small mammal trapping.

Image 5In addition to investigating the effects of fire on timber rattlesnakes, I am also looking at the effects of prescribed burning on vernal pool amphibians.  From time-to-time, prescribed burns are conducted right next to a vernal pool.  This disturbance may reduce canopy cover over the vernal pool, raise temperatures within the vernal pool, and change water chemistry.  Long-term effects may also include changes in soil composition surrounding the vernal pool which may lead to more run-off into the vernal pool.  To determine these effects more clearly, I am measuring the physio-chemical characteristics of 4 vernal pools (2 that will be burned over next spring and 2 that will remain untouched).  I have deployed weather stations in each vernal pool that will track water temperatures, air temperatures, relative humidity, wind speeds, rain fall, and amount of solar radiation reaching the vernal pool.  I am also measuring DO, pH, and conductivity each time I visit the vernal pool, in addition to surface area and depth of the vernal pools.  During these visits, I am surveying for larval amphibians, egg masses, and invertebrates.  So far we have seen many wood frogs, Jefferson’s salamanders, and spotted salamanders.  However, we seemed to skip “spring” this year and things warmed up very quickly.  Two vernal pools completely dried up! And the other two are getting very shallow!  We were able to add on another vernal pool to replace one that dried up, but things aren’t looking good for this year’s tadpoles and larval salamanders…  Next year, we will burn over the vernal pools and investigate changes in water chemistry and physical characteristics of each pool.

OLYMPUS DIGITAL CAMERA

A spotted salamander (Ambystoma maculatum) eggmass in one of the vernal ponds.

 

These salamander eggs are definitely ready for their close-up.

 

Working with one of the weather stations in a vernal pool (prior to the dramatic dry-down!)

Lastly, Mark Herr and I will begin a project looking at ecological trade-offs between thermal resource acquisition and predation at gestation sites of various sizes.  We will be deploying operative temperature models and foam predation models at 6 gestation sites (3 small and 3 large sites).  We will also radio track a couple gravid females at each site to determine body temperatures, survival, and lay dates.  For more on this project, see Herr’s post!  And for more on all of these projects, stay tuned to future posts!