The Lizard Log

The Langkilde Lab in Action


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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!


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A Rattlesnake Summer

This past summer I began putting the pieces together for my 4 year project investigating the effects of prescribed fire on Timber Rattlesnakes.  The objectives of this project will be to determine how Timber Rattlesnakes are directly impacted by the fire and to determine how rattlesnakes are affected by changes within their environment which are caused by the fire.  This past summer’s objectives, however, were to basically get my feet wet, get to know the areas that may serve as potential study sites, get to know the focal species, and attempt to understand how to work with state agencies (SPOILER ALERT => this last objective would prove to be the most difficult).  It took awhile to get permits and all other paper work in line for the project, but all-in-all the summer was a great success because I identified 2 potential study sites (and possibly 2 more), I learned a great deal about these wonderful little creatures, and with the help of 2 great technicians (Rex Everett and Mark Herr) we came up with a couple great side projects.

Timber Marked

Male Timber Rattlesnake post-data collection. Note the painted rattle which allows us to identify it as a previous capture if we happen to stumble upon him later in the day. For all rattlesnakes we recorded basic morphometrics, sex, reproductive status, and marked the individual with a PIT tag which will allow us to identify it if captured much further down the road.

To date, we have identified two great study sites (and possibly more).  The first is located in Forbes State Forest and will be a rather large burn (a little over 600 acres!).  We’ve identified at least three potential gestation sites in this area, and although we were not able to spend a great deal of time down in Forbes, we know through talking with state foresters that there is a healthy population of Timber Rattlesnakes in the immediate area.  The actual area was nicknamed the “Snake Pit” by the district forester.  Aside from being a beautiful landscape, it is also the highest elevation within the state!  The “Snake Pit” is scheduled to burn in 2016 via an aerial ignition burn (dropping fire from helicopters!), which will provide me with a full pre-burn year to collect data in 2015 (Fantastic!).  In addition to Forbes, we also have a smaller prescribed burn planned for Rothrock State Forest.  We have visited this area quite frequently throughout the summer and we’ve captured a handful of Timber Rattlesnakes within the area as well (including one individual that we’ve radio-tracked to a den site).  The odd thing about this area is that all of the rattlesnakes we’ve captured thus far… have all been males of various ages.  Where are the females?!?  The presence of 1 year old males, however, suggests that the females are hanging out somewhere near by but we have not found where….  But, it leads us to question why we did not find any gravid females hanging out on the fantastic rocky slopes within the area?  Was this just a bad year for gravid females? Could the females be down in the valleys hunting chipmunks and gathering the energy needed for future reproductive bouts?

Gestation Site Paired

On the left, rising out of the thick ocean of Mt. Laural is a beautiful rock slab bathed in sunlight. This is fantastic gestation site. The large cap rock atop of the rock slab provides cover for the gravid females and refuge from high temperatures during the mid-afternoon and low temperatures at night. On the right, another type of gestation site is the large rock fields strewn out among Pennsylvania’s mountain sides. These gestation sites may be 100 m long and very open. Although this provides good thermal habitat for longer periods each day, would snakes be detected by predators more in this largely open area?

Throughout the summer we located close to 50 Timber Rattlesnakes.  Although we did not find gravid rattlesnakes at some potential study sites, we found many gravid rattlesnakes at other sites.  Sometimes these gravid rattlesnakes were in small areas that were about 10 m X 10 m (top left picture).  These smaller areas had all the essential habitat characteristics for a gestation site: an open canopy, rocks to lay out on, and rocks to hide underneath.  Other times, gravid rattlesnakes were found in large rock fields (top right picture).  Obviously the thermal environment would differ between these gestation sites.  Sun light would hit the more open rock fields early in the morning and last till much later in the day as compared to the smaller gestation sites surrounded by towering trees.  This may translate into the gravid Timber Rattlesnakes being able to maintain a preferred, optimal body temperature for a longer period of time each day within the more open rock fields.  Maintaining this optimal body temperature for a longer period of time each day may translate into more energy available for developing offspring and shorter gestation periods.  However, these more open areas may provide an advantage to visual predators such as hawks.  So would it be more beneficial for a gravid Timber Rattlesnake to gestate within a large open rock field despite the potential increased risk of encountering a predator?  To answer this question, a Penn State undergrad, Mark Herr, and I are putting together a side project for next summer where we will measure the thermal properties and predation intensity of these different types of gestation sites.  Additionally, we will radio-track gravid females at each gestation site in order to determine body temperatures maintained by individuals, duration of time spent at gestation sites, and date when females birthed young.  This should be a fantastic study! This past summer we began collecting preliminary data at a few gestation sites (using biophysical models) and found that operative temperatures at smaller gestation sites averaged 6 degrees C less than operative temperatures at large rock fields.  Additionally, this was a cooler summer than years past and only the gravid females at large rock fields birthed young at those gestation sites.  Gravid rattlesnakes from smaller gestation sites remained gravid as they traveled back to their den sites.  Most of these individuals appeared to return to their dens gravid, which likely means bad things for those potential young (i.e., mortality).

Mark and Neonate

On the left, Penn State undergrad, Mark Herr, collects habitat data at a smaller gestation site. Note the biophysical model in the foreground next to the backpack. These models will measure the operative temperatures for Timber Rattlesnakes, which are basically the potential body temperature of an individual if it was not thermoregulating (i.e., if it were conforming to the environment). On the right, a neonate Timber Rattlesnake hiding under a birch leaf (… that is a small leaf). Only at large, open gestation sites that maintained warmer operative temperature did we find neonates this summer.

DSCF5529

Gravid females from smaller gestation sites returned to their dens still gravid.  This likely spells disaster for the potential young.  Can you find the Timber Rattlesnake at this den?

Next spring we are ready to hit the ground running as snakes begin to emerge from their den sites.  In addition to the project’s main objectives, we are also prepping for a few side projects.  In addition to the project described above, I am also trying to understand why Timber Rattlesnakes choose one potential gestation site over another.  I will also be surveying and monitoring vernal pools within burn sites to determine how amphibians are affected by prescribed burning.  Stay tuned as we continue this project.  In addition to Mark, I also have one of the best Timber Rattlesnake expert in the state assisting me with this project: Rex Everett.  Together Rex, Mark, and myself are determined to make this project a success.  Additionally, we will be taking on at least two more technicians for next summer and any other undergrad interested in reptile ecology, thermal biology, and conservation.  For more information feel free to contact me at cah62@psu.edu.

Me and Timber1

The fearless leader collecting data on a Timber Rattlesnake found crossing the road at Rothrock State Forest.

Rex and Ratsnake

Rex Everett, snake expert, with a large Rat Snake found adjacent to the planned burn area at Rothrock State Forest