Saturday, July 21, 2012

Duke TIP Summer Amphibian Biology Course

A Duke TIP biology student holding an Axolotl | Ambystoma mexicanum
This past June, I instructed an intensive three week amphibian biology course at The New College of Florida in Sarasota. The class was offered as part of Duke University's Talent Identification Program's summer studies program. Duke TIP is a major leader in identifying academically talented students and providing innovative programs to support the development of their optimal educational potential. Months earlier, we were asked by Duke TIP to design a college level amphibian biology class, and although the class coincided with the busy amphibian reproductive season here at the Garden, we wanted to take advantage of this amazing opportunity to work with Duke TIP and these incredible students. The class sold out immediately and there was a waiting list! With careful planning and lots of help from frog volunteers and staff, we were able to send me down to instruct the course.

I arrived at New College five days before the students arrived to prepare and meet the other faculty, and on the night I arrived there was a thunderstorm that lasted for several hours. In the distance, I could hear the advertisement call of Narrowmouth toads (Gastrophryne carolenensis, they sound a little like angry sheep) and so I investigated the sounds coming from the edge of campus that first night.

The 'puddle' or ephemeral wetland we used for the field studies portion of the class. 8 species were detected during the month, including some ephemeral wetland breeding obligates, which was a major focus of the class
When I located the source (pictured above), it seemed to be just a depression that had filled with the excessive rain, and the toads were merely taking advantage. Certain species will take advantage of substantial rain events like these and breed in just about any puddle if it collects enough water. Narrowmouth toads and Southern toads are examples of these types of any puddle breeders. As long as there is water, they can reproduce in ponds, puddles, tire tracks, pool covers, etc... .

Later in the evening however, more species arrived and quite a frog community began to develop. It was starting to look like this was more than a grassy depression filled with rainwater ... .

When a puddle recurs annually, or close to it, it can provide a unique microhabitat that is rich in biodiversity. These ephemeral, or temporary wetlands dry out every year, leaving little evidence in the dry season that they even existed. Yet these ponds, pools and puddles fill up again every year and attract an assortment of amphibians, reptiles, aquatic macro-invertebrates and birds that one can only find in an ephemeral wetland. Wetlands that dry out every year are free of fish — a major predator of frogs, tadpoles and eggs — and that is one reason certain species are obligated to reproduce in temporary pools. Every year, amphibian's that reproduce in pools like this are in a race against time — if the tadpoles don't metamorphose before the pond dries out, they won't make it and there won't be any recruitment that year.

Vernal pools dry out fast without rain, and by June 22nd
 our study pond was almost gone. The students were able
to see first hand the hydrodynamic pressures vernal ponds can put on
larval amphibian development.
By the second night of rain on campus, I had detected eight species of frog in the puddle. This was very exciting to me as some of the species I had worked with before — Toads! Oaks, Southerns and Spadefoots — and were very familiar to me, but the main source of excitement was in figuring how to incorporate this incredible aquatic resource into the curriculum. I spent every night there before the students arrived, taking photographs and video clips. We just couldn't have hoped for a better resource for the class and I was anxious to share all this great material I was finding with my students.




The students arrived, and I finally met my thirteen thirteen(ish) year-old geniuses ... a group of teens and pre-teens who wanted to spend their summer studying amphibian biology at the college level. These extraordinary students arrived excited and eager, and I only hoped I had enough material to keep them interested for 6 hours a day.

For the first day of class, I presented a 'Vernal Pond Case Study' where we looked in depth at ephemeral wetlands and the types of animals that one can find in them. In an attempt to whet their appetites, I described one of my favorite species of obligate ephemeral wetland breeding amphibians — Spadefoot toads (Scaphiopus holbrokii) and how when their seasonal ponds dry out too quickly, hormonal cues trigger a 'cannibal morph' in certain larvae so they can begin eating their vegetarian brothers and sisters. A rather interesting adaptation for reproduction with a hard deadline.  When interest was piqued, I revealed that the case study pond was actually right around the corner, and that we would be using this puddle extensively for our class field biology and laboratory components. The class went from 9 - 4pm, 6 days a week; and we were able to spend an hour or two at the puddle nearly every day.

Tadpole collection and IDs. In the first few days, the students successfully ID'd many species of tadpole (no small task!) using Amphibians and Reptiles of GA (Jensen, et al...) and the posters provided by DNR on Endangered Species Day here at the Garden.

Certain animals, such as turtles and tortoises need direct sunlight, so we took some of the class specimens out for morning walks after breakfast while we discussed the day's topics.

Lydia, my amazing TA, and recent New College graduate in biology demonstrating an effective belly rub on a Cane toad | Bufo marinus

Visual demonstration of suction feeding in Pipa pipa after discussing the biomechanics associated with different feeding strategies

Tadpole sifting became an increasingly common activity as the pond continued to dry out and tadpoles were collected en masse and sorted by species as well as developmental stage. 

A student releasing Cuban tree frog metamorphs in a nearby unoccupied cat-tail pond. That is what we, as a class, decided to do with any invasive Cuban tree frogs were found in our study pond. 

Having a HD projector in the classroom made amphibian IDs much easier

A student investigating the aposematic coloration on the belly of a Firebelly toad | Bombina orientalis

The lobby outside of the herp lab provided a great, safe area to have 'hands on' herp experiences. The New College administration would allow specimens in no other facility on campus. Well, they let us bring animals into the classroom as long as they couldn't jump out of a petri dish.

Students love salamanders! Here is a student with a slimy salamander (Plethodon glutinosus) on his arm.

Teaching at Duke TIP was an incredibly challenging experience for me, as I had to be vigilant about providing enough material for these brilliant students. I am grateful for the time I had there with them —they, and the whole experience was incredibly inspiring.