Current
Research
Mechanisms
of Anuran Community Assembly in the Bolivian Gran Chaco
Tadpoles have served as a model organism to understand the mechanisms
shaping lentic communities, however, a majority of
these studies have been conducted in temperate regions. Temperate zone
anuran assemblages contain fewer species with conservative reproductive
strategies and body morphologies as compared to tropical communities.
It is not known whether the generalities produced from studies of
temperate regions are applicable to tropical communities.
The Bolivian Gran Chaco has over 30 species of anurans that possess a wide diversity of reproductive strategies (e.g. foam nests) and body morphologies (e.g. carnivorous tadpoles). Using the Chacoan tadpole assemblage as my model system, my research aims to understand the mechanisms shaping community assembly in lentic waterbodies in the tropics. I am just beginning my research in this area and I will have more details as time progresses.
Pictured above (left) is one species of frog-eating frog, a Cranwell's Horned Frog (Ceratophrys cranwelli) metamorph with it carnivorous tadpole. Pictured above (right) are a pair of Physalaemus biligonigerus depositing their eggs in a foam nest. The nest floats on the pond's surface, protecting the eggs from dessication if the pond dries, otherwise the nest slowly breaks down and releases the tadpoles into the pond.
Previous Research
Vagility
of aquatic salamanders; implications for wetland
connectivity.
In summer 2007, I participated in a National Science Foundation REU
program at the Savannah River Ecology Laboratory (SREL) under the
tutelage of Dr. Whit Gibbons (pictured above left) and his gradate
student, Tom Luhring.
My project examined
the movement ecology of two species of poorly studied aquatic
salamanders; the Greater Siren (Siren
lacertina; pictured above
right) and Two-toed Amphiuma (Amphiuma
means).
These species of
large salamanders (they can grow to nearly a meter in length) occupy
wetlands as far as 0.7 km from the next closest waterbody, which is
suggestive of considerable dispersal ability. However, their
dispersal ability and mode has yet to be conclusively determined.
In a laboratory experiment, I assessed the vagility of these
two
species under three simulated environmental conditions: terrestrial,
shallow standing water, and complete
submerge. Both species demonstrated a trend toward exhaustion in all
treatments, but were able to disperse the farthest in the submerged
treatments. To disperse, these species likely rely on the formation of
aquatic corridors during flooding events. Therefore, the human
activities that disrupt the formation of these aquatic corridors may
have important implications for wetland connectivity.
Effective
culvert design and placement to facilitate passage of
amphibians across roads.
During my senior year at SUNY-ESF, I assisted Drs. David Patrick and
James Gibbs on a project aimed to aid transportation departments when
designing structures to alleviate road mortality of amphibians. We
assessed the crossing frequencies of Spotted Salamanders (Ambystoma maculatum)
and American
Toads (Bufo
americanus) within
a known crossing "hotspot" and examined that in relation to the habitat
variables in the surrounding area. We also created an experimental
array of culverts to examine if the migrating Spotted Salamanders
showed any preference in their use of these structures. Salamander
crossing was closely associated with the presence of flowing water on
the upslope, while toads tended to cross in areas where wetlands were
absent on the downslope across the road. Additionally, the
salamanders showed no preference in their use of the culverts. Our
results suggest that there are areas within crossing "hotspots" that
show species-specific patterns of occurrence. Also, even though Spotted
Salamanders showed no preference
for use, it may vary among species, thus a variety of structures may be
most efficient in mitigating road mortality.
Summer
microhabitat use of the Greater Siren (Siren
lacertina)
and Two-toed
Amphiuma (Amphiuma
means) in
an isolated wetland.
During the summer of 2008, I returned to SREL as an REU student to
continue my research on the ecology of S. lacertina
and A.
means. The habitats of these
species have been
described on the coarse scale (e.g. ponds, swamps), but their
microhabitat use within these bodies of water have not been examined. I
set traps in three different microhabitats in a wetland; the water's
surface and benthic zone (both in deep water), and a littoral
zone. Siren lacertina
were captured more frequently in the benthic zone, while A. means
were captured more in the littoral zone. This difference in
microhabitat use may reflect a difference in prey availability (aquatic
insects were captured more frequently in the benthic zone with S. lacertina,
while fish and
crayfish were captured more in the littoral zone with A. means),
or the salamanders may
be minimizing competitive interactions.