Biology Foreign Studies

Costa Rica and Little Cayman

During a 10-week term, I traveled around Costa Rica and Little Cayman to conduct ecology fieldwork with 13 students and 6 faculty. At each site, we arrived, explored, asked questions about our surroundings, designed and executed research protocol, collected and analyzed data, and wrote and presented our findings. In such a rigorous program, I had the chance to develop skills in experimental design, field methods, quantitative analysis, scientific writing, and extensive collaboration.

Effects of exposed limestone on terrestrial snail shells

Site: Palo Verde, Costa Rica

Authors: Callum Backstrom, Samuel Gochman, Caroline Koller, and Mariko Whitenack

Understanding resource limitations on biological processes can help explain population abundance and distribution. Does the presence of limestone outcrops affect the distribution of terrestrial snails, which use calcium to construct their shells? By collecting samples and classifying them by morphospecies, we found that abundance was significantly higher near the outcrops, indicating that calcium is a limiting resource for shell development regardless of the shell's morphology. 

The effects of bromeliad size and density on macroinvertebrate communities in phytotelmata

Site: Monteverde, Costa Rica

Authors: Callum Backstrom and Samuel Gochman

Understanding the processes that structure communities in geographically isolated ecosystems is a central problem in ecology. Could the tanks of water (phytotelmata) inside bromeliad plants act as islands that affect the taxonomic richness of aquatic invertebrates within? Collecting the contents of 30 phytotelmata, we counted and classified the organisms by feeding group. We found that, while proximity of plants did not affect richness, there was evidence of differences in trophic structures.

Density and parasitism of Bomeria plants

Site: Cuerici, Costa Rica

Authors: Samuel Gochman and Louise Barias

Plants have evolved many strategies to combat predation and improve their fitness. Does aggregation increase the risk of predation due to greater visibility or does it dilute the risk for each plant through predator swamping? Bomeria plants flower in clusters and might employ predator swamping to combat their fly parasites. We collected 809 flowers to investigate aggregation and parasitism. We found that clustering flowers does not reduce parasite damage, but geographic location might. The study indicated that aggregation may not be an effective defense strategy for all plants.

Spatio-temporal distributions of terrestrial hermit crabs

Site: El Campanario, Costa Rica

Authors: Amber Ahronian, Rebecca Flowers, Sam Gochman, and Hannah Nash

Organisms have various strategies for sharing resources in an environment 

(intraspecific niche differentiation). How do terrestrial hermit crabs use the beach and adjacent leaf litter throughout the day? To investigate, we 1) surveyed densities and sizes of crabs during day and night to determine spatio-temporal distribution; 2) conducted habitat preference trials to test for the effects of competition on distribution; and 3) measured crab temperatures on both substrates to examine the role of thermoregulation in determining their distribution. We found that all crabs prefer leaf litter, but smaller crabs occupy the beach during the day and larger crabs do so at night. Results indicat that behavioral thermoregulation plays a primary role in their spatial and temporal distribution.

Coloration in the Honduran white bat

Site: La Selva, Costa Rica

Authors: Amber Ahronian, Samuel Gochman, Hannah Nash, and Leah Valdes

Organisms often resemble their environments for camouflage, and coloration can aid in thermoregulation. The Honduran white bat roosts in tents constructed from Heliconia leaves, which create chromatic and thermal environments. Does having white fur create an advantage for blending in and staying cool? To investigate, we 1) extracted visual contrast values from photographs of white- or black-bodied objects in simulated leaf tents and 2) recorded temperatures of those objects and real roosting bats. Results indicated that white fur makes for a lower visual contrast with adjacent leaves when viewed from below and that while white fur reduces temperature compared to black fur. This might require more energy to maintain a high body temperature, but the thermal expense might be offset by concealment from predators on the ground. Thus, coloration in animals can result in tradeoffs and might be driven by the context in which animals are most vulnerable.

Effect of fish traffic on territorial behavior in cocoa damselfish

Site: Central Caribbean Marine Institute, Little Cayman

Authors: Callum Backstrom, Eric Brunner, Samuel Gochman, Caroline Koller, and Leah Valdes

Animal behavior is limited by tradeoffs between resource acquisition and energy expenditure. Optimal decision theory asserts that decision-making is influenced by environmental conditions, such as competition for food resources. Do cocoa damselfish, which maintain algal gardens, experience a tradeoff between feeding and defense? To investigate this tradeoff, we measured traffic and frequency of defense and eating in 45 juvenile fish. With higher traffic, the fish defended more and ate less, and some individuals were more active than others. Our study contributes to an understanding of how energetic tradeoffs influence territorial behavior.

An investigation of diel migration and feeding activity in Caribbean populations of Silverside fishes

Site: Central Caribbean Marine Institute, Little Cayman

Authors: Callum Backstrom, Eric Brunner, Samuel Gochman, Hannah Nash, and Leah Valdes

Predatory behavior is often coupled with the characteristic behaviors of prey. Our study investigates how predator-prey dynamics affect the daily migration patterns (through the water column) of silversides and their zooplankton prey. Through field surveys, we examined how time of day affects the abundance of silversides, density of zooplankton, and habitat temperature. We found that silverside daily migration roughly mirrors plankton migration, although temperature variation might play a large role through metabolic rate. Such a discovery may offer additional insight into diel migratory patterns of other planktivorous fish with large geographic ranges.

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