Danielle R. Kirsch
Integrative Biology Ph.D. Candidate - Oklahoma State University
Current Research
Parental predation risk exposure timing and offspring embryonic development
The freshwater snail Physa acuta is documented to have reduced hatching success (i.e. survival and emergence of hatchlings from their eggs) as it ages, and this reduction is compounded by predation risk exposure during the parent's life. In this experiment I expose snails to predator cues at 3 key points in their lives - in the egg, immediately after hatching, and immediately prior to mating - to see how predation risk exposure timing impacts the hatching success of offspring, and what process(es) during development might be causing the observed reductions in hatching success with age and predation exposure.
Previous Research
Behavioral and physiological effects of safety cues
Prey response to risk cues is well documented from many species. When prey detect risk cues, they often reduce activity or alter space use to avoid predation. Increased stress from exposure to risk cues can also elicit physiological changes such as increased respiration rate. A recently developed theory suggests that, under low levels of detected predation risk, prey may utilize "safety cues" as indicators of how low predation risk really is. A potential example of a safety cue is detecting behaviors from other at-risk individuals—such as foraging and mating—that would not be present if a predator had been detected nearby.
Physa acuta, a species of freshwater snail, is well documented as responding to chemical cues from injured conspecifics and predators, such as the crayfish Procambarus simulans. When detecting risk cues, P. acuta will float to the surface of the water and sometimes leave the water altogether. I am using this snail-crayfish system to investigate the effects of safety cues on snail behavior and physiology. Specifically, I am working on determining the components of safety cues and measuring their effects on snail behavior and respiration.
Wikimedia Commons
Temperature preference in Hyla chrysoscelis tadpoles
Behavioral thermoregulation is particularly important in fully aquatic ectotherms, such as tadpoles, because they are limited in their selection of preferred temperatures based on what temperatures are present in the water around them. ​
I created a horizontal thermal gradient and subjected individual tadpoles to this gradient for one hour, measuring their location in the gradient every 15 minutes. The average temperature selected was compared between tadpoles. I utilized an added component of the presence or absence of hindlimbs (a proxy for developmental stage) to divide the tadpoles into two distinct groups. Tadpoles with visible hindlimbs preferred significantly warmer temperatures than tadpoles without visible hindlimbs. These results correlate with results found in studies using tadpoles of other species that also showed a preference for warmer temperatures later on in development.
Read our Journal of Herpetology publication here.
Inter-Kingdom resource competition and non-consumptive effects in a freshwater system
Bluegill (Lepomis macrochirus) fill an interesting position in certain aquatic food webs. Larval bluegill have been shown to compete with bladderwort--a carnivorous plant--for zooplankton. Largemouth bass (Micropterus salmoides) are a common bluegill predator documented to have consumptive and non-consumptive effects on their prey.
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I set up mesocosms to test different components of this food web: bluegill alone, bluegill + bladderwort, bluegill + caged largemouth bass, bluegill + bladderwort + caged largemouth bass. There was no significant difference in growth between treatments, although there was a large amount of variation within each treatment which suggests that individual bluegill respond differently to the same initial conditions. Other studies have shown that individuals of the same species can exhibit "behavioral syndromes" that are relatively constant throughout life; if different bluegill in the experiment expressed "bold" or "shy" behavioral syndromes, that could partially explain the large amount of variation within treatments.
Food chain efficiency in desert stream communities
I was an NSF REU intern in Dr. John Sabo's desert stream ecology lab at Arizona State University in the summer of 2017. The project I worked on focused on how hydrologic regime shifts, such as floods and droughts, impact desert community dynamics. More specifically, I was interested in how food chain efficiency is affected by stream hydrology. Our analysis combined measures of primary production, water chemistry, fish biomass, and water flow metrics to calculate food chain efficiency and what factors influence it.
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