Honors Theses and Capstones

Date of Award

Spring 2024

Project Type

Senior Honors Thesis

College or School

COLSA

Department

Department of Biological Sciences

Program or Major

Neuroscience and Behavior

Degree Name

Bachelor of Science

First Advisor

Brittany Jellison

Abstract

Climate change has led to increased CO2 absorption by ocean surface waters, resulting in decreased pH levels, a phenomenon known as ocean acidification (OA). A primary class of marine organism behavior is impacted by OA, in particular, olfactory-mediated behaviors related to foraging and feeding success. However, the biological mechanisms responsible for the documented impairment of foraging and feeding-related behaviors remains in question. We find that juvenile American lobsters (H. americanus) exhibit significantly faster rates of total feeding times in response to short-term low pH exposure. However, total search time and total handling time were not affected by pH when examined separately, indicating that an additional variable not considered in this study may be responsible for the increase in total feeding rates. We hypothesize that increases in total feeding rates are a short-term exposure response to low pH levels due to increased energetic demands and a higher biological importance on acquiring food energy resources. We suggest that slower rates of feeding and impaired behaviors seen in past literature are likely a result of longer-term exposure effects. We also review proposed physiological mechanisms for the impairment of marine organism chemoreception. We suggest that environmental interactions with odorants and receptors, specifically protonation events, alter the odorant affinity for respective receptors as an immediate cause for chemoreception impairments. It is possible a reversal of ion flow through the GABAA receptor results in behavioral alterations seen in more long-term exposures via the “GABAAR Model.” The review portion of this paper also suggests that future OA research efforts should be aimed at considering understudied factors such as exposure length, food availability, and ontogenetic implications.

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