Date of Award

Winter 2019

Project Type

Dissertation

Program or Major

Biological Sciences

Degree Name

Doctor of Philosophy

First Advisor

Winsor H Watson

Second Advisor

Jason S Goldstein

Third Advisor

Daniel R Howard

Abstract

The Gulf of Maine is currently experiencing rapid environmental changes, in the form of warming temperatures, increasing acidity, and a benthic ecosystem that is dominated by the American lobster (Homarus americanus) as the sole major predator and most significant fishery. The overall goal of my dissertation research was to investigate how the increased stress from warmer, more acidic, waters might impact individual lobsters, and thus lobster populations. To address this overall objective it was necessary to develop novel methods for investigating lobster behavior and reproduction, a theme that will run throughout this dissertation. In Chapter Two, I developed a new technique for quantifying the sperm in the spermatophores produced by male lobsters and used it to determine how often these males can recharge their spent sperm and mate with another female. In Chapter Three, I tested the impact of shell disease, which has been linked to warming waters in Southern New England, on mating behavior, mate choice and sperm allocation. I found that only the most severely diseased lobsters were affected, and that male lobsters likely allocated less sperm to severely diseased females. In Chapter Four I present the results of experiments designed to determine if ocean acidification could impact the ability of lobsters to detect food odors and thus their foraging behavior. The results I obtained indicated that drops in pH associated with increased oceanic CO2 slowed the responses of juvenile and adult lobsters to the presence of herring bait and reduced the time they spent handling it. Finally, in Chapter Five, I developed a method for measuring the distance lobsters walked using accelerometers, to set the stage for experiments designed to understand the impact of warming oceans on lobster behavior and physiology both in the laboratory and their natural habitat. In addition, I designed a novel datalogger that also recorded their heart rate and feeding activity while the lobsters were freely moving in their natural habitat. This system, and the other devices I developed during my research, will make it faster, cheaper, and easier to investigate fine-scale changes in American lobster behavior, physiology and reproduction in their natural habitat. Ultimately, my goal is to improve our understanding of the potential consequences of climate change on lobsters, and then use this information to inform both the scientists who manage this important resource and the people who depend on this resource to make a living.

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