Publication Date:
2022-05-25
Description:
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2014
Description:
White sharks (Carcharodon carcharias) are highly migratory, ecologically important,
vulnerable, and understudied marine predators. Ecogeochemistry, which takes advantage of
natural variations in chemical signatures recorded in body tissues, can help determine lifetime
movement, age, and ontogenetic diet history in difficult to study species. Shark vertebrae are
constructed of distinct layers of tissue laid down sequentially over an individual’s lifetime and
may preserve a chemical record of environmental exposure. In this thesis, I investigate the
ecology of the understudied northwest Atlantic (NWA) white shark population by applying
several ecogeochemistry techniques to their vertebrae. I generate the first radiocarbon (Δ14C) age
estimates for adult white sharks, dramatically extending the maximum age and longevity
compared to earlier age studies. Δ14C results also verify a lack of reworking of vertebral material
and hint at possible sexual dimorphism in growth rates. Using amino acid and bulk stable isotope
analyses, I show that individual sharks have marked variation in feeding and movement, and that
pinnipeds do not constitute a large portion of their diet. Finally, I explore the utility of elemental
chemistry to retrospectively infer movement. This work provides an important informational
baseline for future NWA white shark ecological studies and conservation and management
efforts.
Description:
I received support from a National Science Foundation Graduate Research Fellowship and
the WHOI Academic Programs Office. The research in this thesis was funded by a National
Science Foundation Grant (OCE 0825148) to S. Thorrold. Additional support came from an
ITCE (Inter-university Training for Continental-scale Ecology) Research in Residence
Fellowship.
Keywords:
Environmental chemistry
Repository Name:
Woods Hole Open Access Server
Type:
Thesis
Format:
application/pdf
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