Graduation Year

2020

Date of Submission

12-2019

Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts

Department

Organismal Biology

Reader 1

Branwen Williams

Reader 2

Cheryl Baduini

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Terms of Use for work posted in Scholarship@Claremont.

Rights Information

© 2019 Rachel Ashton Lim

Abstract

Due to their characteristic annual band-forming growth pattern, corals are useful long-term, high-resolution bioarchives for paleoceanographic reconstructions. The isotopic compositions of coral tissues indicate abundances of prey types and nutrients in the water column, as the stable isotope ratios of upper-trophic level consumer tissues have been shown to closely resemble that of their diet. However, isotope signatures can be challenging to interpret due to a variety of factors, such as limited knowledge surrounding the extent of adaptability of individual specimens to changes in abundances of different food types over time. This study observed three species of uniplanar, branching corals in the order Alcyonacea: Muricea californica, Muricea fruticosa and Lophogorgia chilensis. Their dietary plasticity over time was evaluated in order to better understand differences in feeding habits between species. Over the long-term (approximately one year and over), the corals appeared to be able to adapt to new food sources, and appears to have stabilized in δ15N values for Muricea spp. Although all species increased mean δ15N values until eventually leveling out, over the short term, δ15N oscillated in different patterns between the two genera. Changes in salinity, pH and alkalinity did not appear to correspond to changes in δ15N in observable trends. It is possible that the morphological characteristics of calyx arrangement and size could affect the way species respond to changes in tank conditions.

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