Symbiont Density, Chlorophyll a, Color Intensity, and Stable Isotope Signatures of  the Temperate Coral Oculina arbuscula from N.C.
Creators: name: Long, Jamie
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2025

description: <p><span id="docs-internal-guid-5a1a493e-7fff-f44b-c61a-7ad83e731a1a"></span></p>
<p dir="ltr" style="line-height: 1.38; margin-top: 0pt; margin-bottom: 0pt;"><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Corals are the foundation of reef ecosystems that are instrumental to the health and abundance of a vast diversity of marine life. Anthropogenic increases in atmospheric carbon dioxide have led to rising ocean temperatures, which are correlated with decreasing symbiont density and chlorophyll</span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: italic; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> a</span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> (chl</span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: italic; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">a</span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">) levels. Extreme levels of temperature stress can cause coral bleaching or complete loss of symbionts. Facultatively symbiotic corals, like </span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: italic; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Oculina arbuscula</span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, can survive without symbionts by relying more on heterotrophic carbon and are thus useful models to study the physiological effects of coral bleaching. This study measured the natural variation in color intensity, symbiont density, chl</span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: italic; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">a </span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">content, and &delta;13C and &delta;15N levels between symbiotic and aposymbiotic colonies of the temperate coral </span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: italic; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Oculina arbuscula </span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">across seasons. Colonies of </span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: italic; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">O. arbuscula</span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> were collected from Radio Island, NC, and symbiont density, chl</span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: italic; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">a</span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, color intensity, and &delta;13C and &delta;15N were quantified. We found that symbiont density and chlorophyll </span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: italic; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">a</span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> were significantly lower, and color intensity was brighter in aposymbiotic colonies, and these trends varied across seasons. We also found that there was greater host-algal &delta;13C and &delta;15N overlap during the summer compared to lower overlap during the winter. These results demonstrate fluctuation in symbiont density, chl</span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: italic; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">a </span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">per cell, color intensity, and stable isotopes in </span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: italic; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">O. arbuscula</span><span style="font-size: 12pt; font-family: 'Times New Roman',serif; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> based on symbiotic state, and could help improve our understanding of the effects of climate change-induced bleaching on coral reefs.</span></p>