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Date Permissions Signed
Date of Award
Master of Science (MS)
Bingham, Brian L., 1960-
Sulkin, Stephen D.
Anthopleura elegantissima, the common Pacific sea anemone, can host two very different algal endosymbionts: zooxanthellae (Symbiodinium muscatinei) and zoochlorellae (Elliptochloris marina). The photosynthetic carbon provided by the symbionts supplements the host's heterotrophic feeding, with zooxanthellae potentially translocating five times more carbon to the host than do zoochlorellae. We developed a method to measure lipid levels of zooxanthellate and zoochlorellate A. elegantissima in different seasons, focusing on non-polar lipids that are important components of gonad and gametes. In July 2009 and January 2010, zooxanthellate and zoochlorellate A. elegantissima were collected from the same habitat at the same tidal height. Non-polar lipids were extracted and separated into classes by thin layer chromatography. A semi-quantitative analysis of the chromatography plates allowed a determination of how lipid identity and quantity varied seasonally and by the symbiotic state of the anemone. Anemones collected in July were, on average, 41% larger than those collected in January. Total non-polar lipid content showed no significant seasonal pattern, but cholesterol and palmitic acid (a fatty acid) were present in greater proportions in all January anemones. Zooxanthellate anemones had significantly more non-polar lipid than zoochlorellate anemones in both seasons, and a significantly greater percentage of their lipid was composed of cholesterol and palmitic acid. The winter decrease in body mass likely resulted from increased rates of fission, metabolism of stored lipids, a decrease in food availability, and seasonally reduced translocation of photosynthetic products from the symbionts to their hosts. The reduction in symbiont-derived products may impact the ability of the host anemone to direct resources to development of gonad tissues. Zoochlorellae, which translocate less carbon to their hosts under most conditions, also appear to translocate different products. These differences would be magnified if A. elegantissima switch from zoochlorellate to zooxanthellate under the conditions of increasing temperature predicted in global climate change scenarios. Whether these changes ultimately increase or decrease fitness and whether such changes will also be seen in other symbiotic cnidarians (e.g., corals), that switch symbionts under environmental stress, are important questions that deserve additional attention.
Western Washington University
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Ponce-McDermott, Monica R., "Lipids of the sea anemone Anthopleura elegantissima: season and symbiont affect content and fractionation" (2012). WWU Graduate School Collection. 245.