Carpenter, Gabrielle and Doo, Steve (2020) Effects of environmental life history on symbiont and holobiont responses to projected ocean warming in a common large benthic foraminifera, Calcarina gaudichaudii. (Master thesis), Northeastern University, Boston, USA, 30 pp.

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Marine ecosystems, particularly coastal environments, are rapidly changing due to anthropogenic impacts resulting in increased global climate change (ocean warming), ocean acidification, hypoxia, and eutrophication. On coral reefs, Large benthic foraminifera (LBFs) play a key role as carbonate producers, contributing up to 5 % of reef-scale carbonate budgets, highlighting the fact that projected climate change has the potential to significantly alter ecosystem functioning. While the response of LBFs to elevated thermal stress is well documented in laboratory studies, the potential influence of adaptation or acclimation through prior environmental life history on this response remains largely unknown. In this study, we conspecific specimens of Calcarina gaudichaudii, a common reef-building LBF, were collected from intertidal and subtidal environments. LBFs were then acclimated in laboratory conditions at ambient (25oC) and elevated (28oC) temperatures, and subsequently exposed to heat stress treatments (25oC, 28oC, 30oC, 33oC). Photosynthetic rates of C. gaudichaudii were significantly decreased in specimens collected at subtidal depths when incubated at 25°C when compared to those incubated at 28°C whereas there was no effect of environmental history on respiration, indicating that symbiont and holobiont responses may differ in LBFs. Additionally, maximum photochemical efficiency (Fv/Fm) significantly decreased as a result of heat stress, although bleaching was not observed. These results highlight the plastic responses of the algal microbiome and indicate environmental history, acclimation temperature, and heat stress interact to affect the physiological status of C. gaudichaudii. These results add to the growing literature which highlight the larger implications of understanding environmental life history as an important factor to consider to better understand how ecosystem processes (e.g. carbonate production) will be altered in the future.

Document Type: Thesis supervision (Master thesis)
Thesis supervisor: Doo, Steve
Programme Area (enter as: PA1/PA2/PA3/PA4/PA5): PA2
Research affiliation: Biogeochemistry and Geology > Geoecology & Carbonate Sedimentology
Date Deposited: 25 Aug 2020 15:21
Last Modified: 01 Oct 2020 13:01

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