| Summary: | Progress Code: completed Statement: This is based on unreplicated data, standard errors are calculated based on microscope field of view pseudoreplicates. The following functional groups were present in very low numbers and therefore there was high variance between counts resulting in high standard error of mean cells per litre estimates; Autotrophic and heterotrophic dinoflagellates, ciliates, other flagellates, discoid centric diatoms (greater than 40, 20 to 40 and less than 20 microns), other centric and pennate diatoms. All other taxa and functional groups have low variance on counts and are statistically viable. Purpose The Southern Ocean is particularly vulnerable to ocean acidification due to its cold temperatures, extensive upwelling and naturally large seasonal fluctuations in pH. Microbes are an important component of these waters through the roles they play in driving productivity, elemental cycles and ocean biogeochemistry, meaning their response to environmental stressors is a key determinant of Southern Ocean feedbacks to global climate change (Arrigo and Thomas, 2004; Arrigo et al., 2008; Kirchman, 2008). Despite their importance, relatively little is known about the sensitivity of Antarctica marine microbes to ocean acidification and this limits our ability to predict the how the Southern Ocean will be impacted in the future, and the feedback this may have on global climate change. This study will assessed the following questions on a natural microbial community from nearshore East Antarctic waters. 1. Is there a change in protistan community composition and abundance with increased concentration of pCO2? And what pCO2 concentration elicits this change? 2. Does an acclimation period allow the protistan community the cope to increased concentrations of pCO2? 3. Is the effect of increased pCO2 concentration species-specific? And if it is, what are the potential driving mechanisms behind these responses? 4. Does the results of this minicosm experiment agree with those of previously conducted ...
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