Public Ocean acidification and warming are global phenomena that will impact marine biota through the 21st century. This project will provide urgently needed predictive information on the likely survivorship of benthic invertebrates in near shore Antarctic environments that is crucial for risk assessment of potential future changes to oceans. As oceans acidify carbonate saturation decreases, reducing the material required to produce marine skeletons. By examining the effects of increased ocean temperature and acidification on planktonic and benthic life stages of both calcifying and non-calcifying ecologically important organisms, predictions can be made on the potential vulnerability of marine biota to climatic change. Project Objectives: This project aims to deliver one of the first assessments of the impacts that ocean warming and acidification through rising CO2 levels will have on Antarctic benthic marine invertebrates and of the adaptive capacity of common Antarctic biota to climate change. The developmental success of species that have a skeleton will be compared to those that do not under controlled conditions of increased sea water temperature and CO2. A comparison of the responses and sensitivity of developmental stages of calcifiers (echinoids, bivalves) and non-calcifiers (asteroids) to elevated CO2 and temperature will generate much needed empirical data for assessment of risk and adaptive capacity of Antarctica's marine biota and will enable predictions of how benthic invertebrates will fare with respect to climate change scenarios. This dataset addresses objective 3, and part of objective 5: 3 - compare the dynamics of biomineralisation with respect to the elemental composition in response to increased temperature and CO2 in species with aragonite and calcite exoskeletons (bivalves) and porous high magnesium calcite endoskeletons (echinoids) to assess the potential for an in-built adaptive response in calcification 5 - compare biomineralisation and elemental signatures in skeletons in larvae of Antarctic molluscs and echinoderms under climate change scenarios with that determined for related species at lower latitudes to assess the relative sensitivity and vulnerability of Antarctic biota. These data are XRD - x-ray diffractometry of the skeleton to provide data on the element content of the calcite mineral. The Mg2+ level is of interest because the higher the Mg content the more vulnerable the skeleton is to ocean acidification. Wt% MgCO3 in the calcite sample - for each category; test (- "shell"); Spines (-= lg primary spines) and secondary spines

Marine sediments often represent an important reservoir of carbonate minerals that will react rapidly to changing seawater chemistry as a result of ocean acidification. Ocean acidification (the reaction of CO2 with seawater) lowers the saturation state with respect to carbonate minerals and may lead to dissolution of these minerals if undersaturation occurs. There are three main carbonate minerals found in marine sediments: 1. aragonite 2. calcite (also referred to as low-magnesium calcite, containing less than 4mol% MgCO3) 3. high-magnesium calcite (greater than 4 mol% MgCO3) Due to the different structure of these minerals, they have different solubilities with high-Mg calcite the most soluble, followed by aragonite and then calcite. As seawater CO2 increases and the saturation state with respect to carbonate minerals decreases, high-Mg calcite will be the first mineral subject to undersaturation and dissolution. By measuring the carbonate mineral composition of sediments, we can determine which areas are most at risk from dissolution. This information forms an important baseline with which we can assess future climate change. The effect of ocean acidification on carbonates in marine sediments will occur around the world, but due to the lower seawater temperatures in Antarctica, solubility is much lower so the impacts will occur here first. This dataset is a compilation of carbonate mineralogy data from surface sediments collected from the East Antarctic margin. The dataset includes sample metadata, bulk carbonate content, %calcite, % aragonite and mol% MgCO3 (i.e. the magnesium content of high-Mg calcite). This dataset was compiled from new (up to 2020) and archived sediment samples that contacted sufficient carbonates (typically greater than 3% CaCO3)/