Living calcifiers do not carry out the calcification reaction in an open water environment in equilibrium with the atmosphere. Claiming precipitation of CaCO 3 during calcification as a net source of CO 2 to the atmosphere is an oversimplification of ocean chemistry that is true only in open water environments. Experiments showing that ocean acidification is damaging to calcifiers have all used experimental pH levels that are not projected to be reached in the oceans until the next century or later today’s oceans, despite recent changes, are alkaline in pH. In this review we assess the evidence concerning such criticisms and find reasons to doubt both. Two criticisms made about this are: (i) ocean acidification has allegedly been shown to cause reduced shell formation in calcifiers (ii) the calcification reaction that precipitates CaCO 3 crystals into the shells is alleged to return CO 2 to the atmosphere. These organisms could serve as a biotechnological carbon capture and storage mechanism to control climate change. Today’s marine calcifiers (coccolithophore algae, Foraminifera, Mollusca, Crustacea, Anthozoa, Echinodermata) remove carbon dioxide (CO 2 ) from the atmosphere, converting it into solid calcium carbonate (CaCO 3 ) which is stable for geological periods of time. Particulate Fe (pFe), in suspended particulate matter (SPM), and other particulate trace metals in TNB could support the hypothesis that biogenic iron may significantly contribute to the bioavailable iron pool, sustaining both primary production and ostracod fauna richness in this area.
Similar results (high abundance and richness in ostracod values) were also recorded in the Terra Nova Bay and in a nearby area characterized by warm water rich in nutrients and composed of water of circumpolar origin flowing from the open ocean southwards onto the continental shelf.
Circumpolar Deep Water could represent the main factor controlling the distribution of ostracods. The abundance and richness values correlate well to nutrient distribution and sediment supply, primarily related to the circulation of different oceanographic regimes affecting the floor of the Ross Sea Shelf. The ostracod fauna from the Western Ross Sea Shelf appears dominated by Australicythere polylyca, Australicythere devexa, Xestoleberis rigusa, Loxoreticulatum fallax, Cativella bensoni, Austrotrachyleberis antarctica and Patagonacythere longiducta, colonizing a variety of shelf environments along a wide bathymetric range. potential controlling factors in Antarctic waters. Our study, based upon surface sediment occurrences, contributes to the better definition of their distribution vs. Ostracoda are a minor but recurrent component of Southern Ocean marine carbonate factories, and their low-Mg calcitic skeletal mineralogy helps in ensuring a noteworthy post-mortem resilience. These results indicate that ocean warming might exacerbate the skeletal maintaining mechanisms of the starfish in a high pCO2 environment and could potentially modify the morphology and functions of the starfish skeleton. yairi, whereas temperature did not however, skeletons exposed to elevated pCO2 and high temperature show a strongly altered skeleton structure compared to ambient temperature. pCO2 as a sole stressor caused alterations on stereom structure and degradation on the skeletal structure of A. The influence of increased pCO2 was more relevant than that of increased temperature on skeletal microstructures. Elevated pCO2 did not induce any statistically significant element alterations of the skeleton in all treatments over the incubation time, but increased pCO2 concentrations might possess an indirect effect on skeletal mineral ratio alteration. Nevertheless, inter-individual variability in skeletal Sr and Ca ratios increased with higher temperature.
The results indicate that temperature is the major factor controlling the skeletal Mg (Mg/Ca ratio and Mgnorm ratio), but not for skeletal Sr (Sr/Ca ratio and Srnorm ratio) and skeletal Ca (Canorm ratio) in A. To assess the impact of exposure to elevated temperature and increased pCO2 on the skeleton of echinoderms, in particular the mineralogy and microstructure, the starfish Aquilonastra yairi (Echinodermata: Asteroidea) was exposed for 90 days to simulated ocean warming (27 ◦C and 32 ◦C) and ocean acidification (455 μatm, 1052 μatm, 2066 μatm) conditions. While many marine calcifying organisms precipitate low-Mg calcite or aragonite, the skeleton of echinoderms consists of more soluble Mg- calcite. Ocean acidification and ocean warming compromise the capacity of calcifying marine organisms to generate and maintain their skeletons.