PRINCIPAL INVESTIGATORS: Inna Sokolova and Elia Beniash
PROJECT NUMBER: IOS-0951079 and IOS-0951139
Global climate change driven by an increase in carbon dioxide (CO2) levels is expected to significantly change biodiversity worldwide. Marine ecosystems are affected by warming due to the "greenhouse effect" and acidification of seawater, because higher partial pressure of CO2 causes a decrease in calcium carbonate (CaCO3) saturation. Marine organisms, especially calcifiers such as corals and mollusks that build CaCO3 skeletons, are adversely affected by these changes, but effects of elevated CO2 levels on their physiology and calcification are not well understood.
Marine calcifiers produce two types of CaCO3: aragonite and calcite. It is hypothesized that high sea water CO2 levels will affect aragonite-producing organisms more than those with calcite skeletons, since aragonite is more soluble than calcite. This project studies three common North American mollusk species with different shell mineralogies: eastern oysters (calcitic), hard shell clams (aragonitic), and blue mussels (mixed calcitic/aragonitic). Investigators will use state-of-the-art analysis to determine how elevated temperature and CO2 affect shell formation, mineralogy, structural and mechanical properties, as well as survivability, growth, energy metabolism and expression of calcification-related genes in these species.
This study will provide new insights into the effects of temperature and CO2 level on energy metabolism and shell calcification in three important mollusk species representing the major calcifiers in coastal ecosystems as well as key species for fisheries and aquaculture. The proposed studies will also provide data for the marine carbon cycle models and help to predict effects of climate change on marine ecosystems and coastal economies worldwide. The project provides training opportunities for undergraduate, graduate, post-doctoral and K-12 students with improved learning through peer- and hands-on programs, curriculum development and will strengthen collaborations among UNC Charlotte, University of Pittsburgh and Johnson C. Smith University.
800x600 Global climate change has worldwide negative impacts on marine environment, although the full scope of these impacts is poorly understood. Rise in atmospheric carbon dioxide and the increase of its partial pressure in the oceans lead to their acidification and reduced degree of calcium carbonate saturation. These changes adversely affect many marine organisms; however marine calcifiers are especially sensitive to elevated CO2. Marine calcifiers produce two crystal polymorphs of calcium carbonate, calcite and aragonite. Calcite is less soluble than aragonite and it has been hypothesized that the increase in CO2 levels will affect aragonite producing organisms to a greater extent than calcite producing ones. Mollusks are the major group of marine calcifiers. They make shells from both calcium carbonate polymorphs and some species produce only calcite or aragonite while shells of others contain both minerals. The majority of mollusk species concentrate in the bentic communities of the oceanic shelf regions and are the major near shore ecosystem builders. Many mollusk species were introduced into mariculture and have a significant value for the economies of costal regions. Hence, it is crucial to understand how high carbon dioxide levels will affect mollusk biomineralization and physiology to be able assess its possible ecological and economic impacts. The objective of the project was to obtain better understanding of possible effects of higher CO2 levels on physiology and biomineralization of mollusks. It was hypothesized that the changes in CO2 levels will impact different mollusk species to a various degree depending on the mineral composition of the shells as well as their physiology. Specifically, this proposal addresses the effects of elevated CO2 levels, on biomineralization and physiology of three common bivalve mollusk species with different shell mineralogy, namely eastern oyster (Crassostrea virginica) with calcite shells, hard shell clam (Mercenaria mercenaria)with aragonite shells and blue mussel (Mytilus edulis) with shells containing both calcite and aragonite. We have hypothesised that the impact of elevated CO2 on biomineralization will be greater in mollusks with aragonite-containing shells as compared to calcitic shells and will result in alterations of shell structure and thus a greater decrease in shell weight, thickness and strength. The results of our studies indicate that: Elevated levels of carbon dioxide affect physiology and biomineralization in different mollusk species differently and the severity of these effects does not directly correlate with solubility of the shell mineral, suggesting that biological factors play predominant role in the mollusk shell biomineralization. Mollusks demonstrate nonlinear response to increasing PCO2. For example we have demonstrated that M. mercenaria body and shell growth accelerate with a mild increase in carbon dioxide, however at high CO2 this trend has reversed. The effects of elevated PCO2 in the mollusk shell growth and mechanical properties can be exacerbated by other environmental factors such as low salinity and high temperatures. These data indicate that the effects of high carbon dioxide levels can be stronger in shallow and estuarine environments. The results of our studies demonstrate that the effects of elevated carbon dioxide on biomineralization in mollusks are highly dependent on the species physiology and are strongly influenced by other environmental factors such as temperature and salinity. Our results strongly suggest that shallow coastal and estuarine communities can be strongly affected by the global climate change in the near future, however these affects will widely vary dependent on the keystone mollusk species and local environmental factors. Our results further suggest that the climate change will affect mariculture of different mollusk species to a different degree. Specifically, we demonstrate that at moderate levels of carbon dioxide predicted by the end of the 21 century M. mercinaria and M. edulis will be impacted to a lesser extent than C. virginica. At the same time the observations that other environmental factors such as salinity and temperature can exacerbate the effects of high CO2 would suggest that some of the mollusk farms will need to relocate to open shore more temperate locations to mitigate the effects of the global climate change. Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4
