FROZEN HEAT | Volume 1

Field studies show dissolved oxygen is strongly depleted in some coastal areas and marginal seas, such as the Black Sea and Baltic Sea, as well as at poorly ventilated and highly productive continental margins. Observational data show the volume of these depleted water masses has expanded significantly in recent decades (Stramma et al. 2008). Models predict the ongoing oxygen loss at continental margins will be amplified over the coming century in response to anthropogenic carbon dioxide emissions (Oschlies et al. 2008). Most fauna living at the sea floor depend on oxygen

and will vanish when dissolved oxygen concentrations in ambient bottom waters fall below a critical threshold value. The spread of low-oxygen conditions is, therefore, a serious threat to fauna living at the sea floor of the affected continental margin areas. Although field studies have not yet demonstrated significant pH decreases or oxygen depletions in the vicinity of methane seeps, it is possible these effects may take a long time to become apparent. Baseline studies might be needed in order to understand these slow environmental degradation issues.

A GLOBAL OUTLOOK ON METHANE GAS HYDRATES 39

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