Investigating Dissolved Oxygen Drawdown in Macquarie Harbour

[摘要] There have been a number of recent reports on, and reviews of, oxygen in Macquarie Harbour (e.g. MHDOWG 2014, ADS 2015, Knight et al. 2015). These identified some potentially large and unquantified processes that are likely to be important in the oxygen balance in Macquarie Harbour. Here we review some observations of dissolved oxygen in Macquarie Harbour and report on the first measurements of biological oxygen demand (BOD) from the water column. Although spatially variable BOD was ~ 2 times benthic respiration. A comparison between long term net drawdown and measured gross rates of oxygen consumption highlights the role of surface exchange in maintaining oxygen levels above the halocline while extended periods without mixing lead to significant periods of low dissolved oxygen in the mid-water column. Elevated levels of labile organic carbon with fatty acid profiles characteristic of farm derived material were detected at a depth of 3m close to the cages and coincident with increased rates of oxygen consumption when compared to the far field site.Based on this study it is recommended that sufficient measurements of BOD be conducted to determine the spatial variability of oxygen drawdown and farm derived organic material throughout the Harbour. In addition a simple model should be developed to better understand processes important to oxygen cycling; particularly mixing which resupplies most of the oxygen. This combination would provide a superior capability to manage oxygen in Macquarie Harbour for the benefit of its many users, the environment and its ecology

[发布日期] 2016-02-17 [发布机构] CSIRO

[学科分类] 地球科学(综合)