Abstract:
Biogeochemical cycles in estuarine habitats contribute significantly to the regulation of the atmospheric climate. In particular, carbon sequestration is a vital ecosystem service, which include recycling and reusing carbon stored in sediment layers. Quantification of carbon uptake has historically involved measuring sediment oxygen consumption and CO2 production. However, these methods lack a direct measure on carbon consumption rates in soft sediment systems. To fill this void, components of ecosystem assays from freshwater and terrestrial systems were used to formulate a new assay that measures soft sediment functions. A new novel assay called ROMA (rapid organic matter assessment) is presented in this thesis. The ROMA assay enables accurate and direct measurements of carbon consumption rates of macrofaunal, meiofaunal and microbial communities in a range of soft sediment habitats. Through the refinement and optimization of the ROMA assay, a suitable bait recipe was developed and showed to be palatable to sediment residing animal communities. This allowed the ROMA assay to be tested in a number of different Auckland estuaries with varying health statuses. It was shown that heavily degraded sites were typified by low carbon consumption rates and essentially, their ability to carry out basic functions was strongly jeopardized. The ability for this newly developed ROMA assay to deliver data on a rapid time scale, and its easy-to-use nature, proved that the assay could be a useful ecological indicator tool.
