Cost-effective monitoring of organic enrichment resulting from salmon mariculture

Two methods of environmental monitoring proposed for the salmon mariculture industry are compared and contrasted on the basis of scientific and cost-e ffectiveness criteria: a technique based on macrofaunal community structure and one using process-oriented sediment geochemistry. For this purpose, fi eld sampling was confined to one salmon farm and a nearby reference site in the Bay of Fundy. Both methods produced significant differences between fa rm and reference sires, as well as meeting other appropriate scientific cri teria. The geochemical method was based on held measurements of sedimentary Eh, by redox electrode, and sedimentary sulphide after fixing the sediment in a sulphur anti-oxidant buffer and ion analyses with Ag/Ag sulphide and combination reference electrode. Both measures can be completed in the fiel d from the sampling vessel. Results suggested that the geochemical method w as of significantly lower cost than the technique based on macrofaunal comm unity structure. This is because of the lengthy laboratory time required to determine the identity and abundance of macrofaunal taxa. Both methods can categorize the sedimentary organic impact as normal, oxic, hypoxic, or ano xic, which depends ultimately on the dominant microflora present. This. in turn, depends on the rate of carbon reaching the sediment as well as its ut ilization by biological and physical processes.