Naturally changing reference conditions: Evidence of isostatic uplift being the main cause of changes in ecological status in a SW Norwegian fjord system

According to the European Water Framework Directive (WFD), restoration actions are needed if present-day ecological quality status (EcoQS) is worse than good. However, less stringent environmental objectives may be allowed water body’s natural condition such that it unfeasible or unreasonably expensive achieve good conditions. In Inner Skjolda- and Grindefjord, an isolated shallow silled fjordsystem on SW coast of Norway, present EcoQS (based benthic foraminifera macroinvertebrates) bad due anoxic conditions in bottom water. Paleoecological foraminiferal data two dated sediment records were used establish situ reference The revealed current did not deviate from which existed just prior onset industrial revolution. Further back time, record showed poor a strong dominance opportunistic species Stainforthia fusiformis, indicating unfavorable for already >2000 years ago. changing during pre-industrial period was probably caused by inner becoming gradually more stratified, stagnant with decreasing oxygen concentrations, response isostatic uplift. Our study shows at location represent succession changes i.e., baseline does have only one but vary naturally over time. We therefore suggest revolution should when defining according WFD.