Perennial oxygen average of lower quartile of fairly stable stratification for < 1 year or slightly longer, Naturally occurring in ? deep parts of Bornholm deficiency monthly measurements longer than growth season; vertical circulation enclosed areas where Basin? (hypoxia/anoxia) during unaffected period type mainly occurs in obstructed by thermo- stratification is relatively ed with (Dec)Jan-May falls below a enclosed areas (e.g. between and/or halocline stable and mixing occurs perennial oxygen threshold /or/ sills) favouring stable formation, lateral mixing infrequently depending deficieny concentration stays below halocline formation and obstructed by on weather and lateral threshold longer than only obstructing lateral transport morphological barriers; transport processes during summer/autumn, processes mixing occurs (bottom currents, saline sometimes for several years infrequently depending water inflow events) in a row, but oxygen on weather and contents rises again to currents/lateral transport values above the threshold processes. once sufficient water exchange has taken place Permanent average of lower quartile of permanent stratification (= >>1 year, Naturally occurring, Byfjorden (Sweden) oxygen monthly measurements year-round plus occurring for circulation/mixing of environmentally deficiency during unaffected period many years, even decades, in deep water occurs rarely, improving measures will (hypoxia/anoxia) (Dec)Jan-May falls below a a row), e.g. in deep inflow of oxygenated have limited or no effect threshold /or/ (sub)basins or fjords where saltwater will raise oxygen on oxygen conditions concentration stays below stable haloclines bordered levels but only for a threshold throughout the by morphological barriers limited period of time year for many years (even prevent or obstruct vertical decades), with only circulation and lateral mixing occasional interruption
Perennial oxygen deficiency (hypoxia/anoxia) ed with perennial oxygen deficieny average of lower quartile of monthly measurements during unaffected period (Dec)Jan-May falls below a threshold /or/ concentration stays below threshold longer than only during summer/autumn, sometimes for several years in a row, but oxygen contents rises again to values above the threshold once sufficient water exchange has taken place fairly stable stratification for longer than growth season; type mainly occurs in enclosed areas (e.g. between sills) favouring stable halocline formation and obstructing lateral transport processes < 1 year or slightly longer, vertical circulation obstructed by thermo- and/or halocline formation, lateral mixing obstructed by morphological barriers; mixing occurs infrequently depending on weather and currents/lateral transport processes. Naturally occurring in enclosed areas where stratification is relatively stable and mixing occurs infrequently depending on weather and lateral transport processes (bottom currents, saline water inflow events) ? deep parts of Bornholm Basin? Permanent oxygen deficiency (hypoxia/anoxia) average of lower quartile of monthly measurements during unaffected period (Dec)Jan-May falls below a threshold /or/ concentration stays below threshold throughout the year for many years (even decades), with only occasional interruption permanent stratification (= year-round plus occurring for many years, even decades, in a row), e.g. in deep (sub)basins or fjords where stable haloclines bordered by morphological barriers prevent or obstruct vertical circulation and lateral mixing >>1 year, circulation/mixing of deep water occurs rarely, inflow of oxygenated saltwater will raise oxygen levels but only for a limited period of time Naturally occurring, environmentally improving measures will have limited or no effect on oxygen conditions Byfjorden (Sweden)