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Assessment: Bothnia Sea (BalEco™ model)
The DIP concentrations in the Bothnia Sea remained under 0.6 µmol l-1 during the year 2006 (in Fig 15 right). The decrease of DIP concentrations started there later than in the Baltic Proper (Alg@line transect) – in the end of May. The concentrations of DIN were high on the spring and winter and exceeded 4 µmol l-1 on the norhen part of the Bothnian Sea (in Fig 15, left). The chlorophyll a values remained low the whole year, but silicate values were high (in Fig. 16). The ratio of DIN:DIP was high and exceed the EUTRO-reference level (16 µmol l-1) for the most of the year (in Fig. 17, left). The DIN:silicate ratio never exceeded 0.5 µmol l-1 (lower EUTRO-acceptable deviation level) during the year 2005 on the Bothnia Sea (in Fig. 17, right).
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Figure 15. On the left: the annual variation of dissolved inorganic phosphate (PO4 µmol l-1) as a function of position and time along the model transect (see Fig. 22) in the Gulf of Bothnia. On the right: the annual variation of dissolved inorganic nitrogen (NO3+NO2 +NH4 µmol l-1). Cumulative day number is used as a temporal scale. BalEco™ ecosystem model results. Click images to enlarge!
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Figure 16. Idem, but chlorophyll a (mg m-3) and silicate (µmol l-1). BalEco™ ecosystem model results. Click images to enlarge!
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Figure 17. Idem, but ratio of dissolved inorganic nitrogen and dissolved inorganic phosphorus (left), ratio of dissolved inorganic nitrogen and silicate (right). BalEco™ ecosystem model results. Click images to enlarge!