Comparing total phosphorus and chlorophyll concentration data, we can see that there are no big differences between our and previous data. In Lake Erken average concentration of total phosphorus in middle of June is 17 µg P/l in the surface water (Weyhenmeyer, 1998). Our data shows that there are 18.3 µgP/l. Chlorophyll concentration in this time usually is 2.5 µg/l (Weyhenmeyer, 1998), our data states that there is 1.8 µg/l. So chlorophyll concentration is somewhat smaller this time.
In Lake Limmaren concentration of total phosphorus is 40 µg P/l in 1991 and 130 µg P/l in 1992 (Pettersson, 1993). Our data states that there are 96 µg P/l, which is an average concentration compering with the older data. Chlorophyll concentrations in the earlier study were 13.7 – 28.1 µg/l (Pettersson, 1993). Our data states that now it is 37.6 µg/l, which is quite bigger than previous data. Limmaren has more phytoplankton than before.
As we can see previous data proves our first and third hypothesis too, because in Lake Limmaren there is a higher concentration of chlorophyll and total phosphorus than in Lake Erken.
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