The Oder Estuary - IOW

µg/l
µg/l
µg/l
225
200
175
150
125
100
75
50
25
0
225
200
175
150
125
100
75
50
25
80
70
60
50
40
30
20
10
0
0
Jahresgang Chlorophyll a im Kleinen Haff
Jahre 1990 - 1999
J F M A M J J A S O N D
Jahresgang Chlorophyll a im Großen Haff
Jahre 1990 - 1999
J F M A M J J A S O N D
Jahresgang Chlorophyll a in der Pommerschen Bucht
Jahre 1990 - 1999
J F M A M J J A S O N D
95%
5%
75%
25%
Median
95%
5%
75%
25%
Median
95%
5%
75%
25%
Median
µg/l
µg/l
µg/l
225
200
175
150
125
100
75
50
25
80
70
60
50
40
30
20
10
0
0
225
200
175
150
125
100
75
50
25
0
Jahresgang Chlorophyll a im Kleinen Haff
Jahre 1980 - 1989
J F M A M J J A S O N D
Jahresgang Chlorophyll a im Großen Haff
Jahre 1980 - 1989
J F M A M J J A S O N D
Jahresgang Chlorophyll a in der Pommerschen Bucht
Jahre 1980 - 1989
J F M A M J J A S O N D
Figure 8.2: Annual course of Chlorophyll-a (µg/l) in the Kleines Haff (top), the Wielki Zalew
(middle) and the Pomeranian Bay (bottom). The figures refer to the periods 1980 –
1989 (right) and 1990 – 1999 (left). Only few data is available for the bay between
1980-1989. Data source: State Agency of Environment, Protection of Nature and
Geology Mecklenburg-Vorpommern (LUNG) and West Pomeranian Voivodeship
Inspectorate in Szczecin (WIOS).
Chlorophyll-a is the major indicator for phytoplankton biomass. Similar to nutrients, chlorophyll-a
concentrations show a high annual and inter-annual variability and long-term trends in the Oder
estuary are problematic and uncertain. In the 1990’s, the averaged median concentrations in the
lagoon started to decrease by about 20 % (compared to the mid 1980’s) and this process still goes
on. This reduction is well in agreement with the reduction of nutrient concentration.
Chlorophyll concentrations describe a typical annual cycle, with high concentrations during the
spring bloom in April, a high level during summer and decreasing concentrations towards winter
(Fig. 8.2). In the lagoon the annual course of chlorophyll during the 1980’s is less even. Winter
algae blooms were observed as well as significant peaks in August. Similar to the lagoon, the mass
53
95%
5%
75%
25%
Median
95%
5%
75%
25%
Median
95%
5%
75%
25%
Median