Macroalgae and phytoplankton as indicators of ... - Naturstyrelsen

Flensborg Fjord on the ranked scale, the response to nitrogen input is
about 2-3 times larger than for open coastal sites. The largest response to
nitrogen input is observed for inner Odense Fjord, Nissum Fjord and
Randers Fjord, sites strongly affected by riverine inputs. Overall the
ranking of the sites by their slopes corresponds well to the expected influence
from land-based nitrogen discharges.
Figure 2.6 Estimated site-specific slopes in TN-nitrogen input relations and 95% confidence intervals for the estimate. Estimates
have been sorted by increasing slopes.
For the 39 different water bodies, reference conditions and boundary values
between ecological status classes were predicted from the regression
model using fixed intercepts and site-specific slopes (Table 2.3). The uncertainty
of these estimates includes a variance contribution from both
the slope and the estimated common intercept of 15.46 µmol l -1 (±0.88).
For the TN concentrations used in the macroalgae calculations the procedure
is similar with the exception that TN annual means represent an
entire year (July-June). Given this, we found values (Table 2.4) that were
slightly lower than those used for chlorophyll due to generally lower TN
levels in July-December compared to January-June.
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