Both the eight site-specific and the generic model explicitly
represented the growing and non-growing seasons of cyanobacteria
by water temperature thresholds. For the site-specific models,
the thresholds of water temperature were 17.97 ◦C, 13.51 ◦C and
14.36 ◦C, respectively, in Meiliang Bay, Zhushan Bay and Western
Lake. These water temperatures distinguishing the low
and high cyanobacteria population were lower than that in other
regions. Generally high cyanobacteria population in Taihu Lake
are not only associated with the elevated temperature and irradiance,
but also the hyper-eutrophication and the driven factor of
wind. The Meiliang Bay, Zhushan Bay and Western Lake are close
to the inflows, thus the nitrogen (N) and phosphorus (P) values
are higher than that in Main Lake and Eastern Lake. The external
nutrients provide potential for the growth of cyanobacteria. In addition,
there are three prevailing winds, the Southeast wind in spring
and summer, the Northeast wind in autumn and the Northwest
in winter in Lake Taihu. The winds drift the cyanobacteria to the
north and west, and allow it to accumulate in the leeward. This
results in the high cyanobacteria population in the area with lower
water temperature, leading to an artefact of low thresholds of water
temperatures. The generic model provided a threshold water temperature
of 13.01 ◦C, lower than most of the temperatures in the
site-specific models. The fitness function of RMSE was inclined to
select the models containing a better prediction in high values. The
Meiliang Bay, Zhushan Bay and Western Lake had lower thresholds
of water temperature and higher cyanobacteria population, leading
to a low water temperature threshold in the generic model.