A new study from the BONUS COCOA project has recently been published:Irma Vybernaite-Lubiene
(Marine Research Institute, Klaipeda University, Lithuania) and co-workers intensively sampled the Nemunas River
just before the
Curonian Lagoon, in order to calculate monthly loads of nutrients generated by
one of the main point pollution sources of the Baltic Sea. During 2012–2016, they patiently created an extensive data set, including all
forms of nitrogen (N), silicate (Si) and phosphorous (P), to investigate seasonal and annual nutrient variations with respect
to discharge, climatic features, and historical trends.
Results show that nutrient
loads varied yearly by up to 50% and their concentrations underwent strong
seasonality, with N and Si limitation during summer. Changes in agricultural
practices resulted in similar N export from the river watershed compared to
historical data (1986–2002), while improvements in sewage treatment led to a
~60% decrease of P loads.
Irma concludes that further P reductions are needed to avoid
unbalanced dissolved inorganic nitrogen and phosphorus (DIN:DIP~10) ecological
stoichiometry in summer, which may stimulate undesired cyanobacterial blooms.
These data are an important contribution to the scattered available information on the largest nutrient source to
the Curonian Lagoon and add another piece to the puzzle explaining the links among
watersheds and downstream transitional aquatic ecosystems suffering non-linear
responses and frequent collapse events (…and furthermore, they allow Irma to dance her PhD in a
couple of months, well done and fingers crossed!).
You can read the full story here:
Vybernaite-Lubiene I, Zilius M, Saltyte-Vaisiauske L, Bartoli M (2018) Recent Trends (2012–2016) of N, Si,
and P Export from the Nemunas River Watershed: Loads, Unbalanced Stoichiometry,
and Threats for Downstream Aquatic Ecosystems. Water