ID:
publications-2582
Type:
Peer reviewed articles
Year:
2020
Authors:
Nasime Janatian, Kalle Olli, Fabien Cremona, Alo Laas, Peeter NÔges
Title:
Atmospheric stilling offsets the benefits from reduced nutrient loading in a large shallow lake
Venue/Journal:
Limnology and Oceanography
DOI:
10.1002/lno.11342
Research type:
Simulation & Modeling
Water System:
Precipitation & Ecological Systems
Technical Focus:
Abstract:
AbstractAs part of a global phenomenon, a 30% decrease in average wind speed since 1996 in southern Estonia together with more frequent easterly winds resulted in 47% decrease in bottom shear stress in the large (270âkm2), shallow (mean depth 2.8 m), and eutrophic Lake VĂ”rtsjĂ€rv. Following a peak in eutrophication pressure in the 1970sâ80s, the concentrations of total nutrients were declining. Nonmetric Multidimensional Scaling (NMDS) ordination of a 54âyear phytoplankton community composition timeâseries (1964â2017) revealed three distinct periods with breaking points coinciding with changes in wind and/or water level. Contrary to expectations, we detected no decrease in optically active substances that could be related to wind stilling, whereas phytoplankton biomass showed an increasing trend despite reduced nutrient levels. Here we show how opening of the âlight niche,â caused by declining amount of suspended sediments, was capitalized and filled by the lightâlimited phytoplankton community. We suggest that wind stilling is another global factor, complementary to climate warming that counteracts eutrophication mitigation in lakes and may provide a challenge to assessment of the lake ecological status.
Link with Projects:
722518
Link with Tools:
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