TY - JOUR
T1 - Impact of zooplankton grazing on phytoplankton in north temperate coastal lakes
T2 - changes along gradients in salinity and nutrients
AU - Christensen, Inge
AU - Pedersen, Lisbeth Kjæreby
AU - Søndergaard, Martin
AU - Lauridsen, Torben L.
AU - Tserenpil, Sh
AU - Richardson, Katherine
AU - Amorim, Cihelio A.
AU - Pacheco, Juan Pablo
AU - Jeppesen, Erik
N1 - Publisher Copyright:
© 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
PY - 2023
Y1 - 2023
N2 - Zooplankton grazing at similar nutrient levels is generally regarded as lower in brackish than in freshwater lakes, but experimental evidence of this is lacking. Accordingly, we conducted short-term zooplankton grazing experiments in bottles with water from 12 Danish brackish lakes covering a large gradient in salinity (0.3–17.4‰) and nutrient concentrations as well as with water from 24 mesocosms established in the same area with various salinities (0.5–12‰), two nutrient levels and low fish density. Grazing was low in 11 of the 12 lakes, even when they were dominated by edible phytoplankton and nutrient addition led to a major increase in phytoplankton biomass. By contrast, grazing was significant in most of the mesocosms, particularly at high nutrient levels and salinities of 8‰ or below where Daphnia dominated. Moreover, grazing decreased the biomass of most phytoplankton taxa, except for a few (e.g. Ankyra at 0.5–2‰ and Ochromonas and Chaetoceros at 8‰). Our results provide experimental support for potentially significant grazing by zooplankton on phytoplankton in brackish lakes up to a salinity of 8‰ at low fish density; however, grazing in summer was generally low in the majority of the lakes, which we attribute to high predation on zooplankton.
AB - Zooplankton grazing at similar nutrient levels is generally regarded as lower in brackish than in freshwater lakes, but experimental evidence of this is lacking. Accordingly, we conducted short-term zooplankton grazing experiments in bottles with water from 12 Danish brackish lakes covering a large gradient in salinity (0.3–17.4‰) and nutrient concentrations as well as with water from 24 mesocosms established in the same area with various salinities (0.5–12‰), two nutrient levels and low fish density. Grazing was low in 11 of the 12 lakes, even when they were dominated by edible phytoplankton and nutrient addition led to a major increase in phytoplankton biomass. By contrast, grazing was significant in most of the mesocosms, particularly at high nutrient levels and salinities of 8‰ or below where Daphnia dominated. Moreover, grazing decreased the biomass of most phytoplankton taxa, except for a few (e.g. Ankyra at 0.5–2‰ and Ochromonas and Chaetoceros at 8‰). Our results provide experimental support for potentially significant grazing by zooplankton on phytoplankton in brackish lakes up to a salinity of 8‰ at low fish density; however, grazing in summer was generally low in the majority of the lakes, which we attribute to high predation on zooplankton.
KW - Brackish lakes
KW - Grazer control
KW - Saline lakes
U2 - 10.1007/s10750-022-05017-1
DO - 10.1007/s10750-022-05017-1
M3 - Journal article
AN - SCOPUS:85140824903
VL - 850
SP - 4609
EP - 4626
JO - Journal of Applied Phycology
JF - Journal of Applied Phycology
SN - 0921-8971
IS - 20
ER -