TY  - JOUR
A1  - Kolmakova, Olesya V.
A1  - Gladyshev, Michail I.
A1  - Fonvielle, Jeremy Andre
A1  - Ganzert, Lars
A1  - Hornick, Thomas
A1  - Grossart, Hans-Peter
T1  - Effects of zooplankton carcasses degradation on freshwater bacterial community composition and implications for carbon cycling
JF  - Environmental microbiology
N2  - Non-predatory mortality of zooplankton provides an abundant, yet, little studied source of high quality labile organic matter (LOM) in aquatic ecosystems. Using laboratory microcosms, we followed the decomposition of organic carbon of fresh C-13-labelled Daphnia carcasses by natural bacterioplankton. The experimental setup comprised blank microcosms, that is, artificial lake water without any organic matter additions (B), and microcosms either amended with natural humic matter (H), fresh Daphnia carcasses (D) or both, that is, humic matter and Daphnia carcasses (HD). Most of the carcass carbon was consumed and respired by the bacterial community within 15 days of incubation. A shift in the bacterial community composition shaped by labile carcass carbon and by humic matter was observed. Nevertheless, we did not observe a quantitative change in humic matter degradation by heterotrophic bacteria in the presence of LOM derived from carcasses. However, carcasses were the main factor driving the bacterial community composition suggesting that the presence of large quantities of dead zooplankton might affect the carbon cycling in aquatic ecosystems. Our results imply that organic matter derived from zooplankton carcasses is efficiently remineralized by a highly specific bacterial community, but does not interfere with the bacterial turnover of more refractory humic matter.
Y1  - 2018
U6  - https://doi.org/10.1111/1462-2920.14418
SN  - 1462-2912
SN  - 1462-2920
VL  - 21
IS  - 1
SP  - 34
EP  - 49
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Tolomeev, Aleksandr P.
A1  - Dubovskaya, Olga P.
A1  - Kirillin, Georgiy
A1  - Buseva, Zhanna
A1  - Kolmakova, Olesya
A1  - Grossart, Hans-Peter
A1  - Tang, Kam W.
A1  - Gladyšev, Michail I.
T1  - Degradation of dead cladoceran zooplankton and their contribution to organic carbon cycling in stratified lakes
BT  - field observation and model prediction
JF  - Journal of plankton research
N2  - The contribution of dead zooplankton biomass to carbon cycle in aquatic ecosystems is practically unknown. Using abundance data of zooplankton in water column and dead zooplankton in sediment traps in Lake Stechlin, an ecological-mathematical model was developed to simulate the abundance and sinking of zooplankton carcasses and predict the related release of labile organic matter (LOM) into the water column. We found species-specific differences in mortality rate of the dominant zooplankton: Daphnia cucullata, Bosmina coregoni and Diaphanosoma brachyurum (0.008, 0.129 and 0.020 day(-1), respectively) and differences in their carcass sinking velocities in metalimnion (and hypolimnion): 2.1 (7.64), 14.0 (19.5) and 1.1 (5.9) m day(-1), respectively. Our model simulating formation and degradation processes of dead zooplankton predicted a bimodal distribution of the released LOM: epilimnic and metalimnic peaks of comparable intensity, ca. 1 mg DW m(-3) day(-1). Maximum degradation of carcasses up to ca. 1.7 mg DW m(-3) day(-1) occurred in the density gradient zone of metalimnion. LOM released from zooplankton carcasses into the surrounding water may stimulate microbial activity and facilitate microbial degradation of more refractory organic matter; therefore, dead zooplankton are expected to be an integral part of water column carbon source/sink dynamics in stratified lakes.
KW  - zooplankton carcasses
KW  - non-predatory mortality
KW  - sinking velocities
KW  - microbial degradation
KW  - Lake Stechlin
KW  - simulation modeling
Y1  - 2022
U6  - https://doi.org/10.1093/plankt/fbac023
SN  - 0142-7873
SN  - 1464-3774
VL  - 44
IS  - 3
SP  - 386
EP  - 400
PB  - Oxford Univ. Press
CY  - Oxford
ER  -