Effects of zooplankton on the sinking flux of organic carbon in Lake Biwa

Yoshimizu, Chikage; Yoshida, Takehito; Nakanishi, Masami; Urabe, Jotaro

doi:10.1007/s102010170014

Cited by 26 publications

(37 citation statements)

References 30 publications

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Section: Discussionmentioning

confidence: 82%

“…Production of humic FDOM that is directly linked to microbial mineralization of organic matter in freshwater systems could be analogous to the pathways of Maeda et al 1987) and 15.3 6 9.9 mmol C m 22 d 21 (n 5 9; Yoshimizu et al 2001). { Rate of primary production between July 1996 and August 1997 (Yoshimizu et al 2001). 1 Air-water carbon dioxide (CO 2 ) fluxes were calculated according to Cole and Caraco (1998) using carbon dioxide partial pressure (P CO2 ), solubility, and wind speed data.…”

Section: Discussionmentioning

confidence: 82%

“…Experiments showing production of humic-like contributing to 7.9% of hypolimnetic mineralization, accounted for about 8.3% of the particulate organic carbon (POC) sinking flux, 1.4% of net primary productivity, and 8.6% of air-water CO 2 influx in Lake Biwa ( Table 5). Note that this comparison of FDOM M production rate to primary production and POC sinking flux is conservative, due to the mismatch with the timescales of previous studies (Maeda et al 1987;Yoshimizu et al 2001). The low concentrations of FDOM M in the surface layers during summer (Fig.…”

Section: Discussionmentioning

confidence: 83%

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Biogeochemical control on fluorescent dissolved organic matter dynamics in a large freshwater lake (Lake Biwa, Japan)

Thottathil

Hayakawa

Hodoki

et al. 2013

Limnology & Oceanography

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The dynamics of fluorescent dissolved organic matter (FDOM) in the large monomictic freshwater Lake Biwa (surface area 675 km 2 , maximum depth 104 m) was studied from December 2010 to December 2011. The proteinlike FDOM (FDOM T ) and dissolved organic carbon (DOC) showed epilimnetic accumulation (FDOM T from 4.42 6 0.22 quinine sulfate units [QSU] to 6.30 6 0.04 QSU; DOC from 80.8 6 2.7 mmol L 21 to 102.7 6 3.5 mmol L 21 ) between nutrient-replete winter mixing to nutrient-depleted stratified periods. This accumulation is attributed to the reduced heterotrophic activity following severe P-limitation. The positive correlation between accumulated DOC and FDOM T in the epilimnion and their uniform reduction in the hypolimnion (, 9%) suggest FDOM T as a proxy for semi-labile DOM. The humic-like FDOM (FDOM M ) generally increased with depth, a pattern similar to nutrients and total carbon dioxide (TCO 2 ), but adverse to dissolved oxygen. The significant positive correlations of FDOM M with apparent oxygen utilization (r 5 0.86, p , 0.001), TCO 2 (r 5 0.91, p , 0.001), nitrate (r 5 0.83, p , 0.001), and phosphate (r 5 0.76, p , 0.001) in the deeper layers suggest that FDOM M is formed during hypolimnetic mineralization. We estimated that , 8% of the organic carbon degraded in the hypolimnion is transferred into humic substances. The minor contribution of DOC (6.4%) to hypolimnetic mineralization suggests that production of humic substances is mainly fueled by the mineralization of sinking biogenic particles. The production and consumption of FDOM in freshwater lakes may influence the quality and bioavailability of carbon exported from these systems.

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Section: Discussionmentioning

confidence: 82%

Section: Discussionmentioning

confidence: 82%

Section: Discussionmentioning

confidence: 83%

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Biogeochemical control on fluorescent dissolved organic matter dynamics in a large freshwater lake (Lake Biwa, Japan)

Thottathil

Hayakawa

Hodoki

et al. 2013

Limnology & Oceanography

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“…Our study was conducted in the monomictic North basin (water volume 28.1 km 3 ; water residence time 5.5 yr), which is deep (maximum depth 104 m), mesotrophic (annual mean levels of total phosphorus, chlorophyll a, and primary production are 0.2 mol L Ϫ1 , 2 g L Ϫ1 , and 104 mmol C m Ϫ2 d Ϫ1 , respectively; Yoshimizu et al 2001, Nishimura et al 2005, and oxygenated (the annual minimum concentration of hypolimnetic dissolved oxygen (DO) concentration is ϳ4 mg L Ϫ1 ), providing a useful test of the hypothesis that the DOM pump operates in large freshwater lakes.…”

mentioning

confidence: 99%

Role of dissolved organic matter in hypolimnetic mineralization of carbon and nitrogen in a large, monomictic lake

2006

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We tested the hypothesis that dissolved organic matter (DOM) is delivered to deep layers by convective mixing in winter, where it contributes to the mineralization of C, N, and P in the oxygenated hypolimnion of large (surface area 674 km 2 , maximum depth 104 m), monomictic Lake Biwa. Basin-scale, seasonal measurements of DOM concentrations revealed that dissolved organic carbon (DOC) and nitrogen (DON) accumulated in the epilimnion during warm seasons and were redistributed into the deeper layer during winter overturn. Hypolimnetic DOC and DON decreased in concentration over the stratification period, indicating mineralization; the contributions of DOM to the total mineralization of C and N were 8% and 30%, respectively. Higher contribution of N relative to C suggests that the N-rich DOM was mineralized at depth. We failed to detect a significant contribution of dissolved organic phosphorus to P mineralization in the hypolimnion, which could be explained by substantial depletion in P relative to C and N of DOM; C : P and N : P ratios were 1,978 and 147, respectively. The data suggest that convective mixing in this monomictic basin delivers DOM to hypolimnetic depths, where it is mineralized during subsequent periods of stratification.

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“…The main origin of hydrophobic acids in Lake Biwa may be humic substances from soils around rivers that flow into Lake Biwa, while hydrophilic DOM may be due to inner production by phytoplankton. [14][15][16][17] However, few studies about the contribution of inner production by phytoplankton to DOM have been carried out; 18 therefore, three kinds of lake phytoplankton, Microcystis aeruginosa, Staurastrum dorsidentiferum, and Cryptomonas ovata were cultivated, and the contribution of DOM released from the phytoplankton was examined to clarify the origin of the organic pollution of Lake Biwa with regard to cultivation and biodegradation. [19][20][21] The characteristics of the algal-derived DOM were investigated using gel chromatography with a fluorescence detector and a three-dimensional excitation-emission matrix (3-DEEM) technique.…”

Section: Introductionmentioning

confidence: 99%

Characterization of Protein-like Fluorophores Released from Lake Phytoplankton on the Basis of Fractionation and Electrophoresis

et al. 2012

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Three kinds of lake plankton were cultivated, and the properties of protein-like fluorophores released from the plankton were characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The results were compared with those by gel chromatography with a fluorescence detector and three-dimensional excitation-emission matrix (3-DEEM). The concentrated protein-like fluorophores of algal dissolved organic matter (DOM) were successfully separated from the fulvic-like fluorophores, and analyzed using SDS-PAGE. SDS-PAGE analysis revealed that the protein-like fluorescence DOM released from Microcystis aeruginosa consisted of proteins with molecular weights of 17, 37, 50, 75, 150 kDa, and greater than 250 kDa. The results of SDS-PAGE were consistent with those of gel chromatography. Those substances with molecular weights greater than 250 kDa may be a polysaccharide-peptide complex, called peptidoglycan, which is a component of bacterial cell walls. The molecular weights of protein-like fluorescence DOM from Staurastrum dorsidentiferum were determined to be 37 and 50 kDa. For Cryptomonas ovata, its DOM was found to be composed of substances with molecular weights of between 10 and 150 kDa. The results by high-performance size exclusion chromatography with chemiluminescent nitrogen detection (HPSEC/CLND) analysis suggest that the proteinlike fluorophores from the plankton might be composed of substances containing organic nitrogen.

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Effects of zooplankton on the sinking flux of organic carbon in Lake Biwa

Cited by 26 publications

References 30 publications

Biogeochemical control on fluorescent dissolved organic matter dynamics in a large freshwater lake (Lake Biwa, Japan)

Biogeochemical control on fluorescent dissolved organic matter dynamics in a large freshwater lake (Lake Biwa, Japan)

Role of dissolved organic matter in hypolimnetic mineralization of carbon and nitrogen in a large, monomictic lake

Characterization of Protein-like Fluorophores Released from Lake Phytoplankton on the Basis of Fractionation and Electrophoresis

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