Bacterial metabolism of organic carbon in the tidal freshwater Hudson Estuary

Findlay, Stuart E. G.; Pace, ML; Lints, David; Howe, Karin

doi:10.3354/meps089147

Cited by 84 publications

(33 citation statements)

References 13 publications

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“…Bacteria are most regularly limited by DOC (Malone, 1977) but may also be limited by nitrogen and phosphorus and may compete with phytoplankton for nutrients (Thingstad et al, 1998). Bacteria can quickly metabolise available DOC acting as a significant carbon sink, as well as a potential link for organic matter subsidising food webs (Findlay et al, 1992). Estuaries are commonly net heterotrophic, indicating the importance of allochthonous carbon to bacterial metabolism (Fouilland and Mostajir, 2010).…”

Section: Introductionmentioning

confidence: 99%

Highs and lows: The effect of differently sized freshwater inflows on estuarine carbon, nitrogen, phosphorus, bacteria and chlorophyll a dynamics

Hitchcock

Mitrovic

2015

Estuarine, Coastal and Shelf Science

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Freshwater inflows play a key role in the delivery of organic carbon to estuaries. However, our understanding of the dynamics between discharge and carbon globally is limited. In this study we performed a 30-month monitoring study on the Bega and Clyde River estuaries, Australia, to understand the influence that discharge had on carbon, nitrogen, phosphorus, bacteria and chlorophyll a dynamics. We hypothesised that 1) discharge would be the most important factor influencing carbon and nutrient concentrations, though during low flows chlorophyll a would also be positively related to carbon, 2) bacteria would be related to dissolved organic carbon (DOC), and chlorophyll a to temperature, nitrogen and phosphorus, and 3) that concentrations of carbon, nitrogen, phosphorus, bacterial biomass and chlorophyll a would be significantly different between large 'flood flows', smaller 'fresh flows' and base flow conditions. We found that discharge was always the most important factor influencing carbon and nutrient concentrations, and that primary production appeared to have little influence on the variation in DOC concentration even during base flow conditions. We suggest this relationship is likely due to highly episodic discharge that occurred during the study period. Bacteria were related to DOC in the lower estuary sites, but phosphorus in the upper estuary. We suggest this is likely due to the input of bioavailable carbon in the upper estuary leading bacteria to be P limited, which changes downstream to carbon limitation as DOC becomes more refractory. Chlorophyll a was positively related to temperature but not nutrients, which we suggest may be due to competition with bacteria for phosphorus in the upper estuary. Carbon, nitrogen and phosphorus concentrations were different under flood, fresh and base flow conditions, though these differences sometimes varied between estuary locations for different resources. Overall, the results demonstrate that discharge plays an important structuring role for carbon, nutrient and bacteria dynamics on the Bega and Clyde Rivers, and that the differences observed between flood and fresh inflows suggest that further study into the influence of differently sized inflow events is important.

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Section: Introductionmentioning

confidence: 99%

Highs and lows: The effect of differently sized freshwater inflows on estuarine carbon, nitrogen, phosphorus, bacteria and chlorophyll a dynamics

Hitchcock

Mitrovic

2015

Estuarine, Coastal and Shelf Science

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“…Therefore, BNP must be subsidized, in large part, by allochthonous input of organic matter into the system (Findlay et al 1991a, Howarth, et al 1992. The conservative distribution of DOC during transport along this reach of the Hudson River further suggests that the majority of organic matter is refractory and that high bacterial abundance and production is supported by a relatively small, and 'unidentified' labile organic carbon pool (Findlay et al 1992, Howarth et al 1992. Results presented here suggest that, indeed, preferential bacterial utilization of HMWOC over the abundant LMWOC fraction is apparent along the estuarine reach of this river.…”

Section: Introductionmentioning

confidence: 99%

Bacterioplankton dynamics and organic carbon partitioning in the lower Hudson River estuary

Sañudo‐Wilhelmy¹,

Taylor²

1999

Mar. Ecol. Prog. Ser.

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ABSTRACT. Surface water samples collected at 10 stations in April 1996 along the entire salinity grad e n t of the Hudson River estuary were fractionated into particulate (POC), dissolved (DOC; <0.45 pm), high molecular weight (HM\VOC; 10 kDa-0.45pm), and low molecular weight (LMWOC; c10 kDa) organic carbon. Bacterial concentrations, production and specific growth rates were also determined at each location. While HMWOC (6 to 26 p M ) exhibited nonconservative removal relative to ideal dilution of river and seawater along the estuary. DOC (176 to 324 PM) showed a nonconservative excess along this salinity gradient. These contrasting distributions suggest that the majority of DOC was exported to the ocean and consisted of low lability material, while a reactive fraction of HMWOC was removed during estuarine mixing. Bacterial abundances (5 to 16 X 10' cells I-'), production (3.4 to 28.7 pg C 1-' d-l), and specific growth rates (0.09 to 0.66 d-l) varied significantly along the salinity gradient. These variables were positively correlated with algal standing stocks (chlorophyll a) and even more coherent with HMWOC distributions. In contrast, bacterial metabolism varied independently of POC. DOC, and LMWOC concentrations Therefore, while HMWOC accounted for <10% of the DOC, this pool appeared to be very dynamic, possibly due to bacterial degradation. However, mass balance estimates indicate that bacterial uptake could remove at most 30% of the HMWOC. suggesting that abiotic processes such as flocculation are probably the major removal mechanism of HMW organic matter within the estuary. Lastly, contrary to previous results from the tidal freshwater section of the Hudson, strong coherence between primary and secondary production and the nonconservative excesses of DOC found in the lower estuary suggest that carbon and bacterial dynamics can vary qualitatively along different reaches of this river.

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“…Estuaries may also receive internal additions of autochthonous DOC (Aminot et al 1990;Peterson et al 1994;Fisher et al 1998; this study) from phytoplankton (Cole et al 1982) and marshes (Teal 1962;Odum 1980). Estuarine DOC has three main potential fates: (1) it may be oxidized directly to CO 2 through bacterial respiration (Findlay et al 1992;Coffin et al 1993;Moran et al 1999) or photo-oxidation (Amon and Benner 1996); (2) it may undergo physicochemical transformations (e.g., flocculate to form less soluble colloids and particles [Sholkovitz et al 1978;Fox 1983;Hedges and Keil 1999]); or (3) it may be exported to adjacent coastal and continental shelf waters (Mantoura and Woodward 1983;Moran et al 1991;Raymond and Bauer 2000).…”

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confidence: 99%

DOC cycling in a temperate estuary: A mass balance approach using natural ¹⁴C and ¹³C isotopes

Raymond

Bauer

2001

Limnology & Oceanography

179

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We measured dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and their corresponding ⌬ 14 C and ␦ 13C values in order to study the sources and fates of DOC in the York River Estuary (Virginia, U.S.A.). The ⌬ 14 C and ␦ 13C values of DOC and DIC at the freshwater end-member indicate that during periods of moderate to high flow, riverine DOC entering the York was composed of decadal-aged terrestrially organic matter. In nearly all cases, DOC concentrations exceeded conservative mixing lines and were therefore indicative of a net DOC input flux from within the estuary that averaged 1.. The nonconservative behavior of DOC in the York River Estuary was also apparent in carbon isotopic mixing curves and the application of an isotopic mixing model. The model predicted that 20-38% of the DOC at the mouth of the estuary was of riverine (terrestrial ϩ freshwater) origin, while 38-56% was added internally, depending on the isotopic values assigned to the internally added DOC. Measurements of ⌬ 14 C and ␦ 13 C of DOC and DIC and marsh organic matter suggest that the internal sources originated from estuarine phytoplankton and marshes. The isotopic mixing model also indicates a significant concomitant loss (27-45%) of riverine DOC within the estuary.Changes in DOC concentration, ⌬ 14 C-DOC, and ␦ 13 C-DOC were also measured during incubation experiments designed to quantify the amounts, sources, and ages of DOC supporting the carbon demands of estuarine bacteria. Results of these experiments were consistent with an estuarine source of phytoplankton and marsh DOC and the preferential utilization of young ( 14 C-enriched) DOC in the low-salinity reaches of the York. However, the average removal of riverine DOC by bacteria accounts for only ϳ4-19% of the riverine pool; therefore, other significant sinks for DOC exist within the estuary.

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Bacterial metabolism of organic carbon in the tidal freshwater Hudson Estuary

Cited by 84 publications

References 13 publications

Highs and lows: The effect of differently sized freshwater inflows on estuarine carbon, nitrogen, phosphorus, bacteria and chlorophyll a dynamics

Highs and lows: The effect of differently sized freshwater inflows on estuarine carbon, nitrogen, phosphorus, bacteria and chlorophyll a dynamics

Bacterioplankton dynamics and organic carbon partitioning in the lower Hudson River estuary

DOC cycling in a temperate estuary: A mass balance approach using natural ¹⁴C and ¹³C isotopes

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Bacterial metabolism of organic carbon in the tidal freshwater Hudson Estuary

Cited by 84 publications

References 13 publications

Highs and lows: The effect of differently sized freshwater inflows on estuarine carbon, nitrogen, phosphorus, bacteria and chlorophyll a dynamics

Highs and lows: The effect of differently sized freshwater inflows on estuarine carbon, nitrogen, phosphorus, bacteria and chlorophyll a dynamics

Bacterioplankton dynamics and organic carbon partitioning in the lower Hudson River estuary

DOC cycling in a temperate estuary: A mass balance approach using natural 14C and 13C isotopes

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DOC cycling in a temperate estuary: A mass balance approach using natural ¹⁴C and ¹³C isotopes