A method of measuring the mineralization by micro-organisms of organic compounds in sea-water

Williams, Peter; Askew, C.G.

doi:10.1016/0011-7471(68)90012-0

Cited by 40 publications

(32 citation statements)

References 8 publications

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“…Microbial activity of leaf material was estimated by measuring 14 C glucose respiration (Williams & Askew, 1968;Peters et al, 1989). Individual leaf disks (1 cm diam.)…”

Section: Methodsmentioning

confidence: 99%

Natural and constrainment-induced factors influencing the breakdown of dogwood and oak leaves

D’Angelo

Webster

1992

Hydrobiologia

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Breakdown rates and microbial colonization patterns of dogwood and oak leaves were measured between November and June of 1987-88 and 1988-89 . Leaves were placed in artificial streams loose (unconstrained), in bags, or in packs . Discharge was maintained at approximately 0 .25 1 s -', and no shredders were present in the streams . Average microbial biomass as ATP, for all species and treatments, increased from near 0 mg g -' AFDW in November to over 8 mg g -' AFDW in June . Microbial respiration increased from about 0 .01 pg glucose respired hr-g -' AFDW in November to about 0 .03 pg hrg -' AFDW in June . Microbial biomass and activity were significantly greater on dogwood leaves than on oak leaves . Dogwood and oak leaf breakdown rates were fastest when unconstrained, -0 .0034 and -0.0027 degree-day -' respectively . Breakdown rates of dogwood leaves were faster in bags ( -0.0025 degree-day -') than in packs (-0 .0015 degree-day -') while rates of oak leaves were not significantly different between bags and packs ( -0.0014 and -0 .00 18 degree-day -' respectively) . Breakdown rates of dogwood and oak leaves obtained in this study were much slower than those obtained by other investigators either in the presence or absence of shredders . A comparison of results from this study with results from other studies revealed that dogwood leaves may be affected more by turbulence, while oak leaves may be influenced more by shredder activity . 39

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“…Microbial activity of leaf material was estimated by measuring 14 C glucose respiration (Williams & Askew, 1968;Peters et al, 1989). Individual leaf disks (1 cm diam.)…”

Section: Methodsmentioning

confidence: 99%

Natural and constrainment-induced factors influencing the breakdown of dogwood and oak leaves

D’Angelo

Webster

1992

Hydrobiologia

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“…Three rods with intact epilithon were removed randomly from each of three zones in each stream and placed into 250-ml jars containing 60 ml water from the corresponding stream. Respiratory rates for glucose and glutamate were determined using a modification of the method of Williams & Askew (1968). A trace amount of [U-14C] glucose (specific activity: 345 mCi mmole-' ; 0.44 pg 1-' final concentration) or [U-14C] glutamate (specific activity: 290 mCi mmole-' ; 0.21 pg 1-' final concentration) were added to separate jars containing the glass rods.…”

Section: Methodsmentioning

confidence: 99%

Evidence of structural and functional adaptation in epilithon exposed to zinc

1989

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Artificial streams were used to study the effect of chronic zinc dosing (0.00,0.05 or 1.00 mg Zn 1-') on epilithic communities during summer and early fall, 1984 and 1985. Following zinc addition, epilithon was periodically measured for '4C-glucose and 14C-glutamate respiration, ash-free dry weight (AFDW), protein, carbohydrate, chlorophyll a (Chl a), pheophytin a (pheo a), and colony forming units (CFU) on zinc amended and unamended media. Transient peaks in glucose respiration rates mg-' protein and AFDW occurred within 5 to 10 days in streams dosed with 1.0 mg Zn 1-' and coincided with decreases in AFDW, protein, carbohydrate, Chl a, and pheo a. Respiration of glutamate did not show a significant response to dosing (a = 0.05). Epilithic plate counts demonstrated more total and zinc-tolerant CFU in dosed than in control epilithon after 20 days. After 30 days, greater biomass and lower protein: carbohydrate ratios were evident in epilithon dosed with 1.0 mg Zn 1-' compared to unamended treatments. Peaks in glucose respiration suggested the presence of zinc-tolerant heterotrophs transiently capable of increased respiration of glucose but not glutamate. Concurrently, minimal but measurable biomass inferred the persistence of zinc-tolerant microorganisms in zinc-dosed epilithon. By the end of the studies, results indicated that metal-tolerant populations replaced metal-sensitive organisms under conditions of elevated zinc concentration. These zinc adapted communities had lower potential value as a food source to grazers (low protein: carbohydrate ratio) and were no longer distinctive with respect to glucose respiration.

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“…The heterotrophic utilization of dissolved substrates was determined by the tracer approach (Williams & Askew 1968) . Uptake rates were measured as a function of time to establish linearity.…”

Section: Methodsmentioning

confidence: 99%

Bacteria in sea ice and underlying water of the eastern Weddell Sea in midwinter

Helmke¹,

Weyland²

1995

Mar. Ecol. Prog. Ser.

126

115

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Bacteria in the water beneath the sea ice of the eastern Weddell Sea were homogeneously distributed. Direct counts resembled values from sprmg and autumn, whereas viable cell counts, total ATP concentrations, as well as heterotrophic assimilation and extracellular enzymatic activities were very low, implying a metabolic inactive bactenoplankton The consolidated sea ice had a very heterogeneous horizontal distribution of microbes on large as well as small scales but vertical profiles in low and densely populated ice cores exhibited similar patterns. A close relation between bacterial colonization of sea ice and genetic ice classes was revealed. Sea ice of the 'predominantly congelation ice' had the lowest bacterial biomass and displayed very low heterotrophic activities which were comparable to those of the water column. Samples of older sea ice belonging to the 'mainly frazil' and 'mixed ice' had maximal numbers of bacteria. They often included high proportions of culturable cells and dividing cells as well as large bacteria The bacteria of these ice classes were active and contributed significantly to the productivity in the Weddell Sea during winter 'Predominantly frazil ice' was less colonized; however, selective bacterial growth was also indicated in this typical winter ice by an increase m the proportions of culturable and psychrophihc bacteria with advancing age of the ice Psychrophilic bacteria dominated in consohdated sea-ice whereas facultative psychrophiles prevailed in young sea-ice and water, corroborating a strict partitiomng m a microbial sea-ice and a seawater regime. Generally, temperature does not appear to be the significant factor for the development of bacterial communities in the surface layer of the eastern Weddell Sea m winter smce the metabolically active bacterial flora develops in the very cold sea-ice environment. The organic matter supply and its unproved usabihty obviously controls bacterial activity as well as the selective enrichment of psychrophiles.

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A method of measuring the mineralization by micro-organisms of organic compounds in sea-water

Cited by 40 publications

References 8 publications

Natural and constrainment-induced factors influencing the breakdown of dogwood and oak leaves

Natural and constrainment-induced factors influencing the breakdown of dogwood and oak leaves

Evidence of structural and functional adaptation in epilithon exposed to zinc

Bacteria in sea ice and underlying water of the eastern Weddell Sea in midwinter

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