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Microbial biomass and productivity in seagrass bedsDifferent methods for measuring the rates of processes mediated by bacteria in sediments and the rates of bacterial cell production have been compared. In addition, net production of the seagrass Zostera capricorni and bacterial production have been compared and some interrelationships with the nitrogen cycle discussed. Seagrass productivity was estimated by measuring the plastochrone interval using a leaf stapling technique. The average productivity over four seasons was 1.28 +/- 0.28 g C m-2 day-1 (mean +/- standard deviation, n = 4). Bacterial productivity was measured five times throughout a year using the rate of tritiated thymidine incorporated into DNA. Average values were 33 +/- 12 mg C m-2 day-1 for sediment and 23 +/- 4 for water column (n = 5). Spatial variability between samples was greater than seasonal variation for both seagrass productivity and bacterial productivity. On one occasion, bacterial productivity was measured using the rate of 32P incorporated into phospholipid. The values were comparable to those obtained with tritiated thymidine. The rate of sulfate reduction was 10 mmol SO4(-2) m-2 day-1. The rate of methanogenesis was low, being 5.6 mg CH4 produced m-2 day-1. A comparison of C flux measured using rates of sulfate reduction and DNA synthesis indicated that anaerobic processes were predominant in these sediments. An analysis of microbial biomass and community structure, using techniques of phospholipid analysis, showed that bacteria were predominant members of the microbial biomass and that of these, strictly anaerobic bacteria were the main components. Ammonia concentration in interstitial water varied from 23 to 71 micromoles. Estimates of the amount of ammonia required by seagrass showed that the ammonia would turn over about once per day. Rapid recycling of nitrogen by bacteria and bacterial grazers is probably important.
Document ID
20040089924
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Moriarty, D. J.
(CSIRO Division of Fisheries Research Cleveland, Queensland, Australia)
Boon, P. I.
Hansen, J. A.
Hunt, W. G.
Poiner, I. R.
Pollard, P. C.
Skyring, G. W.
White, D. C.
Date Acquired
August 21, 2013
Publication Date
January 1, 1985
Publication Information
Publication: Geomicrobiology journal
Volume: 4
Issue: 1
ISSN: 0149-0451
Subject Category
Man/System Technology And Life Support
Distribution Limits
Public
Copyright
Other
Keywords
NASA Program CELSS
NASA Discipline Life Support Systems
Non-NASA Center
NASA Discipline Number 61-10

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