Different 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.

中文翻译：

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海草床中的微生物生物量和生产力

已经比较了测量沉积物中细菌介导的过程速率和细菌细胞产生速率的不同方法。此外，还比较了海草 Zostera capricorni 的净产量和细菌产量，并讨论了与氮循环的一些相互关系。海草生产力是通过使用叶片缝合技术测量质体间隔来估计的。四个季节的平均生产力为 1.28 +/- 0.28 g C m-2 day-1（平均值 +/- 标准偏差，n = 4）。使用掺入 DNA 的氚化胸苷的比率，一年中五次测量细菌生产力。沉积物的平均值为 33 +/- 12 mg C m-2 day-1，水柱的平均值为 23 +/- 4 (n = 5)。样本之间的空间变异性大于海草生产力和细菌生产力的季节性变化。有一次，使用 32P 掺入磷脂的比率来测量细菌生产力。这些值与用氚化胸苷获得的值相当。硫酸盐还原率为 10 mmol SO4(-2) m-2 day-1。产甲烷率很低，m-2 day-1 产生了 5.6 mg CH4。使用硫酸盐还原率和 DNA 合成率测量的 C 通量的比较表明，厌氧过程在这些沉积物中占主导地位。使用磷脂分析技术对微生物生物量和群落结构进行的分析表明，细菌是微生物生物量的主要成员，其中严格厌氧菌是主要成分。间隙水中的氨浓度从 23 到 71 微摩尔不等。对海草所需氨量的估计表明，氨每天大约会循环一次。细菌和食草动物对氮的快速循环可能很重要。