Decomposition processes in mangrove mud in the Fly River estuary, Papua New Guinea

Microbial productivity, nutrient chemistry and rates of nutrient regeneration were examined in muds of different mangrove forests in the Fly Delta, Papua New Guinea.Three forest types Rhizophora-Bruguiera, Nypa and Avicennia-Sonneratia with high and low intertidal stations in each forest type.Sedimentary variables were: temperature; grain size; salinity; porosity; and percent sand, silt and clay.Microbial samples were measured for chlorophyll a, phaeopigments and bacterial numbers. Bacterial production rates were measured by two procedures: the rate of [3H]methyl thymidine ( = Tdr) incorporation into DNA and by the rate of [3,4,5-3H] leucine (L = Leu) incorporation into protein.Dissolved nutrient (DOC, DON, DOP, ammonium, nitrite, nitrate and phosphate, silicate) flux measurements and primary production (O2 flux) were made for each site.Cores were taken for measurements of solid-phase elements and porewater nutrients at each site.
To examine microbial productivity, nutrient chemistry and rates of nutrient regeneration in muds of mangrove forests.
This research project was a component of a larger project to determine the influence of freshwater and detrital export from the Fly River system on adjacent pelagic and benthic systems.

本研究针对巴布亚新几内亚弗莱三角洲（Fly Delta）不同红树林泥质湿地的沉积物，开展了微生物生产力、营养盐化学特征及营养盐再生速率的分析。研究共覆盖3类红树林群落：红树-木榄群落（Rhizophora-Bruguiera）、水椰群落（Nypa）以及白骨壤-海桑群落（Avicennia-Sonneratia），每类群落均布设高潮位与低潮位潮间带站位。
本次研究测定的沉积环境参数包括：温度、粒度组成、盐度、孔隙度，以及砂、粉砂、黏土的百分含量。对微生物样品开展了叶绿素a（chlorophyll a）、脱镁色素（phaeopigments）及细菌数量的检测；细菌生产力通过两种方法测定：一是[³H]甲基胸苷（[³H]methyl thymidine，简称Tdr）掺入DNA的速率，二是[³,4,5-³H]亮氨酸（[³,4,5-³H]leucine，简称Leu）掺入蛋白质的速率。
针对每个站位，均完成了溶解态营养盐（溶解性有机碳DOC、溶解性有机氮DON、溶解性有机磷DOP、铵态氮、亚硝态氮、硝态氮、磷酸盐及硅酸盐）通量与初级生产力（O₂通量）的测定；同时采集沉积物柱样，用于固相元素与孔隙水营养盐的分析检测。
本研究旨在解析红树林泥质湿地沉积物中的微生物生产力、营养盐化学特征及营养盐再生速率。
本研究项目为一项大型研究的子课题，该大型研究旨在明确弗莱河系统输出的淡水与碎屑物质对邻近远洋及底栖生态系统的影响。