A comparative study of materials flows between seagrss-and seaweed-based ecosystemes in tropical lagoon.

热带泻湖海草和海藻生态系统物质流的比较研究。

基本信息

批准号：
06041028
负责人：
KOIKE Isao
金额：
$ 10.88万
依托单位：
University of tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

The Purpose of this study is to evaluate the cycling of carbon and nitrogen and their coupling with the metabolisms of biological communities in seagrass beds and in seaweeds in tropical lagoon. We made an extensive field observation in the tropical lagoon located at south of Suva, Fiji from 1994-1996. In the lagoon, there is a dense Syringodium seagress bed and also Halimeda population around the seagrass bed. Following are the some outcomes from the field survey.(1) Combing with the available data of aero-photographs and our field observation, the seagrass bed near the Dravuni Island expanded their size to about 6 times during the last 20 years. This increase in size was also confirmed for the latest 3 years field observation, indicating 22m expansion of seagrass bed to the shore side. The island has a population of some 100 peoples, which is rather stable during the last 20 years. But, the village equipped water supply system from the well about 5-6 years ago. Possible reason for th … More e seagrass increase is the change of nutrients load from the island due to the increase of water usage.(2) Together with the change of seagrass bed, we found the change of epibenthic community distribution such as Ascidians and Lagenophyra. Some of those animals harbor symbiotic alage, which are significant primary producers in the tropical lagoon. The symbiotic character of those animals seems to be important factor controlling the small scale distribution with in seagrass bed and Halimeda communities.(3) Stable isotope analyzes of 15-N and 13-C in various biological communities and suspended organic materials in the seagrass bed and its vicinity gave some interesting insight of food web structure in this ecosystem. Using the significant difference in both 13-C and 15-N rations in seagrass and their epiphytic algae, which are partially due to the nitrogen fixation by blue green algae, filamentous algae was suggested as a primary food source of epibenthic and other benthic animals. Active nitrogen fixation by filamentous blue green was also confirmed experimentally using C2H2 method. Less

这项研究的目的是评估碳和氮的循环及其与海草床和热带泻湖海藻中生物群落的代谢结合。 1994年至1996年，我们在位于斐济Suva南部的热带泻湖中进行了广泛的野外观察。在泻湖中，海草床周围有一个密集的海洋杂志床，还有Halimeda人口。以下是现场调查中的一些结果。（1）与我们的空气光仪的可用数据和我们的野外观察数据梳理，在过去20年中，德拉沃岛附近的海草床将其大小扩大到大约6倍。在最新3年的现场观察中，还证实了这种大小的增加，表明海草床扩展到岸边。该岛的人口约100人，在过去的20年中相当稳定。但是，大约5 - 6年前的村庄等效供水系统。增加海草的可能原因是由于用水的增加而导致岛上养分负荷的变化。（2）随着海草床的变化，我们发现了表皮群落分布的变化，例如阿西迪亚人和拉甘烯酚。其中一些动物含有共生的阿拉奇，它们是热带泻湖中重要的主要生产者。这些动物的共生特征似乎是控制海草床和Halimeda群落中小规模分布的重要因素。（3）在各种生物群落中，稳定的15-N和13-C的同位素分析，以及海草床中的有机材料及其附近悬挂的有机材料，其附近为这个生态网络提供了一些有趣的食物网络结构。使用海草及其附生藻类中13-C和15-N级别的显着差异，部分是由于蓝绿藻类固定的氮固定，丝状藻类被认为是表外表征和其他底栖动物的主要食物来源。还使用C2H2方法对丝状蓝绿色的活性氮固定也得到了证实。较少的