Developmental Process and Material Flow in Tropical Seagrass Beds

热带海草床的发育过程和物质流

基本信息

批准号：
01041027
负责人：
KOIKE Isao
金额：
$ 5.76万
依托单位：
The 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：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01041027/
关键词：
Seagrass bed ecosystem Primary production Nitrogen metabolism Filter feeders Symbiosis Epiphytes Benthos Herbivorous fish

项目摘要

It has been clarified by previous studies that tropical seagrass ecosystem has several food-chains consisting by high diversity of seagrasses and benthic animals in Papua New Guinean seagrass bed, which locates in center of seagrass distribution. Otherwhile, in marginal Fijian seagrass beds, there was pure stands of Syringodium isoetifolium.1. Concentration of nutrients in ambient seawater and within seagrass vegetation was very low, while it in interstitial water of seagrass bed sediment was 10-100 times of ambient seawater. It is originated from decomposition of detritus accumulated in sediments. Organic carbon and nitrogen in sediment of bare bottom did not change from bottom surface to 20 cm deep, and the C/N ratio was ca.10 (g/g). While, organic carbon in seagrass bed sediment reduced to 1/3 at 20 cm deep, but organic nitrogen did not change unlikely in carbon. This suggests that nitrogen has never been lost in bacterial metabolism and is effectively taken up again by seagrasses.2 … More . Biomass and primary production of Syringodium pure stand were measured by (1) marking method, (2) oxygen evolution measurement, (3) lacuna gas volumetry. The production rates were 2.5-11.2 g/m2/day. This range of primary production was not low compared with high diversity seagrass beds in Papua New Guinea, because of very dense stand in Syringodium stand.3. Characteristics of Fijian seagrass bed are in abundant filter feeding benthic animals, in spite of poverty in phytoplankton. Among the animals, bivalves can be sustained themselves by a mechanism in which detritus from seagrass and epiphytes is accumulated in high concentration within dense seagrass stands. Otherwhile, compound ascidians attached to seagrass leaf, having abundant biomass (ave. 14.8 g/m2), contribute also to primary production, because of symbiosis with algae. It was estimated by our experiments that the ascidians obtained half and half of nutrients from CO2 fixation by symbiotic algae and subordinate nutrition by filter feeding. In nitrogen metabolism, independent nutrition was effective. Less

前期研究表明，位于海草分布中心的巴布亚新几内亚海草床中，热带海草生态系统具有由高度多样性的海草和底栖动物组成的多条食物链，而在斐济的边缘海草床中，也存在着由海草和底栖动物组成的多条食物链。 1. 周围海水和海草植被内的营养物质浓度很低，而海草床沉积物间隙水中的营养物质浓度则较低。是环境海水的10-100倍，来源于沉积物中积累的碎屑分解，裸露底部沉积物中的有机碳和氮从底面到20厘米深度没有变化，C/N比约为10（ g/g），而海草床沉积物中的有机碳在20厘米深处减少至1/3，但有机氮在碳中几乎没有变化，这表明氮从未在细菌代谢中损失，并被有效地再次吸收。 2 … 更多紫丁香纯林的生物量和初级产量通过 (1) 标记方法、(2) 析氧测量、(3) 空隙气体体积法测量。生产率为 2.5-11.2 克/平方米/天。与巴布亚新几内亚的高多样性海草床相比，这一范围的初级产量并不低，因为斐济海草床的特征是非常密集。尽管浮游植物贫乏，但在丰富的滤食性底栖动物中，双壳类动物可以通过海草和附生植物的碎屑在茂密的海草中大量积累的机制来维持自身。叶具有丰富的生物量（平均 14.8 g/m2），由于与藻类共生，因此也有助于初级生产。根据我们的实验估计，海鞘获得了。一半的养分来自共生藻类的二氧化碳固定和滤食的辅助营养。在氮代谢中，独立营养的效果较差。