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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

以往的研究表明，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。在斐济边缘的海草床上，有纯林的异叶紫草1。周围海水和海草植被中的营养盐浓度很低，而海草底泥间隙水中的营养盐浓度是周围海水的10-100倍。它起源于沉积物中积累的碎屑的分解。裸露底泥中有机碳和有机氮从底面到20 cm深度变化不大，C/N比约为10(g/g)。而海草底泥中的有机碳在20 cm处减少到1/3，而有机氮在碳中变化不大。这表明氮在细菌新陈代谢中从未丢失，并有效地被海藻重新吸收。2…更多。采用(1)标记法、(2)放氧法、(3)腔隙气体容积法测定了羊草纯林的生物量和初级生产量。产量为2.5~11.2g/m2/d。与巴布亚新几内亚的高多样性海草床相比，这一初级生产量的范围并不低，因为信天翁林分的密度非常高。斐济海草床的特点是丰富的滤食性底栖动物，尽管浮游植物贫乏。在动物中，双壳类可以通过一种机制来维持自己，在这种机制中，海草和附生植物的碎屑在密集的海草林中高度积累。另外，复合海鞘附着在海草叶上，具有丰富的生物量(Ave.14.8g/m2)，由于与藻类共生，对初级生产力也有贡献。通过实验估计，海鞘细菌通过共生藻类固定二氧化碳获得了一半的营养物质，并通过滤食获得了次级营养物质。在氮素代谢方面，独立营养是有效的。较少