Biomass loss and nutrient redistribution in an Indonesian Thalassia hemprichii seagrass bed following seasonal low tide exposure during daylight
Biomass loss and nutrient redistribution in an Indonesian Thalassia hemprichii seagrass bed following seasonal low tide exposure during daylight
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DOI：
10.3354/meps148251
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发表时间：
1997-02
影响因子：
2.5
通讯作者：
J. Stapel;R. Manuntun;M. Hemminga
中科院分区：
文献类型：
--
作者：
J. Stapel;R. Manuntun;M. Hemminga
印度尼西亚Barang Lompo岛的潮间带礁滩在大潮期间每天暴露在空气中数小时。暴露时间显示出季节性模式。在1月至6月期间，礁坪仅在夜间干涸，而在7月至12月期间，仅在白天暴露。在1993年7月至12月的低潮日光照射期间，叶和根茎生物量（g m（-2））分别下降了61%和37%。总根茎长度保持不变。叶片的C-和P-浓度（干重%）没有变化，而叶片N-浓度增加了25%。C-，N-和P-含量的叶片表现出下降，是密切相关的叶片生物量下降。在根茎中，C-浓度下降了8%，但N-和P-浓度分别增加了111%和25%。根茎中C含量（g m（-2））下降了43%，N含量增加了46%，P含量没有变化。叶片和根茎的总生物量的总C-和P-含量分别下降了46%和34%，但N-含量没有变化。铵和磷酸盐的浓度在水柱和孔隙水磷酸盐没有显着不同，在白天曝光相比，在夜间曝光。然而，在日光照射期间，孔隙水中的铵浓度高出1.6倍。结果表明，在一段时间内频繁的日光照射，在潮间带海珠海草床的营养状况发生了很大的变化。尽管生物量减少，总氮含量在叶片和根茎一起是恒定的，这是通过增强氮积累的根茎。讨论了两种可能解释全叶和根茎含氮量稳定之和的理论。第一种理论将海草床描述为一个相对封闭的营养循环系统：分离的叶子碎片仍然被困在草甸中。第二种理论假设，由于日光照射，光合作用的冠层的一部分的损失有一系列的后果，微生物的N-转化过程中的沉积物，这间接影响植物的氮素状况。这项研究表明，Thalassia hemprichii，覆盖的潮间带热带近海珊瑚岛，这通常被认为是一个营养不良的环境，是相当有弹性的一个显着的冠层死亡和随之而来的营养损失的礁坪。【关键词：日光照射;海草;生物量再分配;养分含量; Thalassia hemprichii;印度尼西亚南苏拉威西岛; konig浅滩; cymodocea-nodosa;丝状水螅;陆源沉积物;大叶藻;白水螅;叶生长;龟;碳酸盐]
The intertidal reef flat of Barang Lompo Island, Indonesia, is exposed to air for several hours per day on the days around spring tides. The time of exposure shows a seasonal pattern. In the period January-June, the reef flat only runs dry at night, whereas in the period July-December, exposure only occurs during daylight. During the low tide daylight exposure period of July-December 1993, the leaf and rhizome biomasses (g m(-2)) declined significantly by 61 and 37%, respectively. Total rhizome length remained unchanged. C- and P-concentrations (% of dry weight) of leaves showed no change, while the leaf N- concentration increased by 25%. C-, N- and P-contents of leaves showed a decline that was strongly correlated to leaf biomass decline. In the rhizomes, C-concentration declined by 8%, but the N- and P-concentrations increased by 111 and 25%, respectively. Rhizome C-content (g m(-2)) declined (43%), N- content increased (46%) and P-content did not change. Total C- and P-contents of the summed biomass of leaves and rhizomes declined by 46 and 34%, respectively, but N-content showed no change. Ammonium and phosphate concentrations in the water column and pore water phosphate were not significantly different during daylight exposure compared to during nocturnal exposure. Ammonium concentration in the pore water, however, was 1.6 times higher during daylight exposure. Results show that during a period of frequent daylight exposure, the nutrient status in the intertidal Thalassia hemprichii seagrass bed changed considerably. Despite biomass reduction, the total nitrogen content in leaves and rhizomes together was constant, which was achieved by an enhanced nitrogen accumulation in the rhizomes. Two theories possibly responsible for the stable sum of the total leaf and rhizome nitrogen content are discussed. The first theory describes the seagrass bed as a relatively closed system with respect to nutrient cycles: detached leaf fragments remain trapped within the meadow. The second theory postulates that the loss of part of the photosynthesising canopy due to daylight exposure has a series of consequences for microbial N-transformation processes in the sediment, which indirectly affects the plants' nitrogen status. This study shows that Thalassia hemprichii, covering the reef flat of an intertidal tropical offshore coral island, which is often considered as a nutrient-poor environment, is rather resilient to a significant canopy die-off and concomitant nutrient losses. [KEYWORDS: daylight exposure; seagrass; biomass redistribution; nutrient contents; Thalassia hemprichii; Indonesia South sulawesi indonesia; banks ex konig; cymodocea-nodosa; syringodium filiforme; terrigenous sediments; zostera capricorni; halodule-wrightii; leaf growth; testudinum; carbonate]