Growth and metabolic responses of the giant clam-zooxanthellae symbiosis in a reef-fertilisation experiment
Growth and metabolic responses of the giant clam-zooxanthellae symbiosis in a reef-fertilisation experiment
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DOI：
10.3354/meps170131
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发表时间：
1998-01-01
影响因子：
2.5
通讯作者：
Yellowlees, D
中科院分区：
文献类型：
--
作者：
Belda-Baillie, CA;Leggat, W;Yellowlees, D
为了评估营养盐升高对与虫黄藻共生的珊瑚礁生物的影响，将巨蛤Tridacna maxims每天暴露于天然珊瑚礁环境中增加的氨和磷酸盐（N，P，N+P）中3至6个月。结果有力地证实了主要的反应共生协会营养富集以前观察到的（T，千兆）在受控的室外条件下。蛤暴露于高氮（10 μ M）下，虫黄藻密度增加，虫黄藻尺寸减小，从宿主新鲜分离的虫黄藻对氮的吸收量下调，蛤血淋巴中的谷氨酸减少，一些游离氨基酸（甲硫氨酸、酪氨酸）库增加虫黄藻中。这些结果证实了巨蛤体内的虫黄藻是原位氮限制的，可以自由地从海水中获取无机氮。也有确凿的证据表明，虫黄藻是P限制在原位以及，可能是由于主机的干扰。虽然动物宿主的N：P比反映了海水中的环境N和P浓度，但虫黄藻的N：P比并不反映海水中的环境N和P浓度。无论P暴露（2 μ M P）的蛤，虫黄藻的N：P比例始终很高（>30：1）和磷酸盐浓度的蛤血淋巴洗澡虫黄藻管系统始终很低（
To evaluate the impact of elevated nutrients on reef organisms symbiotic with zooxanthellae, giant clams Tridacna maxims were exposed daily to increased ammonia and phosphate (N, P, N+P) in their natural reef environment for 3 to 6 mo. The results strongly corroborate the major responses of the symbiotic association to nutrient enrichment previously observed (with T, gigas) under controlled outdoor conditions. Exposure of the clams to elevated N (10 mu M) increased zooxanthellae density, reduced zooxanthellae size, down-regulated N uptake by zooxanthellae freshly isolated from their hosts, and reduced glutamate in the clam haemolymph, with increased pools of some free amino acids (methionine, tyrosine) in the zooxanthellae. These results confirm that the zooxanthellae in giant clams are N Limited in situ and have free access to inorganic N from the sea water. There is also corroborating evidence that the zooxanthellae are P limited in situ as well, possibly due to host interference. While the N:P ratios of the animal host reflected ambient Nand P concentrations in the sea water, those of the zooxanthellae did pot. Regardless of P exposure (2 mu M P) of the clams, zooxanthellae N:P ratios were consistently high (>30:1) and phosphate concentrations in the clam haemolymph bathing the zooxanthellae tube system consistently low (