Release of dissolved organic carbon and nitrogen by the zooxanthellate coral Galaxea fascicularis
Release of dissolved organic carbon and nitrogen by the zooxanthellate coral Galaxea fascicularis
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DOI：
10.3354/meps172265
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发表时间：
1998-01-01
影响因子：
2.5
通讯作者：
Allemand, D
中科院分区：
文献类型：
--
作者：
Ferrier-Pages, C;Gattuso, JP;Allemand, D
已知珊瑚释放大量的颗粒和溶解的有机碳（POC和DOG）和氮（PON和DON）。POC和PON的粘液形式的生产已经得到了比较好的研究，但很少有数据可用于DOC和DON的珊瑚释放。为了研究珊瑚的碳和营养循环的几个方面，DOC和DON的释放喂养和未喂养的菌落的虫黄藻珊瑚Galaxea fascicularis（林奈1767）在实验室中测量在受控条件下。殖民地要么喂卤虫或供应氮和磷富集的海水。我们测量了DOC和DON通量从珊瑚使用高温催化氧化法和DOC释放的C-14-photodetracate使用放射性同位素技术。珊瑚释放出大量的溶解有机物（DOM）。在上午和下午观察到两个大的释放峰。DOC浓度从约100亩M（背景水平）增加到300 - 1700亩M，这取决于殖民地的大小和营养状态。DON浓度也从15 μ M增加到120 μ M释放速率从2 - 3 μ mol DOC和0.5 - 0.6 μ mol DON变化（mg蛋白）（-1）d（-1）（对于未饲喂的菌落）至1-3 - 25 μ mol DOC和1 - 3 μ mol DON（mg蛋白质）（-1）d（-1）（卤虫喂养的菌落）至4 - 6 μ mol DOC和0.2 - 1.3 μ mol DON（mg蛋白质）（-1）d（-1）（营养物富集的菌落）。因此，美联储的珊瑚比未喂养的殖民地释放更多的DOC，但往往保存有机氮，这表明异养营养可能会作为新的营养来源的珊瑚。计算的碳平衡的unfed殖民地表明，DOC释放约14%的净每日光合固定碳。在释放的每个峰值之后，DOM的浓度回落到常规背景水平。因此，研究了自由生活的、表生的和/或细胞内的细菌在DOM摄取中的作用。用C-14-碳酸氢盐标记菌落，随后在用和不用原核抑制剂处理的过滤海水中释放C-14-DOM。没有随后的摄取C-14-DOM的抑制剂的存在下，观察，表明细菌可能发挥重要作用DOM的吸收。这一过程可能导致珊瑚群落内的营养物质循环紧密，并可能使珊瑚在贫营养沃茨中茁壮成长。
Corals are known to release large amounts of particulate and dissolved organic carbon (POC and DOG) and nitrogen (PON and DON). Production of POC and PON in the form of mucus has been relatively well studied, but very few data are available on the release of DOC and DON by corals. In order to investigate several aspects of carbon and nutrient cycling in corals, release of DOC and DON by fed and unfed colonies of the zooxanthellate coral Galaxea fascicularis (Linnaeus 1767) was measured in the laboratory under controlled conditions. Colonies were either fed with artemia or supplied with nitrogen- and phosphorus-enriched seawater. We measured DOC and DON fluxes from corals using the high temperature catalytic oxidation method and DOC release as C-14-photosynthate using a radioisotope technique. Corals released significant amounts of dissolved organic matter (DOM). Two large release peaks were observed in mid-morning and mid-afternoon. DOC concentrations increased from ca 100 mu M (background level) to 300-1700 mu M, depending on the size of the colony and the trophic status. DON concentrations also increased from 15 to 120 mu M Release rates varied from 2-3 mu mol DOC and 0.5-0.6 mu mol DON (mg protein)(-1) d(-1) for the unfed colonies to 13-25 mu mol DOC and 1-3 mu mol DON (mg protein)(-1) d(-1) for the artemia-fed colonies to 4-6 mu mol DOC and 0.2-1.3 mu mol DON (mg protein)(-1) d(-1) for the nutrient-enriched colonies. Fed corals therefore released more DOC than unfed colonies, but tended to conserve organic nitrogen, suggesting that heterotrophic nutrition may serve corals as a source of new nutrients. Calculations of the carbon balance for the unfed colonies showed that DOC release represents ca 14% of the net daily photosynthetically fixed carbon. Following each peak in release, concentrations of DOM fell back to routine background levels. The role of free-living, epibiotic and/or intracellular bacteria in the uptake of DOM was therefore investigated. Colonies were labelled with C-14-bicarbonate and the subsequent release of C-14-DOM was followed in filtered seawater treated with and without prokaryotic inhibitors. No subsequent uptake of C-14-DOM was observed in the presence of inhibitors, suggesting that bacteria may play an important role in DOM uptake. This process may lead to tight nutrient recycling within coral colonies and may enable corals to thrive in oligotrophic waters.