Influence of decomposing jellyfish on the sediment oxygen demand and nutrient dynamics
Influence of decomposing jellyfish on the sediment oxygen demand and nutrient dynamics
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DOI：
10.1007/s10750-008-9586-7
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发表时间：
2008
期刊：
影响因子：
2.6
通讯作者：
E. West;D. Welsh;K. Pitt
中科院分区：
文献类型：
--
作者：
E. West;D. Welsh;K. Pitt
水母种群可以迅速增长，获得大量生物量，因此可以代表生态系统中的重要碳和氮储存。开花通常也是短暂的，仅持续数周或数月，之后种群会迅速下降，沉入底部并分解。在澳大利亚新南威尔士州史密斯湖的围隔实验中，研究了分解水母（Catostylmosaicus，Scyphozoa）对底栖溶解氧和营养盐通量的影响。将沉积物（10 l）分别置于10个中型生态系统（50 x 40 cm，30 cm深，体积约60 l）中，向这些中型生态系统提供连续的新鲜泻湖水。一个水母（1.6公斤湿重或~25克C m-2）被添加到每个五个中围，其余五个中围作为对照。在为期9天的时间内，对底栖生物和水柱之间的溶解氧、有机和无机营养盐交换进行了14次测量。死亡的水母组织的mesocosm沉积物的加入，最初导致在外流的磷酸盐，溶解的有机氮和溶解的有机磷的水柱。溶解性有机氮和溶解性有机磷的流出率超过8倍和25倍以上，分别比在控制围隔生态系统中测量。这可能是由于细胞内的营养浸出的水母组织。随着分解的进行，大量的铵被释放到水体中，沉积物需氧量增加，表明细菌分解占主导地位。总的来说，除了死水母造成了454%的增加，铵流出量和209%的增加，沉积物耗氧量在9天的实验相对于对照。大量水母在水华爆发后的分解可能是一个重要的营养来源，根据系统的不同，可能对初级生产产生重大影响。此外，取决于水柱中的混合程度，腐烂的水母也可能导致底层水缺氧。
Jellyfish populations can grow rapidly to attain large biomasses and therefore can represent significant stocks of carbon and nitrogen in the ecosystem. Blooms are also generally short-lived, lasting for just weeks or months, after which time the population can decline rapidly, sink to the bottom and decompose. The influence of decomposing jellyfish (Catostylus mosaicus, Scyphozoa) on benthic dissolved oxygen and nutrient fluxes was examined in a mesocosm experiment at Smiths Lake, a coastal lagoon in New South Wales, Australia. Sediment (10l) was placed in each of 10 mesocosms (50 x 40 cm, 30 cm deep and ~ 60 l volume) which were supplied a continuous flow of fresh lagoon water. One jellyfish (1.6 kg wet weight or ~25 g C m-2) was added to each of five mesocosms, with the remaining five mesocosms serving as controls. Exchanges of dissolved oxygen, organic and inorganic nutrients between the benthos and water column were measured 14 times over a period of nine days. The addition of dead jellyfish tissue to the mesocosm sediments initially resulted in an efflux of phosphate, dissolved organic nitrogen and dissolved organic phosphorus to the water column. Dissolved organic nitrogen and dissolved organic phosphorus effluxed at rates more than 8 and 25 times greater than those measured in control mesocosms, respectively. This was probably due to the intracellular nutrients leaching from the jellyfish tissues. As decomposition proceeded, a large quantity of ammonium was released to the water column and sediment oxygen demand increased, indicating bacterial decomposition was dominant. Overall the addition of dead jellyfish caused a 454% increase in ammonium efflux and 209% increase in sediment oxygen demand over the 9-day experiment relative to the controls. The decomposition of large numbers of jellyfish after major bloom events could be a significant source of nutrients and, depending on the system, could have a major impact on primary production. Moreover, depending on the degree of mixing in the water column, decaying jellyfish may also contribute to bottom water hypoxia.