Uptake of sedimentary organic matter by the deposit-feeding Baltic amphipods Monoporeia affinis and Pontoporeia femorata
Uptake of sedimentary organic matter by the deposit-feeding Baltic amphipods Monoporeia affinis and Pontoporeia femorata
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DOI：
10.3354/meps313135
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发表时间：
2006-01-01
影响因子：
2.5
通讯作者：
Elmgren, Ragnar
中科院分区：
文献类型：
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作者：
Byren, Lars;Ejdung, Gunilla;Elmgren, Ragnar
一些底栖动物主要以新沉积的植物碎屑为食，而另一些则更多地以与沉积物混合并在被摄入之前经过成岩过程修饰的旧物质为食。利用3种同位素示踪剂，研究了波罗的海片脚类动物（Monoporeia affinis (Lindstrom)）和Pontoporeia femorata Kroyer)对不同年代沉积食物的吸收。这些片脚类动物被提供新鲜的c -14标记的硅藻，这些硅藻散布在一层薄薄的未标记的沉积物层上，下面是一年前的沉积物，其中添加了C-13和n -15标记的硅藻。因此，碳-14的吸收表现为对新鲜有机物的表层摄食，而碳-13：氮-15的吸收表现为对陈年植物碎屑的地下摄食。春季以1岁成虫为试验对象，夏季以3月龄幼虫为试验对象，采用单种或混合种进行试验。成虫对C-14的吸收量（初始干质量1.6 mg）是羊角蒿（初始干质量1.7 mg）的5倍，表明羊角蒿对新鲜植物碎屑的吸收量更大，而羊角蒿对C-13:N-15的吸收量显著高于羊角蒿，表明该物种对来自深层沉积物的陈旧有机质的依赖性更大。在实验中，成虫一直在沉积物深处进食，而成虫则根据食物质量改变进食深度。这两个物种的幼鱼（初始干质量为0.1 mg）对示踪剂的吸收相似，并以地表和地下沉积物为食，这表明幼鱼比成鱼更有可能进行种间食物竞争。两种幼鱼的质量特异性碳-14吸收量均高于成鱼。无论是成虫还是幼虫，单种处理的碳-14吸收量都高于混合处理，表明混合处理的食物竞争密度更高。
Some benthic deposit-feeders mainly eat freshly deposited phytodetritus, while others feed more on older material that has been mixed with the sediment and modified by diagenetic processes before being ingested. We studied the uptake of sedimentary foods of different ages by the Baltic amphipods Monoporeia affinis (Lindstrom) and Pontoporeia femorata Kroyer in laboratory experiments using 3 isotopic tracers. The amphipods were offered fresh C-14-labelled diatoms spread on top of a thin unlabelled sediment layer, underlain by 1 yr old sediment to which C-13- and N-15-labelled diatoms had been added. Thus, C-14 uptake represented surface feeding on fresh organic material, and C-13:N-15 uptake subsurface feeding on aged phytodetritus. Experiments using a single species only or mixed species were conducted in spring with 1 yr old adults and in summer with 3 mo old juveniles. Adult M. affinis (initial dry mass 1.6 mg) took up similar to 5 times more C-14 than P. femorata (initial dry mass 1.7 mg), indicating that M, affinis depended more on fresh phytodetritus, while P. femorata had significantly higher C-13:N-15 uptake, showing a greater reliance of this species on aged organic matter from the deep sediment. In experiments, adult P. femorata consistently fed at depth in the sediment, whereas adult M. affinis modified feeding depth depending on food quality. Juveniles (0.1 mg initial dry mass) of both species had similar tracer uptake and fed both on surface and subsurface sediment, suggesting greater potential for interspecific food competition in juveniles than in adults. Juveniles of both species had higher mass-specific C-14 uptake than adults. Single species treatments had higher C-14 uptake than mixed treatments in both adults and juveniles, indicating food competition at the higher density of the mixed treatments.