Effects of low dissolved oxygen on zooplankton predation by the ctenophore Mnemiopsis leidyi
Effects of low dissolved oxygen on zooplankton predation by the ctenophore Mnemiopsis leidyi
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DOI：
10.3354/meps280163
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发表时间：
2004-01-01
影响因子：
2.5
通讯作者：
Purcell, JE
中科院分区：
文献类型：
--
作者：
Decker, MB;Breitburg, DL;Purcell, JE
低溶解氧（DO）的发生是由垂直分层和过量的养分输入引起的，是水生系统中广泛存在的重要物理特征。由于一些胶状物种，如叶栉水母比它们的猎物和竞争对手更能耐受低氧浓度，因此缺氧可能对营养相互作用产生深远的影响。以浮游动物（主要是Acartia tonsa）为食的栉水母在1.0、2.0、3.0 mg l（-1）和空气饱和（约7 mg l(-1)） DO条件下的捕食、清除率和消化率进行了测量。大型栉水母对浮游动物的清除率（平均22.5毫升，范围7至46毫升）在低氧浓度下比在常氧条件下更高。相比之下，小的浮游动物（平均2.9毫升，范围1至10毫升）M leidyi的消耗在DO水平之间没有差异。同样，在低至1 mg l（-1）的氧浓度下，栉水母的消化速率不变。随着DO浓度(1.0、2.0、3.0 mg l（-1）和空气饱和浓度的降低，tonsa桡足类跳跃频率显著降低。在低溶解氧条件下，这种猎物行为的变化可能会影响遇到和捕获率，潜在地使不耐受的猎物在低氧水域中更容易被捕食。胶状物种比鱼类更能耐受缺氧，它们可能能够栖息在低氧区域，而浮游动物食性鱼类则需要高氧。这可能导致胶状捕食者在受严重缺氧影响的地区占主导地位，并可能改变这些系统中的能量途径。
The occurrence of low dissolved oxygen (DO), caused by vertical stratification and excess nutrient inputs, is an important and widely occurring physical feature in aquatic systems. Because some gelatinous species, such as the lobate ctenophore Mnemiopsis leidyi are more tolerant of low DO concentrations than their prey and competitors, hypoxia may have profound effects on trophic interactions. Predation, clearance and digestion rates of ctenophores feeding on zooplankton (primarily Acartia tonsa) were measured at 1.0, 2.0, 3.0 mg l(-1) and air-saturated (approximately 7 mg l(-1)) DO. Clearance of zooplankton by large ctenophores (mean 22.5 ml, range 7 to 46 ml) was greater at low DO concentrations than under normoxic conditions. In contrast, consumption of zooplankton by small (mean 2.9 ml, range 1 to 10 ml) M leidyi did not differ among DO levels. Similarly, ctenophore digestion rates were unchanged at oxygen concentrations as low as 1 mg l(-1). Jumping frequency of A. tonsa copepods decreased significantly with decreasing DO concentration (1.0, 2.0, 3.0 mg l(-1) and air-saturated). Such changes in prey behavior in low DO could affect both encounter and capture rates, potentially making less-tolerant prey more vulnerable to predation in hypoxic waters. Gelatinous species, which are more tolerant of hypoxia than fishes, may be able to inhabit regions of low oxygen that are avoided by zooplanktivorous fishes with high oxygen requirements. This could lead to dominance of gelatinous predators in areas affected by severe hypoxia and might alter energy pathways in these systems.