Estimating In Situ Zooplankton Non-Predation Mortality in an Oligo-Mesotrophic Lake from Sediment Trap Data: Caveats and Reality Check.
Estimating In Situ Zooplankton Non-Predation Mortality in an Oligo-Mesotrophic Lake from Sediment Trap Data: Caveats and Reality Check.
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DOI：
10.1371/journal.pone.0131431
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Grossart HP
中科院分区：
文献类型：
--
作者：
Dubovskaya OP;Tang KW;Gladyshev MI;Kirillin G;Buseva Z;Kasprzak P;Tolomeev AP;Grossart HP
死亡率是浮游动物种群生物学的主要驱动因素，但在描述浮游动物种群动态、食物网相互作用和营养动态的模型中，它的约束性很差。由于非捕食因素的死亡率往往被忽视，即使非捕食浮游动物大规模死亡的轶事证据已被反复报道。估计非捕食死亡率的一种方法是测量尸体的清除率，特别是在静止的浅水水体中，下沉是主要的清除机制。我们使用沉积物陷阱，以量化原位尸体下沉速度和非捕食死亡率在2013年连续8天的枝藻Bosmina longirostris在寡-中营养湖Stechlin的结果进行了比较，对来自体外尸体下沉速度测量和经验模型校正的湍流再悬浮和微生物分解的尸体在体外下沉速度的估计。我们的研究结果表明，后两种方法产生不切实际的高死亡率0.58-1.04 d-1，而沉积物陷阱的方法，当使用得当，产生的死亡率估计为0.015 d-1，这是更符合同期人口丰度数据和生理死亡率从文献中。浮游动物尸体在进入底栖生物之前可能会暴露在水柱微生物中数天;因此，非捕食死亡率不仅影响浮游动物种群动态，还影响微生物和底栖生物食物网。这将是特别重要的碳和氮循环系统中，经常性的仲夏浮游动物种群下降，由于非捕食死亡率观察。
Mortality is a main driver in zooplankton population biology but it is poorly constrained in models that describe zooplankton population dynamics, food web interactions and nutrient dynamics. Mortality due to non-predation factors is often ignored even though anecdotal evidence of non-predation mass mortality of zooplankton has been reported repeatedly. One way to estimate non-predation mortality rate is to measure the removal rate of carcasses, for which sinking is the primary removal mechanism especially in quiescent shallow water bodies. We used sediment traps to quantify in situ carcass sinking velocity and non-predation mortality rate on eight consecutive days in 2013 for the cladoceran Bosmina longirostris in the oligo-mesotrophic Lake Stechlin; the outcomes were compared against estimates derived from in vitro carcass sinking velocity measurements and an empirical model correcting in vitro sinking velocity for turbulence resuspension and microbial decomposition of carcasses. Our results show that the latter two approaches produced unrealistically high mortality rates of 0.58-1.04 d-1, whereas the sediment trap approach, when used properly, yielded a mortality rate estimate of 0.015 d-1, which is more consistent with concurrent population abundance data and comparable to physiological death rate from the literature. Zooplankton carcasses may be exposed to water column microbes for days before entering the benthos; therefore, non-predation mortality affects not only zooplankton population dynamics but also microbial and benthic food webs. This would be particularly important for carbon and nitrogen cycles in systems where recurring mid-summer decline of zooplankton population due to non-predation mortality is observed.