温度对微型鞭毛虫摄食细菌的影响

为研究温度对微型鞭毛虫（Nanoflagellates，NF）摄食细菌的影响，于广西近岸海区采集NF自然群落，置于实验室不同温度下（14℃、22℃、28℃）培养9天，观察细菌和NF的丰度变化。并以荧光细菌标记法研究不同温度下异养微型鞭毛虫（Hetertrophic Nanoflagellates，HNF）和含色素微型鞭毛虫（Pigmented Nanoflagellates，PNF）对细菌的摄食率，计算不同类型NF的群落摄食率。此外，研究还比较了不同粒径PNF （<3 μm和3~10 μm）对细菌的摄食。结果表明，不同类型的NF对细菌的摄食率由大到小为:3~10 μm PNF、HNF、小于3 μm PNF。较之PNF，HNF的摄食受温度影响较小。PNF的摄食率在22℃最大。而且，不同大小PNF的摄食对温度的响应有所不同。升温可以提高3~10 μm PNF的摄食率，但会抑制小于3 μm PNF的摄食。而降温抑制3~10 μm PNF的摄食，但降温对小于3 μm PNF摄食的抑制作用比升温小。但无论是3~10 μm PNF还是小于3 μm PNF，升温均会降低其丰度。而由于丰度减小对群落摄食率的影响更大，因此，升温降低PNF的群落摄食率。

The effects of temperature on the bacterivory of nanoflagellates

In order to investigate the temperature effects on the bacterivory of nanoflagellates (NF), natural NF community was collected from the coastal water in Guangxi, China. The NF was cultured under different temperatures (14℃, 22℃, and 28℃), during which the variations of the bacteria and NF abundance were observed. Fluorescently labeled bacteria were used to trace the grazing of bacteria by NF, and the community consumption rate of NF was calculated. Moreover, the ingestion rates of bacteria were compared between the PNF of different sizes (<3 μm and 3-10 μm). The results indicate that the ingestion rates arranged from high to low are 3-10 μm PNF, HNF, and <3 μm PNF. The ingestion rate of HNF is less affected by temperature than PNF, and the ingestion by PNF peaks at 22℃. Interestingly, the PNFs of the two sizes respond differently to temperature changes. The high temperature promotes the ingestion rate of 3-10 μm PNF but inhibits the ingestion rate of <3 μm PNF. The low temperature inhibits the ingestion rate of 3-10 μm PNF, but the inhibition of low temperature on the grazing of <3 μm PNF is less than high temperature. The abundances of both 3-10 μm PNF and <3 μm PNF are lowest in high temperature, and community consumption rate is mostly contributed by abundance. Therefore, for community consumption rate, the high temperature reduces the consumption of PNF on bacteria.