纺锤水蚤摄食生态学研究进展

纺锤水蚤(Acartia)是温带、亚热带近岸水域优势的小型桡足类,在区域生态系统的物质循环与能量流通中起着重要作用。综述了国内外对纺锤水蚤食性、摄食机制、摄食影响因子及摄食转化效率的研究工作:纺锤水蚤为杂食性,偏爱高营养的动物性饵料,摄食浮游植物和微型浮游动物时分别采取滤食策略和伏击策略,摄食过程受到自身生理状态和环境因子的共同调节。其对食物的利用效率约为60%,其他40%通过Sloppy feeding和排泄等方式以溶解形式释放到海水中。目前摄食研究多以实验模拟为主,自然现场研究手段有限,分子生物学技术有望促进认识其在自然生态系统中的地位与作用。

Advances in feeding ecology of Acartia

Acartia is a genus of small marine copepod dominating the zooplankton community in temperate and subtropical coastal ecosystems,and plays an important role in the elemental cycling and energy flow.This paper mainly summarizes the progress on Acartia feeding ecology including their feeding habits,feeding mechanism,regulatory factors and transfer efficiency.Acartia spp.are omnivorous feeders with a wide food spectrum including microalgae,detritus suspensions,micro-zooplankton such as ciliates and heterotrophic dinoflagellates,and nauplii of copepods,but show a preference to micro-zooplankton rather than phytoplankton.They have two feeding strategies,suspension feeding and ambush feeding,and can switch between these two strategies in different food environments: when feeding on phytoplankton Acartia spp.generate feeding currents and filter cells brought by the currents;when feeding on micro-zooplankton they act as ambush grazers.The clearance and ingestion rates are regulated by the predator characteristics and environmental factors.Generally,females have higher clearance rates than males.Their developmental stage and physiological condition will influence the filtering process as adults are bigger in size and stronger in migrating capacity than juvenile stages,and the metabolic capacity can also have feedback impacts on feeding activities.The influential environmental factors include temperature,salinity,light and turbulence.The optimal temperature and salinity are between 15—25℃ and 25—30 respectively,the clearance rates will be depressed if the environmental temperature and salinity exceed this range.They exhibit a feeding rhythm entrained by light dark cycle with increased feeding activities at night.Small levels of turbulence can enhance the feeding rates based on ambush strategy but will inhibit suspension feeding.Approximately 3%—5% of food filtered will be lost by sloppy feeding,and 60% of the ingested food will be used for metabolism,growth and reproduction,while the remaining part is directly released in forms of dissolved organic carbon(DOC) to environment by excretion and other ways.The DOC can be used by the bacteria community and phytoplankton which is of great significance to micro-loop.These results,which were mainly based on incubation experiments,can hardly reflect the natural feeding conditions.Application of molecular biology techniques will help us to understand the true trophic relations and hence material flow in coastal ecosystem.