浮游胶质被囊动物暴发机制及海洋碳泵效应

Swarms of pelagic gelatinous tunicates and their roles in marine biological carbon pump

滤食性浮游被囊动物在开阔大洋和沿海海域中大量存在,通过黏液网来大量过滤海水浓缩食物颗粒以供种群快速增殖,是生物碳泵的关键组成,对海洋生物地球化学循环和生态系统能量流动均有重要意义。文章从浮游被囊动物生物学特征、植食性滤食作用、生活史特异性等方面综合论述了国内外关于浮游被囊动物在摄食海洋微型生物、调节海洋生物碳泵(biological carbon pump,BCP)和改变微型生物群落结构以及联系深海食物网等方面的作用。概括了国内外影响浮游被囊类暴发的食物因素、生活史特征、海洋动力过程及气候变化等相关研究进展。浮游被囊动物通过黏液过滤打包真光层微型生物,产生的粪便球和胶质死体快速沉降而输出成为胶质碳泵,从而增加BCP效率,改变微型生物碳循环途径;作为上层海洋生态系统与深海生态系统的媒介,胶质坠落在深海群落和底栖动物食物网中扮演重要作用。文章最后总结了其他胶质碳泵的相关研究进展,并提出在全球变化背景下,未来的研究应该更多地着眼于动力过程对不同生活史阶段浮游被囊动物的垂直移动和集群的影响,并将过滤摄食对微生物群落影响及繁殖策略响应与海洋物理、化学和生物环境多维度联系起来,全面解释浮游被囊类暴发的内在和外在机制,有助于准确评估海洋被囊类胶质碳泵效率及其对全球变化的响应。

Mucus-feeding pelagic tunicates are widely distributed in the open ocean and coastal waters,which have very high rates of reproduction,and the ability to form massive blooms.In this review,we provide a qualitative overview of the combination of high particle consumption and swarms of pelagic tunicates led to accumulate at the ocean floor as jelly-POM(particulate organic matter),substantial contributions to vertical export fluxes.As well as the swarms in relation to environmental drivers and unique life-history adaptation,its role in pelagic-benthic coupling,structure and energy flow of marine food web by selecting feeding are reviewed.Because pelagic tunicates have high filtering rates and efficiencies and can reach great abundances,they have the potential to remove a significant fraction of shelf water column primary production,are exported via mucous aggregates,fecal pellets,and jelly falls sinking to depth or restructure shelf pelagic food webs.The study of jelly-falls represents a major challenge in the understanding of the biological pump mainly due to technical/sampling hurdles,the ecological significance of pelagic tunicate blooms,for instance,the rate of this downward carbon flux may be further enhanced through in-situ observations on pelagic tunicates’diel vertical migrations together with quantitative net catches.Future work should pay more attention to the coupling between fine scales of hydrodynamic grazing and breeding rates under in situ conditions,and link bloom impact on carbon cycling to more dimensions of the physical,chemical,and biological ocean environment,in order to more accurately assess the efficiency of the jelly carbon pump and its response to global change.