Review on contribution of ancient organic carbon to aquatic food webs

Abstract

传统理论认为，支撑水生态系统食物网的碳主要来自于系统内部的初级生产者，如藻类、大型水生植物等，或者来自陆源输入的新鲜且容易分解的有机质；而部分生物或非生物生产的有机碳，在冰川、冻土等环境中可停留数百年至数千年（定义为老碳），由于储存环境稳定、物理化学性质顽固，难以参与水生生态系统有机碳循环.近年来这一观念不断被挑战.研究表明老碳能够参与水生态系统食物网碳循环：可以被微生物分解利用；被浮游动物、无脊椎动物直接或者间接摄取、或沿着营养级传递至鱼类、水禽等高级消费者.这意味着除了内部初级生产，老碳是支撑水生态系统重要的碳源.本文概述了当前老碳与水生态系统食物网关系研究最新进展和所取得的研究成果，介绍放射性¹⁴C同位素技术在水生态学领域的应用，同时提出研究中存在的问题以及未来研究应关注的方向，以期促进我国水生态系统碳循环研究的进一步发展.;Traditionally, aquatic ecosystem consumers are considered to mainly feed on primary production derived organic carbon (OC) from contemporary photosynthesis(e.g. algae, macrophytes) or on fresh terrestrial OC from watershed that is less refractory than previously thought. Due to structure stability and stubborn physicochemical feature, some biotical or abiotic OC stored in glacier and permafrost systems for hundreds to thousands years (defined as ancient or highly aged OC) may be hardly incorporated into biogeochemistry process in aquatic ecosystems. Recent studies, however, have increasingly revealed that ancient OC may be an important resource for microbes, zooplankton, invertebrates, and higher trophic consumers such as fish and waterfowl and significantly subsidizes food webs of aquatic ecosystems. The ancient OC of aquatic consumers indicates that a shortage of modern primary production may not necessarily limit or constrain the food supply to consumers in aquatic ecosystems. In this paper, we have summarized the research progresses on the relationship between terrestrial ancient OC and aquatic food webs worldwide, introduced the application of ¹⁴C technology in aquatic ecology, and pointed out the problems existing in the studies and the direction in the future research. This study will promote the research of carbon cycle of aquatic ecosystems in China.