Do fish regulate phytoplankton in shallow eutrophic Northeast Brazilian reservoirs?
Do fish regulate phytoplankton in shallow eutrophic Northeast Brazilian reservoirs?
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DOI：
10.1046/j.1365-2427.2003.01037.x
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发表时间：
2003-04-01
影响因子：
2.7
通讯作者：
Mata, MR
中科院分区：
文献类型：
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作者：
Lazzaro, X;Bouvy, M;Mata, MR
1.在一项比较研究中，我们研究了潜在的鱼类结构浮游食物网浅中营养到超富营养巴西东北部水库。食物网主要由鱼类（兼性食鱼动物、多面手食鱼动物和杂食动物）、小型草食浮游动物和水华蓝藻三大类群组成，沿岸的大型水生植物很少.对13个水库（1995-99年27个采样日期）数据的主成分分析显示，真光层深度、以蓝藻为代表的浮游植物相对密度（即占浮游植物总密度的百分比）和以杂食动物和兼性食鱼动物为代表的鱼类相对生物量（即占总生物量的百分比）解释了数据中的大部分方差。物理化学条件、湖泊形态和降雨是次要影响因素.浮游植物与鱼类的行会结构有关。叶绿素含量随总磷和杂食性鱼类相对生物量的增加而增加，随兼性食鱼性鱼类相对生物量的增加而减少，但与草食性浮游动物的生物量和平均体长无关。叶绿素浓度、丝状蓝藻和群体蓝藻密度随兼性食鱼动物与杂食动物生物量之比（FP：OM）的增大而减小.我们提出了两个互补的机制，观察鱼类和浮游植物之间的关系。在兼性食鱼动物生物量较低的情况下，幼年食虫鱼类可能会对沿岸的带浮游动物产生营养级联。无论食鱼动物的生物量如何，由于杂食性或非杂食性觅食行为的优势，食鱼动物和杂食性动物可能通过多通道杂食性调节浮游植物.操纵实验需要进一步探讨，根据水库的使用优先顺序，渔业管理是否可以改变FP：OM的比例，以提高鱼类产量或减少浮游植物密度和蓝藻水华。
1. In a comparative study, we examined the potential for fish to structure planktonic food webs in shallow mesotrophic to hypereutrophic Northeast Brazilian reservoirs. The food webs were dominated by three guilds of fish (facultative piscivores, generalist planktivores and omnivores), small herbivorous zooplankton and bloom-forming cyanobacteria, with few littoral macrophytes.2. A principal component's analysis on data from 13 reservoirs (27 sampling dates in 1995-99) revealed that euphotic depth, the relative density of phytoplankton (i.e. the percentage of overall phytoplankton density) represented by cyanobacteria, and the relative biomass of fish (i.e. percentage of overall biomass) represented by omnivores and facultative piscivores, explained most of the variance in the data. Physico-chemical conditions, lake morphometry and rainfall were secondary factors.3. Phytoplankton was related to fish guild structure. Chlorophyll concentration increased with total phosphorus and the relative biomass of omnivorous fish, decreased with the relative biomass of facultative piscivores, but was unrelated to the biomass and mean body size of herbivorous zooplankton. Chlorophyll concentration and the densities of filamentous and colonial cyanobacteria decreased with the ratio of the biomass of facultative piscivores to that of omnivores (FP : OM).4. We propose two complementary mechanisms for the observed relationships between fish and phytoplankton. At a low biomass of facultative piscivores, juvenile zooplanktivorous fishes may induce a trophic cascade on zooplankton in the littoral zone. Regardless of piscivore biomass, piscivores and omnivores may regulate phytoplankton via multichannel omnivory because of the predominance of omnivorous or detritivorous foraging behaviour.5. Manipulative experiments are needed to explore further whether, depending on priorities in the use of the reservoir, fisheries management could alter the FP : OM ratio either to enhance fish yields or to reduce phytoplankton densities and cyanobacterial blooms.