From November 2020 to August 2022, the diet of 12 fish species from the Samandeni reservoir was examined in order to describe the diet and the trophic level of each of them. The analysis of this vital function allows ...From November 2020 to August 2022, the diet of 12 fish species from the Samandeni reservoir was examined in order to describe the diet and the trophic level of each of them. The analysis of this vital function allows a better knowledge of the concerned ecosystem and gives opportunity for its better management. The fish were sampled with gill nets and cast net. A total of 213 stomach contents of individuals belonging to 12 species grouped in 7 families and 10 genera were analysed. Results showed low to medium vacuity coefficients. The preys were mainly composed of fish, insects, detritus, zooplankton and phytoplankton. Variability in the use of resources by individuals was evident. Thus, the 12 species were classified as fish-eating predators, granivorous, zooplanktivorous, insectivorous and filter-feeding microphages. Then, the fish trophic structure of the Samandeni reservoir was elaborated.展开更多
文摘From November 2020 to August 2022, the diet of 12 fish species from the Samandeni reservoir was examined in order to describe the diet and the trophic level of each of them. The analysis of this vital function allows a better knowledge of the concerned ecosystem and gives opportunity for its better management. The fish were sampled with gill nets and cast net. A total of 213 stomach contents of individuals belonging to 12 species grouped in 7 families and 10 genera were analysed. Results showed low to medium vacuity coefficients. The preys were mainly composed of fish, insects, detritus, zooplankton and phytoplankton. Variability in the use of resources by individuals was evident. Thus, the 12 species were classified as fish-eating predators, granivorous, zooplanktivorous, insectivorous and filter-feeding microphages. Then, the fish trophic structure of the Samandeni reservoir was elaborated.
文摘为了解中东大西洋渔业产区渔获物的资源状况,根据世界粮农组织(FAO)提供的该海域1950—2019年的渔获量数据,结合渔获种类的平均营养级(mean trophic level,MTL)信息,运用统计学方法分析70年间渔获物平均营养级和营养级平衡指数(fishing in balance,FiB)的变动规律,以掌握该海域渔业资源的可持续利用情况。结果显示,MTL大致可分为4个阶段,1950—1956年,MTL指数在3.20左右,无明显变化;1957—1963年,MTL指数迅速上升至3.44;1964—1996年,MTL在波动中趋于下降,历史最高值(3.54)出现在1985年;1997—2019年,MTL稳定在较高水平,其中2018年为该阶段最低点3.35。FiB指数整体呈上升趋势,1950—1956年,FiB指数呈小幅波动增加;1957—1974年,FiB指数显著上升;1975—1996年,FiB指数呈平稳波动状态;1997—2019年,FiB指数整体呈小幅增长趋势。结果表明,中东大西洋海洋生态系统相对稳定,但潜在的渔业资源量越来越少,开发潜力有限。
文摘长身高原鳅(Triplophysa tenuis)对维持木扎提河的水生态系统物质和能量流动具有重要作用。文章基于脂肪酸生物标记法和碳、氮稳定同位素(δ^(13)C、δ^(15)N)技术研究了长身高原鳅的食性和营养生态位特征。结果显示,其肌肉中共检测出22种脂肪酸,其中有8种饱和脂肪酸、6种单不饱和脂肪酸、8种多不饱和脂肪酸;由特征脂肪酸组成情况推测,长身高原鳅对浮游动物、硅藻、陆地植物或喜摄食硅藻的鱼虾均有摄食,表现为杂食性。长身高原鳅的δ^(13)C和δ^(15)N分别介于-27.09‰~-20.98‰和5.71‰~8.45‰,营养级介于2.68~3.48。雌雄样本间的δ^(13)C、δ^(15)N和营养级均不存在显著性差异(P>0.05);雄性样本核心生态位(Standard ellipse area,SEAc)和总生态位(Total area of convex hull,TA)均高于雌性。δ^(13)C与体长间表现为极显著正相关性(P<0.01),δ^(15)N和营养级与体长间不具有显著相关性。70~80 mm体长组与90 mm以上体长组SEAc面积不存在重叠且在聚类分析中被分为不同组。综上,长身高原鳅的食性为杂食性且食物组成随体长变化而不同,作为营养级偏高的捕食者,长身高原鳅能延长食物链长度,增加食物网复杂性,有利于维持水域生态系统的稳定性。
