鱼类对生态系统下行影响敏感指标初探

The Primary Study of Sensitive Fish Top-down Index

通过 2 0 0 0年春季对辽宁 3座大型水库的浮游生物和底栖动物的两次调查发现 :①早春的浮游植物量高的水库 ,浮游动物的多样性指数较大 ,鲢鳙的平均年渔获量也较高 (P <0 .10 ,P <0 .2 5 ) ;②随着温度的提高 ,第 2次测定这种结果发现该现象消失 ,发现浮游植物多样性指数较第 1次调查的变化率与渔获量存在极显著的负相关关系 (P <0 .0 1) ,浮游植物量空间分布的不均匀度与渔获量存在极显著的负相关关系 (P <0 .0 2 ) ,浮游动物空间分布不均匀度较第 1次的变化率与渔获量存在显著负相关关系 (P <0 .0 7) ;③进一步对 3个水库各采样点的生物量以及多样性指数与该点环境指标的相关分析发现 ,第 1次采样期间三水库的浮游动物与环境指标相关显著 (P <0 .0 5 ) ,第 2次采样期间只有渔获量最低的碧流河水库的浮游动物量与环境指标存在一定相关关系 (P <0 .10 ) ;④鲤鲫的年渔获量与第 2次调查的底栖动物多样性指数存在负相关关系 (P <0 .2 0 ) ,与底栖动物量空间分布的不均匀度存在正相关关系 (P <0 .30 )。在三水库的渔获量与鱼现存量呈相近比例的假设条件下 ,认为 :(1)鱼类的下行影响首先会使低等生物群落的多样性指数降低到一定水平 ,并使生物量空间分布的均匀程度发生变化 。

By investigating the biomass and community constructions of plankton and benthic invertebrate of three reservoirs in Liaoning twice in the spring of 2000, we got following results. ① The reservoir with the most abundant phytoplankton (p<0.10) has highest zooplankton diversity (Shannon-Weaver Index) and the most planktivorous fish abundance (PFA) (p<0.25). ② The situation disappears in the second sample, as the water became warmer, whereas the changed rate of phytoplankton diversity from the first sample has great significant negative correlativity to the planktivorous fish (p<0.01). Spacial unevenness (also the coefficient of variability, CV) of phyto-plankton is great significantly negatively correlative to the PFA (p<0.02). The changed rate of zooplankton spacial unevenness from the first sample has significant negative correlativity to the PFA (p<0.07). ③ Furthermore, the zooplankton biomass of each site in the three reservoirs is significantly correlative to the environmental index of according site in the first sample (p<0.05), but only that in Reservoir Biliuhe has correlativity to the environmental index (p<0.10). ④ The cyprinoid abundance has negative correlativity to the CV (p<0.20) and pacial unevenness (p<0.30) of the second benthos samples. From all above results, we get the following conclusions. (1) The top-down influence of planktivorous or benthic omnivorous at first is to influence the biodiversity and spacial unevenness of plankton or benthic invertebrate, both of which are the sensitive indexes to access the influence of the fish on the water biosystem. (2) The biomass as the only index to analyze the influence is often insensitive.