Research on the quality of downward migration passage of juvenile silver carp stressed by ammonia nitrogen
In order to quantify the impact of ammonia nitrogen stress on fish habitat quality,a two-dimensional hydrodynamic and water quality model was set up in the main stream of Huaihe River from Lutaizi to the Yaohe sluice through three landscape ecological characteristic indices,namely:suitable habitat area,patch number and habitat connectivity.Typical indigenous migratory fish juvenile silver carp was used as the target species.Under the assumption of Class III water quality standard for the inflow boundary with the ammonia nitrogen concentration of 1.0 mg·L-1,the impacts were evaluated for low,medium and high flow rates in the study site,respectively.In comparison with the benchmark case where no ammonia nitrogen index was considered,the results showed that:(1)the suitable habitat area of the downstream migration passage was decreased by 1.6%,6.7%and 3.4%respectively;(2)the fragmentation was increased by 4.5%,28.7%and 3.6%respectively;(3)the connectivity was decreased by 54.3%,34.6%and 24.8%respectively.It is clear that the impact of ammonia nitrogen stress on the suitable habitat area is insignificant,but considerable on the patch number for the medium flow rate which boasts the highest fragmentation,indicating that there is a certain degree of positive correlation and synergy between the impacts of ammonia nitrogen and fragmentation.Finally,the decline range of connectivity is negatively proportional to the flow rate of inflow boundary.The qualification of the different impacts of ammonia nitrogen stress on different landscape ecological characteristic indices can improve the construction of fish habitat indicator system and help to manage the required flow rate in the natural rivers for the water quality demand of juvenile silver carp.
ammonia nitrogenjuvenile silver carphabitat model2-D water quality simulationmigration passage
万方数据
维普
