| This study was focused on the wetland and fishery resources in the Peng'an section of the Jialing River.Based on the 3S technology,six periods(1993,1998,2003,2008,2013,and 2017)Landsat remote sensing images data were used to analyze the evolutionary of landscape patterns and the major driving force in the Peng'an section during 1993 to 2017 by the means of landscape pattern index.Simultaneously,status of the fishery resources in the Peng'an section of the Jialing River(8.3 km watercourse,where 3.8 km in front of the Jinxi Dam and 4.5 km behind the Jinxi Dam was included in our detection range)was detected by Biosonics DT-X sounder from July,2018 to June,2019.Based on the hydroacoustic surveys,the dynamics of the landscape pattern and status of the fishery resources were analyzed.In this study,we explored the main driving force of the evolutionary for the riverine wetland landscape,the factors affecting the current status and dynamic regulation of fishery resources,and the influence of water environment change on fishery resources to provide the basis for fishery resource protection and management in the protected area.The main results are as follow:1.Combined the six periods Landsat remote sensing images in 1993,1998,2003,2008,2013 and 2017 with the landscape field reserch in 2017,the landscape in Peng'an section of the Jialing River can be divided into six types,they are river,residential area,grassland,woodland,cultivated land and bare land,respectively.Results indicated that the area of riverine and woodland landscapes were ascending continually from 1993 to 2017.The riverine landscape increased from 33.249 km2 to 43.558 km2,increased by 31%,and the forest landscape increased from 11.824 km2 to 30.085 km2.However,other landscape types showed a decreasing trend.All but the riverine landscape were displayed the trend of simplified,miniaturized,and broken.Driving force analysis results showed that the population growth and economic development were two important reasons of landscape pattern evolution when ignore the factors of unreasonable used and wasted of landscape resources.2.The density and biomass of the fish in the Peng'an section of the Jialing River were changed with the month.On the horizontal direction,the annual average density and biomass of fish were 0.6739±0.2084 ind/m3 and 0.1887±0.0637 kg/m3,the largest density(2.1761±1.0042 ind/m3)and biomass(0.4224±0.1827 kg/m3)was appeared in July,2018 and February,2019,respectively.However,on the vertical direction,the annual average density and biomass of fish were 0.2366±0.1973 ind/m3 and 0.0793±0.0426 kg/m3,respectively.The largest density and biomass on the vertical direction were emergeed in September,2018,which were 0.9696±0.7295 ind/m3 and 0.3415±0.2936 kg/m3,respectively.3.The density and biomass of fish in front of the Jixi Dam and behind the Jinxi Dam in the Peng'an section of the Jialing River were significant different at both horizontal and vertical directions.On the horizontal distribution,the density and biomass of fish in front of the Jinxi Dam was smaller than that behind the Jinxi Dam.The fish density and biomass in front the dam were 0.2616±0.2013 ind/m3 and 0.0569±0.0012 kg/m3,respectively.However,the fish density and biomass behind the dam were 1.0861±0.9723 ind/m3 and 0.3204±0.2381 kg/m3,respectively.The density and biomass of fish on the vertical direction was contrary to the horizontal distribution.The density(0.3819±0.1972 ind/m3)and biomass(0.1207±0.0927 kg/m3)in front of the dam were greater than them behind the dam(density: 0.0913±0.0748 ind/m3,biomass: 0.0378±0.0061 kg/m3).The difference of the volume and depth of water in the river between upstream and downstream of the Jinxi Dam may be the major reason which cause the uneveness distribution of fish density and biomass.4.No matter on the horizontal and vertical distribution,the fish density in the Peng'an section of the Jialing River was showed seasonal difference between upstream and downstream of the Jinxi Dam.In related to horizontal distribution,the highest fish density was appeared in summer(0.1936±0.1271 ind/m3)and the lowest fish density was come from autumn(0.0149±0.0028 ind/m3)in the upstream of the Jinxi Dam.However,the highest and lowest fish density in the downstream of the Jinxi Dam were presented in autumn(0.1585±0.1156 ind/m3)and summer(0.0119±0.0008 ind/m3),respectively.In respect of vertical distribution,the highest fish density was emerged in summer(0.5131±0.3781 ind/m3)and the lowest density was appeared in spring(0.0028±0.0004 ind/m3)in the upstream of the Jinxi Dam.On the other hand,the highest and lowest fish density in the downstream of the Jinxi Dam were found in summer(0.3111±0.1974 ind/m3)and winter(0.0132±0.0079 ind/m3),respectively.5.Statistical results indicated that no seasonal difference(P>0.05)of fish density was detected both in the upstream and downstream of the Jinxi Dam at the horizontal distribution.In terms of the vertical distribution,significant difference of the fish density among season was not found(P>0.05)in the upstream of the Jinxi Dam.However,in the downstream of the Jinxi Dam,the fish density was significant different among season(P <0.05).The variation of fishery activities and prey distribution between upstream and downstream of the Jinxi Dam may be the primary reason which cause the seasonal difference of the fish density. |
PDF Full Text Request