| As a common small crustacean in salt lake,abundant nutrition,its naupllarids are good open bait for fish,shrimp,crab and other aquaculture products,and the demand for harvest eggs in fishery market is increasing gradually.Ebi lake is rich in bounty resources,and its egg production used to account for 2/3 of China’s bounty.However,with the ban on harvest of bounty in Ebi Lake,a lot of bounty resources were wasted.In this study,the extraction index of the egg zone was proposed based on multi-source remote sensing data,and the inversion model of the dormant egg zone was constructed by combining the measured reflectance of the ground with the spectral response function of the satellite.In the past half century,the inflow of Ebi Lake decreased sharply,and the area of Ebi Lake decreased sharply,which has become the second largest ecological degradation area in Xinjiang.Ebi lake area decrease the lake salinity increase,then the Fairy shrimp eggs hatching rate as well as the fairy shrimp resources have an impact,so this research with the aid of ENVI5.3 software of 1990-2021,when the plentiful multi-source remote sensing image using normalized Ebi lake water body index NDWI are extracted,and calculate its area,and combined with the lake area is dynamic,And runoff data and meteorological data were used to analyze the area change of Ebi lake in recent 30 years.It is found that the average area of Ebi Lake during the wet season in the past 30 years is 638km~2,which is in a relatively stable period.The overall change trend is decreasing,increasing and decreasing.From 1990 to 2021,the K value is-1.56%,indicating that the area of Ebi Lake is decreasing on the whole.The area of Ebi Lake is mainly dominated by surface runoff with a correlation coefficient of 0.67,and the recharge runoff is dominated by Boltala River runoff with a correlation coefficient of 0.74.The influence of evaporation on lake area was second only to that of surface runoff,and it was negatively correlated with the change of lake area,with the correlation coefficient of-0.25.Because evaporation is much higher than precipitation,the impact of precipitation on Ebinhu lake is also negatively correlated with the correlation coefficient of-0.18.Air temperature and sunshine duration also have a weak influence on the area of Lake Ebi,which indirectly affects the area of Lake Ebi through precipitation and evaporation,respectively.In this study,based on the analysis of spectral characteristics of ground objects in Ebinhu lake,the index BSI was proposed based on green light and near-infrared band,and the accuracy was good,which was suitable for multi-source satellite data.BSI index was used to extract the egg zones from satellite images from April to October of 2010to 2021,and the area change was analyzed.The results showed that the area of the egg zone was higher in April and May,decreased from May to July,occasionally increased,and increased from July to September,from September to October,the increasing trend of eggs slowed down,and the adults in the lake almost died.It was found that the area of Ebi Lake was the main factor affecting the area of fertile year egg zone,and the correlation coefficient was 0.45.The influence of precipitation and wind speed on the area of fertile egg zone was next,with correlation coefficients of 0.25 and 0.22,respectively.There was a negative correlation between air temperature and sunshine duration and the area of egg zone with correlation coefficients of-0.18 and-0.14.Evaporation had the lowest correlation,which was only-0.04.It can be seen that the combined effect of meteorological factors not only affects the area change of lake water,but also directly or indirectly affects the area change of the egg zone.Combined with2010-2016 harvest eggs catch found that Ebi lake fairy shrimp the ban issued after the Ebi lake environment is still not improved,visible fairy shrimp fishing is not the main cause of the Ebi lake environmental damage,and the reasonable fishing can bring considerable economic benefit to Ebi lake,provide certain economic support for Ebi lake governance.In this study,indoor spectral experiments were carried out to measure the reflectance and dry weight of the dormant eggs of C.fernata.It was found that the reflectance increased with the increase of dry weight,and the correlation between them was the highest at 815nm wavelength,with correlation coefficient R=0.85.It is found that the BSI index has the highest correlation with the dry weight of dormant eggs by using the measured reflectance corresponding to the central wavelength of different satellite sensors,R=0.87,and the value of multi-source satellite is approximately the same.Stepwise regression equation was constructed by using BSI index calculated from simulated satellite reflectivity and measured dry weight,and it was found that the index model was the optimal model for inversion of satellite scale dormant eggs after verification. |
