Preliminary Studies On The Basic Biological Property And Habitat Suitability Of Liobagrus Styani In Streams Of Southern Jiangsu Province

To investigate the current status about stream fish stocks in the mountainous areas in the southern of Jiangsu province,this paper highlighted the basic biological characteristics,dynamics of populations about Liobagrus styani determined the environmental factors affecting the growth and reproduction of the scorpion,and mastered the dietary composition and trophic structure of the sorghum,which provided a theoretical basis for further research on L.styani.In addition,it combined with the current status of fish stocks and the characteristics of environmental factors in this paper.The relevant measures for stream environmental protection are proposed to strengthen the protection of stream fish and restore its original ecological environment(1)Preliminary studies on the age and Growth Characteristics of Liobagrus styani in Streams of Southern Jiangsu ProvinceStudying the age structure and growth characteristics of fish,not only elaborates the basis of biological research,but also serves an important role in conservation and restoration of fish germplasm resources.It has been reported that L.styani was distributed in the middle and lower reaches of the Yangtze River.But there are no detail reports on its distribution.Based on the first discovery for its distribution in Jiangsu Province by the fishery resource survey,it is urgent to study the basic biological characteristics of L.styani A total of 221 L.styani in Streams of Southern Jiangsu Province were collected using handheld pulse sampling device in January 2017 to April 2019,and set 105 L.styani free into the streams with vigorous.The age structure of L.styani was analyzed with the vertebrae identification.The relative growth rate,instantaneous growth rate,growth constant,growth index was calculated.The results showed that the L.styani vertebrae are irregular,and the annual vertebrae rings are clear with alizarin red dye liquor.The age of L.styani in the study ranged from 1 to 5 years,and the fishes between 2 and 3 years are dominant,which are about 71.85%.Their average length and weight are(71.56± 11.47)mm and(5.76±2.47)g,respectively.The fitting equation of the relationship between the length(L)and the external diameter of vertebra(R)is L=22.134R+34.551,and the fitted relationship between the weight(W)and length(L)is W=3×10-5L2.836.The von Bertalanffy growth equations of the L.styani are Lt=108.45[1-e-0.1330(t+3.8058)]and Wtd=17.74[1-e-0.1330(t+3.8058)]2.836,respectively.The inflexion age on the growth is 4.04 a,the corresponding length and weight is 70.22mm the 5.17g at this age,respectively.The ratio of male to female was 1:1.04 of L.styani.(2)Study on the Feeding Habits of Liobagrus styaniAtotal of 221L.styani in Streams of Southern Jiangsu Province were collected using handheld pulse sampling device in January 2017 to April 2019,and set 105 L.styani free into the streams with vigorous.Chironomidae and Ephemeroptera are the main baits of L.styani by morphological identification and a total of 21 species were obtained by DNA molecular technology.The mainly food in the stomach are Chironomidae and Ephemeroptera,but it's not found in the intestinal tract,thus,it's very likely that the food has been digested of L.styani.Meanwhile,Desmodesmus,Phaeopyxis and Cyperus are not found in the stomach,and it means that aquatic plants are not digested.Therefore,the food habit of L.styani is sarcophagi,and the mainly food are Chironomidae and Ephemeroptera.The average length is(72.51 ±8.99)mm,and the Jejunum rate sample size accounts for 25%of the total sample size.The highest contribution proportions of zoobenthos to L.styani is 60.7%,and the contribution proportions of Neocaridina denticulata sinensis is 23.3%.The average value of nutrition level is between 1 to 3.88 in Streams of Southern Jiangsu Province.The trophic level of L.styani is 3.33,it's close to the trophic levels of Odontobutis obscurus,Misgurnus anguillicaudatus and Rhinogobius giurinus.The most trophic level of Monopterus albus is 3.88,They are all the top consumers of the stream ecosystem.(3)Assessment of Habitat Suitability Index of Liobagrus styaniTo evaluate the choice preference of L.styani habitat.A total of 221 L.styani in Streams of Southern Jiangsu Province were collected using handheld pulse sampling device in January 2017 to April 2019,and set 105 L.styani free into the streams with vigorous.The one factor analysis of variance,correlation analysis and canonical correspondence analysis,then habitat suitability curves were established and habitat suitability index was finally calculated.The 6 indicator factors,including abundance of temperature,substrate,dissolved oxygen,depth,flow velocities and chlorophyll a,were selected from 17 environmental factors.The result showed that the descending order of 6 metrics by weight on HSI was chlorophyll a,flow velocities,depth,dissolved oxygen,substrate and temperature.Yixing's 5 has the highest HSI in Summer and HIS is 0.6 over,then,Yixing's 8 HSI is greater than 0.3.HSI of other points is less than 0.3.The results show that L.styani likes the type of pebble.The most suitable dissolved oxygen is 8.8-9.2 mg/L and the optimum depth of water is 0.18-0.3m.The results can provide a scientific reference for L.styani species conservation and nature reserve construction and management.It has important value to give reference for protecting and resource recovery of L.styani.