On Shrimp Resources And Utilization From Karst Cave Of Guangxi,Southwestern China

The karst area in China reaches 36.1,000 km²,which accounts for 15.6%and 1/3of the global karst area and the national land area.Among them,the karst areas in China are mainly southern karst.As one of the facades of karst in southern China,Guangxi is one of the most perfect developing regions of humid tropical-subtropical karst in the world and one of the most important karst landforms in the world.Carbonate rocks are distributed in 79 counties and cities,with an area of 96400 km²,accounting for 9.84%and 40.72%of the total karst landforms and Guangxi Zhuang Autonomous Region.From July 2018 to December 2019,this paper investigates shrimp resources and related tourist caves in Nanning,Hechi,Baise,Chongzuo,Guilin and Yulin.The main results are as follows:1.A total of 56 caves were investigated to obtain more than 500 cave shrimp and related physicochemical factors and habitat characteristics.By using traditional taxonomic methods,23 species of cave shrimp were preliminarily identified,including 12 species of Caridina,3 species of Neocaridina,2 species of Thphlocaridina,and 6 species of Macrobrachium,which greatly enriched the shrimp germplasm in China Resources can provide basic materials for animal ecology,systematic chemistry and species protection.2.Traditional taxonomy and phylogenetic analysis were used to study the collected shrimp specimens.Three new species of the genus Caridina were found in the family atyidae,respectively,Caridina huanjiangensis sp.nov.,Caridina dacaiensis sp.nov.and Caridina mashanensis sp.nov.,and one new species of the genus Macrobrachium in the family Palaemonidae,Macrobrachium tenuipes sp.nov.,has greatly enriched the germplasm resources of cave shrimp in China.The morphological differences between the three new species of Caridina and related species are mainly the length and shape of rostrum,the number and distribution of teeth on the upper and lower margins,the shape,length,and logarithm of the interstitial spines,the shape of the endopod of the male 1^stpleopod,and the position,length,shape of the appendix interna,the shape and position of appendix masculina of the male 2^ndpleopod and and the location and length of the appendix interna,number of active spines of uropodal diaeresi,and the morphological characteristics of the body pattern and color.The difference between the Macrobrachium tenuipes sp.nov.and Macrobrachium superbum is mainly the length of the rostrum and the distribution and quantity of the upper and lower edge teeth,the proportion of each section of the pereiopod in the second pair of mature individuals and the size of the body pattern and egg.Phylogenetic analysis of three new species of Caridina shrimps using mitochondrial COI gene sequences,Caridina huanjiangensis sp.nov.,Caridina dacaiensis sp.nov.,and Caridina mashanensis sp.nov..The genetic distance between species is 0.10 and 0.11 respectively,and the genetic distance between Caridina dacaiensis sp.nov.and Caridina mashanensis sp.nov.is 0.06.Meanwhile,they belong to different branches in phylogenetic trees.When analyzing the phylogeny of Macrobrachium using combined data of COI and 18s r RNA,the genetic distances between Macrobrachium tenuipes sp.nov.And Macrobrachium superbum were 0.16(COI)and 0.03(18S r RNA),and the boundary between the two species in the phylogenetic tree was very clear.The results were consistent with traditional morphology,Macrobrachium tenuipes sp.nov.was a new taxon.3.Compared with the same type of shrimp in surface water,it was found that the shrimp living in the underground water body of the cave,after convergent evolution and natural selection and reproductive isolation,the morphological structure of the cave shrimps has produced a series of adaptive characteristics,such as eye loss,body color degradation and tactile acuity.In this study,five trogloxene such as Neocaridina palmata did not change any of their external morphological characteristics such as eyes,body shape,and appendages.Both the eutroglophile and the troglobiont have adaptability to the cave environment in terms of their external morphological characteristics.For example,9 species of eutroglophile such as Caridina guangxiensis show normal morphological characteristics,extended eyes,blood red or pale yellow and transparent body color;Typhlocaridina lanceifrons,etc.the eyes of this kind of real cave creatures are partially or completely degraded.They are bullet-shaped,their body color is degraded,they are red transparent or pure white,and their appendages are slender and sensitive to touch.This series of adaptive characteristics is of great significance in the study of degradation,comparative biology,and the study of compound trait variation,and can provide a good reference for evolutionary research.4.Cave shrimps exhibit extremely high rarity and endemicity,are extremely harsh to the living environment and are vulnerable to human pressure,such as environmental pollution,groundwater exploitation and cave tourism.In this study,the type locality of Typhlocaridina lanceifrons was investigated in July 2018 and March2019,did not find the species.Moreover,because of human activities and the development of scenic spots,its living environment was seriously damaged,which made it in extinction.Therefore,there is an urgent need for more research on the ecosystems of cave shrimps or related species,along with legislative action to integrate biodiversity conservation and needs into the decision-making process of water resources management,thus protecting fragile karst ecosystems.5.Cave tourism is one of the most important tourist resources in Guangxi,but there are many problems in the process of development and utilization.For example,among the 10 tourist caves in this study,such as the National Seven Star Rock of three tourist caves,have the problems of lack of protection of natural and human resources and the sharp increase of tourists,and the Bama Crystal Palace at the autonomous region level and the Jinlun Cave at the local level of seven tourist caves,have the problems of much the same,short travel and so on.In the development of cave tourism resources,we should sum up the experience and lessons on the existing basis,maintain the vitality of cave tourism resources,make full use of the rich natural and human resources of cave tourism,so as to effectively improve the conversion rate of cave resources.First of all,strengthen the protection of cave ecological environment and establish an effective karst ecological environment protection system.Secondly,looking for special caves and other tourism resources joint development,so that tourism product structure optimization,resulting in superposition effect.Finally,keep up with the market demand,learn more domestic and foreign peer experience,introduce or create a new development model,greatly improve the attraction of tourist destinations.