Spatial pattern of fish community in the Erhai Lake

Abstract

The Erhai Lake is an extant production base of Yunnan province for aquatic products.Due to the environment and fishery pattern change,the fish fauna of the Erhai Lake are varied.How about the status? How about the fish community structure and its distribution? There are less typical reports till now.This study investigated species composition and abundance of fish at 21 sites in the Erhai Lake for two times in August and November 2009,respectively.The fish nets for each station at about 5:00 pm on the first day and harvested at 5:00 am on the second day.Three samples were conducted at each site for each sampling.Species composition and number of individuals,sampling time,environment factor,latitude and longitude of the sampling site,types of nets were recorded.The fishes were identified and classified.The data were analyzed and interpreted with diversity index(Shannon-Wiener index;Pielou index),similarity coefficient(Sorenson index;Bray-Curtis index) and various multivariate statistical methods(CLUSTER;MDS;ANOSIM;SIMPER).The results showed there were 23 species,belonging to 5 orders and 9 families.The fish community of Erhai Lake could be divided into three groups: alongshore community(CⅠ),open water community(CⅡ) and upstream community(CⅢ).Analysis of similarity(ANOSIM) and similarity of percentage(SIMPER) showed the differences among these groups were significant(R=0.735,P0.01).The indicator species of CⅠ were Hemiculter leucisculus,Carassius auratus,Pseudorasbora parva,etc.,and their contribution of similarity in CⅠ was 80.71%.The indicator species of CⅡ were Aristichthys nobilis,Hypophthalmichthys molitrix,Megalobrama amblycephala,etc.,and their contribution of similarity in CⅡ was 98.2%.The indicator species of CⅢ were C.auratus,P.parva,Acheilognathus elongates,etc.,and their contribution of similarity in CⅢ was 94.94%.The average contribution of dissimilarity between CⅠ and CⅡ was 76.8%,the discriminating species were H.leucisculus,A.nobilis,P.parva,etc.,and their contribution of dissimilarity was 88.63%.The average contribution of dissimilarity between CⅠ and CⅢ was 54.94%,the discriminating species were H.leucisculus,A.elongates,Abbottina rivularis,etc.,and their contribution of dissimilarity was 78.99%.The average contribution of dissimilarity between CⅡ and CⅢ was 91.62%,the discriminating species were P.parva,H.molitrix,A.nobilis,etc.,and their contribution of dissimilarity was 85.82%.The CⅠ and CⅢ were mainly composed of small sized fishes,and CⅡ was larger ones.In conclusion,the diversity in spatial structure of fish community reflected the environmental heterogeneity in Erhai Lake.