Population Estimation of An Invasive Alien Species, Cherax quadricarinatus (von Martens, 1868) in Lido Lake, Indonesia

Abstract

Indonesia is a mega biodiversity country in the world, including native aquatic species. Some alien species could be a problem for aquatic biodiversity. The Redclaw crayfish or lobsters, Cherax quadricarinatus, is native in freshwater habitats of Australia. Unfortunately, C. quadricarinatus is also recognized as invasive, having already established wild populations in some lakes in Indonesia. The research was conducted to investigate the abundant of C. quadricarinatus as alien species in Lido lake, Indonesia. The research was conducted in October 2018 (transition) and February 2019 (wet season) at Lido lake, Bogor Resident, West Java, Indonesia. Around forty traps were installed along the lake line. Traps were set during the day and collected the next day. Caught lobsters were counted and marked on the carapace with nail polish and then the lobsters were returned to the lake. The Schnabel mark-recapture method is used in calculating abundance. The result showed that the abundant of C. quadricarinatus was high in October 2018 (N=2285) and February 2019 (N=2595) and the abundant of C. quadricarinatus was higher than native crustacean species, Macrobrachium sintangense, in Lido lake. There were slightly different ratio of C. quadricarinatus sex ratio between October 2018 and February 2019 but based on the chi-square test showed that in two periods data sampling were found not significantly different at the 95% level confidence. It was the first evidence that C. quadricarinatus could be an invasive alien species and it is well established in Lido Lake, Indonesia.