| The habitat of harmful mussel (Musculista senhousia) widely distributed in arkshell mariculture zone of Korea was surveyed in this article. Through the mixed breeding trial of arkshells-mussel and mussel-clamworms, it exposed the influence of M. senhousia on habitat sediment and ambient shellfish survival and suggested to eliminate negative impact created by the mussel utilizing polychaeta benthonic organism (Perinereis aibuhitensis). Furthermore, gonadal development cycle and tolerance of embryos and spat for environmental factors of M. senhousia have also been studied. The purpose of this thesis is to supply relevant academic reference for controlling M. senhousia population and enhancing aquaculture production of arkshell.The main experimental results were showed as below:1. Physicochemical factors investigation on habitat environment of mussel M. senhousia in Yeosu regionA part of physicochemical parameters of mussel M. senhousia habitat environment were investigated in Seonso area etc., Yeosu city within a year. According to analysis results, water volume of the mussel inhabit place owns lower DO values, but higher COD values. The AVS values in sediment of Seonso at November significantly higher than that of other periods. However, the COD and TIL values in sediment appeared the higher value at August and was not significant compared with other periods. Mean AVS, COD and TIL values in habitat sediment during a year were 0.43 mg/g·dry,38.31 mg/g·dry and 13.08% respectively.2. Impact of mussel (M. senhousia) emergence on growth and breeding sediment quality of arkshellDifferent numbers of mussel (M. senhousia) (Group A:10 mussel individuals; Group B:30 mussel individuals; Group C:50 mussel individuals) were bred with arkshells respectively, and arkshells (50 individuals) bred individually was deemed as control group. At the 90th day, AVS and COD values of group C were significantly higher than control group (p<0.05), but there was no significant difference for TIL values among groups (p>0.05). The arkshell survival rates of mixed-breed groups were lower than the control group and the arkshell survival rate of group C at the 90th day was only 20.2±3.5% which was significantly lower than that of the control group (p<0.05).3. Influence of clamworms (P. aibuhitensis) on growth and habitat sediment quality of M. senhousiaThe mussel (M. senhousia) (50 individuals) was mixed bred with clamworms as quantity gradient (Group A:50 clamworm individuals; Group B:100 clamworm individuals; Group C:150 clamworm individuals; Group D:200 clamworm individuals). The results indicated the AVS, COD and TIL values were significantly different among these mixed-breed groups (p<0.05). Group D with the largest numbers of clamworms showed the lowest values. Meanwhile, the survival rates of M. senhousia were also indirectly affected by mixed breeding with clamworms, but it was not significant (p>0.05). The mussel survival rates of group D was 58±3.3% at the 75th, lower than that of other groups.4. The gonadal development and reproductive cycle of mussel M. senhousiaThe mussel (M. senhousia) samplings were carried out from Yeosu city each month. According to histological features of gonad development, the gonadal development cycle was divided into five stages:proliferative stage (Feb.-Mar.), growing stage (Mar.-May/Jun.), ripe stage (May/Jun.-Sep.; spermary:Aug.-Sep.; ovary:May/Jun.-Sep.), spawning stage (Sep.-Nov.) and recovery stage (Dec.-Feb.). Among the developmental period, gametes persistent emission stage was from September to November with water temperature 19.5～25.2℃。The existence of a sexual rest period has been observed in current study. Yolk-filled eggs were present evidently from June, but it past through summer rest and occurred to spawn at the latter half of September, simultaneously with spermatozoon.5. Water temperature and salinity tolerance of embryos and spat of the mussel, M. senhousiaThe effects of water temperature (embryos:0～35℃; spat:0～40℃) and salinity (embryos:5～40; spat:0～100) on embryonic development and spat survival of the mussel M. senhousia were investigated in current study. The optimal conditions for the mussel embryos were temperature 20-25℃and salinity 25-35 according to survival rates. The higher temperature within this range correponding to the lower duration. Optimisation of mussel spat survival was under temperature 25-30℃and salinity 30-40, higher than those of the embryo, which hinted M. senhousia embryos were much more vulnerable than the spat. When water temperatures below 15℃, the embryonic survival rates were significantly declined (46% at 15℃and 0 at 10℃).
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