| Preliminary study on biological characteristics and variational disciplinarian ofAsterias amurensis collected from the coastal of Fushan Bay of Qingdao inanniversary, have been finished; the effects of temperature, predator size and prey sizeon the feeding selectivity has been analyzed by the selective feeding of A. amurensison Ruditapes philippinarum; experiments are carried out to investigate the behavioraland metabolic responses，righting time and activity coefficient of the A. amurensis todifferent concentrations of chemical substances (ammonium chloride, ammoniumnitrate, ammonium carbonate, ammonium acetate and acetic acid); preliminarydiscussion has been finished on starfish control strategy according to the results ofexperiments, aims at providing basic information for behavioral ecology andpredators controlling in artificial reef area. The main study and results are as follows:1. Preliminary study on the biological characteristics of A. amurensis in thecoast of QingdaoPreliminary study on biological characteristics of A. amurensis collected from thecoastal of Fushan Bay of Qingdao from June2011to May2012, has been finished.Periodic characteristic of morphological parameters has been resulted by measuring.The results show the dominant lengths are50-70mm of the adult length and themaximum is91.2%in January. Interradial radius, the length of digestive gland, thelength of gonad and radius are linear relationships. Relationship between weight andradius is power function，W=2×10-3R2.298shows its allometry. Pyloric caecal index(PI)and gonadal index (GI) are inverse correlation，PI increase from December to nextJuly and it arrives the maximum and the minimum is in October and November whenGI is the maximum; sex ratio is1.05:1；High temperature can promote the gonadaldevelopment in summer, low temperature can stimulate their breeding in autumn; theybreed in November to next January.2. The preliminary studies on selective feeding of A. amurensis on R.philippinarumUnder laboratory conditions, the selective feeding of A. amurensis (4-8cm) on Ruditapes philippinarum (20-40mm) at different temperatures (5℃,10℃,15℃,20℃,25℃) have been studied. The prey profitability, prey size selectivity, totalconsumption and feeding rate are examined and the effects of temperature, predatorsize and prey size on the feeding selectivity are analyzed. Results show that A.amurensis prefers to feed on those preys with high prey profitability withintemperature range of5-15℃, and the prey profitability are significantly affected byboth the predator size and prey size. No significant effects of temperature on the preyprofitability can be observed. The prey consumption of A. amurensis increases withthe increase of temperature, and reach the maximum consumption at15℃, which isthe optimal temperature for A. amurensis. The prey consumption decreased with theincrease of temperature when higher than15℃. Significantly higher feeding rate of A.amurensis is observed at day than at night. Based on the analysis of the coastaltemperature data of Qingdao and the reproductive habit of R. philippinarum, weconclud that the temperature in May and June is the most suitable for A. amurensis‘sfeeding and growth. A. amurensis from4cm to8cm can eat nearly ten thousand onlyin a month. Once there is a blooming of A. amurensis, the reproduction of R.philippinarum will be greatly affected and inshore cultivation‘s losses will be great.3. The behavioral research of A. amurensis under chemical substances such asammonium salts and acetic acidThe present study explored the Asterias amurensis (4-8cm) selective feeding onRuditapes philippinarum (20-40mm) by different temperatures (5℃,10℃,15℃,20℃,25℃) in laboratory condition. The prey profitability, prey size selectivity,total consumption and feeding rate were used to analyse the effects of temperature,predator size and prey size on selective feeding of A. amurensis. Results showed thatprey profitability were significantly affected by both the predator size and prey size(P<0.0001). No significant effects of temperature on the prey profitability wereobserved (P=1.0000). According to prey profitability model, four kinds of A.amurensis got maximum when they fed those preys by20mm,23mm,30mm and35mm respectively. The values were0.62mg/min,0.70mg/min,0.83mg/min,0.94mg/min. The predictions were in accordance with experimental results. Withintemperature ranging from5to15degree and A.amurensis from5to8cm, the preyconsumption increased as the temperature went up, and reached the maximum consumption at15℃, which was the optimal temperature for A. amurensis. Thevalues were0.37g/d,0.45g/d and0.54g/d. The prey consumption decreased with theincrease of temperature when higher than15℃. Significantly higher feeding rate wasobserved at day than at night. It’s concluded that the in May and June, the temperatureof Qingdao was the reproduction of R. philippinarum and the most suitable for A.amurensis’s feeding and growth. Therefore, the prevention and clearing of starfishshould be reinforced.4. Preliminary study on control and clear strategy of starfishSuggestions on the control and clear strategy are discussed taking A. amurensis anexample.(1) Take different contol methods according to the life history and feedingcharacteristics of A. amurensis. Larval stage-setting plankton nets; Fixationstage-using scallop cage attached; Breeding season-finishing star parents.(2)Chemical defense and trapping. When starfish outbreak, we can use trap andammonium-release bags in farming areas to expel starfish. After that starfish’s feedingopportunities and the harm on shellfish aquaculture are reduced.(3) Develop the newfishing tools to improve fishing efficiency.(4) Biological control and removal by theuse of predators of starfish. |
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