Research Of Grazing Selectivity Of Several Intertidal Shellfishes To Diet Microalgae Based On FQ-PCR Technique

The effects of several microalgae on growth of four juvenile intertidal shellfishes (Tegillarcagransa Linnaeus, Cyclina sinensis Gmelin, Scapharca subcrenata Lischke and Sinonovaculaconstricta Lamarck) widely cultivated in the industry of shellfish artificial breeding was studied bythe ecology experiments. And the dietary effects of several microalgae on the four juvenile int-ertidal shellfishes were identified. Four representative diet microalgae (Chaetoceros calcitrans,Isochrysis galbana, Tetraselmis helgolandica and Nannochloropsis oculata) were selected andused for the grazing selective experiments. It was researched that changes of the content of4microalgae at different time points in the grazing process of four juvenile shellfishes combinedwith FQ-PCR technique. And the relationship of different grazing selectivity of the four juvenileintertidal shellfishes among four diet microalgae was confirmed.It was found in the study of dietary effects in different microalgae that different microalgaehave different effects on the same juvenile shellfishes, and the same microalgae also have differenteffects on different juvenile shellfishes. It was suitable for enlage cultivation as quality diet ofIsochrysis galbana and Chaetoceros calciterans for the good dietary effects they showed on the allfour j-uvenile intertidal shellfishes. However, the dietary effect of Nannochloropsis oculata wasbad on t-he four juvenile intertidal shellfishes, and it was just suitable for small-scale cultivationbut not good to expanding culture as a main microalgae used in the industry of shellfish artificialbreeding.The study of grazing selectivity of the four juvenile shellfishes showed that it was positive co-rrelation between the dietary effects of microalgae and the above-mentioned four kinds of shellfis-hes, and it had nothing to do with the cell granularity of diet microalgae. In the four juvenile shell-fishes, it had a strongest grazing selective effect on Isochrysis galbana of the Cyclina sinensisGmelin, while the other three juvenile shellfishes on the Chaetoceros calcitrans. The study also fo-und that it had a stronger grazing selective effect on Isochrysis galbana than Tetraselmis helgolan-dica in the grazing process of Scapharca subcrenata Lischke and Sinonovacula constricta Lama-rck when lacking the Chaetoceros calcitrans which was top priority grazed by the two juvenile sh-ellfishes. The phenomenon was not turned up in Tegillarca gransa Linnaeus and Cyclina sinensisGmelin that it had a grazing selective effect on the suboptimum diet microalgae when lacking the easiest grazed microalgae. In addition, it was showed on Nannochloropsis oculata with the worstdietary effect that the four juvenile shellfishes exert "minor grazing" or even "refuse grazing". Itwas suggest that the juvenile shellfish had a poor ability to grazing the diet with a bad dietary effectif the microalgae of high quality were rich in the grazing environment, and even excreted in the fo-rm of spurious excrement.