Genomic DNA from the muscle of marsh clam (Corbicula leana)from Gochang was extrected in order to identify genetic differences and similarity by randomly amplified polymorphic DNAs-polymerase chain reaction. 3.28 of the 23.0 polymorphic bands per lane were found to be polymorphic in marsh clam. Also, about 4.34% of total polymorphic bands were either specific to marsh clam. The major common bands of 0.28 kb generated by primer OPB-15 (GGAGGGTGTT) were present in every individuals, respectively, which were polymorphic. This common bands which present in every individuals should be diagnostic of specific strains, species and-or their relatedness. Primer OPB-19 (ACCCCCGAAG) produced the highest number of specific bands, which was 12. The specific minor band of 0.07 kb was present in lane 22, which were polymorphic. Especially, only a specific band (1.35kg) identifying individuals was observed in lane 22.

Out of 20 primers, 6 generated a total of 1,11 major and minor RAPD bands, producing approximately 4.2 average polymorphic bands pe primer in shortnecked clam (Ruditapes philippinarum) population from Anmyeondo. The bandsharing value altered form 0.15 to 0.74, with the average of 0.5, as calculated by bandsharing analysis. The RAPD profiles obtained with DNAs of two populations from Anmyeondo and Seocheon, respectively, were considerably different (0.20 and 0.51, respectively). The varying degrees of difference among populations may also be of relevance to the retricted hybridization of wild bivalve. Besides gene mapping and breeding applications, PCR-RAPD system could be very useful for the rapid certification and quality control of seed production and for every projects based on PCR amplification of specific bivalve DNA fragments.

To investigate the food organisms of the Tridentiger trigonocephalus during the juveniles stage, the stomach contents of fish, captured in the intertidal zone of Chungchongnam-do Sochon-gun Su-myon Dodun-ri getween on early June from end of May 1999, were observed. Total length of the juveniles of T. trigonocephalus was 5.5mm∼9.0mm size, and the participation rate of feeding was 68.5%. Main food organisms were such as copepods, shrimp larvae, polychaete larvae, and these occupied more than dry weight 2%. Copepods among them dominated the most quantitys by average 67.5%, and next, food organismsms appeared much by order of polychaete larvae and shrimp larvae etc.. Therefore, most important food organisms of juvenile stage of T. trigonocephalus were copepods, polychaete larvae, shrimp larvae etc.