ISSN : 1225-3480
The purpose of this study was to examine various cryoprotective agents (CPAs) and diluents on post-thaw motility and fertility of Haliotis discus hannai sperm based on movable sperm ratio (MSR), sperm activity index (SAI), fertilization and hatching rate. To evaluate the optimal CPA for cryopreservation of H. discus hannai sperm, the sperm was diluted in three extenders (sea water filtered, 1 M glucose, 1 M, sucrose) containing one of three CPAs (dimethty sulfoxide [DMSO], glycerol [G], ethylene glycol [EG]) at the concentration of 1, 2.5, 5, 10, 20%, and then frozen in programmable freezer. Sperm diluted with sea water containing 2.5% DMSO had the best post-thaw MSR (40.0 ± 2.9%), SAI (3.3 ± 0.1%), fertilization rate (50.8 ± 15.0%) and hatching rate (76.5 ± 4.5%).
Polydora spp., which bores and burrows into the shells of bivalves may inhibit the growth and/or increase the mortality of commercially important shellfish, Crassostrea gigas. The purpose of this study was to examine the changes of commercial value and cellular immunological function in Pacific oyster, C. gigas according to the Polydora spp. infestation grade. The condition index was decreased with higher infestation grade. In cellular immune response analysis, phagocytosis was increased with higher infestation grade although there were no significant differences in adhesion and viability. In conclusion, infestation by Polydora spp. could be an indirect factor if accompanied by disease and/or environmental contamination rather than directly related to the death of oyster.
This study was executed to obtain information on the sex ratio, sexual group maturity, fecundity and main spawning period necessary in the management of the fisheries resources of Octopus minor in Korea. The sex ratio (female:male) of O. minor was 1:1.15 (female 46.4%) illustrating higher ratio of male. The mantle length of 50% sexual group maturity by using logistics model was analyzed to be 3.6 cm and 5.6 cm for female and male, respectively. The absolute fecundity was analyzed to be average 124.4 per individual. The relative fecundity was analyzed to be 14.2 for 1 cm in mantle length and 0.9 for 1 g in total weight. The gonadsomatic index (GSI) was the highest in April (7.80) and October (2.17) for female and male, respectively. The gonad displayed seasonal histological changes, and the main spawning period of O. minor was April-May.
This study was conducted to investigate the effect of shellfish farming on benthic community structure. The characteristics of benthic environment and macrobenthic community were studied at 13 oyster farms in three bays (Gamak, Goseong and Jaran Bay). Sediment samples were collected at the center and edge of each farm and control stations, considering the distance from the facilities. Acid Volatile Sulfide (AVS), Total Organic Carbon (TOC), number of species and macrofaunal density were slightly higher in center stations and decreased with distance from the farms, indicating that shellfish farming had a possibility of making some changes in benthic ecosystem at least directly under the facilities. The dominant species were polychaete Lumbrineris longifolia and Aphelochaeta monilaris, bivalve Theora fragilis and amphipod Sinocorophium sinensis in most of the stations. Especially, Capitella capitata appeared more prominently in some center stations. However, for benthic health index, there were no great differences among stations, which implied that impact of shellfish farming was not so significant as to deteriorate ecological quality of benthic ecosystem.
Cristaria plicata is enlisted as an endangered wild species class Ⅰ under the Red data list of National Institute of Biological Resources, South Korea. In this study, we have attempted to do molecular phylogenetic analysis by using metallothionein (CpMT) gene of C. plicata. The complete CpMT cDNA sequences were obtained from unigenes (analyzed NGS transcriptome data) of C. plicata. We used Illumina Hi-Seq 2500 next-generation sequencing platform to characterize the transcriptome resources of C. plicata. De novo analysis using the Trinity program and TGICL clustering resulted in the number of 374,794 (276,264,683 bp) unigenes. CpMT sequences were 210 bp coding for a protein 70 amino acid residues using sixpack (EMBOSS package) and genscan software. Multiple sequence alignment and phylogenetic analysis were performed by MEGA7 software. Molecular phylogenetic analysis indicates that CpMT has similarity with various mollusks such as Hyriopsis cumingii and Unio tumidus (Order Unionoida).
Starting from November 2013 to April 2015, collection of sediments as well as biological specimen was carried out at 45 sampling stations to understand inhabitation and distributional pattern of species belonging to Class Caudofoveata in coastal waters of Korea. The results indicated that 1, 1, 8 species belonging to Class Caudofoveata were collected with a range of 10 mm in length and those were identified as Scutopus sp. (Family Limifossoridae). This finding was meaningful in that 2 species in total belonging to Family Limifossoridae were found besides Chaetoderma japonicum which was previously identified. Most Scutopus sp.-K collected in this study was appeared at the depth of 150-160 m in the eastern part of the sea off the south coast in Korea, especially in the depth of 1,600 m in the eastern part and 90 m in the western part of the sea. Therefore, it can be concluded that Scutopus sp.-K was distributed at the range of 90-1,600 m in depth and sediments where the species in habit had 00 . in the mean grain size.
Five species of Muricid molluscs collected from the Korean waters were identified as Coralliophila bulbiformis (Conrad, 1837), Coralliophila erosa (Roding, 1798), Mipus arbutum (Woolacott, 1954), Vokesimurex rectirostris (Sowerby II, 1841) and Mancinella echinulata (Lamarck, 1822). This is the first record from the Korea, providing a description of the species with illustration for the shell morphology. Including the present new records, the family Muricidae contained 23 genera and 46 species in the Korean waters.
