Gwangyang Bay, a semi-closed water channel, has habited various shellfish species and has been much influenced because of introduction from Sumjin River and sewage discharge from Gwangyang City, as well as enriched nutrients from industrial complex. We have determined the analysis of long-term monitoring data in water qualities including nutrients in Gwangyang Bay during 1987-2010, except for 1991, 1995, 1996, 1998, 2002 and 2003 of which these years do not enough water quality data to analysis in this study. In May, June, July, August, September and October were carried out the analysis of temperature, salinity, DO, transparency, SS, DIN, DIP, COD, Chl-a, and ocean climate. Temperature, salinity, DO, DIN, DIP, COD were analyzed in surface and bottom. These water parameters were showed in yearly fluctuations, in particular, salinity and DIN were a significant difference between surface and bottom based on One-way ANOVA because of intensive precipitation and irradiation in summer. However, the period of summer is the highest number of larvae in shellfish which possibly has increased their mortality because of osmotic pressure from freshwater. Higher SS and lower transparency were associated with decreasing the photosynthesis in phytoplankton, but higher Chl-a in this study was possibly contributed to more introduction of pico or nano-phytoplankton than that of commonsize phytoplankton. Consequently, it is necessary for long-term monitoring in Gwangyang Bay to produce a sustainable shellfish farming and maintain marine eco-system.
The present study was performed reviewing references determine the infection status of Korean freshwater fishes and relation with climate change of Korean peninsula. The most common infections of Korean freshwater fishes are flatworms (trematodes) and spiny-headed worms (acanthocephalans). Total 61 species of Korean freshwater fishes for infectious disease has been reviewed. Among them, 44 species of freshwater fish belong to Cyprinidae and 17 species for Cobitidae, Siluridae, Bagridae, Amblycipitidae, Synbranchidae, Centropomidae, Odontobutidae, Belontiidae, and Channidae. The Korean freshwater fishes had total 35 kinds of parasite pathogenic organisms (Acanthocephala opsariichthydis, Centrocestus sp., Cyathocotyle sp., Diplostomum orientale, Diplostomum sp., Echinochasmus sp., Echinostoma sp., Genarchopsis sp., Holostephanus metorchis, Metacercaria hasegawai, Metagonimus sp., Metorchis taiwanensis, Neoplagioporus zacconis, Palliolisentis chinanensis, Palliolisentis chunjuensis, Prosorhpynchus sp., Centrocestus armatus, Clonorchis sinensis, Holostephanus nipponicus, Metorchis orientalis, Cyathocotyle orientalis, Pseudexorchis major, Exorchis oviformis, Trachelobdella sinensis, Metagonimus miyata, Isoparorchis hypselobagri, Clinostomum complanatum, Centrocestus asadai, Metagonimus yokogawai, Echinostoma cinetorchis, Echinochasmus japonicus, Diplozoon nipponicum, Metagonimus takahashii, Carassotrema koreanum, and Echinostoma hortense). Maximum infections belonged to Pseudorasbora parva as Cyprinidae had 19 kinds of parasite organisms, including Centrocestus armatus, Clinostomum complanatum, Clinostomum complanatum, Clonorchis sinensis, Cyathocotyle orientalis, Echinochasmus japonicus, Exorchis oviformis, Holostephanus metorchis, Holostephanus nipponicus, Metacercaria hasegawai, Metagonimus yokogawai, Metorchis orientalis, Metorchis taiwanensis, Pseudexorchis major, Cyathocotyle sp., Diplostomum sp., Echinochasmus sp., Metagonimus sp. and Prosorhpynchus sp. Human foodborne trematode infections are an important public health concern in Korea. In the future, under the climatic extremes on Korean peninsula such as floods, drought and temperature variability, in particular, the susceptibility of freshwater fishes to infection will be decreased.
The distribution of dissolved oxygen (DO) and its variability in Chunsu Bay were studied. Monthly hydrographic survey and realtime monitoring for water quality conditions were carried out in study area. Vertical distribution of DO shows the formation of hypoxia in the bottom water in the vicinity of the artificial dyke and net cage aquaculture site in summer. Annual mean of DO was 8.4 mg/l, with minimum monthly mean of 6.9 mg/l in July and maximum of 11.2 mg/l in March. Temporal variation of DO at bottom water around the net cage aquaculture site shows pronounced oscillatory characteristics with range of 0.5~7.0 mg/l. Coherency analyses between the tidal range and DO concentration shows that variation of DO is significantly coherent with tidal range at semi-diurnal period with 1~3.5 hours phase-lags. A simple DO budget model was set up to account for the formation of the extreme hypoxic conditions in Chunsu Bay. The governing equation is based on the mass-balance for kinetic process with simplified parameter of source and sink terms of DO. the source term is represented by replenishment through the vertical and horizontal diffusion and mixing. the sink terms comprise function of sediment oxygen demand (SOD) and carbonaceous biochemical oxygen demand (CBOD). The result of numerical solution indicates the dominant role of SOD as the overriding factor against the oxygen supply.
This study was conducted to survey the habitat selection by the Eastern Bean Goose Anser fabalis in the Upo wetland, Changnyeong gun. South Korea from October 2004 to March 2005. The mean number of Eastern Bean Geese was 2,104 individuals during the study period. The minimum number of about 100 individuals was observed in October 2004, and the maximum number of about 3,000 individuals was observed in November 2004 and January 2005. Fourteen sites were classified with respect to water depth and dominant food plant types, and the number of geese using the 14 sites was recorded every week. The sites that were mainly used were S-2 in Sajipo and Z-1 in Jjokjibeol in October, S-2 and S-4 in November, sites U-2 in Upo and Z-1 in December, sites U-2 and S-4 in January and February, and sites U-2 and Z-1 in March. Three aquatic plants, Scirpus fluviatillis, Trapa japonica, and Zizania latifolia were the main food for geese in the Upo wetland. We determined the monthly habitat selection indexes (Jacob’s index) for the three habitat types, which were classified according to three aquatic plant species. The habitat selection index of the area where Zizania latifolia predominated from October to February had the highest score of 0.40~0.47 among the three habitat types. This indicated that Bean Geese strongly preferred the habitat where Zizania latifolia predominated from October to February. By contrast, the habitat where Scirpus fluviatillis predominated was selected mainly in March. Faecal samples were collected randomly at the six sites mainly used by the geese each month. Zizania latifolia predominated in faeces from October to November, but the proportion of Scirpus fluviatillis and Trapa japonica in faeces increased from December to February.
Among 3,358 islands in Korea, about eighty five percentage of them are uninhabited islands. Concerning this, Ministry of Land, Transport and Maritime Affairs (MLTM) has been seeking to settle the fundamental policy on the preservation, the utilization, and the development of the uninhabited islands and to search the proper types of management suitable for the specialities by inhabited islands. As part of such research, we participated the humanities and social science research from May 2012 to January 2013 by MLTM intended for 171 uninhabited islands in Mokpo City, Yeosu City, Jindo-Gun, and Shinan-Gun of Jeollanam-Do for the purpose of the effective management and utilization of the uninhabited islands. First of all, in this treatise, we report the results of the humanities and sociological research about nine uninhabited islands nearby Gakyeo island in Shinan-Gun of Jeollanam-Do.
This study was conducted to evaluate the feeding value of black soldier fly pupa (BSFP) on fecal microorganism, immunoglobulinm egg quality and egg production laying hens. One hundred twenty laying hens were assigned to 4 treatments (0, 5, 7 and 10% BSFP) with 3 replicates for 8 weeks. The formulae of 4 experimental diets were modified to contain 18% CP and 2,900 kcal/kg. All the treated groups differed in feed intake, egg production, egg weight and egg mass compared to those of a control group. The egg weight and production were increased (p < 0.05) in BSFP groups compared to the control. The HDL-C was increased (p < 0.05) in BSFP groups compared to the control. The level of immunoglobulin IgG and Haugh unit were increased (p < 0.05) in BSFP groups compared to the control. These result suggested that the addition of BSFP to the layer diet could improve the egg quality and the laying performance.
Yellow tea thrip (Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) is anthophilous pests of many crops worldwide including five flavor berry. And the mealy bug (Pseudaulacaspis cockerelli (Cooley) (Hemiptera: Diaspididae)) is one of the hardest pests to control. Its body is covered with white waxy threads, which often make a chemical pest control useless. Five flavor berry (Schisandra chinensis Baill) is used in traditional Chinese medicine. So, the development of biological control against the major pest on five flavor berry is of great interest. In this work, a treatment of Chrysoperla nipponensis (Okamoto) was applied to five flavor berry fields infested by P. cockerelli and a treatment of Amblyseius swirskii Athias-Henriot was applied to two types of five flavor berry fields infested by S. dorsalis. Even though our tests found significant differences between the two culturing method(sod culture, nonwoven type mulching), the treatment of biological control agents decreased or a little increased the fruit damage, which was comparable to the chemical insecticide treatment. In the sod culture experiment, thrip population was significantly low and increased at a lower rate than in the nonwoven type mulching. It may be suggested from these results that A. swirskii and C. nipponensis as IPM program and sod culture could be incorporated into the integrated pest management system on five flavor berry.
Biological control of Pseudococcus comstocki (Kuwana) with new indigenous natural enemy (Chrysoperla nipponensis (Okamoto)) was carried out on tropical plant (Trachycarpus fortunei (Hook)) from May to July in 2013. Control experiments were conducted at Tropical Plant Resources Research Center of Korea National Arboretum, Pocheon, Korea. Chrysoperla nipponensis was released once (20 larvae/m2) to control Pseudococcus comstocki on 11st May in 2013. We investigated the density of leaf-feeding P. comstocki at intervals of approximately 7 days after introducing their natural enemy, C. nipponensis. The densities of P. comstocki were suppressed 22.4% (after 4 weeks) and 8.2% (after 6 weeks) after introducing C. nipponensis.
We measured the grain size and metallics elements (Li, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg, Pb, Fe and As) of surface sediments collected from 27 sampling sites in the Abalone aquaculture. The concentration range and average value of metallics elements were also below the sediment quality guidelines (TEL). As the pollution level was estimated by using enrichment factor (Ef) and index of geoaccumulation (Igeo), the enrichment factor (Ef) was about 1 for most of metallic elements were smaller than 1. However Arsenic (As) had highest value of 2.35. Index of geoaccumulation (Igeo) for the metallic elements (As, Pb and Mn) were ranged Igeo-class 0 (practically unpolluted) and most metallics elements (Li, V, Cr, Fe, Co, Ni, Cu, Zn, Cd, Hg and Fe) were ranged Igeo-class 0~2, indicating that the pollution levels of metallic elements should not be significant. It is necessary to keep monitoring pollution level in Abalone aquaculture to conserve the blue belt.