• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.41 no.6
• /
• pp.471-477
• /
• 2008

Development of egg, larvae and juveniles for the Pacific mackerel, Scomber japonicus are described following natural fertilization in the indoor tank of $25^{\circ}C$ water temperature. Following a routine hormone treatment technique for the brood stock, male and female mackerels were artificially matured by intramuscular injections of LHRHa at a dosage of $400{\mu}g/kg$ body weight (BW)+Domperidone at a dosage of $4{\mu}g/kg$ body weight (BW) to induce maturation in a separate aquarium and induced natural spawning. Fertilized eggs were ca. 1.0 mm in diameter; spherical in shape with a single oil globule; pelagic and non-adhesive. Hatching occurs 41 hours after fertilization at $23-24^{\circ}C$. The newly hatched larvae was 3.03 mm in average total length (ATL), the mouth and anus were not open, oil globule located in posterior end of yolk sac, and preanal length was 42.8% of TL. The larvae measuring 2.89 mm ATL, almost absorbed yolk sac and oil globule material in 2 days after hatching, in which the mouth and anus were open. Melanophores, branch or star in shape were observed on the top of head, peritoneal region and along the ventral contour. In 13 days after hatching, the larvae was 6.88 mm ATL, its posterior end of notochord began to flex upward, finfold of caudal fin appeared, jaw teeth were already formed. In 19 days after hatching, the larvae was 7.71 mm ATL completed only caudal fin rays (9+8), and preanal length was 49.4% of TL. In 37 days after hatching, the larvae was 27.4 mm ATL already completed all the fins, and preanal length was 59.9% of TL.

• Korean Journal of Ichthyology
• /
• v.17 no.3
• /
• pp.195-204
• /
• 2005

The population ecology of Rhinogobius brunneus was investigated on, tributaries of the Bukhan River from May 2003 to June 2005. The habitat was mostly a rapids area with pebbles and cobles in the lower part of the stream. The cohabitation fishes were Zacco platypus, Zacco temmincki, Microphysogobio yaluensis and Iksookimia koreensis. The males and females become sexually mature after one year. Spawning season was from May to June with water temperatures in the range $22{\sim}25^{\circ}C$. The prosperous period was from late May to early June. The average number of eggs in the ovary was $989{\pm}511$ (range, 151~2,209). The year-round sex ratio of female to male was 1 : 0.90. The total length in this population indicated that the below-40 mm group is one year old, 40~52 mm group is two years old, 52~65 mm group is three years old, and the longer-than-65 mm group is over four years old. There were no differences in total length distribution between the males and females. Nests were built up at a water depth of $13.7{\pm}5.8$ (5~31) cm and a current velocity of $9.6{\pm}4.8$ (10~19) cm/sec. Brood size (egg number) of the parental male was $1,974{\pm}1810$ (egg number = $95.022_{TL}-3507$, $r^2=0.3591$, N = 33). Newly hatched larvae that drifted downstream to the lake returned to the stream during late June to August; the smallest size in this population was 20 mm in total length.

• Korean journal of applied entomology
• /
• v.57 no.2
• /
• pp.87-95
• /
• 2018

Nosema spp. (NS) causes severe problems to honey bee colonies including the death of the highly infected ones. Searching for effective materials to control this parasite is very important. The objectives of this study were to identify the calendar for the prevalence of NS and other bee diseases, and to test the efficacy of three materials: diluted honey mixed with lemon juice (M1), chamomile extract mixed with sugar syrup (M2) and sutrivet mixed with sugar syrup (M3) against Nosema. To realize these objectives, diseases of brood and adult honey bees were surveyed over one year. Also, the efficacy of M1, M2 and M3 against Nosema was evaluated under field and laboratory conditions. The results showed that few diseases for immature and mature stages of honey bees were recorded. NS was detected during winter and spring in link with low temperature and high relative humidity. Under field conditions, M2 reduced the infection by 36.66% while M3 by 23.33% and finally M1 by 13.33%. In the laboratory, the highest efficacy was to M2 followed by M1 and finally M3. The three materials impacted the percentage of survived bees significantly higher than infected bees without any treatments over the experimental period. The study suggests the potential role of chamomile as a natural material to control NS.

• Journal of Aquaculture
• /
• v.20 no.3
• /
• pp.160-167
• /
• 2007

Embryonic and pre-leptocephalic larvae development of the eel, Anguilla japonica, are described following natural fertilization in the indoor tank of $23^{\circ}C$ water temperature. Following a routine hormone treatment technique for the brood stock, female eels were artificially matured by weekly intramuscular injections of salmon pituitary extracts (SPE) at a dosage of 20 mg/kg body weight (BW) for a total of 10-14 doses to induce ovarian maturation, while male eels received weekly intramuscular injections of human chorionic gonadotropin (HCG) at a dosage of 1 IU/g BW for a total of 6-10 doses to induce testicular maturation in a separate aquarium and induced natural spawning. Fertilized eggs of about 1.0 mm in diameter were pelagic and showed a typical discoidal cleavage. Hatching occurs 38 hrs after fertilization at a water temperature of $23^{\circ}C$. The newly hatched larvae measured about 3.0 mm in total length and the number of myomeres averages 42. Their mouths and anuses were opened at 4.5 days and the yolk sacs of the pre-leptocephalic larvae were almost absorbed at 6.5 days after hatching. Pre-leptocephalic larvae survive for 14.5 days. At this time they are $5.87{\pm}0.25mm$ in total length and have about 98 myomeres. However, morphological characterization of embryonic and pre-leptocephalic larvae were not different between natural fertilization and artificial fertilization by the dry method.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.9 no.4
• /
• pp.261-263
• /
• 1976

In 1975, a trial for channel catfish spawning was made for the first time in Korea, by stocking 11 pairs of brood fish in a $470m^2$ earthen pond provided with 5 cans of 35 cm in diameter with depths of about 60 cm as spawning nests. The same trial and another pen cage method combined with pituitary injection were practiced in 1976. All these trials failed without any spawning. On the other hand 4 females and 1 male were put in a recycling water system indoor aquarium for exhibition purpose it late spring of 1976. After removing 3 females which were injured from being bitten by the male, remaining one pair of the catfish spawned successfully in July and the most eggs developed normally. The water in the recycling system showed the pH range of 7.2 to 7.4,and mean water temperature of every 10 day period of a month gradually increased from 19.3 to 23.6C until spawning. The outdoor .ponds where the spawning was failed received water from the same origin as the indoor recycling system, and the mean temperature of every ten day period ranged Iron 17.2 to $29.8^{\circ}C$ in 1975 and 19.7 to $28.4^{\circ}C$ in 1976 these being considered well falling in the optimum range for catfish spawning, but pH ranged from 7.3 to 9.5 under the influence of photosynthesis of algae and weeds in the ponds. The high pH value may suppress the spawning of catfish as pointed out by Nelson in 1957.

• Journal of Korean Society of Forest Science
• /
• v.82 no.4
• /
• pp.406-419
• /
• 1993

In spite of the economical and sivicultural importance, tending methods of natural broad leaf tree have not been established in Korea. In the present study, the structure of crown and biomass of Quercus variabilis were analyzed to obtain the basic information on pruning practice. There was not correlated between clear length of sample tree and tree height and D.B.H. The stratum with the largest leaf and branch weight was lower part of the stratum with the largest branch increment. The degree of contribution of branch to knotless trunk production (${\Delta}{\omega}_B(Z)/{\omega}_B(Z)$ and ${\omega}_L(Z)/{\omega}_B(Z)$) decreased from the upper part to the lower part. As an example of the application of the ecological data to pruning practice, the author attempted to estimate the effect of pruning with this experimental stand. Two methods of pruning were investigated. One is the removal of branches according to a definite external indication such as clear length rate of branch, and the other is the removal of barnches according to a definite height.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.29 no.4
• /
• pp.474-480
• /
• 1996

Physicochemical changes of milt during the spermiation period were investigated in black seabream (Acanthopagrus schlegeli) reared in recirculating seawater system. The spermiation period for the milt collection in cultured brood stock was from 11 April to 4 June. During the spermiation period, average milt volume (ml/100 g body weight) was $0.70{\pm}0.33\;ml$ and maintained high level from 2 May to 4 June. The total number of stripping spermatozoa per 100 g body weight reached the maximum value $(3.32{\times}10^{10})$ in 9 May, then decreased rapidly thereafter. Spermatozoa concentration per ml reached the minimum value in 2 May. There was no change in spermatocrit for the spermiation period. Total protein, total lipid, glucose and Na concentration in spermatozoa and seminal fluid were lower than those in plasma. Total protein, total lipid and K concentration in spermatozoa were higher than those in seminal fluid. The glucose concentration in spermatozoa and seminal fluid in April and May were significantly higher than those in June.

• The Korean Journal of Pesticide Science
• /
• v.10 no.3
• /
• pp.196-200
• /
• 2006

In this study we investigated fecundity and survivorship of four staple Korean freshwater cladocerans for their whole life to develop a new standard method used for ecological risk assessment of pesticide. The tested Korean freshwater cladocerans were Daphnia obtusa, Daphnia sp., Moina macrocopa and Simocephalus vetulus. In addition, standard test species, Daphnia magna endorsed formally by the major international organizations was tested together in order to compare with the reproductive characteristics of Korean cladocerans. A total of 358 young was produced by D. magna, whereas, 297 young was reduced by Daphnia sp. throughout the entire life. The average life span of Daphnia magna was 50 days much longer than any other Korean species. Nevertheless all of the Korean water flea tested showed good fecundity, produced over 60 young for 21 days as the validation criterion for reproduction toxicity test in Ecological Effects Test Guidelines published by USEPA. Especially Moina macrocopa produced their first brood in 4 days. Therefore 10 day reproduction test with Moina macrocopa may be an alternative good method to save cost and time to elucidating the effects of hazardous substances on the reproduction of aquatic invertebrates.

• Korean Journal of Environmental Biology
• /
• v.36 no.2
• /
• pp.165-173
• /
• 2018

We sampled vomit of black-faced spoonbills(Platalea minor) during the brood-rearing season (from June 2011 to June 2014) at the Namdong reservoir in Incheon and analyzed the food components in the vomit using microscopy and next-generation sequencing (NGS). Microscopic observations primarily helped in identifying osteichthyes (bony fishes), crustaceans, and polychaetes. In particular, species belonging to the families Mugilidae and Gobiidae among the fish, and Macrophthalmus japonicas among the crustaceans, were observed at high frequency. Results of NGS analysis revealed the predominant presence of bony fish (42.58% of total reads) and crustaceans (40.75% of total reads), whereas others, such as polychaetes (12.66%), insects (0.24%), and unidentified species (3.78%), occurred in lower proportions. At the species level, results of NGS analysis revealed that Macrophthalmus abbreviates and Macrobrachium sp. among the crustaceans, and Acanthogobius hasta, Tridentiger obscurus, and Pterogobius zacalles among the bony fish, made up a high proportion of the total reads. These food species are frequently found at tidal flats in the Songdo and Sihwa lakes, emphasizing the importance of these areas as potential feeding sites of the black-faced spoonbill. Feed composition of the black-faced spoonbill, as evaluated by analyzing its vomit, differed when the evaluations were done by microscopic observation or by NGS analysis. Evaluation by microscopic observation is difficult and not error free, owing to the degradation of the samples to be analyzed; however, NGS analysis is more accurate, because it makes use of genetic information. Therefore, accurately analyzing food components from morphologically indistinguishable samples is possible by using genetic analysis.

• The Korean Journal of Zoology
• /
• v.8 no.2
• /
• pp.89-127
• /
• 1965

1. This report is on the outcome of observation made up the breeding process of Narcissus flycatcher, Muscicapa narcissina zanthopygia, using 15 ness-boxes at Seoul and Kwang Nung Experimental forest in 1964, and the relevant feeding habit was studied by the collar method of wrapping the necks of thenestlings for 50-60 minutes or more in some cases from 1963 to 1964. 2. The Narcissus flycatcheris a common summer resident throughout Korea arriving at the end of April. The earliest data of arrival of this species in Seoul, is April 26, 1964. They migrate southward from the later part of September to early part of October. 3. In a week after their arrival , they start to build nest after a brief courtship. Male and female prepare their nest ina nestboxes in 4 or 5 days. Nests are usually found in the moss, which provide definite frame-work. The inner side of the nest is usually composed of roots of Gramineae or leaves of pine, oak or other broad leave tree. 4. The laying period is generally from the later part of April to the middle of June : and the number of eggs laid is from 3 to 8 , therefore 5 in average : eggs are pink with traces of milky yellow blending of light auburn and orange red spots and chicken-egg-like in shape. 5.The incubation takes place for 7-12 days from the middle part of May to the middle of June, in the order of male and female . The hatching rate tends to increase in proportion to clutch size. 6. The feeding period usually lasts 15 days in average from the early part of June to the middle of July and the feeding urge tends to increase in proportion to brood size. 7. The animals invading into their nest-boxes are red ants, chipmunks, bees , barkbeetles and philippine red-tailed shirkes, etc. 8. On the basis of analysis covering 714 birds in 31 nests, the food they consumed during the nesting period of nestlings were mostly of animal matters composing of : insect larvae form-39. 88% insect adult form 36.26%, insect pupae-0.19%, spider-17.75% and other animal matters 5.92% , Besides a small amount of plant pieces were found . As to the insect larvae, Lepidoptera was the largest in the content followed by Hymenoptera , Orthoptera and Coleoptera. As to the insect adult, Diptera was the largest in the content followed by Coleoptera, and Hymenoptera. In view of forest protection, noxious insect was of 69.38%, useful insect 4.39%, and spider 17.75%. 9. The rich assortment of its food, the ability of acquiring various insect (adults as well as larvae), its destruction of great numbers of harmful insects , and its quick assimilation artificial nesting with the nest-boxes of 2.5-3cm entrance hole employed, allow us to conclude that the flycatcher may be successfully employed in the elimination of fores pests. The above results are only that part obtained near Seoul in the middle of Korea, however, if we would extend the scheme to other broad areas using similar techniques, the nest-boxes could not only be well used by the birds, but also it would help to prevent the increase of harmful. insects.