• Animal cells and systems
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• v.7 no.4
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• pp.345-348
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• 2003

The effects of acute acid stress on hatching success and hatching period of laboratory-reared hermaphroditic fish Rivulus marmoratus were examined. The effects of acute acid toxicity on mortality was also determined in three life stages of this fish. There was a significant negative effect of acid stress on hatching performance in the R. marmoratus embryos. The hatching success was only 5% at pH 3.5 compared to over 78% at pH higher than 4.0. The hatching period was also delayed by low pH treatments. The larval and juvenile stages were more sensitive to acid toxicity on mortality than the adult stage, but larvae and juveniles showed similar sensitivity. The 96-h LC50 value was pH 3.8 in larval and juvenile stages and pH 3.3 in adult stage.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.415-424
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• 2015

This research was conducted to reveal the characteristics of breeding ecology of oriental scops owl (Otus sunia stictonotus) inhabiting in South Korea according to the nest types during the breeding season from march to October for two years (2011 and 2012). Oriental scops owl nested in woodpecker's nest holes (46.1%), natural tree holes (38.5%), and artificial wood boxes (15.4%). These nests were located on following trees: Zelkova serrata, Paulownia coreana, Celtis sinensis, Salix chaenomeloides, Salix babylonica, Fraxinus rhynchophylla, Robinia pseudoacacia and Platanus occidentalis. The hatching success was 91.4%, fledging success was 83.0%, and breeding success was 75.9%. The factors of the breeding failure were falling (57.1%), abandonment (28.6%), hatching failure (7.1%), and others with unknown cause of death (7.1%). According to nest types, the fledging success (69.2%) of woodpecker's nest holes were low and the hatching success (79.2%) of natural tree holes were also low due to hatching failure and abandonment. However, hatching success, fledging success, breeding success were high in the artificial nests as all the eggs hatched and succeeded in fledging. Therefore, we suggested that artificial nests can cover the weaknesses of natural nests as well as increasing the breeding success. However, long-term research on installation place, height, and hole sizes of the artificial nest are required in order to clearly reveal the effects on the breeding success of oriental scops owl.

• Journal of Ecology and Environment
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• v.29 no.1
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• pp.35-39
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• 2006

During the breeding seasons in 2002 and 2003, the influences of vegetation cover on breeding processes of Black-tailed Gulls (Laurs crassirostris) were studied on Hongdo Island. We checked dutch sizes, calculated hatching success and survival rates on day 15 and a vegetation cover, There was significant positive relationship between vegetation cover and hatching success, and survival on day 15. In order to analyze the relationship, sample nests were categorized as 'exposed' and 'covered' nests, and the breeding processes at each nest were compared. Hatching success and survival on day 15 in covered nests were significantly higher than ones in exposed nests. However, in clutch size, there was no significant difference. The rate of the hatching and survival failure was different amongst the categorized nests. The primary cause of hatching failure in covered and exposed nests was 'disappeared', and the primary causes of survival failure on day 15 were 'disappeared' and 'killed by adults'. The failure in exposed nests was significantly larger than that of covered nests. In the breeding of Black-tailed Gulls on Hongdo Island, vegetation cover influenced the survival of eggs and chicks as the cover provided shelter against predators and extreme weather.

• Journal of Ecology and Environment
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• v.31 no.3
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• pp.201-206
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• 2008

This study was conducted to determine clutch size and habitat usage of Kentish plovers (Charadrius alexandrinus) breeding on Sinja-do lslet in the Nakdong Estuary from 22 April to 12 July in 1995 and from 21 April to 20 June in 1996. The Kentish plover preferred grasslands and damp sands to dry dunes as nesting sites. The difference in hatching success among these microhabitats was attributed to high tides, which washed away many nests on damp sands, and strong winds, which frequently shifted the sand to bury eggs on dry dunes. The main mortality factor in grasslands was predation by magpies Pica pica. Each clutch contained one to four eggs, with a mode of three eggs. Hatching success was highest in two-egg clutches and lowest in one- and four-egg clutches. The mean interval for egg laying was 1.8 days between the first and second eggs and 2.1 days between the second and third eggs. The average incubation period was about 24.2 days.

• Journal of Aquaculture
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• v.14 no.1
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• pp.17-27
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• 2001

Effects of temperature (10, 12, 14, 16, 18 and 2$0^{\circ}C$) and salinity (22.0, 24.5, 27.0, 29.5, 32.0 and 34.5 ppt) were studied on incubation period, hatching success, survival and growth of alevin and juvenile seabass, L. japonicus. Embryonic development was accelerated with increasing temperature but it was not influenced by salinity. Hatching success was the highest at 14$^{\circ}C$ and 34.5 ppt. Higher temperature also accelerated the development of mouth opening, absorption of yolk and oil globules, and alevin growth. Survival of the 5-day old Juvenile was accelerated in the following order : 14<16<18<20<12$^{\circ}C$. Rearing experiment of the juvenile for 30-day indicated the faster growth at 13, 20 and 27 ppt than at 34 ppt.

• Ocean and Polar Research
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• v.28 no.2
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• pp.201-207
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• 2006

We studied variation in clutch size, hatching, fledging and breeding success of the Black-tailed Gull (larus crassirostris) at Hongdo Island, which supported the largest breeding colony of the species, in South Korea in 1997 and 2000 to 2003. Cluck size was recorded in 1,388 nests and breeding success was estimated in 83 nests. Mean clutch size was 1.89 t 0.65. A total of 63.9% of the eggs hatched and 53.5% of the chicks survived until fledged. Breeding success was 34.2%. Causes of breeding failure were eggs missing (14.9%), rotten eggs (15.5%) and predation (2.4%) during the incubation period and chicks missing(35.8%), starvation (7.4%) and pecked chicks (3.2%) during the chick rearing period. In 2002, the main causes of breeding failure were eggs missing (17.2%) and rotten eggs (6.9%) during the incubation period and missing chicks (15.5%), starvation (3.5%) and pecked chicks (6.9%) during the chick rearing period. Most chick mortality occurred within three days after hatching.

• Korean Journal of Environment and Ecology
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• v.22 no.1
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• pp.59-65
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• 2008

This study is mainly focused on the mating of 9 couples of Eagle Owl Bubo bubo habitating in Paju, Ganghwa Island, Icheon, Sihwa Lake, Chungju. For this study, from 2005 to 2007, regular filming and mornitoring for the breeding ecology and copulation behavior of 9 couples of Eagle Owl in the nest and near area had been done. Clutches ranged in size from one to four eggs but averaged 2.27 eggs(n=15), hatching success rate was 71 %(n=34) and fledgling success rate was 83%(n=23). Through the filming and mornitoring, it was found that Eagle Owl continued to copulate each other even after hatching and kept its copulation until the chicks left their nest($7\sim8$ weeks after hatching). This copulation behaviour without fertilization seems to be done for confirming, maintaining and strengthening of pair-bond by the necessity of both male and female, and to aim at stable breeding of their chicks.

• Korean Journal of Environmental Biology
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• v.38 no.4
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• pp.625-633
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• 2020

The effects of temperature and salinity on egg development and settlement of the ascidian Herdmania momus were investigated. Adult specimens were collected from the Dodu Yacht facility in Jeju Island, Korea(33°30'30.54"N, 126°27'55.46"E) in August 2018. Egg development and larval settlement were observed and recorded at 8 h intervals using a stereomicroscope, under nine temperature (10, 13, 16, 19, 22, 25, 28, 31, and 34℃), and four salinity regimens (28, 30, 32, and 34 psu). The highest hatching rate (82.8±7%) was observed at 32 psu and 25℃ and the lowest hatching rate (1.0±2%) was at 34 psu and 13℃. The developmental rate (0.222±0.0994) was highest at 28 psu and 28℃, and lowest (0.016±0.008) at 30 psu and 13℃. The highest settlement success rate (77.1±5%) was at 32psu and 25℃ and the lowest(0.1±1.0%) was at 30psu, and 13℃. The rate of settlement(0.080±0.000) was highest at 28psu and 28℃, and lowest(0.013±0.000) at 30psu and 13℃. Both hatching and settlement success rates increased as temperature increased and tended to decrease beyond an optimal temperature range. Herdmania momus preferred 30-34 psu salinity and 22-25℃ temperature. This study provides baseline information about the life history of H. momus, and important data to control the damage caused by the increase in number and distribution of this invasive ascidian.

• Journal of Life Science
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• v.19 no.11
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• pp.1611-1616
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• 2009

This study was conducted to determine the characteristics in breeding of the little tern Sterna albifrons in Shinja-do and Doyo-Deung in Nakdong estuary. The data was obtained in the middle and late 1990's and in the mid 2000's, which were analysed for the breeding information of the little tern. In Shinja-Do, a total of 638 nests were observed in 1995, and the average numbers of eggs laid per nest were 2.48. In 2004 and 2005, 94 and 456 nests were observed, and the average number of eggs laid per nest was 2.16 and 2.53, respectively. There was a significant difference between the average numbers of eggs laid per nest for the 3 respective years. In Doyo-Deung, a total of 269 nests were observed in 1998, and the average number of eggs laid per nest was 2.16. In 2004 and 2005, 1,023 and 1,123 nests were observed, and the average numbers of eggs laid per nest were 2.33 and 2.52, respectively. There was a significant difference (p<0.001) between the average number of eggs laid per nest as well. Hatching success rate by nesting site in Shinja-Do was calculated in 1995. Type A nest (nest located on dry sand land) showed a 56.8% success rate, and type B nest (nest located on the land with dwarf grass), type C nest (nest located on moist land) and type D nest (nest located on the land with shells) showed 55.3%, 36.6% and 59.3% success rates, respectively. The average hatching success rate in Shinja-Do was 54.5%. The most crucial factor for hatching failure was flood, especially, for the type C nests. The hatching success rate by the nesting site in Doyo-Deung showed an average of 73.2%. It was high in type D nest (83.8%) and type A nest (75.9%), and low in type C nest (59.7%). Again, the most crucial factor for hatching failure was flood, especially, for the type C nests. Nakdong estuary has been through many changes over time, particularly in recent. Therefore, continuous efforts to keep it a breeding place for the little tern are urgently required, including overall management of land, protection of reef and sand, etc.

• Journal of fish pathology
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• v.20 no.3
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• pp.257-267
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• 2007

The hypo-salinity effects on fertilized eggs, embryos and larvae were investigated in olive flounder (Paralichthys olivaceus) obtained from hatcheries in Cheju-Island, Yeosu and Chungnam. Those were treated to eight concentration; 0, 3.4, 6.7, 10.1, 13.4, 20.2, 27.4 and 33.6 ‰. It was not discrepancy in the survival rate and hatching success rate of fertilized embryos obtained from different regions. Also, in the larvae, the regional difference was not appeared. The survival rate and hatching ability of embryos significantly diminished in the lower groups than 13.4 ‰ compared to 33.6 ‰. After fertilization, namely embryos are tolerant of a wide range of salinity (13.4 - 33.6 ‰). Reduced salinity induced an increase of the malformed embryo and larvae including various deformities; irregular embryos membrane (or yolk sac depression), fin erosion and swim bladder inflation in the flounder embryo. The hatching success of embryos was significantly reduced in lower salinity than 13.4 ‰. Notably, the reduction of larval survival rate significantly was observed in ≤10.1 ‰ treated groups with the same manner of survival rates of the embryos. Additionally, olive flounder was found to be adequate model for measuring external impulses because there are no the regional differences.