• Journal of the korean society of oceanography
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• v.31 no.3
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• pp.144-149
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• 1996

I investigated the predation impact by the heterotrophic dinoflagellate Protoperidinium cf. divergens on copepod eggs in the presence of co-occurring phytoplankton prey (a preferred red-tide dinoflagellate Gonyaulax polyedra) and the selective feeding on mixtures of both prey. The ingestion rates of P. cf. divergens on Egg N (unidentified round copepod eggs with a smooth surface, about 80 in diameter) decreased by only 1.7-2 times when mean G. polyedra concentration increased by 57-115 times. In mixed prey experiments, P. cf. divergens preferred Egg N over G. polyedra even at 1.1 ${\mu}g$C $ml^{-1}$ or 470 cells $ml^{-1}$ of the latter. A strong preference of P. cf. divergens for Egg N over G. polyedra can be responsible for this relatively small effect. Protoperidinium may sometimes have a considerable predation impact on the populations of Egg N even during phytoplankton blooms or red-tide periods.

• Korean journal of applied entomology
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• v.32 no.1
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• pp.61-67
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• 1993

Experiments were conducted to study the functional response of Amblyseius longispinosus Evans to egg densities (10-80) of Tetranychus urtica Koch under different egg distributions (clumped & uniform) and arena sizes (3, 9 & 16 $cm^2$). The searching success of A. longispinosus was affected by the spatial distribution and density of the prey but not by the arena size. there was a highly significant negative correlation (r=-0.85; p=0.0001) between predation amount and distances between preys. The predation response showed a type III functional response. The random predator equation satisfactorily described A. longispinosus predation. The search rate ranged from 0.1030 to 0.1504 under distribution of the prey while it ranged from 0.0546 to 0.276 under uniform distribution.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.3
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• pp.108-116
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• 2006

To investigate the factors controlling the spring population of Acartia hongi, egg production, hatching time of egg and predation pressure were measured. Egg production was maintained the superior position between winter and spring. Egg production was positively correlated with not only water temperature when water temperature was below $7^{\circ}C$ but also chlorophyll-a concentration when it was from $7^{\circ}C$ to $21^{\circ}C$. A regressive equation of development time$(D_e,\;day)$ of eggs derived from water temperature$(T,\;^{\circ}C)$ was obtained as $D_e=18.9(T-0.4)^{-1.0}$, showing longer development time at water temperature below $5^{\circ}C$. In Cross Correlation Analysis(CCA) to examine the time-lag relationship among abundances of developmental stages of A. hongi, egg production rate calculated by multiplying population egg production rate by hatching time showed more significant correlation with nauplii abundance than population egg production rate. Therefore, it suggests that hatching time is also recognized by a factor controlling formation of population and especially, in winter, high abundance of egg derived from high daily egg production rate and delayed hatch by low water temperature become the origin of initial spring population of nauplii. Egg predation by Noctiluca scintillans, suggesting a negative factor in formation of A. hongi spring population, was observed. During spring, A. hongi eggs were found in $2.9\sim21.1%$ of individuals of N. scintillans. It was deduced that $1.2\sim49.5%$ of the eggs produced by A. hongi was preyed on by N. scintillans. In conclusion, the factors controlling spring population of A. hongi were regarded as high egg production by winter generation, the delayed development time of egg by low temperature, and egg predation of N. scintillans.

• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.401-405
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• 1999

Comprehensive collecting survey were performed fer study on ovipositioning habits and developmental process of Rana temporaria dybowskii from mid February 1998 to late May 1998 from Kyunggi-do, Kangwon-do and other areas in South Korea. Oviposition occurred in both running water and pool between late February and late May. In lotic habitat, they laid egg mass in irregularly ball shaped, and eggs were sticked to substrates such as stone or macrophytes. On contrary, in the pool, they laid an oval shaped egg mass not sticked to any other substrates. Every egg was hatched at day 7, and all developmental processes were completed at days 71 after oviposition. Developmental process of this species was relatively short, and this may increase predation activities during abundant prey season.

• 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.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.461-467
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• 2012

Developmental characteristics of Geocoris pallidipennis were investigated at a constant temperature ($20{\pm}1$, $25{\pm}1$, $30{\pm}1$, $35{\pm}1$, $37.5{\pm}1$ and $40{\pm}1^{\circ}C$), under long day illumination 16:8 (L:D) and constant relative humidity ($80{\pm}10%$). From egg to adulthood, the lower developmental threshold and the effective accumulative temperature were $14.8^{\circ}C$ and 399.1 day-degree, respectively. The experimental results at $35^{\circ}C$ were as follows. The egg period was 5.6 days (hatchability: 81.1%) and the nymphal period was 14.3 days (1st: 3.2, 2nd: 2.2, 3rd: 2.7, 4th: 2.7, 5th: 3.6). Female longevity was 33.8 days and the oviposition period was 29.2 days. Total egg production was 111.2 eggs and the maximum daily egg production was 14.8 eggs (in 7th days). However, although some eggs and nymphs developed at $37.5^{\circ}C$, G. pallidipennis could not develop at $40^{\circ}C$, The total egg production at $40^{\circ}C$ was only 22.1 eggs. When G. pallidipennis was fed on Bemisia tabaci pupae, daily prey consumption by nymphs (1st, 3rd and 5th) and adults was 1.9, 7.3, 18.7 and 29.5, respectively.

• Korean journal of applied entomology
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• v.34 no.3
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• pp.234-242
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• 1995

The functional responses of the female Cyrtorhinus lividipennis on brown planthopper (BPH), Nilaparvata lugens, eggs and their predation behavior were investigated at six temperature conditions; 20, 23, 26, 29, 32, and $35^{\circ}C$. C. lividipennis was found to prefer young BPH eggs, especially 3-day-old eggs the most. The functional responses for female C. lividipennis on BPH eggs fitted the Holling's Type-I true predator-prey Rogers' (1972) model at all temperatures tested except $35^{\circ}C$ at which the negative Th value was produced. With the temperature increased up to 32$^{\circ}C$, the instantaneous attacking rate(a) increased from 0.1923 at $20^{\circ}C$ to 0.5085 at $32^{\circ}C$, while the handling time (Th) was gradually decreased as low as 0.0151 at $32^{\circ}C$. C. lividipenis preferred the BPH eggs laid on the upper part of rice stem when the BPH egg density was high, but there was no significant difference in the preference when the egg density was low. The preference was more obvious in high temperature conditions such as above 29$^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.1
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• pp.105-113
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• 1995

Seasonality in biomass and egg Production was investigated for Calanus sinicus, one of the major copepods in Asan Bay, Korea. Biomass of this species in this restricted embayment showed only one Peak in spring, but e99 Production showed two Peaks, spring (April and May) and fall (September). Average egg Productions during the spawnlng seasons were 16.3 egg/female/day (spring) and 7.6eggs/female/day (fall) with maximum egg Production of 39.0 eggs/female/day. Food concentrations in this bay measured'1 terms of particulate organic carbon (POC) were relatively high around the year, and correlation between egg Production and POC was not significant. With the food Provided sufficiently animals Produced a lot of fecal Pellets, but egg Production was ceased after several days of experiment. From these results it was believed that egg Production in this bay was influenced by food quality and feeding history rather than food concentrations. Habitat temperatures also seem to have influence on egg Production from the tacts that no egg was Produced at extreme habitat temperatures, although the correlation between the two was not significant. In this bay, two generations with different time periods seem to progress yearly. Distribution was coupled with life cycle only at certain time of the year. During the other periods predation pressure by the higher trophic levels and shift of the centers of the distributions toward deeper outer bay seemed to be responsible for the observed distribution and egg Production of this species in this bay. Comparing with the Previous reports, migration of fairly long distance and continual reproduction seemed possible for this species.

• Ocean and Polar Research
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• v.31 no.3
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• pp.277-282
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• 2009

Saunders' gulls (Laurs saundersi) which are listed as globally vulnerable species on the IUCN Red List are distributed in East Asia and breed mainly in China and Korea. Their population is estimated to be between 7,100 to 9,600. Songdo reclaimed lands in the western coast of South Korea are the main breeding sites for these species. However, most of these breeding sites have been seriously disturbed in the last several years because of new urban development constructions. This study was conducted to provide baseline data on the breeding ecology of Saunders' gulls. Since 1998, the breeding population has rapidly increased in South Korea, with the number of nests rising from 85 nests in 2000 to 185 nests in 2005. Egg volume is more variable than breadth or length. Clutch size, hatching and breeding success were $2.9{\pm}0.81$ (n=182, mean$\pm$sd.), 48.07% (75 hatched egg/156 eggs) and 29.08% (155 fledglings/533 eggs), respectively. Factors affecting breeding failure were predation, rainfall, starvation and supernormal clutches. These results are provided along with other cited literature to argue for conservation of Saunders' gulls.

• Korean journal of applied entomology
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• v.36 no.4
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• pp.311-316
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• 1997

This study was conducted to evaluate the effect of temperatures on the egg and nymphal development andadult longevity of green mirid bug, Cvrtorhinus lividipennis Reuter. In addition, predation on eggs of brownplanthopper, Nilupurvurcz lugens ~t:l and small brown planthopper, L~orlelphux .striatellus Fallen by C.lividipennis were studied at different temperatures. Hatchability of C. lividipennis was about 96% at 23"C,88% at 26"C, 75% at 29$^{\circ}$C and 64% at 32$^{\circ}$C. Egg duration of C. lividipmnis was 1 1.0 days at 23"C, 10.0 at26"C, 6.7 days at 29$^{\circ}$C and 5.6 days at 32$^{\circ}$C. Nymphal duration of C. 1i1~idiperzni.ws as 13.7 days at 23"C,12.7 days at 26$^{\circ}$C. 10.2 days at 29$^{\circ}$C and 9.1 days at 32$^{\circ}$C regardless of food sources. Nymphaldevelopment was the shortest at 4th instar and the longest at 1st instar irrespective of temperatures and foodsources. Adult longevity of C. livirlipennis was was about 22.0 to 23.5 days at 23$^{\circ}$C. 19.0 to 20.0 days at26"C, 16.0 to 17.0 days at 2Y0C, and 1 1.0 to 12.0 days at 32$^{\circ}$C. There was no significant difference in adultlongevities on food sources. Number of eggs comsumed by adult C. lividipennis were about 56 to 61 and 56to 57,56 to 60 and 47 to 49,43 to 46 and 40 to 42, and 28 to 30 and 26 to 27 at 23'C. 20$^{\circ}$C. 29$^{\circ}$C and 32"C,respectively. Egg consumption by adult C. lividiprrznis was slightly higher at female and on N. lugens eggthan at male and on L. striatellus egg. Dail 2.0 to 3.0 eggs were consumed by adult C. lividipc,nni.s.ail 2.0 to 3.0 eggs were consumed by adult C. lividipc,nni.s.