• Title/Summary/Keyword: Chuuk

Search Result 36, Processing Time 0.027 seconds

Histological Observations of the Female Reproductive Cycle of Honeycomb Grouper, Epinephelus merra in Chuuk (Chuuk에 서식하는 Honeycomb Grouper, Eplinephelus merra 암컷의 생식주기)

  • Song Young Bo;Park Yong Ju;Takemural Akihiro;Kim Han Jun;Choi Myun Sik;Choi Young Chan;Lee Young Don
    • Development and Reproduction
    • /
    • v.7 no.1
    • /
    • pp.23-28
    • /
    • 2003
  • The seasonal reproductive cycle of the female honeycomb grouper, Epinephelus merra, inhabiting Chuuk was examined by histological observations of the ovaries. The gonadosomatic index (GSI) began to increase in February and peaked in March. Histological observations revealed many oocytes laden with yolk in the ovaries from March to April. From June to January, the ovaries were occupied by immature oocytes. These results suggest that the reproductive season of E. merra in Chuuk is from March through April.

  • PDF

Reproductive Condition of the Tropical Blacklip Pearl Oyster, Pinctada margaritifera (Linnaeus 1758) from Chuuk Lagoon, Federated State of Micronesia during the Summer Months in 2003 (Chuuk Lagoon에 서식하는 흑진주조개, Pinctada margaritifera (Linnaeus 1758)의 2003년 하계 생식소 발달 및 산란 특성)

  • Kang, Do-Hyung;Park, Heung-Sik;Yi, Soon-Kil;Choi, Kwang-Sik
    • Ocean and Polar Research
    • /
    • v.27 no.3
    • /
    • pp.351-358
    • /
    • 2005
  • Reproductive condition of the tropical blacklip pearl oyster, Pinctada margaritifera collected during the period July through September 2003 from Chuuk Lagoon, Federated State of Micronesia was investigated using histology. The level of gonad development for each pearl oyster was determined with an average score of five microscopic fields, and the average score was used as the maturity index (ML). All wild pearl oysters collected in July did exhibit fully ripe eggs in their ovaries ($45{\sim}50{\mu}M$ in diameter), indicating that they were ready for spawning. In mid August most wild pearl oysters were in spawning and M1 dropped dramatically from mid- to late September, suggesting that the wild pearl oyster completed spawning during this period. In contrast, the cultivated pearl oysters collected in mid-September held ripe eggs in the ovaries and only a few of them spawned, indicating that gonad maturation of the cultivated pearl oyster was somewhat slower than that of the wild pearl oyster in Chuuk Lagoon during the summer period. Histological analysis also indicated that spawning of the pearl oyster is rather incomplete and they may spawn continuously during summer.

Echinoderm Fauna of Chuuk, The Federated States of Micronesia

  • Lee, Taekjun;Shin, Sook
    • Animal Systematics, Evolution and Diversity
    • /
    • v.30 no.2
    • /
    • pp.108-118
    • /
    • 2014
  • Micronesia is an island nation located north of Papua New Guinea in the Pacific Ocean. A survey was conducted on Chuuk, which is one of the four main islands of Micronesia, from 11-25 Nov 2012. Echinoderms collected at one intertidal area as well as at 16 SCUBA diving points of 10-40 m depths in the subtidal zone were identified based on morphological characteristics. In total, 35 species from 165 individuals were identified: two crinoids, eight asteroids, four ophiuroids, seven echinoids, and 14 holothuroids. Among them, one asteroid, one ophiuroid, one echinoid, and two holothuroids were newly recorded from Micronesia.

Reproductive Cycle of Top Shell, Trochus niloticus in Chuuk Island, Micronesia (Micronesia Chuuk Island에 서식하는 Top shell, Trochus niloticus의 생식주기)

  • Jin, Young-Seok;Park, Yong-Ju;Kim, Han-Jun;Na, Oh-Soo;Song, Young-Bo;Lee, Chi-Hoon;Choi, Myun-Sik;Rho, Sum;Lee, Young-Don
    • The Korean Journal of Malacology
    • /
    • v.20 no.1
    • /
    • pp.65-73
    • /
    • 2004
  • Gametogenesis, changes of gonad bulk index (GBI), monthly variation in oocyte diameter, reproductive cycle and spawning with lunar cycle of the top shell, Trochus niloticus were investigated by histological examination. The specimens were sampled in the coastal waters of Chuuk Island, Micronesia, form November 1999 to September 2000. T. niloticus is a gonochorism, and the female and male were present in an approximately 1:1 ratio (p > 0.05). The ovary contained with the oocyte of yolk stage, the testis composed of the spermatid and spermatozoa at around the year. Monthly GBI were higher at February, March, April and June than the other months. Major spawning occurred between April and May, and June and July but the individuals of partially spawning were presented throughout the year. GBI with lunar cycle were higher at the full moon than the other lunar phase. These results suggest that the spawning occurred between the full moon and last quarter moon.

  • PDF

Mesozooplankton Community in the Chuuk Lagoon of the Federated States of Micronesia (마이크로네시아 축 주의 석호환경 내 동물플랑크톤 군집: 종조성 및 개체수)

  • Kang, Jung-Hoon;Kim, Woong-Seo;Cho, Kyu-Hee
    • Ocean and Polar Research
    • /
    • v.27 no.4
    • /
    • pp.463-476
    • /
    • 2005
  • Mesozooplankton samples were collected to investigate the spatial distribution in the Chuuk lagoon of the Federated States of Micronesia through three surveys from 2002 to 2004. Average temperature was $28.70^{\circ}C$ in August 2002, $30.17^{\circ}C$ in October 2003 and $29.18^{\circ}C$ in July 2004 at a water depth of 2rn. Average salinity was 33.95 psu in August 2002, 33.56 psu in October 2003 and 33.77 psu in July 2004. Total rnosozooplankton consisted of 70 taxa during the study period, among which copepods were the most diverse group. Foraminiferans, radiolarians, copepods and appendicularians, which comprised about 70% of total zooplankton abundance, were important components in the zooplankton community. Within the copepod group, Acartia spp., Centropages spp. and Undinula spp. were dominant in August 2002, Acartia spp., Centropages spp., and Oithona spp. in October 2003, and Acartia spp., Undinula spp., and Oithona spp. in July 2004. Total zooplankton abundance was high around Weno Island, while low in stations located in the northern part of Weno Island. High abundances of appendicularians were found in the southern part of weno Island as well as around Weno Island. Appendicularians foraminiferans, radiolarians, Sagitta spp. and immature copepods accounted for most of the distribution pattern of the mesozzoplankton community throughout the study area. These results suggest that appendicularians may be potential food items for fish larvae around Weno Island in the Chuuk lagoon states.

Eight New Species of Genus Coscinoderma (Demospongiae: Dictyoceratida: Spongiidae) from Chuuk Island, The Federated States of Micronesia

  • Sim, Chung Ja;Kim, Young A
    • Animal Systematics, Evolution and Diversity
    • /
    • v.30 no.4
    • /
    • pp.248-259
    • /
    • 2014
  • This paper describes eight new species of the genus Coscinoderma from Chuuk Island, the Federated States of Micronesia. This genus is characterized by very fine, meandering uncored secondary fibres. All the new Coscinoderma species are compared with eight other valid species from tropical regions. Coscinoderma folium n. sp. is characterized by its large thickly foliate shape, and cored primary fibres are easily found between secondary fibres in choanosome. Coscinoderma lacium n. sp. differs in having round conules and no cored primary fibres. Coscinoderma cavernosa n. sp. is distinguished from other species by its cavernous shape and long sharp conules. Coscinoderma wenoa n. sp. is characterized by long conules and primary fibres. Coscinoderma mappula n. sp. differs in having a thick sand crust in the choanosome. Coscinoderma bakusi n. sp. is characterized by having several oscules at the top of the sponge and color changed grey to dark brown in alcohol. Coscinoderma pollax n. sp. is characterized by having a small thumb shape. Coscinoderma truki n. sp. similar to C. pollax in shape but differs in cored primary fibres with many spicules.

Observations on some mangrove-associated algae from the western Pacific (Guam, Chuuk, Kosrae, and Pohnpei)

  • West, John A.;Kamiya, Mitsunobu;Loiseaux de Goer, Susan;Karsten, Ulf;Zuccarello, Giuseppe C.
    • ALGAE
    • /
    • v.28 no.3
    • /
    • pp.241-266
    • /
    • 2013
  • The mangrove algal flora of Guam and the Federated States of Micronesia has been poorly explored. We add to our knowledge of this region by observations of collections from these regions. This paper presents new and additional records of: Rhodophyta-Acrochaetium globosum, Colaconema sp., Caulacanthus indicus, Bostrychia moritziana / B. radicans, B. radicosa, B. simpliciuscula, B. kelanensis and B. tenella, Murrayella periclados, and Caloglossa ogasawaraensis; Chlorophyta-Boodleopsis carolinensis; and Phaeophyceae-Dictyota adnata, Dictyotopsis propagulifera, and Canistrocarpus cervicornis. Most specimens were cultured to investigate their reproductive biology and many specimens were further identified using molecular data. Low molecular weight carbohydrates (dulcitol, sorbitol, and digeneaside) were identified in samples of B. radicosa and B. simpliciuscula. We also present data on manganese-rich deposits found on B. simpliciuscula and B. tenella in culture, possibly formed by epiphytic bacteria.

Physical Oceanographic Characteristics between Hawaii and Chuuk Observed in Summer of 2006 and 2007 (2006년과 2007년 여름에 관측한 Hawaii-Chuuk 사이의 물리특성)

  • Shin, Chang-Woong;Kim, Dong-Guk;Jeon, Dong-Chull;Kim, Eung
    • Ocean and Polar Research
    • /
    • v.33 no.spc3
    • /
    • pp.371-383
    • /
    • 2011
  • To investigate the physical characteristics and variations of oceanic parameters in the tropical central North Pacific, oceanographic surveys were carried out in summer of 2006 and 2007. The survey periods were classified by Oceanic Ni$\tilde{n}$o Index as a weak El Ni$\tilde{n}$o in 2006 and a medium La Ni$\tilde{n}$a in 2007. The survey instruments were used to acquire data on CTD (Conductivity Temperature and Depth), XBT (Expendable Bathythermograph), and TSG (Thermosalinograph). The dominant temporal variation of surface temperature was diurnal. The diurnal variation in 2007, when the La Ni$\tilde{n}$a weather pattern was in place, was stronger than that in 2006. Surface salinity in 2006 was affected by a northwestward branch of North Equatorial Current, which implies that the El Ni$\tilde{n}$o affects surface properties in the North Equatorial Current region. Two salinity minimum layers existed at stations east of Chuuk in both year's observations. The climatological vertical salinity section along $180^{\circ}E$ shows that the two salinity minimum layers exist in $2^{\circ}N{\sim}12^{\circ}N$ region, consistent with our observations. Analysis of isopycnal lines over the salinity section implies that the upper salinity minimum layer is from intrusion of the upper part of North Pacific Intermediate Water into the lower part of South Pacific Subtropical Surface Water and the lower salinity minimum layer is from Antarctic Intermediate Water.

Species Composition of Fish from Sea Grass Bed in Chuuk Lagoon, Micronesia (마이크로네시아 축 환초내 잘피밭의 어류 종조성)

  • Choi, Young-Ung;Yoon, Kon-Tak;Lee, Dae-Won;Kim, Taihun;Kim, Yoonchil;Park, Heung-Sik
    • Ocean and Polar Research
    • /
    • v.35 no.4
    • /
    • pp.441-452
    • /
    • 2013
  • The fish species composition of seagrass bed in Chuuk Lagoon, Micronesia, was investigated every month from August 2009 to July 2011, using a seine net for fish caught. A total of 32 fish species belonging to 18 families under 6 orders were identified during the study period. Of these fish, Atherinomrus lacunosus, and Strongylura incise were the major dominant species representing 85.0% in total number of individuals. The number of species and individuals were high from August to December 2009, 2010. The biomass was highest in September 2010 and the diversity index was higher in September 2009, April, August 2010 and July 2011. The 14 dominant species could be divided into 2 groups of 3 individuals based on appearance patterns; (1) resident species and temporal species (9 species, e.g. Atherinomrus lacunosus), juvenile and adults living in seagrass beds and juveniles living only in seagrass beds; (2) temporal species (2 species, e.g. Hemiramphus lutkei), juveniles living only in seagrass beds; (3) temporal species (3 individuals, e.g. Caranx sexfasiatus). For some species, the appearance patterns were affected by water temperature. However, the relationships between sea currents, salinity, tide, and structure of fish assemblage remain unclear. Further studies that regularly monitor sea grass habitats are necessary to clearly understand the correlation between environmental factors and sea grass habitat use patterns in fish assemblages.

Annual Reproductive Cycle of the Neon Damselfish Pomacentrus coelestis, in Chuuk Lagoon, Micronesia (Micronesia, Chuuk Lagoon에 서식하는 파랑돔(Pomacentrus coelestis)의 생식년주기)

  • Kim, Han-Jun;Han, Jeonghoon;Hur, Sung-Pyo;Lee, Kyun-Woo;Choi, Young-Ung
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.54 no.2
    • /
    • pp.180-187
    • /
    • 2021
  • This study was conducted to investigate the reproductive characteristics of the Neon damselfish Pomacentrus coelestis in Chuuk lagoon (7°27' N, 151°53' E), Micronesia, Equatorial Pacific Ocean. The specimens used in this study were collected from August 2009 to September 2010 from around the coral reef area at a depth of 3-10 m in the northwest coast of Weno Island. Overall, 228 individuals were collected over 14 months from this area, of which 115 were females and 108 were males. Among 108 males, 30 were found to be hermaphrodites and the sex of 5 individuals could not be determined. The overall sex ratio was approximately 1.06:1 (female:male), and the ratio of sexually active individuals was 0.79:1. The gonadosomatic index (GSI) fluctuated and showed the highest value of 8.43±1.21 in December 2009 and the lowest value of 3.36±0.71 in September 2009 in sexually active females. Males showed the highest GSI value of 2.64±0.93 in June 2010 and the lowest value of 0.35±0.06 in July 2010. Based on the fluctuation of GSI, the trends in the appearance of monthly sexually active individuals, and biopsy of the gonads, P. coelestis was found to be a hermaphrodite species of protogynous type and is considered to be reproductively active throughout the year.