• ALGAE
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• 제36권1호
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• pp.25-36
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• 2021

The mixotrophic dinoflagellate Tripos furca causes red tides in the waters of many countries. To understand its population dynamics, mortality due to predation as well as growth rate should be assessed. Prior to the present study, the heterotrophic dinoflagellates Noctiluca scintillans, Polykrikos kofoidii, Protoperidinium steinii, and mixotrophic dinoflagellate Fragilidium subglobosum were known to ingest T. furca. However, if other common heterotrophic protists are able to feed on T. furca has not been tested. We explored interactions between T. furca and nine heterotrophic dinoflagellates and one naked ciliate. Furthermore, we investigated the abundance of T. furca and common heterotrophic protists in coastal-offshore waters off Yeosu, southern Korea, on Jul 31, 2020, during its red tide. Among the tested heterotrophic protists, the heterotrophic dinoflagellates Aduncodinium glandula, Luciella masanensis, and Pfiesteria piscicida were able to feed on T. furca. However, the heterotrophic dinoflagellates Gyrodiniellum shiwhaense, Gyrodinium dominans, Gyrodinium jinhaense, Gyrodinium moestrupii, Oblea rotunda, Oxyrrhis marina, and the naked ciliate Rimostrombidium sp. were unable to feed on it. However, T. furca did not support the growth of A. glandula, L. masanensis, or P. piscicida. Red tides dominated by T. furca prevailed in the South Sea of Korea from Jun 30 to Sep 5, 2020. The maximum abundance of heterotrophic dinoflagellates in the waters off Yeosu on Jul 31, 2020, was as low as 5.0 cells mL-1, and A. glandula, L. masanensis, and P. piscicida were not detected. Furthermore, the abundances of the known predators F. subglobosum, N. scintillans, P. kofoidii, and Protoperidinium spp. were very low or negligible. Therefore, no or low abundance of effective predators might be partially responsible for the long duration of the T. furca red tides in the South Sea of Korea in 2020.

• Ocean and Polar Research
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• 제28권3호
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• pp.305-315
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• 2006

In order to examine the transition of zooplankton community by the Saemangeum sea dyke, the temporal and spatial distribution of zooplankton community with relation to environmental variables was investigated using data collected in 2004 and 2005. Sixty-one zooplankton taxa were identified. Average abundance (except Noctiluca scintiliam) ranged from 236 to 1810 indiv. $m^{-3}$, and was the highest in May 2005 and the lowest in february 2005. Dominant species were Acartia hongi and Paracalanus indicus, and cirripedia nauplii and zoea were dominant groups. After the closure of the 4th sea dyke, brackish species such as Tortanus derjugini and Pseudodiaptomus inopinus are widely distributed while the abundance of N. scintillans decreased in the northern area inside the dyke. In canonical correspondence analysis (CCA) for examining the relationships among zooplankton, stations and environmental variables, the northern area inside the dyke was distinguished from the other areas and was represented by Acartia spp, and brackish copepods.; Also, this area was characterized by high chlorophyll a concentration and COD, and low diversity.

• 한국수산과학회지
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• 제55권2호
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• pp.154-170
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• 2022

The zooplankton composition, abundance, community structure, and species diversity in the major commercial fishery species spawning grounds in the southern coast of Korea were investigated in this study. A total of 80 taxa were sampled, with the mean abundance range of 5,612-11,720 ind. m^-3 and the mean biomass range of 41.6-1,086.8 mg m^-3. The dominant species were Paracalanus copepodites, Paracalanus parvus s. l., Oithona copepodites, Paracalanus nauplii, Noctiluca scintillans, Oithona similis, and Ditrichocorycaeus affinis. The species diversity indices were highest in August, suggesting that diversity is influenced by neritic and oceanic warm-water species. A cluster analysis with non-metric multidimensional scaling (nMDS) revealed three groups of zooplankton communities. The April and May samples clustered into Group A, having the highest mean total zooplankton abundance and lowest species diversity, consisting mainly of temperate species located in the middle region of the southern coast of Korea. Cluster Group B was from the early summer season (June) and contained the highest species diversity with some oceanic and neritic zooplankton species. Cluster Group C from the summer season (July and August) mainly comprised P. parvus s. l. and O. similis. The redundancy analysis (RDA) indicated that abundance is positively correlated with salinity, and chlorophyll-a concentrations.

• 수산해양기술연구
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• 제22권4호
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• pp.1-20
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• 1986

Physical, chemical and biological surveys on Nakdong River estuary were made from October, 1985 to September, 1986. 1. For all the seasons except summer, the sea surface temperature in northwest area of the line which linked from Seo Island to Jisim Island was I-2$^{\circ}$C lower than in southeast area, but in summer the sea surface temperature in northwest area was I-2$^{\circ}$C higher than in southeast area. On the contrary, bottom temperature of coastal area was 1$^{\circ}$C higher than that of oceanic area except winter. 2. Surface salinity in summer and fall has minimum value of 1. 9%0 and maximum value of 32.9%0. This large variation was caused by the runoff of the Nakdong River. Effect of less saline Nakdong River water in northwest area of the line which linked from Seo Island to Jisim Island was greater than in southeast area. A strong current rip always formed near this line. 3. The yellowish-green colored zone was observed in the Nakdong River estuary throughout the year by influence of river discharge. The characteristics of the water quality in the zone have shown that the water color was grade 7 by the Forel water-color meter, transparency was less than 4 m, and concentration of suspended solids was more than 5 mg/1. This water body was in the state of eutrophication in terms of chlorophyll-a and inorganic nitrogen concentration during summer season. 4. During the study period, total 276 taxa were identified. Most of them were diatoms and dinoflagellates which consisted of 97.5%. The component ratio of the above two groups was 84.4% and 13.1 % respectively. Diatoms were plentiful in December and dinoflagellates in July. Dominant species were Nitzschia seriata in October, Thalassiosira rotula in December, Skeletoncma costatum in April, and Nitzschia longissima in July. 5. A total of 47 zooplankton taxa was identified from the samples collected. Copepods were numerically the most important components of zooplankton communities in the study area. The domir:ant copepod species were Paracalanus parvus, Acartia clausi and Temora turbinata. Noctiluca scintillans was the next important component. The other zooplankton with minor abundance were Cladocera. Sagitta spp., Cnidaria, Mysidacea, Lucifer spp. and Amphipoda. 6. During the study period, fishes from 47 families and 87 species were sampled in th~ study area. The four most abundant fish species were Rep~mucen//'s valencicnnei, Leiognathus n~cha!is, Amblychaeturicllthys hexanema and Sardirel/a zun:zsi. The fish species of the secondary importance in abundance were Cynoglossus joyneri, Sillago sihama, Engra~lis japonicus, Encdrias nebulos'l, Acanthogobius flavimanus, Trichiurus lepturus, LiParis tanai/ai, Cynagloss//'s interruptus, Aj)ogon line:z!us, Thrissz la 1l.'1la!ensis, and Limanda yokohamac.

• 대한원격탐사학회지
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• 제33권2호
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• pp.213-230
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• 2017

위성기반 적조 탐지 알고리즘들은 특정 해역, 적조 종을 중심으로 개발되어 왔다. 하지만 한반도 주변해역의 빠르고 정확한 적조 감시를 위해서는 한반도 주변의 전 발생 해역과 다양한 적조 종을 대상으로 한 연구가 필수적이다. 본 연구에서는 한반도 주변해역을 대상으로 GOCI 영상을 활용하여 적조 영역의 스펙트럼 특성과 위성기반 적조 탐지 알고리즘의 적합성을 분석하였다. 그 결과, 적조 종들의 클로로필 함량과 적조가 출현하는 해역의 탁도에 따라서 스펙트럼 특성이 달라졌다. 또한 기존 적조 탐지 알고리즘을 GOCI 영상에 적용하였으며, 이를 통해 기존 임계값으로는 적조 영역 추출에 한계가 있음을 알 수 있었다. 이를 개선하기 위해 적조 종들을 클로로필 함량의 차이에 따라 두 그룹으로 나누어 적조 감시 체계를 제시하였다. 총 5 단계를 거쳐 적조 영역과 비적조 영역을 구분하였으며, 적조 속보를 기준으로 했을 경우 최종 추출된 적조영역이 기존 알고리즘으로 추출된 영역에 비해 적절한 결과를 나타냈다. 이러한 적조 감시 체계를 활용한다면 한반도 주변의 모든 해역과 다양한 적조 종에 대한 빠르고 정확한 감시로 인해 효율적인 적조 감시가 가능할 것이다.

• 한국해양환경ㆍ에너지학회지
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• 제9권2호
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• pp.109-119
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• 2006

2001년 가을철 대발생 시기에 인위적으로 상승 첨가된 동물플랑크톤이 식물플랑크톤에 미치는 영향을 파악하기 위해 중형폐쇄생태계를 이용한 연구가 남해안의 장목만에서 연구되었다. 2500리터 용량의 폴리에틸렌 백 4개에 현장 해수를 채운 후, 현장에서 플랑크톤 네트(망목: $300{\mu}m$)로 수직 예인하여 얻은 동물플랑크톤 시료를 이용하여 실험 구가 대조구보다 6배 높도록 조성하였다. 연구기간동안 대조구와 실험구 폐쇄생태계 간의 식물플랑크톤 군집에서는 유의한 차이가 없었다(one-way ANOVA, p>0.05). 대조구와 설험구에서 배양 초기 높은 값을 나타낸 식물플랑크톤의 현존량 및 엽록소-a는 실험 종료시까지 급속히 감소하였다. 식물플랑크톤 군집을 대표한 우점 분류군은 규조류로서 Skeletonema costatum, Pseudo-nitzschia seriata, Chaetoceros curvisetus, Ch. debilis, Cerataulina pelagica, Thalassiosira pacifica, Cylindrotheca closterium과 Leptocylindrus danicus로 구성되었다. 배양 10일째에 대조구와 실험구에서 최대를 나타낸 야광충은 중형동물플랑크톤 총 개체수 변화를 주도한 최 우점종 이었고, 다음으로 우점한 분류군으로 배양 7일째에 최대를 나타낸 요각류였다. 배양초기에는 인위적 첨가로 인해 실험구안의 요각류 개체수가 대조구에 비해 높았으나, 이후에는 실험 종료 시까지 뚜렷한 차이가 없었다. 이는 젤라틴성 동물플랑크톤의 조절에 의한 것으로 여겨지며, 실험구내의 유즐동물과 메듀사의 개체수와 길이분포가 대조구에 비해 높았던 점이 이를 뒷받침한다. 그런데 초식자인 요각류의 개체수가 상위포식자에 의해 감소한 후 식물플랑크톤 현존량이 다시 증가하는 연쇄효과가 나타나지 않았다. 이는 주요 초식자인 요각류 Acartia erythraea가 식물플랑크톤을 효과적으로 조절하지 못하고 있음을 의미하며, 그 이유로 A. erythraea의 낮은 초식률, 식물플랑크톤의 빠른 침강으로 인한 조우 기회 감소, 그리고 질소결핍 환경으로의 변화에 의한 것으로 판단된다.