• Journal of the korean society of oceanography
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• 제37권2호
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• pp.76-81
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• 2002

I investigated whether US naval pulp wastes (pulverized paper products), which is planned to be dumped into offshore waters, may affect the ecology of major components of marine zooplankton. The presence of slurry (0.6% concentration - wet weight ; wet weight) did not significantly affect the population growth rates of the heterotrophic dinoflagellate Polykrikos kofoidii fed on Lingulodinium polyedrum, but significantly reduced the ingestion rates of the calanoid copepods Acartia spp. on L. polyedrum and those of the copepod Calanus pacificus on Akashiwo sanguinea (previously Gymnodinium sanguineum). However, C. pacificus, originally exposed to 0.6% slurry for 24 hour, can recover its feeding rates when slurry disappears. Therefore, if slurry is diluted quickly due to trubulence after being dumped at 0.6% concentration, its presence may not affect Calanus. Chemicals leached from slurry did not affect the feeding rate of Calanus. Therefore, mechanical interference by slurry on the feeding and/or swimming of copepods may be mainly responsible for the reduction of the ingestion rates.

• Ocean and Polar Research
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• 제31권3호
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• pp.265-276
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• 2009

Acartia hongi is the most dominant and widespread planktonic copepod in Gyeonggi Bay, Yellow sea. Ingestion rates and selectivity of A. hongi on phytoplankton and planktonic ciliates were determined in the laboratory. Ingestion rates of A. hongi on planktonic ciliates and phytoplankton increased in proportion to prey concentration increase. When A. hongi was fed with various mixture combinations of planktonic ciliates and phytoplankton, their ingestion rate on ciliates tended to increase as the percentage of ciliates in prey biomass increased. Clearance rate of A. hongi on planktonic ciliates was higher than for phytoplankton in all experiments without regard to relative percent of ciliate biomass. This trend suggests that A. hongi was preferentially preying on planktonic ciliates. Under mixed prey availability, it is likely that selective feeding and higher clearance rate of planktonic ciliates by A. hongi is related to the higher nutritional value of ciliates compared to phytoplankton. Therefore, our results suggest that selective ciliate feeding by A. hongi will positively benefit its growth and abundance, and as a result negatively impact the population dynamics of planktonic ciliates in Gyeonggi Bay.

• ALGAE
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• 제38권1호
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• pp.57-70
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• 2023

The mortality rate of red-tide dinoflagellates owing to predation is a major parameter that affects their population dynamics. The dinoflagellates Ansanella granifera and Ansanella sp. occasionally cause red tides. To understand the interactions between common heterotrophic protists and A. granifera, we explored the feeding occurrence of nine heterotrophic protists on A. granifera and the growth and ingestion rates of the heterotrophic dinoflagellate Gyrodinium dominans on A. granifera as a function of prey concentration and those of Oxyrrhis marina at a single high prey concentration. The heterotrophic dinoflagellates Aduncodinium glandula, G. dominans, Gyrodinium moestrupii, Luciella masanensis, Oblea rotunda, O. marina, Polykrikos kofoidii, and Pfiesteria piscicida and the naked ciliate Strombidium sp. were able to feed on A. granifera. With increasing mean prey concentrations, the growth and ingestion rates of G. dominans feeding on A. granifera rapidly increased and became saturated or slowly increased. The maximum growth and ingestion rates of G. dominans on A. granifera were 0.305 d^-1 and 0.42 ng C predator^-1 d^-1 (3.8 cells predator^-1 d^-1), respectively. Furthermore, the growth and ingestion rates of O. marina on A. granifera at 1,700 ng C mL^-1 (15,454 cells mL^-1) were 0.037 d^-1 and 0.19 ng C predator^-1 d^-1 (1.7 cells predator^-1 d^-1), respectively. The growth and ingestion rates of G. dominans and O. marina feeding on A. granifera were almost the lowest among those on the dinoflagellate prey species. Therefore, G. dominans and O. marina may prefer A. granifera less than other dinoflagellate prey species. The low mortality rate of A. granifera may positively affect its bloom formation.

• Journal of Preventive Medicine and Public Health
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• 제47권1호
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• pp.7-17
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• 2014

Risk assessment considers the situations and characteristics of the exposure environment and host. Various physiological variables of the human body reflects the characteristics of the population that can directly influence risk exposure. Therefore, identification of exposure factors based on the Korean population is required for appropriate risk assessment. It is expected that a handbook about general exposure factors will be used by professionals in many fields as well as the risk assessors of the health department. The process of developing the exposure factors handbook for the Korean population will be introduced in this article, with a specific focus on the general exposure factors including life expectancy, body weight, surface area, inhalation rates, amount of water intake, and soil ingestion targeting the Korean population. The researchers used national databases including the Life Table and the 2005 Time Use Survey from the National Statistical Office. The anthropometric study of size in Korea used the resources provided by the Korean Agency for Technology and Standards. In addition, direct measurement and questionnaire surveys of representative samples were performed to calculate the inhalation rate, drinking water intake, and soil ingestion.

• ALGAE
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• 제35권3호
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• pp.263-275
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• 2020

Water temperature is known to affect the growth and feeding of marine dinoflagellates. Each dinoflagellate species grows well at a certain optimal temperature but dies at very cold and hot temperatures. Thus, changes in water temperatures driven by global warming and extremely high or low temperatures can affect the distribution of dinoflagellates. Yihiella yeosuensis is a mixotrophic dinoflagellate that can feed on only the cryptophyte Teleaulax amphioxeia and the chlorophyte Pyramimonas sp. Furthermore, it grows fast mixotrophically but rarely grows photosynthetically. We explored the direct and indirect effects of water temperature on the growth and ingestion rates of Y. yeosuensis feeding on T. amphioxeia and the growth rates of T. amphioxeia and Pyramimonas sp. under 7 different water temperatures (5-35℃). Both the autotrophic and mixotrophic growth rates of Y. yeosuensis on T. amphioxeia were significantly affected by temperature. Under the mixotrophic and autotrophic conditions, Y. yeosuensis survived at 10-25℃, but died at 5℃ and ≥30℃. The maximum mixotrophic growth rate of Y. yeosuensis on T. amphioxeia (1.16 d^-1) was achieved at 25℃, whereas the maximum autotrophic growth rate (0.16 d^-1) was achieved at 15℃. The maximum ingestion rate of Y. yeosuensis on T. amphioxeia (0.24 ng C predator^-1 d^-1) was achieved at 25℃. The cells of T. amphioxeia survived at 10-25℃, but died at 5 and ≥30℃. The cells of Pyramimonas sp. survived at 5-25℃, but died at 30℃. The maximum growth rate of T. amphioxeia (0.72 d^-1) and Pyramimonas sp. (0.75 d^-1) was achieved at 25℃. The abundance of Y. yeosuensis is expected to be high at 25℃, at which its two prey species have their highest growth rates, whereas Y. yeosuensis is expected to be rare or absent at 5℃ or ≥30℃ at which its two prey species do not survive or grow. Therefore, temperature can directly or indirectly affect the population dynamics and distribution of Y. yeosuensis.

• ALGAE
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• 제29권2호
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• pp.153-163
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• 2014

Mesodinium rubrum is a cosmopolitan ciliate that often causes red tides. Predation by heterotrophic protists is a critical factor that affects the population dynamics of red tide species. However, there have been few studies on protistan predators feeding on M. rubrum. To investigate heterotrophic protists grazing on M. rubrum, we tested whether the heterotrophic dinoflagellates Gyrodiniellum shiwhaense, Gyrodinium dominans, Gyrodinium spirale, Luciella masanensis, Oblea rotunda, Oxyrrhis marina, Pfiesteria piscicida, Polykrikos kofoidii, Protoperidinium bipes, and Stoeckeria algicida, and the ciliate Strombidium sp. preyed on M. rubrum. G. dominans, L. masanensis, O. rotunda, P. kofoidii, and Strombidium sp. preyed on M. rubrum. However, only G. dominans had a positive growth feeding on M. rubrum. The growth and ingestion rates of G. dominans on M. rubrum increased rapidly with increasing mean prey concentration < $321ngCmL^{-1}$, but became saturated or slowly at higher concentrations. The maximum growth rate of G. dominans on M. rubrum was $0.48d^{-1}$, while the maximum ingestion rate was 0.55 ng C $predator^{-1}d^{-1}$. The grazing coefficients by G. dominans on populations of M. rubrum were up to $0.236h^{-1}$. Thus, G. dominans may sometimes have a considerable grazing impact on populations of M. rubrum.

• ALGAE
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• 제29권2호
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• pp.137-152
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• 2014

Mixotrophic protists play diverse roles in marine food webs as predators and prey. Thus, exploring mixotrophy in phototrophic protists has emerged as a critical step in understanding marine food webs and cycling of materials in marine ecosystem. To investigate the feeding of newly described mixotrophic dinoflagellate Ansanella granifera, we explored the feeding mechanism and the different types of species that A. granifera was able to feed on. In addition, we measured the growth and ingestion rates of A. granifera feeding on the prasinophyte Pyramimonas sp., the only algal prey, as a function of prey concentration. A. granifera was able to feed on heterotrophic bacteria and the cyanobacterium Synechococcus sp. However, among the 12 species of algal prey offered, A. granifera ingested only Pyramimonas sp. A. granifera ingested the algal prey cell by engulfment. With increasing mean prey concentration, the growth rate of A. granifera feeding on Pyramimonas sp. increased rapidly, but became saturated at a concentration of $434ngCmL^{-1}$ (10,845 cells $mL^{-1}$). The maximum specific growth rate (i.e., mixotrophic growth) of A. granifera feeding on Pyramimonas sp. was $1.426d^{-1}$, at $20^{\circ}C$ under a 14 : 10 h light-dark cycle of $20{\mu}Em^{-2}s^{-1}$, while the growth rate (i.e., phototrophic growth) under similar light conditions without added prey was $0.391d^{-1}$. With increasing mean prey concentration, the ingestion rate of A. granifera feeding on Pyramimonas sp. increased rapidly, but slightly at the concentrations ${\geq}306ngCmL^{-1}$ (7,649 cells $mL^{-1}$). The maximum ingestion rate of A. granifera feeding on Pyramimonas sp. was 0.97 ng C $predator^{-1}d^{-1}$ (24.3 cells $grazer^{-1}d^{-1}$). The calculated grazing coefficients for A. granifera feeding on co-occurring Pyramimonas sp. were up to $2.78d^{-1}$. The results of the present study suggest that A. granifera can sometimes have a considerable grazing impact on the population of Pyramimonas spp.

• 한국해양학회지:바다
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• 제10권1호
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• pp.19-30
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• 2005

강화도 장화리의 펄 갯벌에 서식하는 저서 원생동물 군집의 계절 분포 및 섭식률을 파악하기 위하여 2002년 4월부터 2004년 4월까지 총 3개의 정점을 선정하여 2-3개월 간격으로 조사를 수행하였다. 저서 원생동물의 현존량과 생물량은 섬모충류와 종속영양 편모류에 의해 98% 이상 우점하여 나타났으며, 그 외 종속영양 와편모류와 아메바 그룹이 일부 시기에 관찰되었으나 중요하지 않은 그룹으로 나타났다. 종속영양 편모류의 현존량과 탄소량은 각각 $0.2-5.9{\times}10^5\;cells\;cm^{-3}$와 $0.02-9.2\;{\mu}C\;cm^{-3}$로 분포하였으며, 생물량은 춘계와 추계에 비교적 높은 분포를 보였다. 종속영양 편모류는 표충 2.5 mm 이내에서 다른 층에 비해 높은 분포를 보였으며, 종속영양 편모류의 수평적 분포는 정점별로 차이가 없는 것으로 나타났다. 종속영양 편모류는 $10{\mu}m$이하의 크기에 의하여 주로 우점하여 나타났으나, 2월과 4월 사이에 $20{\mu}m$ 이상의 종속영양 유글레나가 높게 출현하였다 섬모충류의 현존량과 생물량은 각각 $0.1-17.8{\times}10^3\;cells\;cm^{-3}$와 $0.02-9.1\;{\mu}gC\;cm^{-3}$ 범위로 분포하였으며 춘계와 추계에 높은 분포를 보였다. 섬모충류 그룹은 주로 하모류에 의해 우점 하였으며, 계절별로 두드러진 우점 종들은 관찰되지 않았다. 섬모충류의 수직적 분포는 표층 2.5 mm이내에서 높은 분포를 보였으며, 정점별 분포는 조간대 상부 정점에 비해 조간대 하부 정점에서 높은 분포를 보였다. 섬모충류의 시.공간적 분포는 저서 미세조류의 생물량 분포와 유사한 양상을 보였다. 조사기간동안 저서 원생동물 그룹의 탄소량은 섬모충류에 의해 평균 66%의 높은 우점률을 보였으며, 저서 원생동물의 계절변동은 저서 미세조류의 변동과 유사한 양상을 보였다. 본 연구에서 저서 원생동물의 섭식률을 측정한 결과 박테리아 생산력과 저서 미세조류 생산력의 각각 13.4-40.7%와 20.1-36.4%를 제거하였으며, 박테리아에 대한 섭식률은 섬모충류에 비해 종속영양 편모류에 의해 더 높은 것으로 나타났다. 박테리아와 돌말류에 대한 저서 원생동물의 섭식률은 춘계에 가장 높았으며 저서 미세생물 먹이 망에서 저서 원생동물은 미세생물 군집의 생물량이 높은 춘계에 박테리아와 돌말류의 포식자로서 중요한 역할을 하고 있음을 시사하였다.

• 한국환경보건학회지
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• 제43권5호
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• pp.438-445
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• 2017

Objectives: The purpose of this study was to develop exposure factor data for the Korean child population, with a specific focus on behavior characteristics such as hand-to-mouth and object-to-mouth and an analysis of influential factors. Methods: We divided environments into two places, which were house/indoor and nursery. A total of 400 children (house/indoor) and a total of 162 children (nursery) were recruited from the cities of Seoul, Incheon, Daegu, and Gwangju. The children were divided into two groups. We conducted direct measurement by using one hour of videotaping alongside questionnaire surveys. This was performed to calculate behavior rates, such as how many children perform hand-to-mouth and object-to-mouth behaviors. Results: The respective average frequencies of hand-to-mouth and object-to-mouth were $0.8{\pm}2.23$ and $0.82{\pm}2.64contacts/hr$ for house/indoor. The respective average frequencies of hand-to-mouth and object-to-mouth were $2.87{\pm}4.63$ and $1.47{\pm}3.84contacts/hr$ in the nursery group. For the mouthing participants, the average frequencies of hand-to-mouth and object-to-mouth were 3.31 and 3.20 contacts/hr in house, and 4.80 and 3.26 in nursery. Compared to other countries such as the USA, the frequencies of hand-to-mouth and object-to-mouth behaviors found in this study were relatively lower. Conclusions: Children have the potential for exposure to toxic substances through non-dietary ingestion pathways by mouthing objects or their fingers. In this study, the mouthing frequency was relatively lower than that found in Western countries. This can be explained that mouthing behaviour may be affected by culture and lifestyle characteristics.

• 한국해양학회지:바다
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• 제4권4호
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• pp.349-362
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• 1999

본 연구에서는 미세오손생물 군집 형성에 있어서 원생동물의 역할을 파악하기 위하여 초기 미생물막 형성과 미세오손생물 군집의 형성 및 부착과정, 부착 박테리아에 대한 원생동물의 포식영향 등이 연구되었다. 이를 위하여 인천내항과 외항(해경부두), 실험실 등에서 부착실험을 10~30일간 계속적으로 수행하였다. 인천내항 실험에서 박테리아와 편모충류는 실험 시작 6시간내에 미생물막을 형성하기 시작하였고 섬모충류는 9시간 경과시에 빈모류가 2 cells $mm^{-2}$ 출현하였다. 부착오손생물인 따개비 Balanus albicostatus의 유생은 실험 첫날부터 부착하기 시작하였다. 수괴가 안정된 인천내항에서 편모충류는 13일경 최대 465 cells $mm^{-2}$ 출현하였고, 섬모충류는 11 일째 63 cells $mm^{-2}$이 최대로 출현하였다. 인천외항에서 편모충류는 초기에 최대 223 cells $mm^{-2}$ 출현하였고, 섬모충류는 5일째 최대 39 cells $mm^{-2}$ 출현하여 인천내항보다는 외항에서 미생물막이 빠르게 발달하였으나 원생동물 출현 개체수는 작았다. 미생물막에 출현한 편모충류는 대부분 자서성인 Metromonas종류와 Bodonids종류였고, 섬모충류는 초기에는 소형 유종섬모충류 종류와 빈섬모충 Strombidium종류였고, 후에는 빈섬모충 Strombidium viridae(60 ${\mu}m$)와 부착성 Suctoria인 Acineta, turherosa가 출현하였다. 오손생물 군집은 따개비 유생이 초기부터 부착하여 7일째 18 개체 $cm^{-2}$ 까지 증가하였다. 이때 따개비 성체가 출현하기 시작하고 9일째부터는 따개비 사체가 발견되기 시작하였다. 이외에 오손생물로 강장동물 Anthozoa sp., 참굴(Crassostrea gigas)유생, 갯지렁이 유생 등이 실험시작 3일 후부터 부착하기 시작하였다. 부착판에 서식하는 요각류 Harpacticus sp. 등과 단각류 등은 미생물막이 잘 발달된 7일 이후에 출현하기 시작하였다. 미생물막 형성에는 알루미늄판이 유리판과 아크릴판보다 다소 유리하였고, 오손생물 군집과 부착판 서식생물 군집의 형성에는 유리판이 알루미늄판 보다 유리하였다. 미생물막 박테리아에 대한 원생동물의 섭취율은 낮은 편이나 포식율은 0.058 $h^{-1}$로 비교적 높아 원생동물이 미생물막 박테리아 개체군 사망에 큰 영향을 미치는 것으로 나타났다.