• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.3
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• pp.268-275
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• 2009

The survival and growth of marine benthic invertebrate larvae such as abalone depend on the nutritional value of micro algae. However, it is difficult to determine the dietary value of the many microalgal species used for food by benthic larvae. Therefore, we tested the benthic copepod, Tigriopus japonicus, which grazes microalgae on substrata in a manner similar to abalone larvae. It also has short generation time and is easy to rear which makes to be easier to examine the dietary value of each micro algal species. We measured the daily production of nauplii from gravid females of T. japonicus fed 26 microalgal species separately. Amino acid and fatty acid content of the micro algae and the copepod was also analyzed. The nauplii production of T. japonicus was the highest (10.7) when they were fed Navicula sp. (B-394) and the lowest (0.8) when they were fed Scrippsiella trochoidea. In Tetraselmis suecica the nauplii production was so high (8.2), which was not significantly different with the diatom group. We determined that Navicula sp. (B-394), Rhaphoneis sp. and T. suecica were good sources of food for T. japonicus. We suggest that a diet of with a mixture of these three micro algal species may be also good for invertebrate larvae such as abalone.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.1
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• pp.180-185
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• 2016

To investigate the feeding habits of Tridentiger trigonocephalus juveniles captured in the intertidal zone of Dodun-ri, Seocheon-gun from the end of May to early June 2012, the gut contents were observed. Feeding incidence of the juveniles increased twice a day, first in the morning and second in the afternoon. The major food organisms of the juveniles (6.5~10.0 mm NL) were composed of copepods (65.4%), amphipods (2.0%), shrimp larvae (14.5%), polychaete larvae (22.6%), and etc. These food items held more than 2 percentage in the dry weight of the total food items.

• Ocean and Polar Research
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• v.32 no.4
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• pp.369-377
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• 2010

To characterize ecotoxicological responses to a natural estrogen, $17{\beta}$-estradiol, we evaluated the life-history of the parental ($F_0$) and first generation ($F_1$) of the harpacticoid copepod, Tigriopus japonicus sensu lato. We evaluated the survival of nauplii and copepodites, the number of days until the emergence of copepodites and adult males, the sex ratio, brooding success, and the first brooding day of adult females. No significant differences in the survival rate were noted in response to treatments with different concentrations of $17{\beta}$-estradiol. However, $17{\beta}$-estradiol induced developmental delay and skewed the sex ratio toward males. Copepod development was delayed significantly in the 0.1 and $1\;{\mu}g\;l^{-1}$ $17{\beta}$-estradiol treatment groups relative to the control group, with a more pronounced delay in the $F_1$ group. Body length and biomass were significantly smaller in the $17{\beta}$-estradiol treated groups than in the controls. The male emergence of T. japonicus s.l. was very high in the 10 and $30\;{\mu}g\;l^{-1}$ $17{\beta}$-estradiol treatment group. Furthermore, exposure to $17{\beta}$-estradiol resulted in morphological deformities such as shrinking and swelling of the urosome, twisted setae of the caudal rami, setal loss of swimming legs, abnormal segmentation of antennules, and dwarfism.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.6
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• pp.666-671
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• 2001

To investigate the food organisms and feeding selectivity of slimy (Leiognathus nuchalis) during the postlarval stage, the gut contents of the fish, captured in Kwangrang Bay in 1995, were observed. The food organisms in the gut were composed of copepod egg and nauplius, Tintinnopsis spp. and Codonellopsis sp. The indices of relative importance (IRI) indicated that Tintinnopsis spp. was the most dominant food item ($80.6\%$), and copepod nauplius was the next ($18.5\%$). Tintinnopsis spp. was the most favorite food item: it occupied $73.8\%$ of gut contents, though it did $39.2\%$ of microzooplankton in the surrounded water. The composition of copepod nauplius was higher in the larvae shorter than 2.0 mm NL. As slimy larvae grew, the size of food organisms in the gut was not changed, and their number increased, and the selectivity for food items increased.

• Korean Journal of Ecology and Environment
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• v.41 no.1
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• pp.81-89
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• 2008

The eco-toxicological effects of endocrine disrupter, 4-nonylphenol (4NP) were observed and detected on the harpacticoid copepod, Tigriopus japonicus s.l. obtained and cultur-ed from our coast. There were no significant differences survival rate, sex ratio, and fecundity on T. japonicus s.l. at as low as $30{\mu}gL^{-1}$ of 4 NP exposure. Whereas, 4NP induced developmental delay, decreasing biomass and body size of nauplius and copepodite. Also, Differentially Expressed Gene (DEG) was conducted to detecting gene expression for potential biomarkers response to 4NP. As a result, full lifecycle research on morphology and gene expression of T. japonicus s.l. suggested potential bioindicators or biomarkers for environmental monitoring and assessments.

• Journal of Aquaculture
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• v.18 no.1
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• pp.52-59
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• 2005

The productivity of cyclopoid copepod, Apocyclops royi fed by various diets (Isochrysis galbana, Tetraselmis suecica, Phaeodactylum tricornutum, concentrated freshwater Chlorella and baker's yeast) was investigated at tile different temperatures ($16-36^{\circ}C$) with different salinities (5-34 ppt). A. royi was cultured in 6 ml vessels (12 wells culture plate). Total production (188 inds.) and daily production (13.4 inds.) of nauplii by A. royi female at $32^{\circ}C$ were significantly higher than those of nauplii at the different temperatures (P<0.05). Development time from nauplii to copepodite and from nauplii to adult tended to increase with increasing water temperature up to 32. And total production (169 inds.) and daily production (9 inds.) of nauplii by A. royi female at 10 ppt were significantly higher than those of nauplii at the different salinities (P<0.05). The fastest development time from nauplii to copepodite and from nauplii to adult was observed at 10 ppt and 15 ppt, respectively (P<0.05). The highest total production of A. royi nauplii and fastest development time from nauplii to adult were obtained in females fed Isochrysis galbana (P<0.05). These results may indicate that the optimum culture temperature and salinity for A. royi are $32^{\circ}C$ and 10 ppt, respectively, and Isochrysis galbana is one of the suitable diets for this copepod.

• Journal of Aquaculture
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• v.19 no.4
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• pp.305-309
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• 2006

This study was carried out to examine the anesthesia and recovery time of the male and gravid female of marine benthic copepod Tigriopus japonicus at 500, 750, 1,000 ppm of MS-222. We also investigated the survival (%) and the nauplii production of T. japonicus for 14 days, which was anesthetized with MS-222. As the concentration of MS-222 was higher, the anesthesia time of the copepod was shorter and the recovery time was longer. The survival (%) of male T. japonicus was significantly higher than that of the gravid female both in anesthetized and control group. But the survival (%) of the male treated with MS-222 did not show the different survival (%) with the control (0 ppm). In contrast, the survival (%) of the gravid female treated with 750 and 1,000 ppm was significantly lower than that of 500 ppm and control. With regard to hatching, as the concentrations was higher, the number of hatching and total nauplii were lower and interval of hatching was longer. However, the gravid female treated with 500 ppm did not show the significant difference with control. We suggest that 500 ppm of MS-222 is the suitable concentration in isolation of T. japonicus.

• Journal of Environmental Science International
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• v.22 no.3
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• pp.359-369
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• 2013

Chronic effects such as reproduction and population dynamics with elevated $CO_2$ concentration were evaluated using two representative marine benthic species, copepod (Tisbe sp.) and amphipod (Monocorophium acherusicum) adopting long-term exposure. Juvenile copepod and amphipod individuals were cultivated in the seawater equilibrated with control air (0.395 mmol $CO_2$/air mol) and high $CO_2$ air having 0.998, to 3.03, 10.3, and 30.1 mmol $CO_2$/air mol during 20 and 46 days, respectively. After the exposure period, the number of benthic invertebrate was counted with separate larval and juvenile stage such as naupliar, copepodid and adult for copepod, or neonate and adult for amphipod, respectively. The individual number of both test species at each life-stage was significantly decreased in seawater with 10.3 mmol $CO_2$/air mol or higher. Recently, the technology of marine $CO_2$ sequestration has been developed for the reduction of $CO_2$ emission, which may cause climate change. However, under various scenarios of $CO_2$ leaks during the injection process or sequestrated $CO_2$ in marine geological structure, the potential risk to organism including various invertebrates can be expected to exposure. So the results of this study suggested that the detailed consideration on the adverse effect with marine ecosystem can be prerequisite for the marine $CO_2$ sequestration projects.

• Journal of Aquaculture
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• v.6 no.3
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• pp.147-157
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• 1993

The harpacticoid copepod, Tigriopus japonicus is one of the most important zooplankton as a live food for the production of marine fish fry. Thus, the salinity tolerance and the optimum culture environment of this copepod in terms of salinity, temperature and light were examined. The food values of 6 kinds of phytoplankters and 2 kinds of yeast were also investigated for mass culture of this copepod. The results are as follows: After 5 day culture in the experiment of salinity tolerance, the survival rates of the gravid female at $0\%\;and\;90%o\;were\;40\%\;and\;70\%$, respectively. However, at salinity ranging from $2\%o\;to\;80\%o$, high survival rates above $85\%$ were observed. It means T. japonicus is very euryhalinous species. Temperature was more important factor than salinity for the fecundity of T. japonicus. The optimum culture conditions of this species were $24^{\circ}C,\;24\%o$, and 3,000 lux with 24 L: 0D. Under these culture conditions, the average fecundity from a gravid female per spawning was 38 nauplii, and the interval time between spawnings were 2.05 days. Phaeodactylum tircornutum seemed to be the most suitable phytoplankton as a live food for T. japonicus, and the large chlorophyta, Tetraselmis suecica showed the lowest food value among 6 phytoplankters and 2 yeasts. The food value of w-yeast was better than that of baker's yeast, and it is similar to that of phytoplankton such as Amphora sp., Chlorella ellipsoidea and Nannochloris oculata. So, the w-yeast seems to be appropriate food source for mass culture of T. japonicus.

• Ocean and Polar Research
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• v.40 no.4
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• pp.213-222
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• 2018

We investigated seasonal variations in the abundance of the adults and the resting eggs of copepods to understand the role of copepod resting eggs for maintaining their population inhabiting the coastal area of Dadaepo, Korea. Adults and resting eggs of copepods were collected bi-monthly with a conical net (45 cm mouth diameter, $330{\mu}m$ mesh size) and van Veen grab ($0.1m^2$ area), respectively, from October 2016 to September 2017. The species of resting eggs were identified using mtCOI gene. The mean abundance of copepods was highest in October ($3686{\pm}1190inds{\cdot}m^{-3}$) and lowest in January ($176{\pm}60inds{\cdot}m^{-3}$) with the dominance of Paracalanus parvus s.l.. Among copepod producing resting eggs, Acartia omorii and Centropages abdominalis were dominant. The mean abundance of resting eggs was the highest in July ($9148{\pm}6787eggs{\cdot}m^{-2}$) and the lowest in October ($530{\pm}348eggs{\cdot}m^{-2}$). Most of the collected resting eggs were identified as A. omorii's. The mean abundances of A. omorii adults and resting eggs were highest in July, and both abundances fluctuated in a similar pattern except in September. In September, A. omorii adults were observed in a state of low abundance, while their resting eggs occurred in a state of high abundance. These results suggest that A. omorii maintain their population by producing a large quantity of resting eggs, particularly diapause eggs, before the seawater temperature rises. These eggs would hatch and be newly recruited to their population when the environmental condition becomes favorable.