Food Value of Cyclopoid Copepod, Paracyclopina nana for Flounder Paralichthys olivaceus Larvae

본 연구는 넙치 (Paralichthys olivaceus) 자어에 대한 요각류 Paracyclopina nana의 먹이가치를 평가하기 위해 두섭식 단계 (rotifer 섭식 단계와 Artemia 섭식 단계)로 나누어 각각 12일 및 16일 동안 수행되었다. Rotifer 섭식 단계 실험에서, 넙치 자어의 생존과 성장은 부화 12일째 rotifer만 공급했을 때 보다 P. nana (nauplii) 단독으로 공급했을 때 더 높게 나타났다. Arteima 섭식단계 실험에서, 부화 30일째 넙치자어의 성장은 P. nana (C4-adult) 단독 공급실험구와 혼합공급(P. nana+Artemia) 실험구가 다른 실험구에 비해 높게 나타났으나 넙치 자어의 생존은 모든 실험구가 유의적인 차이를 보이지 않았다. P. nana nauplius와 성체(C4-adult)의 n-3 HUFA 함량은 각각 4.0%와 5.4%였다. 결과적으로, 기수산 요각류 P. nana는 해수어 종묘생산을 위한 초기생먹이로 효과적인 것으로 판단된다. This study investigated the food value of Paracyclopina nana for flounder Paralichthys olivaceus larvae in two feeding stages, rotifer (for 12 days) and Artemia (for 16 days). In the rotifer feeding stage, survival and growth of flounder larvae in the only P. nana (nauplii) feeding experiment were higher than in the only rotifer feeding experiment on 12 DAH (days after hatching). In the Artemia feeding stage, the growth of flounder larvae in the only P. nana (C4-adult) feeding experiment and mixture feeding experiment (P. nana+Artemia) were higher than in other experiments on 30 DAH, but the survival of flounder larvae did not differ significantly among experiments. The n-3 HUFA contents of nauplius and C4-adult were 4.0% and 5.4%, respectively. Overall the results of this study indicate that the brackish water cyclopoid copepod, P. nana, is an effective live food organism for larval seedling production of marine fish.22Nkc

Toxicity of micro polystyrene particle for marine copepod Tigriopus japonicus

본 연구는 마이크로플라스틱의 크기에 따른 생물영향을 조사하기위해 대표 마이크로플라스틱으로 polystyrene bead를 선정하였고 이 polystyrene bead가 요각류 T. japonicus의 생존, 발달기간 및 nauplius 생산력 등에 미치는 영향을 급성 및 2세대 만성독성실험을 통해 평가하였다. 본 실험에서 T. japonicus는 실험시 사용된 모든 크기의 polystyrene bead를 섭취하는 것으로 확인되었으며 먹이생물인 T. suecica와 polystyrene bead가 공존하는 환경에 노출되었을 때도 T. japonicus의 장내에서 먹이인 T. suecica와 섞여 있는 polystyrene bead를 다량 확인할 수 있었다. T. japonicus의 성체암컷과 nauplius(N1～2기)가 다양한 polystyrene bead 크기와 농도에 노출되었을 때, 96시간 동안 모두 생존하는 것으로 나타났다. 2세대 만성독성 결과, T. japonicus는 F0세대에서, 0.05 µm bead에 노출되었을 경우, 고농도인 12.5 µg/mL 이상 처리구에서는 성체까지 생존하지 못하고 폐사하는 것으로 나타났으며 F1 세대에서는 1.25 µg/mL 처리구도 성체까지 생존하지 못하고 폐사하였다. Nauplius에서 copepodid 및 nauplius에서 성체까지 발달기간은 생존율 결과와 비슷한 양상을 보였으나 성비는 모든 실험구가 유의적인 차이를 보이지 않았다. 성체암컷의 nauplius 생산수를 보면, 가장 작은 size bead (0.05 µm)는 fecundity에 영향을 받지 않았지만 0.5와 6 µm bead 처리구는 모든 농도에서 악영향을 받은 것으로 나타났다.독성실험을 통해 평가하였다. 본 실험에서 T. japonicus는 실험시 사용된 모든 크기의 polystyrene bead를 섭취하는 것으로 확인되었으며 먹이생물인 T. suecica와 polystyrene bead가 공존하는 환경에 노출되었을 때도 T. japonicus의 장내에서 먹이인 T. suecica와 섞여 있는 polystyrene bead를 다량 확인할 수 있었다. T. japonicus의 성체암컷과 nauplius(N1～2기)가 다양한 polystyrene bead 크기와 농도에 노출되었을 때, 96시간 동안 모두 생존하는 것으로 나타났다. 2세대 만성독성 결과, T. japonicus는 F0세대에서, 0.05 µm bead에 노출되었을 경우, 고농도인 12.5 µg/mL 이상 처리구에서는 성체까지 생존하지 못하고 폐사하는 것으로 나타났으며 F1 세대에서는 1.25 µg/mL 처리구도 성체까지 생존하지 못하고 폐사하2

Mass culture of the brackish water cyclopoid copepod Paracyclopina nana Smirnov

해산 copepod는 어류 양식을 위한 초기먹이생물로 가장 이상적인 것으로 알려져 있으며 최근 이들의 대량배양에 관한 연구가 많이 시도되고 있다. 따라서 본 연구는, 기수산 copepod인 Paracyclopina nana의 대량생산을 위해, 실용화 가능한 배양방법개발의 일환으로 rotifer 대체를 위한 P. nana의 nauplius 생산법과 Artemia 대체를 위한 P. nana의 C4-성체 생산법으로 나누어 대량배양을 시도하였다. P. nana의 nauplius 생산 시, 수확된 nauplius는 약 95% 이상이 N1-N2였다. 15일 동안 수확된 nauplius의 일일 평균 생산량은 1, 2차 각각 6.9×106 , 7.2×106 였으며, 배양수 내의 암컷과 포란한 암컷의 수는 시간이 경과할수록 약간 감소하는 경향을 보였으나 15일 동안 비교적 일정한 개체수를 유지하는 것으로 나타났다. C4-성체의 생산시, 수확된 copepod의 비율은 C4-수컷, 암컷 및 포란한 암컷이 각각 약 49%, 28% 및 18%였으며 일일 평균 생산량은 1, 2차 각각 8.2×105 , 9.0×105 개체였다. 결과적으로, P. nana 대량배양 방법에서 nauplius와 C4-성체의 일정한 생산이 가능하였으며 어류의 입 크기에 따라 배양 방법의 선택에 의해 연속적인 먹이 공급이 가능할 것으로 판단된다. Marine copepods are ideal live prey for fish larvae, and many studies on the mass culture of the organism have been reported. This study performed a mass culture of the brackish copepod Paracyclopina nana containing nauplius and C4-adult production methods. In nauplius production, the harvested nauplii over 95% were comprised of N1 and N2. Daily mean nauplius production of two trials for 15 days were 6.9×106 and 7.2×106 individuals, respectively. The densities of the adult females were maintained at a similar level of the initiation during production. In C4-adult production, the proportion of harvested copepods containing C4-adult males, females and ovigerus females were 49%, 28%, and 18%, respectively. The daily mean nauplius production of the two trials for 16 days were 8.2×105 and 9.0×105 individuals, respectively. As a result, the continuous production of P. nana using the mass production system was successful. Therefore, the continuous and stable feeding for fish larvae in aquaculture would be possible by the selection of the copepod culture method depending on the mouth size of the fish.22Nkc

Ingestion responses of the copepod Tigriopus japonicus exposed to the water accommodated fraction (WAF) and chemically enhanced WAF (CEWAF) of crude oil

The water accommodated fraction (WAF) and chemically enhanced WAF (CEWAF) by oil spills reduce the filtration or feeding of marine copepods. This study examined the feeding response of the harpacticoid copepod, Tigriopus japonicus exposed to WAF or CEWAF to understand whether decreased feeding of the copepod by oil exposure is induced by food avoidance or medium toxicity. In the medium without WAF, there was no difference in the ingestion rate of the copepod among all polluted diets those were exposed to different concentrations of WAF. The present of WAF in the medium however caused a decrease in the ingestion rate at 100% WAF treatment. In the mixed diet treatment with adhesive diatoms and Tetraselmis suecica, T. japonicus had significantly lower ingestion rate on adhesive diatoms than on others in the medium with CEWAF. As a result, decreased ingestion of T. japonicus by oil exposure was caused by not an avoidance of polluted diet but oil toxicity in medium.o WAF or CEWAF to understand whether decreased feeding of the copepod by oil exposure is induced by food avoidance or medium toxicity. In the medium without WAF, there was no difference in the ingestion rate of the copepod among all polluted diets those were exposed to different concentrations of WAF. The present of WAF in the medium however caused a decrease in the ingestion rate at 100% WAF treatment. In the mixed diet treatment with adhesive diatoms and Tetraselmis suecica, T. japonicus had significantly lower ingestion rate on adhesive diatoms than on others in the medium with CEWAF. As a result, decreased ingestion of T. japonicus by oil exposure was caused by not an avoidance of polluted diet but oil toxicity in medium.1

Response of the ubiquitous pelagic diatom Fragilariopsis doliolus to manganese nodule exposure

Increasing in metal demand and rising in its commodity prices have aroused a shift of exploration and development expenditure to the marine mineral resources from deep seabed. Before starting the mining from deep seabed, the biological impact of tailing disposal of mineral should be evaluated for sustainable development of the marine environment. Diatoms are a good indicator of aquatic quality due to their sensitivity to pollutants. Most of ecotoxicity tests using diatom, however have been conducted to the fresh water or coasts, there was no candidate diatom for ecotoxicity test in the ocean environment. The primary objective of this study was to evaluate the effect of manganese nodule on the pelagic diatom Fragilariopsis doliolus. We tested the effects of the particles of manganese nodule and its leachate on the growth of the diatom. All cultures were able to survive in the presence of particle of manganese nodule and its leachate. The growth rate of diatom did not effect in exposure of the leachate, but it was inhibited with increasing of the particle concentration (96h EC50=0.35 g L-1). Although we only based on the growth rate of the diatom, F. doliolus may be a suitable organism to assess the effects of toxicity in ocean in situ bioassay because the diatom is ubiquity and suitability for use under laboratory conditions. In future works, the other endpoints such as gene expression and deformity of diatom will be1

Population Growth of a Tropical Tintinnid, Metacylis jörgensenii on different Temperature, Salinity and Diet: A laboratory study

This study investigated the effect of temperature, salinity and algal diet to find the optimum condition for the mass culture of tropical tintinnid Metacylis jörgensenii. This tintinnid had a small, hyaline and ovoid lorica. Oral diameter, length and maximum width of the lorica were 36.7 μm, 49.5 μm and 44.5 μm, respectively. M. jörgensenii reproduces with binary fission, and then daughter cells make their loricae. When the tintinnid was cultured with Isochrysis galbana at 30°C in this study, the maximum population growth rate (1.7/day) and the highest culture density (840 cells./mL) were observed at 30 and 33 ppt, respectively. M. jörgensenii showed small size, higher population growth rate and density. Thus, they seem to be a test organism or potential candidate as a live food for fish larvae.iameter, length and maximum width of the lorica were 36.7 μm, 49.5 μm and 44.5 μm, respectively. M. jörgensenii reproduces with binary fission, and then daughter cells make their loricae. When the tintinnid was cultured with Isochrysis galbana at 30°C in this study, the maximum population growth rate (1.7/day) and the highest culture density (840 cells./mL) were observed at 30 and 33 ppt, respectively. M. jörgensenii showed small size, higher population growth rate and density. Thus, they seem to be a test organism or potential candidate as a live food for fish larvae.2

Effect of Light Intensity on Survival, Growth and Productivity of the Cyclopoid Copepod Paracyclopina nana : A Laboratory Study

To determine the optimum light intensity for mass culture of the brackish-water cyclopoid copepod Paracyclopina nana, survival, growth, and productivity of the copepod were examined at several light intensities (0, 10, 100, 500, 1,000 lx). The survival rate of P. nana from nauplius to adult decreased with increasing light intensity. The highest survival rate was found under the dark condition, with 61.7% surviving; no significant difference was observed between 0 and 10 lx (51.7%) and the lowest survival rate was with 100 lx (26.7%). Survival rates at 500 and 1,000 lx were significantly lower in comparison with other conditions. The developmental period from nauplius to copepodid (5.8 days) and to adult (11.8 days) at 10 lx was significantly shorter than in the other treatments. Daily mean nauplius production of adult females over 7 days at 0, 10 and 100 lx was significantly higher than at 500 and 1,000 lx. In the 1,000 lx treatment, 99% of the adult females died on the 14th day. The optimum light intensity for the mass culture of P. nana could be 10 lx, which had no adverse effects on survival, development, or reproduction.22Nkc

Tycoplanktonic diatoms in reef flats around Moen Island (Weno) in Chuuk Lagoon, Micronesia

The present study enhance the knowledge on the biodiversity of diatoms in Chuuk, Micronesia following the study on the seaweed-associated diatoms (Park et al. 2018). The phytoplankton samples collected from 5 sites of reef flats using a 20-μm mesh sized net, are analyzed. 124 diatom taxa are documented, of these, 86 species are additionally observed apart from the epiphytic diatoms. Most taxa are benthic as a tycoplanktonics, and the euplanktonic diatoms are rare. Although many taxa remain to unidentified status, we note some apparent differences in common and distinctive species that able to characterize the coral reefs diatom in Chuuk, Micronesia.2

A cloud-like mass bloom forming dinoflagellate, Bysmatrum sp. at the tidal pool of South Korea

A cloud-like mass bloom forming dinoflagellate, Bysmatrum species was observed from the tidal pool of Geoje-do and Jeju Island in South Korea. The thecal plate formula is typical for the genus: P0, X, 4', 3a, 7", 6c, 4s, 5'", 2"". Cells are 20.6 um wide. The epitheca is conical with slightly straight to round sides and larger than the hypotheca, which is trapezoidal with round sides. The overall morphological characters of the Bysmatrum species are similar to B. gregarium and B. subsalsum. In the phylogenetic analysis using SSU and LSU rDNA, the Bysmatrum species locates between B. gregarium and B. subsalsum clade. Although the detail structures such as apical pore complex and sulcus are not observed yet, the sequence data indicates this Bysmatrum species seem to be a new to science. Further studies on the morphological details will be clear the taxonomic position of the Korean tidal pool Bysmatrum species.2