• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.3 no.4
• /
• pp.271-275
• /
• 1998

Controversial observations on the effect of pre-attached bacteria on the attachment of diatoms to artificial surfaces immersed in seawater have been made. Furthermore, it is not known whether or not pre-attached bacteria on artificial surfaces influence attachment of diatoms in natural seawater. In this study, we used various surfaces to which marine bacteria were pre-attached for different incubation periods. In the first experiment, glass slides were initially attached by marine natural bacteria with different exposure time (0-133 hr) and then immersed into seawater for a certain time period. The attachment of diatoms was not affected by the abundance of pre-attached bacteria (p > 0.05). The maximum abundance of attached diatoms was found on control surfaces, and the minimum abundance on surfaces where attached bacterial abundance was highest. In the second experiment, glass slides and acryl slides, either attached by marine natural bacteria for 6 days or coated by agar, were immersed in seawater. Untreated slides were also employed. On the surfaces of acryl slides with the most abundant attached bacteria ($5.4{\pm}0.02{\times}10^5\;cells\;cm^{-2}$), abundances of attached diatoms were less than those on untreated slides. On the surfaces of glass slides with bacterial abundance of $2.5{\pm}1.0{\times}10^5\;cells\;cm^{-2}$, however, abundances of attached diatoms were not different from those of untreated slides. On the agar-coated slides, the immigration rate and immigration coefficient were on average > 2 folds compared to other surfaces, indicating high rates of diatom attachment on mucilage simulated surfaces. Therefore, it seems that pre-attachment of bacteria is not prerequisite for the attachment of diatoms on artificial surfaces.

• 한국해양학회지
• /
• v.28 no.1
• /
• pp.69-71
• /
• 1993

Food items of the five species of marine cladocerans were reported to be largely confined to centric diatoms. Reexamination of the prey items, however, revealed that flagellar organisms were also well fed by cladocerans. This additional finding suggests that marine cladocerans might extend their food items to weakly motile flagellates e.g., Prorocentrum micans, Protoperidinium sp. and unidentified flagellates.

• Journal of Aquaculture
• /
• v.8 no.4
• /
• pp.355-366
• /
• 1995

In order to identify some suitable diatoms as a live food source, effects of seven diatom species (Chaetoceros simplex, Navicula incerta, Phaeodactylum tricornutum, Nitzschia closterium, Skeletonema costatum, Thalassiosira pseudonana, Thalassiosira weissflogii) were examined on specific growth rate, mean celt volume, chemical composition and general fatty acid composition. In cell volume. T. pseudonana was the smallest $(125{\mu}m^3)$ and T. weissflogii the largest $(824{\mu}m^3)$. However the specific growth rate of the largest diatom was the lowest (0.5016/day), and that of S. costatum was the highest (0.9928/day). The crude protein content of seven diatom species varied from $18.96\%$ (T. pseudonana) to $24,4\%$ (T, weissflogii). The crude lipid content of C. simplex was the highest $(8.43\%)$, and that of T. pseudonana was the lowest $(3.13\%)$. The total content of polyunsaturate fatty acids which are important for bivalve larvae was higher in C. simplex than those in other species. The total percent of polyunsaturate fatty acids from N. incerta and T. weissflogii was relatively lower than that from other species. Dietary value of seven diatom species were finally examined with Pacific oyster larvae Crassostrea gigas. In this experiment, C. simplex showed the highest survival rate and growth, and the larvae feed on S. costatum and T. weissflogii showed the poorest results. This results C. simplex could be more useful live food for bivalve larvae than other diatom species tested.

• Journal of Marine Life Science
• /
• v.5 no.1
• /
• pp.9-16
• /
• 2020

We evaluated the toxic effects of antifouling paint (irgarol and diuron) on the population growth rate (r) of the marine diatom, Skeletonema costatum. The r of S. costatum was determined after 96 hrs of exposure to irgarol (0, 0.31, 0.63, 1.25, 2.5 and 5 ㎍ l^-1) and diuron (0, 7.81, 15.63, 31.25, 62.5 and 125 ㎍ l^-1). It was observed that r in the control (absence of irgarol and diuron) were greater than 0.04, while r in the treatment groups decreased with increasing irgarol and diuron concentrations. Irgarol and diuron reduced r in a dose-dependent manner with significant decreases occurring at concentrations above 0.63 and 15.63 ㎍ l^-1, respectively. The EC₅₀ values of r in irgarol and diuron exposure were 1.09 and 45.45 ㎍ l^-1. No observed effect concentration (NOEC) were 0.31 and 7.81 ㎍ l^-1, the lowest observed effect concentration (LOEC) were 0.63 and 15.63 ㎍ l^-1. This result indicate that a concentration of greater than 0.63 ㎍ l^-1 of irgarol and 15.63 ㎍ l^-1 of diuron in marine ecosystems induced to decreasing r of S. costatum. Also, these toxic values can be useful as a baseline data for the toxic evaluation of irgarol and diuron in marine ecosystems.

• 한국해양학회지
• /
• v.16 no.2
• /
• pp.57-98
• /
• 1981

This study deals with the marine dinoflagellates observed in 50 samples collected in the vincinity of Yeosu from August 1979 to May 1980. Forty-nine species were identified and these taxa are attributed to 10 genera, of which 2 are infraspecific taxa. Two families, 3 genera, and 32 species are new records for the Korean coastal waters. Small dinoflagellates recorded in this study are ascribed to the use of volumetric samplers instead of nets. In this area, the armored forms are the most important components of the dinoflagellates (39 taxa). All species are illustrated by photomicroscopy. There are 49 pictures of taxa. An attempt has been made to provide more correct references to each species. There are comparative descriptive information, taxonomic comments, and distributional data for each species.

• Korean Journal of Environmental Biology
• /
• v.36 no.3
• /
• pp.385-391
• /
• 2018

Toxic assessment of PBDEs (BDE-47, BDE-209) has carried out using the rates of population growth in marine phytoplankton, Skeletonema costatum. The population growth rate (r) in S. costatum was determined after 96 hours of exposure to BDE-47 (2,2'4,4'-Tetrabromodiphenyl ether) and BDE-209 (2,2', 4,4'-Decabromodiphenyl ether). It was observed that r-value in the controls (absence PBDEs) was greater than 0.04 and further a decrease was observed in a dose-dependent manner. BDE-47 reduced population growth rate in a dose-dependent manner and a significant reduction occurred at a concentration greater than $0.31mgL^{-1}$, but BDE-209 had no effect on population growth rate even at concentrations greater than $125mgL^{-1}$. The population growth rate in the presence of BDE-47 and BDE-209, $EC_{50}$ values were $0.55mgL^{-1}$ and >$125mgL^{-1}$, and NOEC values were $0.16mgL^{-1}$ and >$125mgL^{-1}$, respectively. Therefore, BDE-47 is considered to be about over 80 times more harmful than BDE-209. In this study, the ecotoxic assessment based on population growth rate in S. costatum can be used as a baseline data for establishment of environment standard quality of BDE-47 and BDE-209 in the marine environment.

• Journal of Marine Life Science
• /
• v.2 no.1
• /
• pp.20-26
• /
• 2017

In this study, we evaluated the toxic effects of heavy metals (As, Cr and Pb) on the population growth rate (r) of the marine diatom, Skeletonema costatum. The r of the species was determined after 96 h (4 days) exposure to As (0, 0.31, 0.63, 1.25, 2.50 and 5.00 mg L^-1), Cr (0, 0.16, 0.31, 0.63, 1.25 and 2.50 mg L^-1) and Pb (0, 1.25, 2.50, 5.00, 10.00 and 20.00 mg L^-1). It was observed that r in the control (absence of As, Cr and Pb) were greater than 0.04, however suddenly decreased with increased heavy metal concentrations. As, Cr and Pb reduced r in a dose-dependent manner and a significant reduction were occurred at concentration of greater than 0.31, 0.31 and 5.00 mg L^-1, respectively. Based on the toxicity, the heavy metal were ranked as Cr>As>Pb, with EC₅₀ (50% effective concentration) values of 0.80, 2.57 and 13.88 mg L^-1, respectively. The lowest-observed-effective-concentration (LOEC) of r in exposed to As, Cr and Pb were 0.63, 0.63 and 10.00 mg L^-1, respectively. Precisely, a concentration of greater than 0.63 mg L^-1 of As, 0.63 mg L^-1 of Cr and 10.00 mg L^-1 of Pb in marine ecosystems induced toxic effect on the r of S. costatum. Based on our results, we suggested that the r of S. costatum might be a useful bio-indicator for the toxicity assessment of heavy metals on the producer in marine ecosystems.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.13 no.2
• /
• pp.106-111
• /
• 2008

Six standard methods for marine ecotoxicological tests were established(or applicated) using marine decomposer, primary producers and consumers. Development processes referred to the standard methods established by USEPA(United States Environmental Protection Agency), international organizations and European methods. However, the standard test species were selected among the domestic species generally found in the Korean waters and sediments. The test methods provide the culture/maintenance of test species, test methods, reproducibility and quality acceptance criteria etc. A total of nine test species were designated including bioluminescent bacteria(Vibrio fischeri), diatom(Skeletonema costatum), seaweed(Ulva pertusa), rotifer(Brachionus plicatilis), benthic copepod(Tigriopus japonicus), benthic amphipods(Mandibulophoxus mai, Monocorophium acherusicum), and fishes(Oryzias latipes, Paralichthys olivaceus). These test species represent the decomposer, primary producer and consumers in marine trophic system in Korean coastal ecosystems, and we recommend the "battery test" including at least one species from the each trophic level for marine ecotoxicological test.

• Korean Journal of Environmental Biology
• /
• v.37 no.3
• /
• pp.372-379
• /
• 2019

We evaluated the toxic effects of phenanthrene (PHE) and zinc undecylenate (ZU) on the population growth rate (r) of the marine diatom, Skeletonema costatum. The r of S. costatum was determined after 96 hrs of exposure to PHE (0, 25, 50, 100, 200 and 300 mg L^-1) and ZU (0, 5, 10, 15, 20 and 25 mg L^-1). The results showed that r in the control (the absence of PHE and ZU) was greater than 0.04, while r in the treatment groups decreased with increasing PHE and ZU concentrations. PHE and ZU were shown to reduce r in a dose-dependent manner, with significant decreases occurring at concentrations above 50 and 10 mg L^-1, respectively. The EC₅₀ values of r in PHE and ZU exposure were 136.13 and 16.95 mg L^-1, respectively. The no observed effect concentrations (NOEC) were 25 and 5 mg L^-1, and the lowest observed effect concentrations (LOEC) were 50 and 10 mg L^-1. These results indicated that concentrations of greater than 50 mg L^-1 of PHE and 10 mg L^-1 of ZU in marine ecosystems induced a toxic effect on the r of S. costatum. These results can serve as useful baseline data for the establishment of safety concentrations of PHE and ZU in marine ecosystems.

• Korean Journal of Environmental Biology
• /
• v.32 no.3
• /
• pp.243-249
• /
• 2014

In this study, we evaluated the toxic effects of heavy metals (Cd, Cu, Zn) on the population growth rate (r) of the marine diatom, Skeletonema costatum. S. costatum. The population growth rate (r) of the species was determined after 96 hrs. of exposure to Cd (0, 0.63, 1.25, 2.50, 5.00, 10.00 ppm), Cu (0, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50 ppm) and Zn (0, 0.31, 0.63, 1.25, 2.00, 2.50, 5.00 ppm). It was observed that 'r' in the control (absence of Cd, Cu and Zn) were greater than 0.05, however suddenly decreased with increased heavy metal concentrations. Cd, Cu and Zn reduced 'r' in a dose-dependent manner and a significant reduction were occurred at concentration of greater than 1.25, 1.25 and 2.50 ppm, respectively. Based on the toxicity, the heavy metal were ranked as Cu>Zn>Cd, with EC50 values of 1.11, 2.13 and 6.84 ppm, respectively. The lowest-observed-effective-concentration (LOEC) of 'r' in exposed to Cd, Cu and Zn were 1.25, 1.00, 2.00 ppm, respectively. Precisely, a concentration of greater than 1.25 ppm of Cd, 1.00 ppm of Cu and 2.00 ppm of Zn in marine ecosystems induced toxic effect on the 'r' of S. costatum. Based on our results, we suggested that the 'r' of S. costatum might be a useful bio indicator for the toxicity assessment of heavy metals in marine ecosystems.