• Ocean and Polar Research
• /
• v.42 no.4
• /
• pp.271-281
• /
• 2020

We investigated mesozooplankton in the Yellow Sea in spring to understand its community structure and relationship with environmental factors. Total mesozooplankton density ranged from 1,542 to 7,367 ind. m-3 and the biomass ranged from 3 to 42 mg C m-3. The total density and biomass had a positive relationship with chlorophyll-a (chl-a) concentration. The mesozooplankton community was divided into two groups at 125.5 E by cluster analysis: one was an inshore group and the other was an offshore group. The inshore group of mesozooplankton was of high density but low diversity, while the offshore group was of high diversity but low density. Copepod Acartia hongi and its copepodites were the most abundant species, comprising 27.8% of the total mesozooplankton density. A. hongi was especially abundant at the inshore, serving as the indicator species of the inshore group. Redundancy analysis found a positive relationship between the density of A. hongi and chl-a concentration. Oithona similis and Centropages abdominalis were 2nd and 3rd dominant species comprising 9 and 7% of the total density, respectively. The density of O. similis was positively related to water depth, but C. abdominalis was related to chl-a concentration. Chl-a concentration seems to influence significantly the mesozooplankton community structure in the Yellow Sea in spring, rather than water temperature or salinity.

• Korean Journal of Environmental Biology
• /
• v.24 no.4
• /
• pp.372-379
• /
• 2006

In order to study temporal fluctuation and ecological characteristics of Noctiluca scintillans, its abundance was investigated in correlation with water temperature, salinity, precipitation, chlorophyll a concentration and copepods abundance in the coastal waters of Incheon from January 1999 to December 2000. N. scintillans was seasonally abundant during spring and autumn with temperature ranging from 10.3 to $21.5^{\circ}C$, but depleted in winter and summer. Low temperature below $4.5^{\circ}C$ in winter and low salinity due to high rainfall in summer led N. scintillans to disappear. A Cross Correlation Analysis (CCA) showed that chlorophyll a concentration was positively correlated with abundance of N. scintillans at the time lags of 10 days. This suggests that phytoplankton may be a contributing factor for increasing abundance of N. scintillans. During spring, eggs of Acartia hongi were found in 2.9 to 21.1% of individuals of N. scintillans. It was deduced that 1.2 to 49.5% of the eggs produced by A. hongi was preyed upon by N. scintillans. Therefore, N. scintillans may control the population size of initial developmental stage of A. hongi in the costal waters of Incheon.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.29 no.4
• /
• pp.415-430
• /
• 1996

Spatio-temporal variations in zooplankton community and ropepod indicator species were investigated along with the interaction between zooplankton distribution and environmental factors in Chinhae Bay. Zooplankton samples were monthly collected at 7 stations from February to September in 1993. A NORPAC net was vertically hauled from bottom to surface, At the same station, environmental factors such as temperature, salinity and COD (chemical oxygen demand) were measured at two different water layers, surface and bottom. In August and September, salinity declined below 30.00‰ , while eutrophic parameters such as COD showed the higher concentrations than those in other months, with higher concentrations at inner bay stations. Salinities were, however, higher at bay mouth areas. These distributional patterns were believed to be caused by input and dispersion of organic matters from nearby land. Zooplankton communities were composed of 7~14. Of these, Noctiluca scintillans was predominant and occupied 90.6‰ of total zooplankton abundance. Cladocera and Copepoda were secondly abundant taxa. Among 6 to 10 copepod species appeared, Acartia omorii and A. hudsonics were most common species during the survey months except March and September. Species diversities were greater, in general, at inner bay than outer bay. The lowest diversity index was observed in February, while the highest in July. Cluster analysis could divide the study area into 2 or 4 zones for each month. Zone 1, mouth area of the bay, was characterized by the influence of offshore waters. Zone II was mixing area. Zone III and IV seemed to be affected by nearby land.

• 한국해양학회지
• /
• v.29 no.2
• /
• pp.132-144
• /
• 1994

The relationship of zooplankton communities and distributions of copepods as indicator species to environmental variables, such as temperature, salinity, chemical oxygen demand (COD) and total inorganic nitrogen (TIN) was studied in Pusan Harbor in October 1990 and January, April and July 1991. Zooplankton communities were analysed by using cluster analysis and species diversity index. Four groups of copepods as indicator species were Acrocalanus gacilis, Euchaeta plana, pareuchaeta russell and Pleuromamma gracilis as the oceanic warm water species; Cemtropages abdominalis as the neritic cold water species; Meridian lucens as the oceanic cold water species Acartia omorii as the polluted water species. the offshore waters of Pusan harbor was dominated by the oceanic warm water species in October and by the neritic cold water species in January and April. This area showed the low values of COD and Tin. the inshore waters of Pusan harbor, where the high values of cod And Tin and the low value of diversity were recorder was represented by A.. omorii. Cluster analysis of the zooplankton community revealed two or three regional areas in Pusan harbor. Area I, the offshore area of Pusan harbor, not only was represented high species diversity and low density of A. omorii but also was dominated copepods in zooplankton roups. Areas II and III were grouped horizontally from offshore to inshore of Pusan harbor. Area II was showed intermediate values in diversity, density of A. omorii and percentage composition of copepods. Area III was revealed the lowest diversity,density of A.omorii and percentage composition of Cladocerans.Coperpoda was a dominant zooplankton group in each area during the study periods except two special cases.Area II was dominated by Noctiluca scintillans in April and Area III was occupied by Cladocerans in July.Distribution of Indicator species and areas demarcated based on cluster analysis showed a close relationship with environments.

• Korean Journal of Environmental Biology
• /
• v.35 no.4
• /
• pp.631-639
• /
• 2017

The relationship between the environmental factors (water temperature, salinity, chlorophyll-a concentration, Noctiluca scintillans density, Diatoms and Dinoflagellates densities) and the zooplankton community was investigated. Zooplankton were seasonally collected at 11 stations of Gwangyang Bay from November 2015 to July 2016. A mean abundance ranged from 544 to $19,753indiv.\;m^{-3}$. The maximum abundance was observed to be $40,000indiv.\;m^{-3}$ in July and the minimum occurred in November with $412indiv.\;m^{-3}$. The zooplankton consisted of 35 taxa, which is dominated by Paracalanus parvus s. l., Corycaeus spp., Oithona spp., Acartia omorii, A. ohtsukai, Centropages abdominalis, unidentified harpacticoids. The result of the Redundancy Analysis (RDA) conducted between the zooplankton and the environmental factors showed that the spring-autumn, summer and winter are separated. The summer was closely related to temperature and diatom density, while the winter was linked to salinity and N. scintillans density (p<0.05).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.8 no.3
• /
• pp.243-250
• /
• 2003

The spatio-temporal distribution of zooplankton community was investigated in Kyeonggi Bay with monthly samples from February 2001 to December 2001 at 5 stations along a transect between Incheon coastal waters and Seongap-Do. Monthly mean abundance of total zooplankton ranged from 1,100(Feb.)∼404,200 indiv./㎥ (Aug.) and annual mean abundance of total zooplankton was 55,000 indiv./㎥. The spatial mean abundance of total zooplankton varied from 114,600 indiv./㎥ (Incheon coastal waters) to 16,500 indiv./㎥ (Seongab-Do). Zooplankton abundance was higher in the inner bay than in the outer bay. Noctiluca scintillans, Acartia hongi, Oithona davisae, Paracalanus crassirostris, Paracalanus indicus and Oikopluera spp. were dominant species in Kyeonggi Bay and they contributed 95％ of annual mean abundance of total zooplankton. Most of dominant species distributed widely in study area throughout the year, however seasonal abundance peak only happened in inner part of the Bay. This pattern suggests that the spatio-temporal distribution of zooplankton is affected by the variations of water temperature and phytoplankton standing stock.

• Korean Journal of Environmental Biology
• /
• v.20 no.2
• /
• pp.118-129
• /
• 2002

Zooplankton was sampled vertically with a Norpac net from Gamag Bay in April, July, September and December, 2001. Copepods were predominant in April and December, and cladocerans in July and Noctituca scintillans in September, respectively. There are high spatio-temporal fluctuations in the abundance of zooplankton with a range of 22-17,197 indiv.$m^3$. In the copepod community, neritic species, Eurytemora pacifica, Acartia omorii, Centropages abdominalis and Calanus sinicus were predominant in April ; Labidocera rotunda and A. erythraea in July; A. erythraea and Paracalanus parvus s. 1. in September; A. omorii and E. pacifica in December. However, oceanic species Eucalanus sp. and Neocalanus sp. were abundant in September. It indicates that although Gamag Bay is semi-closed, the distribution pattern of zooplankton is seasonally strongly affected by oceanic waters in addition to neritic ones.

• Ocean and Polar Research
• /
• v.28 no.1
• /
• pp.45-56
• /
• 2006

This study investigated primarily the toxic effects of bis(tributyltin)oxide (TBT) and DDT (Dichlorodiphenyltrichloroethane) on the mortality of adult Acartia omorii and barnacle nauplii as well as the hatching rate of A. omorii. Subsequently, compound effects of TBT and DDT on the mortality of immature copepods were tested in order to assess whether or not synergistic influence existed in the mixture of sublethal concentration of two pollutants. Mortality of adult A. omorii increased as exposure concentration of DDT increased in the range of from 0.0001 to 1ppm. Egg hatching rate of the copepod showed no distinctive difference in the range between 0.1 and 10ppm, while barnacle nauplii showed abnormal motility of their appendages in the range of 0.0001 to 1 ppm. Mortality of adult A. omorii increased as TBT concentration increased within the range of 1 and 10 ppb, whereas egg hatching rate of the copepod showed no linear response to the same exposure range. Moreover, copepod nauplii were almost motionless even though copepod eggs hatched under the exposure condition of TBT $(0{\sim}10 ppb)$ and DDT $(0{\sim}10 ppm)$, respectively, suggesting that the nauplii are hard to develop into adult stage. On the basis of the sublethal concentration less than the 24-h $LC_{50}$, 0.001 ppm (DDT) and 2 ppb (TBT) were selected to confirm the compound effects of two pollutants on the mortality of immature copepods. Mortality of immature copepods under the condition of mixture of the two pollutants was higher than that in the single exposure condition. This result seems to indicate that synergistic effects of sublethal toxicants can make a more hazardous effect on the survival of immature copepods even though the concentration of single toxicant is not lethal to copepods in the marine environment.

• Ocean and Polar Research
• /
• v.33 no.3
• /
• pp.235-253
• /
• 2011

The annual variation of mesozooplankton community in the Jangmok harbor of Jinhae Bay was studied in relation to environmental variables. Sampling was carried out weekly from January to December 2009. During the study periods, mesozooplankton community consisted of 44 taxa and the annual mean abundance was 8308 inds. $m^{-3}$. The maximum abundance was observed to be 50043 inds. $m^{-3}$ in August and the minimum in April with 1013 inds. $m^{-3}$. Of these, Penilia avirostris, cirripedia larvae, Evadne tergestina, Acartia omorii, Oikopleura s, Paracalanus parvus s. l., Eurytemora pacifica, Podon s, Oithona s, and Acartia steueri were observed as dominant species in Jangmok bay and they also contributed to 79% of total mesozooplankton. According to non-metric multidimensional scaling (nMDS) and cluster analysis based on the mesozooplankton community data from each season, the community was divided into three groups. The first group included appearence species in winter and spring season, which is mainly dominated the copepod such as A. omorii and E. pacifica. The second and third group was composed with observed species in summer and autumn, respectively. Based on the SIMPER (similarity percentages), P. avirostris in summer and cirripedia larvae in autumn were significantly dominated. Our results indicate that although the mesozooplankton abundances in Jangmok harbor fluctuated abruptly, its annual variation was strongly influenced by water temperature.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.28 no.5
• /
• pp.517-532
• /
• 1995

Distribution of zooplankton was studied based on the zooplankton samples from collected 15 stations in Deukryang Bay in July and September, 1992 and January and March, 1993. Zooplankton biomass $(mg/m^3)$ showed maximum in March and minimum in July, whereas abundance $(inds./m^3)$. showed maximum in September and minimum in March. Variation in biomass depended on changes in body size of Sagitta crassa. S. crassa of large body size resulted in high biomass in March. Noctiluca scintillans and copepods in September showed high abundance but low biomass. Species composition and abundance were closely related to seasonal variation of water temperature. Of the dominant zooplankton taxa, decapod larvae were predominant in July, copepods in September and January, and coelenterates 3n March. Three copepod species, Paracalanus indicus, Acartia pacifica and Pseudodiaptomus marinus were dominant in July and March, September, and January, respectively.