• ALGAE
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• 제22권3호
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• pp.185-192
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• 2007

A study was carried out in nine fertilized fish ponds under three treatments (T-I, T-II and T-III) at Bangladesh Agricultural University, Mymensingh to see the bloom of euglenophytes with the intention of observing its impact on the growth of fish in culture condition. Some water quality parameters viz., temperature, dissolved oxygen, pH, PO4-P and NO3-N concentration and some biological parameters viz., phytoplankton population and growth of fish were monitored at fixed intervals. Euglenophytes showed a heavy bloom in late August in the ponds of T-II. The bloom was occurred by the genera, Euglena, Phacus and Trachelomonas of which Euglena was the most dominant genus. In relation of water quality parameters with euglenophytes bloom, it was hypothesized that euglenophytes prefers higher temperature and acidic environment with higher nutrient concentrations. Acidic environment and nutrient enrichment enhanced the bloom of euglenophytes which hampered the growth of other beneficial algal groups (chlorophytes and bacillariophytes) and fish. Due to heavy bloom, the fishes breathed with difficulty at the surface. The fishes in the heavy bloom ponds presented the weight values were lower than verified for those in the ponds where the bloom did not occur. Total production (calculated) of fish in different treatments ranged from 1355.89 to1760.63 kg ha–1 with significantly (p < 0.05) lowest in the ponds of T-II.

• 한국수산과학회지
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• 제37권3호
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• pp.215-225
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• 2004

Biomass and community composition of microphytobenthos in the Saemankeum tidal flat were studied by HPLC analysis of the photosynthetic pigments from November 2001 to November 2002. The environmental factors of sediment were also investigated to examine the relationship between microphytobenthos biomass and sedimentary environments. The detected photosynthetic pigments of microphytobenthos were chlorophyll a, b, c, fucoxanthin, 19'-hexanoyloxyfucoxanthin, violaxanthin, diadinoxanthin, alloxanthin, diatoxanthin, zeaxanthin+lutein, peridinin and beta-carotene. Pheophytin a, the degradation product of chlorophyll a, was also detected. The results of pigmen analysis suggest the presence of diatom (fucoxanthin), euglenophytes (chlorophyll b), chlorophytes (chlorophyll b + lutein), cyanobacteria (zeaxanthin), cryptophytes (alloxanthin), chrysophytes (fucoxanthin + violaxanthin), prymnesiophytes (19'-hexanoyloxyfucoxanthin) and dinoflagellates (peridinin). Chlorophyll a concentration in the top 0.5 cm of sediment was in the range of $0.24\;mg{\cdot}m\^{-2}\;-32.11\;mg{\cdot}m\^{-2}$ in the study area. The increase of chlorophyll a concentration in the spring indicates the occurrence of a microphytobenthic bloom. In the summer, there was a sharp decrease of the chlorophyll a concentration which was probably due to high grazing activity by macrobenthos. The annual mean chlorophyll a concentration in the study area was low compared to that in most of other tidal flat areas probably due to active resuspension of microphytobenthos and high grazing activity by macrobenthos. There was no clear relationship between microphytobenthos biomass and sedimentary environments because of a large variety of physical, chemical and biological factors, Pigment analysis indicated that while diatoms were dominated in the microphytobenthic community of the Geojon tidal flat, euglenophytes and/or chlorophytes coexisted with diatoms in the Mangyung River tidal flat.

• 한국해양학회지:바다
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• 제10권1호
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• pp.8-18
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• 2005

강화도 장화리 펄 조간대 지역에서 2002년 5월-2004년 4월까지 저서미세조류의 계절분포를 조사하였으며, 저서미세조류의 일차생산력 측정과 HPLC를 이용한 색소분석 방법으로 저서미세조류의 생산능력 및 분류군별 분포를 파악하였다. 강화도 갯벌에서 저서미세조류는 조간대 중부에서 많은 현존량을 보였다 강화도 갯벌에서 저서미세조류의 계절별 현존량 변동은 $2.3-140.9{\times}10^5\;cells\;cm^{-2}$의 범위로 하계와 동계에 낮은 현존량을 보였고 2003년 2월에서 4월까지 저서미세조류의 대증식 헌상이 나타났다. 저서미세조류는 대부분 저서성 돌말류가 우점종으로 출현하였고, 특히 연중 Paralia sulcata가 전 정점에서 우점하여 출현하였다. 그외에 Cylindrotheca closterium과 Nitzschia sp.가 2월과춘계에 크게 우점하였다. HPLC 색소분석을 통한 저서미세조류 군집조성은 돌말류를 포함하여 유그레나류, 남조세균, 녹조류, 은편모조류, 황갈조류, 와편모조류 등 다양한 종류가 출현하고 있는 것으로 나타났다. Chl a의 함량은 1.18-34.25 mg $m^{-2}$의 범위로 평균 7.60 mg $m^{-2}$을 보였다. Fuco/Chl a는 평균 0.7로 나타나 연구기간동안 돌말류가 전체 저서미세조류 생물량의 대부분을 차지하고 있음을 보여주었으며 Chl b/Chl a는 평균 0.17로 유그레나류와 녹조류가 일정 시기에 서로 공존하여 서식하는 것으로 나타났다. 평균 일차생산력의 화는 4.2-113.0 mgC $m^{-2}\;hr^{-1}$비 범위로 평균 33.9 mgC $m^{-2}\;hr^{-1}$로 나타났고, 초기기울기 $(\alpha)$의 변화범위는 0.002-0.005$(mgC\;mgchl-a^{-1}\;hr^{-1}){\cdot}({\mu}E\;m^{-2}\;s^{-1})^{-1}$로 측정되었다. 동화계수(Pm)는 0.50-1.32 mgC $mgchl-a^{-1}\;hr^{-1}$의 변화범위를 보였고, 일일 일차생산력은 20.9-678.1 mgC $m^{-2}\;d^{-1}$ 범위로 평균 206.7 mgC $m^{-2}\;d^{-1}$을 보여 일반적인 갯벌에서의 생산력 범위를 보였다.

• ALGAE
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• 제32권4호
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• pp.285-308
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• 2017

Cochlodinium polykrikoides red tides have caused great economic losses in the aquaculture industry in many countries. To investigate the roles of metazooplankton in red tide dynamics of C. polykrikoides in the South Sea of Korea, the abundance of metazooplankton was measured at 60 stations over 1- or 2-week intervals from May to November 2014. In addition, the grazing impacts of dominant metazooplankton on red tide species and their potential heterotrophic protistan grazers were estimated by combining field data on the abundance of red tide species, heterotrophic protist grazers, and dominant metazooplankton with data obtained from the literature concerning ingestion rates of the grazers on red tide species and heterotrophic protists. The mean abundance of total metazooplankton at each sampling time during the study was 297-1,119 individuals $m^{-3}$. The abundance of total metazooplankton was significantly positively correlated with that of phototrophic dinoflagellates (p < 0.01), but it was not significantly correlated with water temperature, salinity, and the abundance of diatoms, euglenophytes, cryptophytes, heterotrophic dinoflagellates, tintinnid ciliates, and naked ciliates (p > 0.1). Thus, dinoflagellate red tides may support high abundance of total metazooplankton. Copepods dominated metazooplankton assemblages at all sampling times except from Jul 11 to Aug 6 when cladocerans and hydrozoans dominated. The calculated maximum grazing coefficients attributable to calanoid copepods on C. polykrikoides and Prorocentrum spp. were 0.018 and $0.029d^{-1}$, respectively. Therefore, calanoid copepods may not control populations of C. polykrikoides or Prorocentrum spp. Furthermore, the maximum grazing coefficients attributable to calanoid copepods on the heterotrophic dinoflagellates Polykrikos spp. and Gyrodinium spp., which were grazers on C. polykrikoides and Prorocentrum spp., respectively, were 0.008 and $0.047d^{-1}$, respectively. Therefore, calanoid copepods may not reduce grazing impact by these heterotrophic dinoflagellate grazers on populations of the red tide dinoflagellates.