The Species Composition of Phytoplankton along the Salinity Gradients in the Seomjin River Estuary in Autumn, 2000: Comparison of HPLC Analysis and Microscopic Observations

Algae > Volume 16(2); 2001 > Article

Algae 2001;16(2): 179-188.

Mi-Ok Park, Chang-Ho Moon, Seok-Yun Kim, Sung-Ryull Yang, Kee-Young Kwon, Yong-Woo Lee

Department of Oceangraphy, Pukyong National University, Division of Civil and Environmental Engineering, Kwangju University

ABSTRACT

Composition of phytoplankton along the salinity gradients in the Seomjin River estuary was investigated with HPLC analysis of photosynthetic pigments and microscopic observations in October, 2000. The locations of sampling sites were set based on the salinity of surface water. A total of 98 species was identified. Among them 79 species(80.6%) were diatoms. Dinoflagellates, green algae, cyanobacteria, cryptomonads, euglenoids and silicoflagellates were also found as minor groups by microscopic observations. The detected photosynthetic pigments of phytoplankton by HPLC analysis were chl a, chl b (green algae), chl c, fucoxanthin (diatom), peridinin (dinoflagellates), diadinoxanthin, alloxanthin (cryptomonads), zeaxanthin (cyanobacteria), beta-carotene. Degradation products of chlorophyll a, phaeoxanthin a and chlorophyllide a, were also detected. The microscopic observations on phytoplankton and relative abundances of each group showed a discrepancy depending on stations. We observed the minor groups at more stations by HPLC than by micosope except dinoflagellates on stations. We observed small sized cells of minor groups which could not be observed under microscope. The discrepancy in detection of dinoflagellates implies that HPLC methods perhaps miss the existence of the some heterotrophic dinoflagellates. Combining HPLC with microscopic method is advantageous in that pigments help find and assign the small cells, whose microscopic observation is difficult.

Key words: chlorophyll a, estuary, HPLC, microscopic observation, photosynthetic pigments, salinity, gradients, Seomjin River