Estimation of phytoplankton succession in a fertilized mesocosm during summer using high-performance liquid chromatographic analysis of pigments

• Published in: Journal of experimental marine biology and ecology Vol. 214; no. 1; pp. 1 - 17
• Main Authors: Suzuki, Koji, Handa, Nobuhiko, Nishida, Tamihito, Wong, Chi Shing
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.1997
• Subjects: Enclosure; HPLC; Marine; Mesocosm; Multiple regression analysis; Phytoplankton succession; Pigments; INE, Canada, British Columbia, Vancouver I., Saanich Inlet; Pigments; Phytoplankton succession; Mesocosm; Enclosure; Multiple regression analysis; HPLC
• ISSN: 0022-0981; 1879-1697
• DOI: 10.1016/S0022-0981(97)00003-8

An enclosure experiment was conducted during the summer of 1994 in Saanich Inlet, Canada. In order to simulate phytoplankton dynamics when new nutrients are supplied into oligotrophic waters, the enclosure, in which nitrate was initially depleted, was artificially fertilized with macronutrients (nitrate, phosphate, and silicate). The abundance and composition of phytoplankton assemblages in the enclosure at three integrated depths (0–4 m, 4–8 m, 8–12 m) were estimated by measuring phytoplankton pigments using high-performance liquid chromatography. Chlorophyll a concentration at 0–4 m increased rapidly twelve-fold after the addition of the macronutrients, and thereafter gradually decreased until the end of the experiment. However chlorophyll a abundances at both 4–8 m and 8–12 m layers did not change much. Multiple regression analyses of chlorophyll a and selected accessory pigments at each depth indicated that fucoxanthin-containing algae, which were mostly not diatoms but raphidophytes on the basis of the results of microscopic analysis, dominated the chlorophyll a biomass in the enclosure throughout the experiment (30–70%). In addition, fucoxanthin in the < 20 μm size-fraction generally accounted for > 60% of the total fucoxanthin at the three depths, suggesting that most of the fucoxanthin-containing algae were probably not microplankton (> 20 μm) but nanoplankton (< 20 μm). Peridinin-containing dinoflagellates, which were mostly microplankton, were a secondary component of the phytoplankton community throughout the enclosure (15–50%). Chlorophyll b-containing green algae, which were mostly nanoplankton, were also a secondary constituent at the beginning of the experiment (10–35%), declining rapidly thereafter in the all layers. These results suggest that motile raphidophytes and dinoflagellates can become the most important phytoplankton groups when new nutrients become available in the surface waters of temperate zone coastal areas during the summer.