Different Roles of Top-Down and Bottom-Up Processes in the Distribution of Size-Fractionated Phytoplankton in Gwangyang Bay
The interactive roles of zooplankton grazing (top-down) and nutrient (bottom-up) processes on phytoplankton distribution in a temperate estuary were investigated via dilution and nutrient addition experiments. The responses of size-fractionated phytoplankton and major phytoplankton groups, as determ...
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doaj-ca7c7ba208504d6495926cead33e76ff2021-07-01T00:26:15ZengMDPI AGWater2073-44412021-06-01131682168210.3390/w13121682Different Roles of Top-Down and Bottom-Up Processes in the Distribution of Size-Fractionated Phytoplankton in Gwangyang BayYoonja Kang0Yeongji Oh1Department of Ocean Integrated Science, College of Fisheries and Ocean Sciences, Chonnam National University, Yeosu 59626, KoreaDepartment of Ocean Integrated Science, College of Fisheries and Ocean Sciences, Chonnam National University, Yeosu 59626, KoreaThe interactive roles of zooplankton grazing (top-down) and nutrient (bottom-up) processes on phytoplankton distribution in a temperate estuary were investigated via dilution and nutrient addition experiments. The responses of size-fractionated phytoplankton and major phytoplankton groups, as determined by flow cytometry, were examined in association with zooplankton grazing and nutrient availability. The summer bloom was attributed to nanoplankton, and microplankton was largely responsible for the winter bloom, whereas the picoplankton biomass was relatively consistent throughout the sampling periods, except for the fall. The nutrient addition experiments illustrated that nanoplankton responded more quickly to phosphate than the other groups in the summer, whereas microplankton had a faster response to most nutrients in the winter. The dilution experiments ascribed that the grazing mortality rates of eukaryotes were low compared to those of the other groups, whereas autotrophic cyanobacteria were more palatable to zooplankton than cryptophytes and eukaryotes. Our experimental results indicate that efficient escape from zooplankton grazing and fast response to nutrient availability synergistically caused the microplankton to bloom in the winter, whereas the bottom-up process (i.e., the phosphate effect) largely governed the nanoplankton bloom in the summer.https://www.mdpi.com/2073-4441/13/12/1682top-down effectbottom-up effectphytoplankton bloomflow cytometryestuaryGwangyang Bay |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Yoonja Kang Yeongji Oh |
spellingShingle |
Yoonja Kang Yeongji Oh Different Roles of Top-Down and Bottom-Up Processes in the Distribution of Size-Fractionated Phytoplankton in Gwangyang Bay Water top-down effect bottom-up effect phytoplankton bloom flow cytometry estuary Gwangyang Bay |
author_facet |
Yoonja Kang Yeongji Oh |
author_sort |
Yoonja Kang |
title |
Different Roles of Top-Down and Bottom-Up Processes in the Distribution of Size-Fractionated Phytoplankton in Gwangyang Bay |
title_short |
Different Roles of Top-Down and Bottom-Up Processes in the Distribution of Size-Fractionated Phytoplankton in Gwangyang Bay |
title_full |
Different Roles of Top-Down and Bottom-Up Processes in the Distribution of Size-Fractionated Phytoplankton in Gwangyang Bay |
title_fullStr |
Different Roles of Top-Down and Bottom-Up Processes in the Distribution of Size-Fractionated Phytoplankton in Gwangyang Bay |
title_full_unstemmed |
Different Roles of Top-Down and Bottom-Up Processes in the Distribution of Size-Fractionated Phytoplankton in Gwangyang Bay |
title_sort |
different roles of top-down and bottom-up processes in the distribution of size-fractionated phytoplankton in gwangyang bay |
publisher |
MDPI AG |
series |
Water |
issn |
2073-4441 |
publishDate |
2021-06-01 |
description |
The interactive roles of zooplankton grazing (top-down) and nutrient (bottom-up) processes on phytoplankton distribution in a temperate estuary were investigated via dilution and nutrient addition experiments. The responses of size-fractionated phytoplankton and major phytoplankton groups, as determined by flow cytometry, were examined in association with zooplankton grazing and nutrient availability. The summer bloom was attributed to nanoplankton, and microplankton was largely responsible for the winter bloom, whereas the picoplankton biomass was relatively consistent throughout the sampling periods, except for the fall. The nutrient addition experiments illustrated that nanoplankton responded more quickly to phosphate than the other groups in the summer, whereas microplankton had a faster response to most nutrients in the winter. The dilution experiments ascribed that the grazing mortality rates of eukaryotes were low compared to those of the other groups, whereas autotrophic cyanobacteria were more palatable to zooplankton than cryptophytes and eukaryotes. Our experimental results indicate that efficient escape from zooplankton grazing and fast response to nutrient availability synergistically caused the microplankton to bloom in the winter, whereas the bottom-up process (i.e., the phosphate effect) largely governed the nanoplankton bloom in the summer. |
topic |
top-down effect bottom-up effect phytoplankton bloom flow cytometry estuary Gwangyang Bay |
url |
https://www.mdpi.com/2073-4441/13/12/1682 |
work_keys_str_mv |
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