Phytoplankton functional group dynamics and environmental drivers in a tropical monomictic lake (Lake Yambo, Philippines)

Tropical monomictic lakes, characterized by a single annual mixing event and prolonged stratification, are particularly sensitive to climatic and anthropogenic pressures. Lake Yambo, a tropical monomictic lake in the Philippines, exemplifies such systems, with stratification prevailing during the s...

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Main Authors: Dimple May Gianne Q. Dumaguit, Maxine A.D. Mowe, Rey Donne S. Papa
Format: Article
Language:English
Published: PAGEPress Publications 2025-06-01
Series:Journal of Limnology
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Online Access:https://www.jlimnol.it/jlimnol/article/view/2231
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author Dimple May Gianne Q. Dumaguit
Maxine A.D. Mowe
Rey Donne S. Papa
author_facet Dimple May Gianne Q. Dumaguit
Maxine A.D. Mowe
Rey Donne S. Papa
author_sort Dimple May Gianne Q. Dumaguit
collection DOAJ
description Tropical monomictic lakes, characterized by a single annual mixing event and prolonged stratification, are particularly sensitive to climatic and anthropogenic pressures. Lake Yambo, a tropical monomictic lake in the Philippines, exemplifies such systems, with stratification prevailing during the southwest monsoon and full lake mixing occurring during the northeast monsoon. This study examined vertical and seasonal variations in environmental conditions and phytoplankton functional group composition in Lake Yambo to assess how seasonal stratification and mixing affect functional groups’ vertical structure. Monthly sampling from March 2024 to February 2025 was conducted from the subsurface to 30 meters at 5-meter intervals. In situ measurements of water temperature, dissolved oxygen, pH, and nitrate (NO₃⁻) were obtained using multiparameter probes, while chlorophyll-a, ammonia, and total phosphorus were analyzed in the laboratory. Phytoplankton samples were collected, identified, and counted, with species comprising at least 5% of the total phytoplankton biomass per period classified into their respective functional groups. Lake Yambo exhibited meso-eutrophic conditions characterized by high total phosphorus concentrations but comparatively low chlorophyll-a levels, suggesting that phytoplankton growth is likely limited by nitrogen availability. Seasonal patterns governed thermal stratification and mixing, which, in turn, regulated vertical nutrient gradients. Stratified conditions during the southwest monsoon led to nutrient trapping and hypolimnetic anoxia, while northeast monsoon mixing redistributed nutrients, particularly NO₃⁻. These transitions strongly influenced the functional group composition. Seven dominant functional groups (B, F, G, H1, J, LO, and P) comprised 81% to 97% of the total phytoplankton biomass. Most functional groups declined with depth, but seasonal and vertical variations were distinct: Group G and H1 thrived in warmer surface waters with low nitrate concentrations. Groups J and LO were associated with cooler, nitrate-enriched surface layers during peak mixing, while Groups B, F, and P were more abundant at deeper layers under the same conditions. These findings support the hypothesis that seasonally driven stratification and mixing in tropical monomictic lakes structure vertical nutrient availability and shape phytoplankton functional group dynamics. Notably, the bloom of Group H1 during post-peak mixing under extreme nitrogen limitation and elevated temperatures poses a health risk, as this group’s descriptor taxon, Dolichospermum, can produce cyanotoxins. Thus, tropical monomictic lakes experiencing greater eutrophication may face increased risks of these toxic blooms. As a representative tropical monomictic system, Lake Yambo offers valuable insights into how similar systems respond to seasonal mixing and nutrient limitations, providing a framework for understanding and managing ecological risks in these environments.
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spelling doaj-art-eb6a6a2ae01c483d87647aae59d70b502025-08-20T02:40:26ZengPAGEPress PublicationsJournal of Limnology1129-57671723-86332025-06-018410.4081/jlimnol.2025.2231Phytoplankton functional group dynamics and environmental drivers in a tropical monomictic lake (Lake Yambo, Philippines)Dimple May Gianne Q. Dumaguit0https://orcid.org/0009-0005-3639-7809Maxine A.D. Mowe1https://orcid.org/0000-0001-9060-4163Rey Donne S. Papa2The Graduate School; Research Center for the Natural and Applied Sciences, University of Santo Tomas, ManilaDepartment of Biological Sciences, National University of SingaporeThe Graduate School; Research Center for the Natural and Applied Sciences; Department of Biological Sciences, University of Santo Tomas, Manila Tropical monomictic lakes, characterized by a single annual mixing event and prolonged stratification, are particularly sensitive to climatic and anthropogenic pressures. Lake Yambo, a tropical monomictic lake in the Philippines, exemplifies such systems, with stratification prevailing during the southwest monsoon and full lake mixing occurring during the northeast monsoon. This study examined vertical and seasonal variations in environmental conditions and phytoplankton functional group composition in Lake Yambo to assess how seasonal stratification and mixing affect functional groups’ vertical structure. Monthly sampling from March 2024 to February 2025 was conducted from the subsurface to 30 meters at 5-meter intervals. In situ measurements of water temperature, dissolved oxygen, pH, and nitrate (NO₃⁻) were obtained using multiparameter probes, while chlorophyll-a, ammonia, and total phosphorus were analyzed in the laboratory. Phytoplankton samples were collected, identified, and counted, with species comprising at least 5% of the total phytoplankton biomass per period classified into their respective functional groups. Lake Yambo exhibited meso-eutrophic conditions characterized by high total phosphorus concentrations but comparatively low chlorophyll-a levels, suggesting that phytoplankton growth is likely limited by nitrogen availability. Seasonal patterns governed thermal stratification and mixing, which, in turn, regulated vertical nutrient gradients. Stratified conditions during the southwest monsoon led to nutrient trapping and hypolimnetic anoxia, while northeast monsoon mixing redistributed nutrients, particularly NO₃⁻. These transitions strongly influenced the functional group composition. Seven dominant functional groups (B, F, G, H1, J, LO, and P) comprised 81% to 97% of the total phytoplankton biomass. Most functional groups declined with depth, but seasonal and vertical variations were distinct: Group G and H1 thrived in warmer surface waters with low nitrate concentrations. Groups J and LO were associated with cooler, nitrate-enriched surface layers during peak mixing, while Groups B, F, and P were more abundant at deeper layers under the same conditions. These findings support the hypothesis that seasonally driven stratification and mixing in tropical monomictic lakes structure vertical nutrient availability and shape phytoplankton functional group dynamics. Notably, the bloom of Group H1 during post-peak mixing under extreme nitrogen limitation and elevated temperatures poses a health risk, as this group’s descriptor taxon, Dolichospermum, can produce cyanotoxins. Thus, tropical monomictic lakes experiencing greater eutrophication may face increased risks of these toxic blooms. As a representative tropical monomictic system, Lake Yambo offers valuable insights into how similar systems respond to seasonal mixing and nutrient limitations, providing a framework for understanding and managing ecological risks in these environments. https://www.jlimnol.it/jlimnol/article/view/2231lake monitoringmixing regimenutrient dynamicsphytoplanktontropical lakes
spellingShingle Dimple May Gianne Q. Dumaguit
Maxine A.D. Mowe
Rey Donne S. Papa
Phytoplankton functional group dynamics and environmental drivers in a tropical monomictic lake (Lake Yambo, Philippines)
Journal of Limnology
lake monitoring
mixing regime
nutrient dynamics
phytoplankton
tropical lakes
title Phytoplankton functional group dynamics and environmental drivers in a tropical monomictic lake (Lake Yambo, Philippines)
title_full Phytoplankton functional group dynamics and environmental drivers in a tropical monomictic lake (Lake Yambo, Philippines)
title_fullStr Phytoplankton functional group dynamics and environmental drivers in a tropical monomictic lake (Lake Yambo, Philippines)
title_full_unstemmed Phytoplankton functional group dynamics and environmental drivers in a tropical monomictic lake (Lake Yambo, Philippines)
title_short Phytoplankton functional group dynamics and environmental drivers in a tropical monomictic lake (Lake Yambo, Philippines)
title_sort phytoplankton functional group dynamics and environmental drivers in a tropical monomictic lake lake yambo philippines
topic lake monitoring
mixing regime
nutrient dynamics
phytoplankton
tropical lakes
url https://www.jlimnol.it/jlimnol/article/view/2231
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AT reydonnespapa phytoplanktonfunctionalgroupdynamicsandenvironmentaldriversinatropicalmonomicticlakelakeyambophilippines