This study investigated seasonal variations in phytoplankton community composition and physicochemical water quality across 90 lakes in South Korea surveyed 2022 to 2024, and examined their relationships with environmental factors. Over the course of four seasons, a total of 952 phytoplankton taxa were identified, with Bacillariophyta (diatoms) and Chlorophyta (green algae) accounting for 64.2% of the total species richness. Diatom species such as Aulacoseira granulata, Fragilaria crotonensis, and Cyclotella meneghiniana were frequently observed regardless of season. In terms of cell density, Cyanophyta were dominant, comprising 85.1% on average, with particularly high summer densities driven by blooms of Microcystis aeruginosa and Aphanizomenon sp. In contrast, diatoms accounted for the highest relative abundance in winter (54.1%). Canonical correspondence analysis (CCA) revealed that Cyanophyta and Chlorophyta were positively correlated with water temperature, TP, COD, and Chl-a, whereas Bacillariophyta and Cryptophyta showed negative correlations with these variables. These results indicate that phytoplankton communities in Korean lakes are highly responsive to variations in temperature and nutrient concentrations, and that summer rainfall-driven nutrient inflow plays a critical role in triggering cyanobacterial blooms. This study provides a scientific basis for understanding seasonal ecosystem dynamics in Korean lakes and offers foundational data for eutrophication management and the development of biological water quality assessment indices.

Abstract
서 론
재료 및 방 법
    1. 조사 지점 및 시기
    2. 시료 채집 및 수질자료
    3. 식물플랑크톤 분석
    4. 통계분석
결과 및 고 찰
    1. 계절별 이화학적 수질 항목 변화
    2. 계절별 식물플랑크톤 종 조성 및 세포밀도 변화
    3. 계절별 식물플랑크톤 주요 출현종
    4. 식물플랑크톤 출현과 환경요인 간의 관계 분석
적 요
REFERENCES

• 김난영(건국대학교 휴먼앤에코케어센터) | Nan-Young Kim (Human and Eco Care Center, Konkuk University, Seoul 05029, Republic of Korea)
• 황순진(건국대학교 휴먼앤에코케어센터, 건국대학교 환경보건과학과) | Soon-Jin Hwang (Human and Eco Care Center, Konkuk University, Seoul 05029, Republic of Korea, Department of Environmental Health and Science, Konkuk University, Seoul 05029, Republic of Korea) Corresponding author
• 심연보(건국대학교 환경보건과학과) | Youn-Bo Sim (Department of Environmental Health and Science, Konkuk University, Seoul 05029, Republic of Korea)
• 장민호(공주대학교 생물교육학과) | Min-Ho Jang (Department of Biology Education, Kongju National University, Kongju 32588, Republic of Korea)
• 박종성(국립환경과학원 수자원연구과) | Chong-Sung Park (Water Resources Research Division, National Institute of Environmental Research, Incheon 22689, Republic of Korea)