Quantifying seasonal changes in structure and stability of lake food webs

2020 Fiscal Year Final Research Report

• Project/Area Number: 17K15056
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Conservation of biological resources
• Research Institution: National Institute for Environmental Studies
• Principal Investigator: Kadoya Taku 国立研究開発法人国立環境研究所, 生物・生態系環境研究センター, 室長 (40451843)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: 群集 / 食物網 / 生物多様性 / 安定性

Outline of Final Research Achievements

This study aimed to elucidate the seasonal changes in the structure and stability characteristics of the food web in Tonle Sap Lake, where the water level changes significantly between the dry and wet seasons. Analysis of stomach contents and nitrogen stable isotope ratios revealed that the trophic level of small piscivores, in particular, was lowered during the wet season. It was suggested that this trophic level decrease was due to the increase in the proportion of invertebrates and plant matter as diet. Furthermore, mathematical model analysis of the food web suggested that the trophic interactions between zooplankton and crustaceans tends to be destabilized, and that omnivorous fish species often play an important role in stabilizing this interaction.

Free Research Field

生態学

Academic Significance and Societal Importance of the Research Achievements

栄養段階や雑食性は、生態系の安定性に大きく影響を与えることが知られている。本研究は、雑食性魚種がトンレサップ湖の生態系の安定性に重要な機能を果たしている可能性があること、さらに、このような栄養段階や雑食性が季節によって大きく変動する可能性を示した。これらの結果は、生態系の安定性を正しく理解し管理方策を考える上では、季節的な食物網の構造や特性の把握が欠かせないことを示している。