REGULATION OF PHYTOPLANKTON COMMUNITIES BY MACROPHYTES IN TROPICAL LAKES: INSIGHTS FROM FIELD MESOCOSM AND LABORATORY-BASED STUDIES

Abstract

Tropical shallow lakes provide key ecosystem services but are vulnerable to anthropogenic impacts that can trigger an undesirable shift to a turbid condition dominated by phytoplankton. I investigated the ability of macrophytes to regulate phytoplankton communities in the tropics and, consequently, evaluated their potential to rehabilitate turbid tropical shallow lakes. Two main approaches were employed: (1) field mesocosm experiments conducted to assess the influence of macrophytes on phytoplankton communities; and (2) a combination of laboratory bioassay and analytical techniques to assess the role of allelopathy in regulating phytoplankton. Different macrophyte growth-forms can reduce overall phytoplankton biomass and alter phytoplankton community structure in tropical lakes, though not as a sole restorative measure. Potential allelopathic mechanisms were identified in the studied macrophytes and could contribute to the effects on phytoplankton. Overall findings highlight the ecological significance of macrophytes in tropical lakes and offers useful insight into the management of tropical lakes.