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1 year ago in Ecology , Limnology By Sallehahsim

What is the role of macrophytes in algal productivity?

I'm building a nutrient-phytoplankton-zooplankton (NPZ) model for a shallow eutrophic lake and need to accurately parameterize macrophyte effects. The literature shows paradoxical findings both inhibition and stimulation of algae. I need a clear breakdown of the primary mechanisms (e.g., nutrient competition, allelopathy, habitat provision) to decide which processes to include under different nutrient loading scenarios.

 

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By Nithin Rao Answered 1 year ago

Modeling this requires understanding the shifting dominance of multiple pathways. I have seen the primary mechanism switch along a nutrient gradient. In mesotrophic conditions, direct nutrient competition from macrophyte roots and shoots is often dominant, starving algae of N and P. As nutrients rise, allelopathy the release of polyphenols or fatty acids becomes a more critical inhibitory pathway. However, you must also parameterize indirect effects: macrophytes provide habitat for zooplankton and fish that graze on algae, but also for snails that reduce periphyton, which competes with macrophytes themselves. I would recommend a modular model where the strength of each pathway is a function of both macrophyte biomass and dissolved inorganic nutrient concentration.

 

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