The Role of Aquatic Plants in Structuring Daphnia Food Quality & Quantity

The Problem

• Shallow lakes are very common, recreationally important and have two stable states: the preferred clear-water, plant-dominated state & the turbid-water, algal-dominated state.
• Large grazing zooplankton (e.g., Daphnia) help maintain the clear-water state by keeping algal populations low.
• Horizontally migrating Daphnia encounter heterogeneity in resource quantity and quality in shallow- and deep-water environments due to algae-plant nutrient competition.
• No studies have specifically examined the horizontal distribution of Daphnia resources in shallow lakes or the effects of this variation on Daphnia growth and reproduction.

Research Question

• Is there a pattern of lower quality & quantity algae with decreasing distance from shore and increasing plant density?
• How does the shallow-water environment affect Daphnia growth rate and reproduction?

Approach

• Whole-lake intensive field surveys of multiple lakes – Summer 2008 & 2009
• In-lake mesocosm experiments – Summer 2009
• Daphnia growth assays and reproduction experiments in the lab – Summer 2009

Funding

• EPA STAR Fellowship Program
• Gates Millennium Scholarship Program
• MSU Center for Water Sciences

Current Employment

Fish and Wildlife Biologist, US Fish and Wildlife Service