San Francisco State University
Zooplankton growth in northern fishless lakes along a gradient in terrestrial organic matter inputs
In many north temperate and boreal surface waters terrestrial organic matter (tOM) inputs have increased over the past several decades. Increased tOM alters lake ecosystem functions by limiting light and introducing nutrients. It is unclear how increased tOM affects lake productivity and bottom-up control. Copepods are a good species for studying lake productivity because they are the principal trophic link between phytoplankton and fish and therefore very important in food web dynamics. In order to determine how tOM influences lake productivity we propose to measure somatic growth rates of copepods across a gradient of tOM in arctic lakes in northern Sweden. Growth rate is the key rate process in copepod secondary productivity. We will measure growth rates of the dominant calanoid copepod, Eudiaptomus graciloides, using a modified version of the artificial cohort method and an image analysis technique in conjunction with tOM concentration measurements. We will also measure chlorophyll, an indicator of phytoplankton biomass, and relate it to copepod growth rate. As tOM is predicted to increase with climate change, this research will be valuable in helping to better understand the effects of tOM on productivity and how it will affect lake ecosystems.
Dates: 15 June - 24 August