GLERL 2006 Milestone Reports

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GOAL 1: Ecosystem

Scientist: Dr. Henry Vanderploeg (GLERL)

NOAA Program: Ecosystem Research

OAR Performance Measure: Research to improve our understanding of the factors affecting ecosystems and the success of ecosystem approaches to management.

NOAA Performance Objective: Access, model and forecast ecosystem resources for management decisions.

Ecosystem Research Program Performance Measure: PM6: Cumulative number of tools and technologies that improve ecosystem-based management.

Milestone: Assess the ability of dreissenid mussels to selectively reject naturally occurring Microcystis colonies and predict their filtering rate on Microcystis and other algae in Lake Erie and Saginaw Bay.

Purpose: Previous work in my lab at GLERL had shown that toxic colonial Microcystis from Saginaw Bay and Lake Erie was rejected by dreissenid mussels and this rejection was the likely reason that Microcystis blooms occurred in lakes invaded by dreissenid mussels. However, to predict the characteristics (morphology and toxicity) of Microcystis blooms promoted, we examined the response of mussels to colonies of various sizes, genetic composition and toxicity

Efforts and Results (to date): A number of feeding and behavior observations were made on mussels given different strains of Microcystis aeruginosa isolated from lakes invaded by zebra mussels and lakes not invaded by mussels. Conclusions from this study are:

Colony size (and mucilage) is a sufficient condition for rejection.
Prevalence of colonies in nature suggests this is a constitutive defense mechanism or that infochemicals inducing this response are present or that there is always selection for colony formers.
Microcystis from invaded and not invaded lakes both elicit the rejection response.
Colony size may be an induced response to infochemicals of mussels.
Microcystin concentration may not be readily responsive to mussel infochemicals.
There is a toxicity response (not necessarily microcystin) in mussels that makes the rejection response more sensitive
More work is necessary to explain the interaction among dreissenid mussels, Microcystis abundance, colony form and toxin concentration
Our results using recently isolated strains from nature showing mussel rejection contrast sharply with the non-rejection response with Microcystis from commercial culture collections; therefore, we cannot learn anything using algae from these collections.

Customer(s): Mangers and the public concerned with human health, water quality, drinking water quality, and ecosystem production.

Cause Factors (if milestone not met): N/A

Revised Completion Date (if milestone not met): N/A

Last updated: 2006-07-14 mbl