Middle Food Web & Exotics

Since 1999, Marsden, McCabe, Beekey, Malchoff, and Hauser have been working on the spread, role, and impacts of zebra mussels and other exotics in Lake Champlain. These studies are relevant to the categories of interactions, food web effects, benthic-pelagic coupling, and food web linkages. Malchoff, Hauser and Marsden are currently documenting sources, vectors, and impacts of current exotic species as well as assessing potential invaders and possible invasion routes. They are also conducting a cost/benefit analysis for prevention of spread via Champlain Canal. Marsden & others have completed the following projects:

Effect of zebra mussel colonization of soft sediments on foraging success by juvenile lake sturgeon (McCabe, Beekey, & Marsden). In prep.

Zebra mussels affect benthic predator foraging success and habitat choice on soft sediments (Beekey, McCabe, & Marsden 2004 Oecologia 141:164-170)

Soft sediment colonization by zebra mussels facilitates invertebrate communities. (Beekey, McCabe, & Marsden 2004 Freshwater Biology 49:1-11)

Mihuc has preliminary data indicating that rotifers are decreasing in abundance in Lake Champlain (E. Brines, pers. comm.) Probably more work is warranted in this area in order to determine the reality of the pattern and evaluate potential causes and effects. E. Brines has shown in lab studies that zebra mussels can change zooplankton nauplii densities. Studies to determine whether this holds in a field setting and the effects of such changes are warranted.

Studies involving the relative impact of introduced species

Define the role of zebra mussels in the ecosystem (current and some concluded)

Are the introduced species becoming the “dominant” group that will “fuel” the lake ecosystem?

Assess the global perspective about the distribution of adult zebra mussels throughout the lake

Projects that ‘monitor’ for input of new exotics

Monitor zooplankton, macroinvertebrate, fish, plant populations in the lake

Exotic impacts on native species

Native reestablishment following pest control

Effect of zebra mussels on habitat of benthic-spawning fishes

Ecological effects of alewives in Lake Champlain

Food web dynamics and fisheries restoration in the Lake Champlain basin

Exotic species distribution and colonization-metapopulation dynamics

Spread of exotic species- requires monitoring, ongoing

Identify habitats most likely for invasion

Dynamics of calcium and zebra mussel development and survival-

Facilitate predictions on potential colonization of zebra mussels

Feasibility study for dispersal barriers- ongoing

Champlain Canal and Richelieu River/Chambly Canal

What is the Lake Champlain –Richelieu River continuum?

Given that the Richelieu River is directly linked with the St. Lawrence River, what are the possibilities of introducing new species via this route?

How does diversity change along the Lake and River?

What are the mechanisms structuring and maintaining (or not) diversity along the Lake Champlain-Richelieu River basin?

Food Web Linkages

Linkages between middle and lower food webs-(some ongoing)

Bottom-up effects

Zebra mussel effects

Linkages between middle and upper food webs-

Top-down effects

Energy flow pathways

Understanding the planktonic food web-

Impact of zebra mussels on nutrients and energy flow

Plankton community dynamics (including zebra mussel veligers)

Quantify smelt densities and their feeding rates (requires monitoring)

Estimate secondary productivity in Lake Champlain (requires monitoring)

Benthic-Pelagic Coupling

Energy flow patterns between benthic and pelagic food webs

Effect of zebra mussels on benthic and pelagic food webs

Impact of zebra mussels on phytoplankton productivity in Lake Champlain (link with the phosphorus issue)

Interaction Studies

The interaction between zebra mussels and other benthic organisms

Smelt-zooplankton interactions

Zebra mussel-phytoplankton interactions

Potential relationship of zebra mussels to blue-green algae blooms in Lake Champlain