skip to content
Cofrin Center for Biodiversity

Archive for the ‘Great Lakes’ Category

Spiders in Search of Beachfront Real Estate!

Dr. Michael Draney (Natural and Applied Sciences) and James Steffen (Chicago Botanic Garden) recently published an article in the journal Great Lakes Entomologist titled “Disjunct Lake Michigan populations of two Atlantic Coast spiders, Disembolus bairdi and Grammonota pallipes (Araneae: Linyphiidae)”.

Steffen and Draney discovered two species of spiders living on the beaches of Lake Michigan that had only ever been found before living near the Atlantic Ocean. Scientists use the word “disjunct” to describe isolated populations like these that are related but widely separated from each other geographically. The discovery that the spiders also live along the shore of Lake Michigan, more than 800 miles inland raises some interesting questions, namely how did these very tiny (less than 2 mm animals) get to the Great Lakes across hundreds of miles of unsuitable habitat?

Populations can become separated from each other when the environment they live in separates into fragments due to geologic or climate events. Continents drift apart, rivers change their course or mountains rise, isolating populations on separate islands of suitable habitat. Populations also become disjunct from each other when species expand their ranges into new territories. This most often happens with species like birds or butterflies that can move long distances, or with species that hitch a ride on floating debris or on (or in) migrating animals.

Beach habitat

Beach habitat.

Can you tell which of the photos is of a beach on Lake Michigan and which is a beach in New Hampshire?

(See the end of this post for the answer.)

While we don’t know how they got so far away from the Atlantic Ocean, the most probable explanation is that individual spiders ballooned inland by releasing long gossamer threads of silk that catch the wind and propel them along like a kite. Ballooning spiders are known to travel even thousands of miles using this technique. Those that were lucky enough to land near the shore of the Great Lakes found themselves in a hospitable and familiar habitat that they could colonize. The spiders do not care where that beach is located as long it provides what they need to survive and reproduce. Suitable habitat probably exists or existed in patches along the St. Lawrence Seaway and the Great Lakes east of Lake Michigan, and spiders may have “island hopped” by ballooning between such somewhat isolated islands of suitable habitat along the way from the Eastern Seaboard to northern Illinois.

Understanding more about disjunct populations like these helps us to understand how specialized species might fare as they become isolated. Under favorable conditions, isolated populations survive, and over time, due to mutation and natural selection, become so genetically different from their far away relatives that the population may evolve into a new species. When conditions are poor and habitats are degraded or lost to development, pollution, or climate change, small isolated populations are more likely to go extinct. By monitoring species like these we can better track the health of the Great Lakes.

Essentially all of the midwest’s plants and animals were absent from the Great Lakes thousands of years ago when the region was glaciated.   Each species has a different history of where it took refuge during those ages, and how it got from there to here.   The intersection of all these unique natural histories contributes to our complex and fascinating regional biodiversity. These Atlantic coast disjuncts are here because of the Great Lakes and the unique coastal habitats they make possible. The present study shows that not just plants (like dwarf lake iris or Pitcher’s thistle) but also animals can be dependent on special Great Lakes coastal habitats. You’ve probably never seen Disembolus bairdi and Grammonota pallipes. Still, these species are two additional (but tiny!) reasons to appreciate our Great Lakes.

The photo on the top was taken by Dr. Robert Howe at White Fish Dunes, WI and the photo on the bottom was taken by Dr. Steve Weeks of dunes in New Hampshire.

Assessing Coastal Hazards in Great Lakes Communities

You know those scenes in movies where the main character is standing on the edge of a cliff and all of the sudden the ground falls out beneath him and he drops into the water? In Great Lakes communities, that is an actual concern for some people.

There has been an increasing demand for a new standard of care to be upheld in the Great Lakes. People demanded that we not just minimize harm but also rehabilitate the Great Lakes. In February 2009 President Obama proposed a $475 million Great Lakes Restoration Initiative Action Plan. The Great Lakes Restoration is now a National Priority.

There are five significant ecosystem problems in the Great Lakes.

  • Toxic Substances and Areas of Concern (e.g. pollution prevention and clean up)
  • Invasive Species
  • Nearshore Health and Nonpoint Source Pollution (e.g. reduce polluted runoff from urban, suburban, and agricultural sources)
  • Habitat and Wildlife Protection and Restoration
  • Accountability, Education, Monitoring, Evaluation, Communication, and Partnerships

 

The green color of the bay comes from chlorophyll present in algae.

Where does the Biodiversity Center fit into all of this? The Center is hosting a workshop that will be held at UWGB on June 19, 2012. This workshop focuses on developing online tools to help local decision-makers address hazard related threats and effects of climate change on Great Lakes communities. For example, if a company wanted to build on a bluff near Lake Michigan they would have to talk to a zoning director about how close to the edge of the bluff they can build. The zoning director could use these online tools to figure out how far away from the edge the building has to be so it won’t be at risk of falling into the water someday due to bluff erosion. The goal of this project is for coastal communities to have a better understanding of how they may be impacted by the hazards of a changing climate, and to provide new tools and information for developing adaptive plans.

At this workshop, decision makers will have the opportunity to interact with the online tools. The tools incorporate geospatial data, science-based information, and visualizations. The goal is for decisions-makers to understand and document the effects of “proposed projects” and what liabilities those projects may create for the community. At the workshop, the instructor will propose a project and the users can use the tools to consider if the project will:

  • Accelerate/amplify existing hazards (e.g. erosion and flooding)
  • Increase infrastructure costs and liabilities related to flooding and shoreline protection
  • Worsen resource management challenges associated with water quality, habitat conservation, and the public trust doctrine
  • Decrease the economic, cultural, physical, and ecological resilience of natural and built coastal environments

After the workshop, the users will give their feedback based on their experience with the online program. This feedback is vital in determining how beneficial these online tools will be for local officials in their decision making tasks.

There are four main categories for the online tools.

  • Hazards Management and Planning: this section of the online tools is based on demographic data, land use and parcel data, hazard and flood maps, and climatology data (e.g. extreme temperatures, precipitation change, and flood events).
  • Coastal Erosion and Bluff Recession Prediction: the section demonstrates the connections between weather and climate conditions, coastal recession, bluff retreat hazards, and shoreline management strategies.
  • Coastal Infrastructure Planning: the section focuses on coastal structures including their maintenance costs, effectiveness and regional impacts (e.g. hardened shorelines, recreational and commercial use).
  • Habitat Conservation and Restoration Planning: this section focuses on protecting the region’s key ecosystem resources, especially maintaining the protective and beneficial functions of natural floodplains.

The National Oceanic and Atmospheric Administration (NOAA) Coastal Services Center and Association of State Floodplain Managers are key partners for this project.