Water Science: Wetland Slime

Worry not! There's probably no reason for alarm, as this is a natural occurrence and is evidence of a functioning wetland. 

The orange slime is a product of iron-oxidizing microbes, which "feed" on iron molecules that come from the soil.  As a result, an orange-colored iron plaque forms on sediment below the water and has the appearance of a toxic, orange "goo". While off-putting, it's actually just a deposit from the bacteria transferring from iron from a solid form (soil) to a solution (water). Without the bacteria, high iron levels would spread into lakes and streams, hindering aquatic life and water quality. This process most often occurs in areas where mineral and iron-rich groundwater seeps into surface water.

wetland slime 3.jpg

This process goes to show the larger role wetlands have in environmental health. Wetlands create a transition zone between aerobic (oxygenated) and anaerobic (non-oxygenated) conditions. Because they're a transition between water, air, and soil, they're a dynamic space balances gas, mineral, and nutrient exchange. Wetland plants (cattails, sedges, and grasses) are a major part of this interaction. With a web of roots that run below the surface (known as rhizome roots) wetland plants provide the structure, or rhizosphere, for these important microbes to grow on. 

wetland slime 2.jpg

Microbes and wetland plants work together to keep a wetland healthy, balanced, and productive by bringing oxygen to the water and plants, they consume methane, balance minerals, and balance pH. With oxygen able to reach the plants in these harsh growing conditions, the plants can do what they do - take up nutrients and support insects, birds, and other wildlife. When it all comes together, it's like one big, natural factory that produces habitat, clean air, and clean water!

With higher than average precipitation in the Twin Cities metro and in VLAWMO over the last few years, groundwater tables are also high. With this, we may see more of this orange slime occurring in streams, wetlands, and in low, wet areas. 

Birch Lake Wetland - Fall.png

 To learn more about iron-oxidizing microbes check out:

Audio transcript: 

The Terramar Project 

Peer-reviewed journal: 

Iron-Oxidizing Bacteria are Associated with Ferric Hydroxide Precipitates (Fe-Plaque) on the Roots of Wetland Plants 

 

Recent Posts

2022 Watershed Award Recipients

VLAWMO is pleased to present this year's Watershed Award recipients. Check our their stories here!

Special Thanks to Paul Duxbury

VLAWMO extends its gratitude to Paul Duxbury for over 5 years of service on the VLAWMO Technical Commission.

Neighborhood Spotlight: Karen Suzukamo

A look at a raingarden, sedge groundcover, and green roof.

Saint Mary's of the Lake Raingarden Renovation

VLAWMO sends its thanks to local Boy Scout Alex Nelson for undertaking a raingarden renovation project for his Eagle Scout badge.

Lake Care Weekend 2022

Fall marks one of the best times of year for this convenient lake care strategy.

More news

View all news