Posts tagged Limnology
The Best Offense is an Observant Defense: Aquatic Invasive Species

In lieu of the exciting results of the Exotic Aquatic Species Watch completed for the Cooperative Lake Monitoring Program in 2018, it is imperative to keep Gratiot Lake free of aquatic invasive species. The watch found no aquatic invasive plant species in Gratiot Lake! The best way to take on aquatic invasive species is to prevent them from colonizing in the first place.

 The Michigan Department of Natural Resources (MiDNR) recently amended the Natural Resources and Environmental Protection Act (Act 451 of 1994) Part 413 with changes for boaters and anglers that take effect March 21, 2019. The changes are intended to better protect waterways from the introduction and spread of aquatic invasive species.

  For more information, click the link below:

 https://www.michigan.gov/invasives/0,5664,7-324-68071_91899---,00.html?utm_source=govdelivery

Key Changes for Boaters:

              All of the following must be completed prior to transporting watercrafts over land:

  • Removing all drain plugs from bilges, ballast tanks, and live wells.

  • Draining all water from any live wells and bilges.

  • Ensuring the watercraft, trailer, and any conveyance used to transport the watercraft or trailer are free of aquatic organisms, including plants.

Key Changes for Anglers:

  • A person shall not release baitfish in any waters of this state. A person who collects fish shall not sue the fish as bait or cut bait except in the inland lake, stream, or Great Lake where the fish was caught, or in a connecting waterway to the body of water if the fish could freely move between the original location of capture the location of release.

  • A person, who catches fish other than baitfish in a lake, stream, Great Lake, or connecting waterway shall only release the fish in the lake, stream, or Great Lake where the fish was caught, or in a connecting waterway of the body of water where the fish was caught if the fish could freely move between the original location of capture and the location of release.

Below is a diagram (from the MiDNR) for how to correctly inspect and drain your watercraft:

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2018 Cooperative Lakes Monitoring Program  
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The 2018 Cooperative Lakes Monitoring Program (CLMP) report was issued and can be reviewed by clicking the button at the bottom of this post.  The results of the report cover the transparency, Phosphorus content, and Trophic Status.  This year’s program also included an Exotic Aquatic Plant Watch.

Transparency is measured using a Secchi disk, a very simple but effective method to determine water clarity. Phosphorus concentration is determined by taking water samples and sending them to a lab for processing. Phosphorus is one of the critical nutrients for algae growth and is important to monitor.  The Trophic Status Index (TSI) is a single figure used to assess the nutrient enrichment of a lake.  

The average Secchi depth is 16.7, which is the same as previous years.  The summer phosphorus sample is 6 parts per billion, which is lower than previous years. The TSI is also lower than previous years at 33, which is influenced by the Secchi depth and the phosphorus content.

The departure in phosphorus and TSI from previous years does not reveal any trends. It is normal for values to fluctuate from year to year. The purpose of the CLMP is to monitor lakes to prompt action when a clear trend in either direction appears. The next step would be to identify the mechanism causing the trend and come up with a solution.

The Exotic Aquatic Plant Watch surveyed multiple locations around the lake to identify and document the extent of invasive aquatic species. As of August 24th 2018, Gratiot Lake does not contain any of the invasive aquatic plant species on the watch list. For a complete list please review the report below.

2017 Cooperative Lakes Monitoring Program Report

Gratiot Lake Conservancy (GLC), in conjunction with some lake locals, collects data points annually to contribute to the Cooperative Lakes Monitoring Program (MiCorps). GLC has been providing data since 1999 to the program and is excited to continue to in the future.

MiCorps is a network of volunteer water quality monitoring programs in Michigan. It was created through Michigan Executive Order #2003-15 to assist the Department of Environmental Quality (DEQ) in collecting and sharing water quality data for use in water resources management and protection programs. To learn more about them click here: About MiCorps .

The 2017 report indicates Gratiot Lake is a 36 on the Trophic Scale Index, a metric used to evaluate the productivity, quality, and condition of a lake. The 36 places Gratiot Lake between an Oligatrophic Lake (think a barren, not very productive lake) and a Mesotrphic lake (medium amount of aquatic life and relatively productive). Given the size of Gratiot Lake, this ranking makes sense and is a good indicator of a healthy lake.

It is important to continue these measurements in order to monitor the condition and quality of the lake. If Gratiot Lake starts moving to a higher or lower number (scale is 0-100), it could indicate a potential problem or threat to the lake’s ecosystem and food web.

Dorothy Jamison taking Secchi Reading at Gratiot Lake in 2014

Dorothy Jamison taking Secchi Reading at Gratiot Lake in 2014

Limnologist, Erick Elgin, Exotic Aquatic Plant Watch training at Gratiot Lake

For about 18 years GLC has participated in Michigan Cooperative Lakes Monitoring Program (CLMP). Since 2006 Dorothy Jamison has been taking readings of lake transparency on average 14 times a year. Every one to two years a water sample from the lake is sent to the state lab to detect the amount of phosphorus present. Overall at Gratiot no major changes have been noted in this monitoring data over the years.

In 2005 and 2006 botanist Janet Marr undertook a comprehensive survey of aquatic vegetation at the lake. The survey revealed that Gratiot Lake was home to good array of beneficial native aquatic plants. As a baseline that survey provides data for comparison in the future. Native aquatic plants provide food and habitat for a healthy community of animals in the lake, including a variety of fish, so the richness and variety of plant species found was a good health indicator for the lake. Janet even discovered one plant that is endangered in Michigan: Subularia aquatica, water awlwort. She didn’t find any aquatic exotic plant species, but recommended that the lake be monitored from time-to-time for any invasive plants before they become problematic.

In July, limnologist Erick Elgin, a water resource educator from Michigan State University Extension Service, came to Keweenaw County to lead an Exotic Aquatic Plant Watch (EAPW) training at Gratiot Lake. GLC recently joined this monitoring effort through the Cooperative Lakes Monitoring Program. CLMP provides this hands-on Exotic Aquatic Plant Watch training so that those interested in lake monitoring to protect their lake can learn how to do just that. This program targets five plant species that pose the biggest threat to Michigan waters: Eurasian watermilfoil, curly-leaf pondweed, hydrilla, European frog-bit, and starry stonewort.

The night before the training, Erick stopped by the GLC Members Meeting held in Eagle Harbor to give an overview of this monitoring program. EAPW is a yearly check-up for the potential entry into inland lakes of invasive aquatic plant species. Of this list, Eurasian watermilfoil is the most immediate threat to Keweenaw lakes.

You can view more info about EAPW on the MiCorps.net website. Go to the “Lake Monitoring” drop- down menu at the top of the page and click on “Lake Training.” Then click on “Exotic Aquatic Plant Watch.”

No invasive species were noted during the training or in sampling done afterwards.

After the EAPW training, Erick presented a lake issues Q&A program in Eagle Harbor. Most questions were about shoreline erosion, lake levels, dams, and floods, especially with regards to Lake Superior shoreline. Although no easy solutions for homeowners were presented, Erick provided the links below.

Pictured above are Erick Elgin (at right) and Keweenaw Invasive Species Management Area (KISMA) Coordinator Sigrid Resh and members of the KISMA weed crew sampling aquatic vegetation with a “weed rake” at Gratiot Lake during the EAPW training.

Pictured above are Erick Elgin (at right) and Keweenaw Invasive Species Management Area (KISMA) Coordinator Sigrid Resh and members of the KISMA weed crew sampling aquatic vegetation with a “weed rake” at Gratiot Lake during the EAPW training.

Sample for benthic flora species using the double headed rake tossing sampling method, aka the ‘weed rake"'.

Sample for benthic flora species using the double headed rake tossing sampling method, aka the ‘weed rake"'.