NWA 10/12/12

A Northwoods Almanac for 10/12 – 25/2012 by John Bates

Freshwater Jellyfish

            On 9/29, Cindy Carpenter reported seeing lots of freshwater jellyfish on 214-acre South Two Lake near Lake Tomahawk, a relatively deep lake for our area with correspondingly clear water. These quarter-sized jellyfish typically hover in the water column from several inches deep to as far down as one can see, and are translucent with a cross shape on their back.

            It’s thought that the jellyfish are one of two species native to China, both of which (Craspedacusta sowerbii and C. sinensis) live in the Yangtze River. Freshwater jellyfish were unknown outside of China until 1880 when the jellyfish were found swimming in a large, water-lily tank at the Royal Botanic Gardens outside London, England. Four years later in 1884, immature jellyfish polyps were found in a stream in Pennsylvania.            

            The jellyfish eventually found their way to Wisconsin and were first reported from a farm pond near Baraboo in Sauk County where wood ducks are speculated to have carried them to the pond. By October 2006, jellyfish had been reported from 40 water basins in Wisconsin, and as of 2012, in 89 Wisconsin lakes.

            The literature on the jellyfish’s natural history in Wisconsin says to look for jellyfish during dry and hot summers, and while this wasn’t officially a drought year for us, it’s certainly been dry. When lake shallows warm rapidly during spring, the jellyfish emerge in mid-June and swim toward the water surface. Only when they are full-grown and densely “bloomed” near the water surface do they draw attention.  And that typically doesn’t happen in Wisconsin until August to mid-September.

            The jellyfish are restricted to a narrow band of water temperature between 65 to 75 degrees. If the water surface of a lake becomes warmer than 75°, as some of our lakes do during hot summer afternoons, the jellyfish congregate in deeper water where they can find their preferred temperature range.

            The jellyfish feed on zooplankton, using their tentacles to sting these critters and capture even larger prey, such as water mites and insect midge larvae. These tiny jellyfish are not considered dangerous to humans. The mature jellyfish live a few weeks, release eggs, and die.

            Their impact, if any, is unclear. While their preference for large, predatory zooplankton could influence zooplankton species structure, no one knows if this is an issue.

Sightings

            A bull moose was photographed swimming across Rest Lake in Manitowish Waters, but other moose were also reported in a number of locations. Usually these are young bulls out for a walk-about, perhaps looking for a female, but who really knows?

            On 9/28, Sharon Lintereur spotted a white-crowned sparrow at her feeders. Tree, Harris, fox, white-throated, and white-crowned sparrows are all migrating through now.

            We’ve had a bevy of American robins, house finches, and yellow-rumped warblers around our house eating our abundant crabapples. One usually doesn’t think of warblers as fruit eaters, but the yellow-rumps have the most diverse diet of our warblers. Hopefully there will be a few crabapples left for the pine grosbeaks and Bohemian waxwings to feed on this winter.

Dark-eyed Juncos

On 9/29, Jane Gau near Boulder Junction reported seeing about a half dozen dark-eyed juncos under her feeder, the earliest she can ever recall seeing them. We’re at the southernmost edge of their nesting range, so we do have local birds that are seen throughout the summer, but it’s usually October that brings large flocks of juncos down out of Canada on their way to their wintering grounds.

Juncos are familiar to nearly everyone because of their ubiquity, abundance, tameness, and conspicuous ground-foraging winter flocks. Audubon (1831) stated that “there is not an individual in the Union who does not know the little Snow-bird,” a reference to its plumage which is characterized by white outer tail-feathers that flash when the bird takes flight and by a gray or blackish hood and back that contrasts with its whitish breast and belly. A recent estimate set the junco’s total population at approximately 630 million, so plenty to go around!

All juncos breeding in the North migrate, because as seed eaters, they need open ground in the winter upon which to forage. East of Mississippi River, females tend to migrate farther south than males, and adults migrate farther than hatching-year birds, a process called “differential migration.” Northern-breeding birds typically begin migrating in September, and are on their wintering grounds by early December.

Juncos commonly migrate at night and some are killed every year in collisions with human-made structures like television towers, indicating that many juncos migrate below tower heights.

In fall and spring, migrant juncos forage almost entirely on the ground and are common on lawns and along roadsides. Their winter food is almost entirely seeds from plants like chickweed, crabgrass, pigweed, knotweed, and sorrel. Analysis of their stomachs have also shown 0–66% sand and gravel, and gravel has even been found in the stomach of their nestlings, therefore being brought by adults. Because they lack teeth, seed-eating birds need to eat grit to help them digest their food. The grit grinds the seeds they eat in the gizzard, while the grit itself is slowly ground down and dissolved allowing the minerals to enter the bloodstream.

Fall Colors

            Autumn colors have peaked and many leaves have dropped, but what a glorious array of colors we were blessed with! Look now for the smoky gold of the tamaracks around our bog lakes – the color usually peaks around 10/15.

           

More Gleanings from the Rest Lake Dam Environmental Analysis

To understand how much water to hold back behind a dam, and how much to equitably disperse over a dam, you have to know how much is coming in. So, the water entering the Manitowish Chain comes from three sources:

1-    Precipitation: we average 34 inches of annual precipitation, which includes our 85 inches of annual snowfall in the watershed.

2-    River flow: the five major river/creek contributors to the Manitowish Chain are: Manitowish River – 48%

            Trout River – 28%

            Rice Creek – 15%

            Papoose Creek – 7%

            Gresham Creek – 2%

3-    Groundwater: groundwater contributes to the system, but the amount of water is difficult to study and poorly understood. During the summer, evaporation rates can be as high as 4 to 6 inches of water surface elevation loss per month; however, summer evaporation loss and groundwater inputs were estimated by the USGS to essentially cancel one another out.

When the Chain is drained 3.5 feet in elevation in late September, nearly 660 million cubic feet of water are released (at 5’0” elevation, the Chain holds 350 million cubic feet, and at 8’6”, the Chain holds 1,010 million cubic feet). Downstream, the narrow river basin typically floods in a few days, and the Turtle Flambeau Flowage is raised about 11 inches during the drawdown.                       

There are about 656 acres of surface water dewatered when the Chain is lowered 3.5 feet, most of which is the littoral zone where aquatic plants grow. The wetlands of the Chain provide important habitat for foraging, nursery, spawning, and cover for a diverse assemblage of fish, wildlife, and other aquatic organisms. They also provide important ecological function such as flood storage retention, water quality protections, scenic beauty, and shoreline protection.

The natural annual flow pattern of northern Wisconsin rivers is characterized by high flows in the spring when rain combines with snowmelt, and low flows in autumn. March 25^th is the average date for spring runoff in the Northwoods, and 75% or more of the spring runoff has passed by April 15^th, the average date when the refill of the Chain is begun. When the process of refilling the Chain begins, the flow in the river below the dam is instantaneously reduced from around 250 cubic feet per second (depending on the year) to 50 to 75 cfs, quickly ending the spring high flows. From the EA: “Many of the backwater and oxbow areas become dewatered and disconnected from the main river channel within 24 to 48 hours. These quickly changing water levels would continue to result in fish standing as well as having direct impacts to other organisms dependent on these habitats.” (See the photos to compare the differences in water depth at these different flow rates).

More from the EA: “Eliminating or reducing the 3.5 foot winter . . . would greatly reduce the frequency of low water conditions in the wetlands and shallow water areas on the Chain. This would increase the wetland functionality, habitat availability, and plant and animal diversity in these areas. In many of the shallow wetlands and bays, there would be sufficient water early in the spring which would restore habitat during critical periods for fish and wildlife reproduction needs.” It would also increase earlier recreational opportunities, and protect against low water levels during drought years.

What about piers and boathouses? There would be need for some landowners to do a one-time fix. “To reduce or eliminate the potential impact of ice, more landowners would likely remove their piers at the end of the summer. For structures that cannot be move, aeration systems and other methods to minimize ice damage would need to be installed by landowners. These methods are commonly employed on thousands of other lakes and impoundments that have a minimal winter drawdown or no drawdown. Other lakes chains in Northern Wisconsin also have numerous permanent structures at or below the ordinary high water mark such as the Eagle River Chain and the Minocqua Chain of Lakes. The Eagle River Chain is usually operated with only a 0.3 foot water level difference year round. The Minocqua Chain has a 1.05 foot difference between summer and winter water levels.”

 The draft environmental analysis (EA) of the Rest Lake Dam is available for public review. See http://dnr.wi.gov/water/basin/upwis/restlakedam/ea.html

Celestial Events

            10/14: We’re down to only 11 hours of daylight.

            10/15: New moon occurs.

10/18: Look at dusk for Mars two degrees south of the crescent moon.

10/20: The peak of the Orionid meteor shower occurs. It’s best viewed predawn                                     on the 20^th and 21^st. Look toward Orion for the best viewing. The Orionids                         average 15 to 25 meteors per hour.

Please share your outdoor sightings and thoughts: call me at 715-476-2828, drop me an e-mail at manitowish@centurytel.net, or snail-mail me at 4245N Hwy. 47, Mercer, WI 54547.