Late Summer Wanderings
by Howard Webb (St. Louis, MO, USA)
Late summer is an interesting time for exploring, especially
for daphina. Results are very unpredictable, as water quality and temperatures
are quite variable. The spring population blooms are past, and many temporary
ponds have dried up (especially with the current drought in the U.S. midwest).
In late July, I was out for a hike at the Arboretum. It has been several
years since I have been there, and they have added a wetlands area since my
last visit. This was my destination, with the intent to see what was there,
and what might have moved into the new habitat.
The Arboretum (Shaw Nature Preserve) is located in Grey Summit, MO, about 30 miles south-west of St. Louis. It was purchased by the Missouri Botanical Gardens in 1925, to protect plants from the St. Louis gardens, which were being threatened by high levels of smog (caused by coal furnaces). The farm land was never needed for the intended purpose, and has over time been restored to prairie and other native habitat. The wetland was added several years ago, by damming up a small stream.
Much of the wetland pond was dry, though there was standing
water at the end toward the dam. What was accessible was covered in water
lilies, and had a water depth of not more than 50cm. The water temperature
was reading about 30°C.
A water sample was take using a cup on the end of my walking stick. The sample was then transported home in a recycled water bottle.
The sample showed a diversity of specimens, actually better than what I thought I would find for this time of year (particularly due to the water temperature). I filtered the sample through silk-screen fabric, and wet-mounted what was retained on the cloth.
The diversity of specimen size makes for some problems. A number of the daphnia were partially crushed under the cover slip, while the smaller rotifers and ciliates were vigorously moving around (even from under the cover-slip, to the excess water around the edges). It was impossible to photograph some of these smaller critters (at 400x) due to their size and speed. In particular, I noticed several ciliates (spirotrichea?) and chlorophyta (micrasterias) and possibly a volvox.
To try and slow them down, I added some club soda to the slide (the CO2 reduced their oxygen, and hence their behavior). Unfortunately, I added too much and most of the soft body animals exploded.
The sub-stage light was greatly reduced (via a rheostat) to increase detail visibility. This does however produce a dark brown image, which was subsequently adjusted with the software (increase gamma and contrast). All images have been reduced from their original size.
Click images to view a larger version.
Remains of unknown
Water temperature: 30°C.
Depth: 50 cm
Location: 38.4760 N 90.8055 W (approx.)
Microscope: Bausch & Lomb monocular, 10x ocular, 4x, 10x and 40x objectives.
Camera: Canon PowerShot A70 3.2 megapixels, 2048x1536 original pixel size. Pictures taken using remote control software from a computer.
Software: Photoshop Elements
Shaw Nature Preserve
Missouri Botanical Gardens
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Published in the August 2005 edition of Micscape Magazine.
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