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Mag. 400x

• A water sample taken on 03/31/2024, from a small vernal stream in a wooded area, using a small sample bottled attached to an extension pole. Air temp 46F.

I'm not certain about the ID, but will check with geraldojpr and roman_romanov. Most fascinating about this specimen is that one semi-cell is 3-radiate (3 lobes) and the other is 6-radiate. An intermediate polymorph! Will its progeny be 3- or 6 radiate or a hybrid of both? Interesting! S. margaritaceum is noted to be "variable in the in the number of radial processes, , with 4-6 being the most often found" (https://www.outerhebridesalgae.uk/desmids/desmid-species.php?id=359) ... I could not find a reference noting 3-radiate S. margaritaceum. The first composite image shows the specimen in lateral view, then beginning to roll backwards. The second composite of 9 photos shows the same specimen making a ~180⁰ rotation about a slanted axis. (Panels 8 and 9 vary only in depth of field, not position of the specimen.) Too cool!
For more reference images of S. margaritaceum see:

• http://www.digicodes.info/Staurastrum_margaritaceum.html
• https://www.desmids.nl/maand/english/staurastrum_margaritaceum.html
• http://desmids.science4all.nl/?Desmid_pictures___Staurastrum&pic=47&page=0

Samples collected by Stephen Shivers, Betty Kreakie, and Bryan Milstead.

Water fairly clear.

With the algae torch we found a total chlorophyll of 15.5 µg/l with 1.7 µg/l due to cyanobacteria.

One horizontal tow collected near the boat ramp.

The phytoplankton assemblage in relative order of occurrence:
Asterionella: https://www.inaturalist.org/observations/12361078
Filamentous green algae: https://www.inaturalist.org/observations/12361174
Dinobryon: https://www.inaturalist.org/observations/12361245
Fragilaria: https://www.inaturalist.org/observations/12361264
Chlorella: https://www.inaturalist.org/observations/12361288
Staurastrum: https://www.inaturalist.org/observations/12361540
Synedra: https://www.inaturalist.org/observations/12361587

Protist: The tiny, circular organism is being observed.
Visual Description: The organism contains many daughter colonies for asexual reproduction which are green in color, hinting that it is from the phylum Chlorophyta. Also, the colonies are surrounded by a gelatinous wall.
Identifying Characteristic(s): The many green, spherical daughter colonies can be easily seen.
Location: The Beach at Castor in Tampa, Florida.
Habitat: Volvox are found in lakes with a lot of nutrients.
Geographic Distribution: Not located in a particular region.
Weather: Found in a sunlit area.
References:
https://www.britannica.com/science/Volvox
https://biologywise.com/volvox-characteristics