Beyond Pond Scum — Algal diversity around Storrs

All the different organisms we call “algae” pretty much span the entire tree of life, as they belong to several evolutionary lineages only distantly related to each other. The BioBlitz will provide opportunities for you to get closely acquainted with cyanobacteria, dinoflagellates, diatoms, euglenoids, chlorophytes, and others. Never heard of those? Chances are, they live right in your back yard.

For the most part, you need a microscope to discern the hundreds of species of freshwater algae occurring in New England. But there are exceptions, and they are not that hard to find once you know what to look for. For example stoneworts, or members of the green algal order Charales, are commonly mistaken for aquatic vascular plants, which they superficially resemble. Upon closer observation, however, it becomes apparent that they are not anatomically complex like “higher” plants and are instead made up of few-celled branched filaments. Two genera are currently known to occur around Storrs: Chara and Nitella. The invasive Nitellopsis obtusa (starry stonewort) is not yet known from Connecticut, but it is a major nuisance in the Midwest and definitely a species to be on the lookout for1.

Chara zeylanica
Nitella flexilis












Another green alga that is easily identified without a microscope does not look green at all. Thanks to their UV-protective carotenoid pigments, members of the genus Trentepohlia take on a red, orange, or yellow coloration. Moreover, they do not live in water! Instead, they inhabit tree bark (some species also grow on rocks or man-made walls) and can cover it in conspicuous reddish films that appear fuzzy upon closer examination. Around Storrs, Trentepohlia is most common on oaks and pines.


While cooling off in a stream or pond, with a fair amount of luck you might find macroscopic red algae (Rhodophyta) growing attached to rocks. Confusingly, these algae will probably look green or brownish on the outside. The soft, slimy, finely branched Batrachospermum can be found in streams or at the edge of ponds. Its somewhat elusive relative, the also branched but more robust, cartilaginous Tuomeya (photo below by Ellen Woods) grows in fast flowing streams such as the Fenton River. On rocks under dams like the Eagleville Dam you can often easily spot abundantly growing Lemanea, a rough, knobby rhodophyte belonging to the same order, Batrachospermales.














If you browse herbarium records of these macroalgae, you will likely notice a significant decrease in specimen numbers over time: most records are decades old, and many are older than a century. Despite this trend, these algae might not be all that rare, but simply aren’t being collected and reported as much now. On the other hand, given the ongoing man-induced habitat and climate changes, some of these species might indeed be declining. Thus, recording their occurrence during the UConn BioBlitz will be an important contribution to our knowledge of their current distribution in Connecticut.


1Sleith, R.S., Havens, A.J., Stewart, R.A. & Karol, K.G. (2015). Distribution of Nitellopsis obtusa (Characeae) in New York, U.S.A. Brittonia, 67, 166-172.