Algae around UConn

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Radiococcaceae2.jpg
Simplified diagram of the eukaryotic tree of life highlighting lineages containing photosynthetic organisms - algae

Biodiversity hidden to the naked eye

Microorganisms are incredibly diverse. A small sample of water from a local pond can contain dozens of species - some related to plants, some related to fungi, and some belonging to completely different, ancient lineages of eukaryotes (see simplified eukaryotic tree of life on the left). Algae are a subset of this diversity: they are organisms that contain a photosynthetic organelle (plastid). Here are a few examples of the charismatic algae found in the vicinity of the University of Connecticut.
Click here to see the map of localities sampled so far
Current total: 102 species!

Stramenopiles

Many microscopic and macroscopic algae belong to the group called Stramenopiles (also referred to as heterokonts). Diatoms, Chrysophytes, and Synurophytes are microscopic, and Phaeophytes (kelps, or brown algae) are mostly macroscopic and marine.

  • Dinobryon is a colonial flagellated alga from the class Chrysophyceae. Another colonial chrysophyte is Uroglenopsis, also found in CT (Middle Bolton Lake).


Uroglenopsis cf. americana from Middle Bolton Lake, Vernon, CT; video here
Dinobryon cf. cylindricum from Walker Reservoir, Vernon, CT


  • Synura is a genus of the Synurophyceae, the sister group of Chrysophyceae. Their plastids give members of both groups a typical golden-brown color. Synurophyceae have cells covered with siliceous scales. Detailed examination of scale morphology is often needed for species identification. Colonies of Synura are not the most elegant of swimmers, but are fun to watch tumbling around.
  • Mallomonas is a common solitary synurophyte. Its cells are also covered in scales and often equipped with long bristles attached to the scales. Note how large the cell is in comparison to the individual cells in the colony of Synura.
Synura cf.uvella from Walker Reservoir, Vernon, CT; video here
Synura cf. caroliniana from Breakneck Pond, Union, CT
Mallomonas caudata from Bone Mill Pond, Storrs, CT


  • Diatoms (Bacillariophyceae) are very common not only in freshwater habitats, but also in marine environments. They can be solitary cells or form chains or stalked colonies. Their cells are enclosed in siliceous cases called frustules, which bear fine ornamentation best visible under high magnifications or under a scanning microscope. These fine structures of the frustules are used to identify diatom species.


Nitzschia sp. from Mirror Lake, Storrs, CT
empty frustule of Pinnularia sp. from Tift Pond, Storrs, CT
Epithemia sp. from Tift Pond, Storrs, CT
Surirella sp. from Tift Pond, Storrs, CT
Cymbella sp. from Tift Pond, Storrs, CT


Melosira sp., a common chain-forming diatom from Middle Bolton Lake, Vernon, CT
Nitzschia sigma, a unicellular diatom from pond on Forest Rd., Mansfield, CT
Tabellaria sp., a common colony-forming diatom from Middle Bolton Lake, Vernon, CT
Rhopalodia gibba, a unicellular diatom from the EEB greenhouse, Storrs, CT
Cocconeis sp., a unicellular diatom from the EEB greenhouse, Storrs, CT
Gomphoneis sp. from stream by the Willington Pizza restaurant, Willington, CT
Asterionella sp. from Breakneck Pond, Union, CT
Eunotia serra from Breakneck Pond, Union, CT
Eunotia sp. from Breakneck Pond, Union, CT
Neidium sp. from a marsh at Bigelow Hollow, Union, CT


  • Gonyostomum is one of the few members of the small phylum Raphidophyta. It can form nuisance blooms.
Gonyostomum semen from a wetland at Bigelow Hollow, Union, CT


Dinoflagellates

Dinoflagellates are members of the Alveolata, a group related to the Stramenopiles. Ceratium and Peridinium are common freshwater genera.

Ceratium hirundinella from Middle Bolton Lake, Vernon, CT
Peridinium cf. cinctum from Breakneck Pond, Union, CT
Gymnodinium sp. from Breakneck Pond, Union, CT


Cyanobacteria

Some "algae" are not even eukaryotic - the photosynthetic Cyanobacteria (some of which gave rise to chloroplasts) are sometimes also referred to as "blue-green algae". They are morphologically diverse, ranging from unicellular to colonial to filamentous. They are very common and in some cases even form toxic blooms.

Gloeocapsa sp. from the EEB greenhouse, Storrs, CT
unidentified colonial cyanobacterium from the pond on Forest Rd., Mansfield, CT
Hapalosiphon sp. from the pond on Eldredge Rd., Willington, CT
Oscillatoria sp. from the Cedar Swamp, Mansfield, CT
Nostoc sp., a colony-forming cyanobacterium from Breakneck Pond, Union, CT
Tolypothrix sp., a filamentous cyanobacterium and its characteristic "false branching"; from Breakneck Pond, Union, CT


Lyngbya sp., a large sheathed filamentous cyanobacterium from Tift Pond, Storrs, CT
Leibleinia, a small filamentous cyanobacterium growing epiphytically on Lyngbya; Tift Pond, CT
Woronichinia naegeliana a cyanobacterium forming compact, round, hollow colonies; Tift Pond, CT

Euglenoids

Euglenoids are an ancient lineage most closely related to Kinetoplastida (best known for the parasite Trypanosoma). They acquired photosynthetic abilities by engulfing a green alga - and therefore they may superficially resemble one. Among the commonly occurring genera are Euglena, Trachelomonas, and Phacus.

  • Unlike green algae, which store energy in form of starch, euglenoids use a different carbohydrate, paramylon. The paramylon bodies are often large and of a white-ish, "shiny" appearance, like the one visible in the Phacus specimen below.
Phacus orbicularis from pond on Forest Rd., Mansfield, CT
a large Euglena sp. from Breakneck Pond, Union, CT; video of another large Euglena species from Tift Pond can be found here
Trachelomonas volvocina from pond on Eldredge Rd., Willington, CT; video of another species here
Trachelomonas armata var. steinii from Tift Pond, Storrs, CT
Strombomonas sp. from Tift Pond, Storrs, CT


Green algae: Chlorophyta

  • Some algae grow on plants or on other algae - epiphytically. Aphanochaete from the order Chaetophorales, is an example of a green filamentous alga growing on another green filamentous alga, Oedogonium (order Oedogoniales).
  • Other free-living filamentous algae are Microspora, the branching Chaetophora, the above mentioned Oedogonium, and Bulbochaete - a relative of Oedogonium with branched filaments ending in long projections.
  • Green algae often produce swimming cells as part of their life cycles. As an example, a video of a swimming cell of Oedogonium can be found here.
Aphanochaete repens growing epiphytically on Oedogonium; from Walker Reservoir, Vernon, CT
Chaetophora sp. from stream by the Willington Pizza restaurant, Willington, CT
Microspora sp. from stream by the Willington Pizza restaurant, Willington, CT
Oedogonium sp. from stream by the Willington Pizza restaurant, Willington, CT; swimming cell video here
Bulbochaete sp. from pond on Forest Rd., Mansfield, CT


Palmodictyon varium, an unusual not-quite-filamentous green alga from Cedar Swamp/Rt. 195, Mansfield, CT
Stigeoclonium flagelliferum, a branching filamentous green alga related to Chaetophora and Aphanochaete; from Cedar Swamp/Rt. 195, Mansfield, CT
Characium sp., another epiphytic green alga, Cedar Swamp, Mansfield, CT
Geminella ellipsoidea, Cedar Swamp, Mansfield, CT
Selenastrum capricornutum, a colonial alga from Breakneck Pond, Union, CT


Ankistrodesmus falcatus, a colonial alga from Breakneck Pond, Union, CT
Kirchneriella lunaris, a colonial alga from Breakneck Pond, Union, CT


  • Some green algae form colonies with defined numbers of cells (4, 8, 16, etc.). Such colonies are called coenobia. Commonly found coenobial green algae are Pediastrum, Stauridium, Coelastrum, Desmodesmus, and Scenedesmus from the order Sphaeropleales. Their sister order Volvocales also contains several coenobial representatives, for example: Eudorina, Pleodorina, Pandorina, and Volvox.
Stauridium tetras from pond on Forest Rd., Mansfield, CT
Desmodesmus denticulatus from pond on Forest Rd., Mansfield, CT
Coelastrum microporum from pond on Forest Rd., Mansfield, CT
Eudorina elegans, a coenobium of flagellates from Breakneck Pond, Union, CT
Pandorina morum, a coenobium of tightly packed flagellates from Breakneck Pond, Union, CT


Pediastrum duplex, a coenobial alga related to Stauridium, from Breakneck Pond, Union, CT
Scenedesmus sp., a close relative of Desmodesmus, from Breakneck Pond, Union, CT
Coelastrum cambricum, a colonial alga from Breakneck Pond, Union, CT


Green algae: Streptophyta

  • The order Desmidiales contains some of the most spectacular of algae. Many species of the crescent-shaped Closterium can be found in the Northeast, as well as Cosmarium, Staurastrum, Euastrum, Micrasterias, Xanthidium, and others.
Tetmemorus brebissonii from a marsh at Bigelow Hollow, Union, CT
Tetmemorus granulatus from a marsh at Bigelow Hollow, Union, CT


Closterium navicula from pond on Forest Rd., Mansfield, CT
Cosmarium denticulatum from pond on Forest Rd., Mansfield, CT
Euastrum verrucosum from pond on Forest Rd., Mansfield, CT
Euastrum cf. oblongum from pond on Forest Rd., Mansfield, CT
Staurodesmus dejectus from pond on Forest Rd., Mansfield, CT


Xanthidium antilopaeum from pond on Forest Rd., Mansfield, CT
Cosmarium sp. from the EEB greenhouse, Storrs, CT
Cosmarium granatum from pond on Forest Rd., Mansfield, CT
Cosmarium contractum from pond on Forest Rd., Mansfield, CT
Staurastrum cf. hirsutum from stream by the Willington Pizza restaurant, Willington, CT


Closterium cf. kuetzingii from pond on Forest Rd., Mansfield, CT
Closterium sp. from pond on Forest Rd., Mansfield, CT
Hyalotheca dissiliens, a filamentous desmid from Cedar Swamp/Rt. 195, Mansfield, CT
Desmidium grevillei, a filamentous desmid from Cedar Swamp/Rt. 195, Mansfield, CT
Desmidium swartzii, a filamentous desmid from Breakneck Pond, Union, CT
Spondylosium cf. pulchrum, a filamentous desmid from Breakneck Pond, Union, CT
Teilingia sp., a small filamentous desmid from Breakneck Pond, Union, CT


Euastrum cf. pulchellum from pond on Forest Rd., Mansfield, CT
Euastrum binale from Breakneck Pond, Union, CT
Euastrum bidentatum from Breakneck Pond, Union, CT
Euastrum affine from Breakneck Pond, Union, CT
Euastrum denticulatum from Breakneck Pond, Union, CT


Micrasterias radiosa, a large desmid from Breakneck Pond, Union, CT
Micrasterias truncata from Breakneck Pond, Union, CT
Micrasterias laticeps from Breakneck Pond, Union, CT


Pleurotaenium nodosum from Breakneck Pond, Union, CT
Staurastrum arctiscon from Breakneck Pond, Union, CT
Bambusina brebissonii from Breakneck Pond, Union, CT
Staurodesmus convergens from Breakneck Pond, Union, CT
Staurastrum cf. ophiura from Breakneck Pond, Union, CT
Cosmarium amoenum from Breakneck Pond, Union, CT


Micrasterias denticulata from Bigelow Pond, Union, CT
Micrasterias rotata from Breakneck Pond, Union, CT
Micrasterias rotata var. japonica from Breakneck Pond, Union, CT
Cosmarium subcucumis from Bigelow Pond, Union, CT


  • The order Zygnematales contains commonly occurring ("weedy") filamentous taxa Zygnema, Mougeotia, and Spirogyra, but also several unicellular genera, for example Netrium or Spirotaenia.
Spirogyra sp. from stream by the Willington Pizza restaurant, Willington, CT
Mougeotia sp. from Cedar Swamp/Rt 195, Mansfield, CT
Netrium digitus from Breakneck Pond, Union, CT
Spirotaenia condensata from Breakneck Pond, Union, CT


  • The Coleochaetales are among the closest relatives of land plants. Some species retain and nourish the fertilized zygote (this is called matritrophy) and form disc-like thalli (bodies) that often grow attached to aquatic plants or other substrates.
Coleochaete scutata from Bigelow Pond, Union, CT


  • Not all algae are microscopic. Aside from the conspicuous marine seaweeds, several freshwater algae are also observable by the naked eye. The green algae of the class Charophyceae (stoneworts) can be found in many water bodies in the Northeast, but can be easily mistaken for aquatic plants.
Nitella flexilis from Walker Reservoir East, Vernon, CT
Chara zeylanica from the EEB greenhouse, Storrs, CT, and a closeup of its reproductive structure (oospore)


  • And let's not forget the most famous lineage of Streptophyta - land plants!
orchids on a stump
sundew - a carnivorous plant, growing on a stump
Breakneck Pond, Union, CT