Key
to the Dominant Diatom Species of the Great Lakes
Radially symmetric and circular in valve view - Eucentric
diatoms (2) |
Radially symmetric, Bipolar or multipolar - Eccentric diatoms
- Not Dominant in the Great Lakes |
Bilaterally symmetric or asymmetric with a thick sternum
running longitudinally along both valves (8) |
2. Eucentric diatoms
Cell length < 2x diameter (3)
|
|
3. Short eucentric diatoms
Valve with an intramarginal zone of costae encircling
the cell - Cyclotella spp. |
Valve evenly ornamented with punctae - Thalassiosira
spp. and Coscinodiscus spp. (Coscinodiscus not
dominant in the Great Lakes) |
Valve ornamented with radiating rows of punctae which
are separated by smooth zones - Stephanodiscus
spp. |
4. Cyclotella spp.
- Cyclotella comensis
- Cyclotella comta
- Cyclotella delicatula
- Cyclotella ocellata
5. Stephanodiscus spp.
- Stephanodiscus alpinus
- Stephanodiscus binderanus
- Stephanodiscus hantzschii f. tenuis
- Stephanodiscus niagarae
- Stephanodiscus parvus
- Stephanodiscus subtransylvanicus
6. Thalassiosira spp. and/or Coscinodiscus
spp.
7. Aulacoseira spp.
- Aulacoseira islandica
- Aulacoseira subarctica
8. Bilaterally symmetric or
asymmetric with a thick sternum running longitudinally along both
valves
Bilaterally symmetric; neither sternum modified to form
a raphe - Araphid Diatoms (9) |
Raphe (on both valves) raised in a keel; raphes central
or displaced toward one side - Nitzschioid
Diatoms (10) |
Raphe otherwise (e.g., on only one valve, reduced to the
ends, asymmetric, wrapped around the margin forming a wing,
etc) - Not Dominant in the Great Lakes |
9. Araphid Diatoms
Colony a zig-zag chain - Tabellaria
sp.
Tabellaria fenestrata, Tabellaria flocculosa, Fragilaria
crotonensis |
Colony a ribbon of rectangular cells with prominent costae
- Fragilaria
sp. |
Colony otherwise (e.g., wheel, spokes, fan, radiating,
etc.) or solitary - Not Dominant in the Great Lakes |
10. Nitzschiod Diatoms
Key
to the Dominant Chrysophyte Species of the Great Lakes
Browse Dominant Chrysophyte
Photos
1.
1 flagella, no lorica - SubOrder
Chromulineae (2) |
2 flagella of unequal length (or non-motile vegetative),
with lorica lacking transverse growth scars - Dinobryon
sp. (3) |
2 apical flagella and a haptonema (looks like a third
flagella, but while it is flexible, it does not beat with
the typical flagellar movement and is usually straight);
unicellular - Haptophyceae |
Flagella - lorica combination otherwise - Not Dominant
in the Great Lakes |
2. SubOrder Chromulineae
Globose colony, each cell with 2 long anterior rods set
in basal cups to either side of the flagellum, 2 parietal
golden-brown chromatophores, cells 9umx15um, colony to 250um
- Chrysosphaerella
longispina |
Otherwise - Not Dominant in the Great Lakes |
3. Dinobryon sp.
Tree-like colony in which the loricas are nearly parallel
and in which the upper portion of the individual lorica is
smooth but the lower portion undulates, base of the lorica
bent and blunt, lorica 7-8 um diameter by 35-50um long - Dinobryon
divergens |
Tree-like colony, individual loricas flared and smooth with
blunt bases (bent or straight), lorica 7-8 um diameter by
30-70 um long - Dinobryon
sociale |
Tree-like colony in which the individual loricas are slightly
flaring and undulate with a sharply pointed base, lorica
6-9 um diameter by 45-100um long - Dinobryon
bavaricum |
Solitary and epiphytic or lorica otherwise - Dinobryon
sp. (Not Dominant in the Great Lakes) |
4. Haptophyceae
*The EPA study on which the list of dominant species is
based did not identify the dominant haptophyte to species.
It was likely Chrysochromulina
parva. |
Key
to the Dominant Dinoflagellate Species of the Great Lakes
Browse Dominant Dinoflagellate
Photos
1.
Motile unicells with an undivided envelope (without walls
or plates) - Order Gymnodiniales
(2) |
Motile unicells with walls and a membrane divided into conspicuous
plates, anterior and posterior portions divided by a deep
groove - Order Peridiniales (3) |
Non-motile - Not Dominant in the Great Lakes |
2. Order Gymnodiniales
-
There is only one Great Lakes genus in this order, relatively
large ovoid cells (30-120um) - Gymnodinium
sp.
3. Order Peridiniales
-
Globose cells, anterior rounded or conical
- Peridinium
sp. |
Long cells, anterior extended into a long
horn, posterior with 2-3 horns- Ceratium
sp. |
4. Ceratium spp.
Anterior horn longer than the rest of the body (including
posterior horns) - Ceratium
hirundinella |
Anterior horn shorter and curved or angled - Ceratiun sp.
(Not Dominant in the Great Lakes) |
Key
to the Dominant Cryptophyte Species of the Great Lakes
Browse Dominant Cryptophyte
Photos
1.
2. Family Cryptomonadaceae
3. Family Cryptochysidaceae
Key
to the Dominant Green Algae Species of the Great Lakes
Browse Dominant Green
Algae Photos
1.
Non-motile solitary cells (2) |
Unicell divided into 2 hemicells - desmids (4) |
Globose colony of 2-8 globose cells enclosed in an enlarged
mother cell wall, gelatinous investment or gelatinized mother
cell (5) |
A flat circular plate of polygonal cells (8) |
Unbranched filament (9) |
Cells or colonies otherwise - Not Dominant in the Great
Lakes |
2. Non-motile solitary cells
| Flat quadrangular cells (3) |
Cells shaped otherwise: spindles, crescents, round, cruciate,
polyhedral (3D - e.g., pyramidal), triangular, pentagonal.
- Not Dominant in Great Lakes. |
3. Flat quadrangular cells
Flat quadrangular cells without spines and with a distinct
cell body. Sides concave (frequently one side incised). Tetraedron
minimum |
Flat quadrangular cells with a tuft of spines at each
corner. Polyedriopsis sp. (Not Dominant in Great Lakes) |
Flat quadrangular cells in which the cell body is extended
into processes at the corners (without spines) such that
the cell body itself is not evident. Cerasterias sp. (Not
Dominant in Great Lakes) |
4. Desmids
Unicell divided into 2 hemicells by a median incision but
without an apical notch. Star-shaped or triangular in both
the vertical and end views (not flat in one plane). Cell
length less than twice the diameter. - Genus Staurastrum (Staurastrum
gracile) |
Cells otherwise - (Not Dominant in Great Lakes) |
5. Globose colony of 2-8 globose cells held
together by an enlarged mother cell wall or gelatinous investment
(~15 known Great Lakes genera have species in this category)
| Cells Small (9-20um) (6) |
Cells Larger (>20um) - Not Dominant in the
Great Lakes |
6. Globose colony of 2-8 globose
cells held together by an enlarged mother cell wall or gelatinous
investment - Cells <20um.
Cells without flagella in families of 2-6 each surrounded
by complete mother cell wall(s) - (mother cell shape may
be distorted, but remains firm/rigid). Oocystis spp. (7) |
Cells arranged otherwise: reticulate, branching,
hollow sphere, fragmented mother cell walls, in clusters without
mother cell walls, gelatinous investment irregular or amorphous
in outline, concentric layers of mucilage, dark zones within
the mucilage, etc. - Not Dominant in the Great Lakes |
7. Oocystis spp.
| Cells ellipsoid, broad with round poles and regularly
thin walls. 1-4 chloroplasts (laminate discs). Cell 9-13um
diameter by 9-19um long. - Oocystis
borgei |
Cells otherwise - Oocystis sp. (Not dominant
in Great Lakes) |
8. Colony a flat circular plate
of polygonal cells - Pediastrum
sp.
9.Unbranched filament
Unbranched filament of disjointed cells in a sheath - Planktonema
lauterborni |
Cells or colonies otherwise - Not Dominant in the Great Lakes |
Key
to the Dominant Blue-Green Algae Species of the Great Lakes
Browse Dominant Cyanophyte
Photos
1.
Filamentous - Order Hormogonales (2) |
Round cells, solitary or colonial - Order Chroococcales (5)
|
Club-shaped attached solitary
or gregarious cells - Chamaesiphonales (Not Dominant in Great
Lakes) |
2. Filamentous Blue-Green Algae
No heterocysts - Family Oscillatoriaceae (3)
|
Heterocysts - Not Dominant in Great Lakes |
3. Filamentous Blue-green Algae
without heterocysts
Straight, bent or tangled filaments (multicellular with
clear cross walls) without an evident sheath - Genus Oscillatoria (4) |
Filaments with a sheath or coiled and lacking cross-walls
(Not Dominant in Great Lakes) |
4. Genus Oscillatoria
Cells 2um diameter by 5-6um long, filament slightly coiled
or spiral and golden color - Oscillatoria
minima |
Short cells 4-10um diameter by 2-5um long; filament straight
or flexed but not coiled, neither tapering nor capitate,
slightly constricted which have rows of granules; blue-green
in color; may be aggregate mass but not arranged in parallel
bundles - Oscillatoria
tenuis
|
Cells and filaments otherwise (e.g., thinner, red or purple,
tapering or capitate, arranged in bundles, etc.) - Oscillatoria
sp. (Not Dominant in Great Lakes) |
5. Order Chroococcales
| Many cells embedded in copious mucilage forming an irregular
or spherical (but not hollow) 3-dimensional colony (6) |
Colony otherwise (e.g., unicellular, aggregates of 2-8, rectangular
plate, or hollow sphere) - Not Dominant in Great Lakes |
6. Rounded cells in an irregular
or spherical colony with copious mucilage
| Cells spherical or globose (not longer than wide) (7) |
Cells oblong or short-cylindric with rounded ends (but length
much less than 10x width) - Anacystis
sp. |
Cell shape otherwise (e.g., length more than 10 times diameter,
cylindric) - Not Dominant in Great Lakes |
7. Spherical or globose cells
in an irregular or spherical colony with copious mucilage
Cells densely and unevenly arranged in an
irregularly shaped colony; pseudovacuoles usually present
-Microcystis
sp. |
Cells remotely and evenly arranged in a globular
colony - Aphanocapsa
spp. |
8. Aphanocapsa spp.
Cells <1um diameter and evenly distributed
- Aphanocapsa
delicatissima |
Cells larger (>1.5um diameter) or in pairs - Aphanocapsa
sp. (Not Dominant in the Great Lakes) |
|
Results
From The Great Lakes National Program Office's Biological Open
Water Surveillance Program Of The Laurentian Great Lakes for
1998 EPA
Great
Lakes Diatom Home Page - University of Michigan
