stream macroalgae of hawai'i: an identification guide to the

Linda LingleGovernor

May 2004

Department of Land and Natural ResourcesDIVISION OF AQUATIC RESOURCES

1151 Punchbowl Street, Room 330Honolulu, HI 96813

Photos by Alison Sherwood

The Department of Land and Natural Resources receives financial support under the FederalAid in Sport Fish and Wildlife Restoration and other federal programs. Under Title VI of theCivil Rights Act of 1964, Section 504 of the Rehabilitation Act of 1973, Title II of the Americanswith Disabilitites Act of 1990, the Age Discrimination Act of 1975, Title IX of the EducationAmendments of 1972, and the laws of the State of Hawaii, the U.S. Department of the Interiorand the State of Hawaii prohibit discrimination on the basis of race, color, religion, sex, nation-al origin, age, and disability. If you believe that you have been discriminated against in any pro-gram, activity or facility, or if you desire information, please write to: Affirmative Action Officer,Personnel Office, Department of Land and Natural Resources, 1151 Punchbowl Street, Rm.231, Honolulu, HI 96813, or the U.S. Fish & Wildlife Service, Civil Rights Branch, 4040 N.Fairfax Drive, Suite 300, Arlington, VA 22203.

Stream macroalgae of Hawai‘iAn identification guide to the common genera

DAR Technical Report 04-02

Alison SherwoodDivision of Aquatic Resources

and Department of BotanyUniversity of Hawai‘i

3190 Maile WayHonolulu, HI 96822

[email protected]

Funded in part by the DLNRCommission on Water Resource Management

Table of Contents

Scope and Purpose of the Guide

How to Use this Guide

Collection and Preservation Techniques

Additional Sources of Information

Key to the Common Genera of Hawaiian Stream Macroalgae

Descriptions of the Genera

Index

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The purpose of this guide is to provide basicdescriptions and photographs of Hawai‘i’s mostcommon stream algae in order to aid state biologistsin their management-based investigations. It isrecognized that time and resources are generally notavailable for species-level taxonomic identificationsof stream algae, and the guide is designed to lead thebiologist to a generic placement, with some additionalsources listed if further information is desired. Giventhat the systematics of most groups of freshwater algaein Hawai‘i have not been investigated using moleculartools and thorough systematic comparisons,identification of collections to the generic level seemsa prudent compromise at this point in time.

Although the vast majority of stream macroalgaein the state require examination at the compoundmicroscope level of magnification for identification, afew of Hawai‘i’s stream macroalgae can be identifiedthrough direct observation. In either case,characteristics such as color, branching pattern andhabitat will be needed.

The guide begins with a description ofrecommended collection and preservation techniquesfor stream macroalgae, along with a bibliography ofidentification literature and websites for freshwateralgae that may be consulted for species-level

identification, clarification of the present guide orsimply to obtain more detailed information onfreshwater algae. A key to the common genera offreshwater macroalgae in Hawaiian streams issubsequently presented. The key employs field-recognizable characters wherever possible; however,in most cases at least some microscopicalexamination is necessary for determination of theappropriate characters. A set of page numbers isprovided next to each genus name in the key - thesepages contain text descriptions of the importantcharacteristics of the genus, along with photographsof representatives (overall habit plusphotomicrographs of diagnostic characters), anestimation of the number of species present inHawaiian streams, and the known distribution ofeach genus within the state of Hawai‘i. Five maingroups of stream macroalgae are recognized andpresented here: 1) Cyanobacteria, or thephotosynthetic prokaryotic organisms, 2)Chlorophyta, or the green algae, 3) Rhodophyta, orthe red algae, 4) Tribophyta, or the yellow-greenalgae, and 5) Bacillariophyta, or the diatoms. Themost common macroalgal groups in Hawaiianstreams are the green algae and Cyanobacteria,followed by the red algae, diatoms and yellow-greenalgae; however, the diatoms possess considerablymore diversity in the periphyton community thanrepresented here. The broad taxonomic category towhich each representative belongs is indicated atthe top of the description pages through the color ofthe heading bar, as follows: Cyanobacteria =turquoise, Chlorophyta = green, Rhodophyta = red,

Scope and Purpose of the Guide

How to use this Guide

1

Tribophyta = yellow, Bacillariophyta = gray.Distribution information, in terms of what is knownso far, is indicated for each genus. It should berecognized, however, that the potential and likelihoodfor extension of ranges on other islands is high.Additionally, the reports included in this guiderepresent records from streams only – many of thesegenera have representatives in marine, brackish andsubaerial/terrestrial habitats, which are not includedhere. The guide has been exclusively illustrated usingHawaiian material.

Since almost all stream macroalgae require atleast some microscopical examination for identifica-tion, collection and preservation techniques shouldbe developed to fit the needs and intentions of thestudy. One necessary piece of equipment for streammacroalgae sampling is a viewbox (or snorkel mask,if the collector is in the water; e.g. for fish surveys).A view box is relatively easy to construct, and canbe made by cutting a square hole in the center of aplastic tupperware container, and using siliconeaquarium gel to seal in a piece of glass cut to thecorrect size. The collection of macroalgae from thestream is accomplished most easily using long-handled forceps, which allow the alga to be removedin one piece at its base. Inclusion of the basal at-tachment is important, since some taxonomic de-scriptions use information pertaining to this part ofthe plant. A few forms may be more easily removed

using a single-edged razor blade (e.g.Hildenbrandia, Calothrix, some diatom films), ortoothbrushes. Some gelatinous growths in sidepools are easily collected using a turkey baster(e.g. Anabaena). It is also important to search allhabitats in the vicinity of the stream to ensurethat all taxa are represented in the collections –including rocks and other bottom substrata infast-flowing stream areas, slow flowing areas atthe edges of the stream, side pools, waterfall faces,seep faces, floating material in the stream andvegetation. As well, macroalgae prefer differentlight regimes, and so both brightly illuminatedand shaded areas should be searched. Scintilla-tion vials or WhirlPak bags work best for storingcollections from the field, but it is important not tooverfill the containers with algae since this willresult in their rapid degradation. Most field collec-tions kept cold (on ice or in a refridgerator) willremain in good condition for several days.

The most highly recommended preservativefor freshwater macroalgae is CaCO3-bufferedglutaraldehyde (a 2.5% solution made fromdilution of 25% glutaraldehyde, add a pinch ofCaCO3 powder to buffer the solution). Thispreservative maintains the original color of thespecimens very well, and also minimizes themorphological distortion inherent in thepreservation process. Samples preserved inglutaraldehyde should be kept cold until they areidentified. Large numbers of collections are easiestto organize in scintillation vials, since these canbe stored in flats of 100 vials in a fridge. In the

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Collection and preservation techniques

absence of glutaraldehyde, Lugol’s Iodine Solutioncould be used, which has the benefit of staining thestarch-positive groups of algae, but affects theoverall color of the samples. Alcohol-basedpreservatives are not recommended since theydestroy important information about specimencolor, and severely distort the internal cellulardetails.

Finally, collections should be thoroughlylabeled with all relevant information, such ascollection location (including GPS coordinates,where possible), the collector, date and habitat.

General Books:

Dillard, G.E. 1999. Common Freshwater Algae of theUnited States. J. Cramer, Berlin/Stuttgart,Germany.

Entwisle, T.J., Sonneman, J.A. and Lewis, S.H.1997. Freshwater Algae in Australia: a Guide toConspicuous Genera. Sainty & Associates, Australia.

Pentecost, A. 1984. Introduction to FreshwaterAlgae. The Richmond Publishing Co. Ltd., Surrey,England.

Prescott, G.W. 1951. Algae of the Western GreatLakes Area. WM. C. Brown Publishers, Dubuque,Iowa, U.S.A.

Websites:

General algal taxonomic information:http://www.algaebase.org/

Bowling Green State University Algal Homepage:http://www.bgsu.edu/Departments/biology/algae/index.html

Great Lakes Diatom Homepage:http://www.umich.edu/~phytolab/GreatLakesDiatomHomePage/top.html

Freshwater Algae from southeastern Ohio:http://vis-pc.plantbio.ohiou.edu/algaeindex.htm

Algae Homepage of the Smithsonian Institution:http://www.nmnh.si.edu/botany/projects/algae/

CYANOSITE – Cyanobacterial research:http://www-cyanosite.bio.purdue.edu/index.html

Desmid information:http://www.desmids.info/

Freshwater algae of the British Isles:http://www.nwl.ac.uk/~loissys/algal_coded_list.htm

Fritsch collection of illustrations of freshwateralgae:http://www.ife.ac.uk/fritsch/

Diatom Collection of the California Academy ofSciences:http://www.calacademy.org/research/diatoms/diatoms.html

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Additional Sources of Information

1.a. Large alga (several to many centimeters inlength) with a plant body differentiated into a stem-like axis with whorls of branches, not surroundedby mucilage – Chara (p.28)

1.b. Organism either microscopic or macroscopic atthe individual level, but cellular structures notevident without microscopic examination - 2

2.a. Alga siphonous, as seen at the microscopiclevel (lacking cellular cross walls), or in some otherform (e.g. needle-shaped colonies) - 3

2.b. Alga filamentous when observed at the lightmicroscopic level (includes crustose algae composedof filaments) - 4

3.a. Alga a felty green mass of filaments, coarse tothe touch, cells a yellowish-green color whenobserved under the light microscope, lacking crosswalls - Vaucheria (p.44)

3.b. Alga forming small star-shaped clusters ofneedle-like cells, usually growing on larger algae ormosses, chloroplasts a golden color - Synedra (p.48)

4.a. Filaments branched when observedmacroscopically or using the light microscope, or

main axis composed of multiple filaments(multiseriate) - 5

4.b. Filaments unbranched, or only veryoccasionally branched when observedmacroscopically or using the light microscope,main axis composed of only a single filament(uniseriate) - 18

5.a. Cell contents blue-green, olive-green orpinkish in color, lacking a nucleus andchloroplast - 6

5.b. Cell contents colored grass-green, yellow-green, or as in 5a, but containing at least onenucleus and chloroplast - 11

6.a. Main axis of the alga (when viewedmicroscopically) composed of multiple filaments ofcells, alga appears cartilaginous and is oftenpigmented a yellowish-brown color - Stigonema(p.24)

6.b. Main axis of the alga composed of only asingle filament (uniseriate) - 7

7.a. Algal filaments uniform in diameter alongtheir length or composed of bead-like cells - 8

7.b. Algal filaments gradually tapering in diameteralong their length - Dichothrix (p.14)

Key to the common genera of Hawaiianstream macroalgae

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8.a. Alga with distinctly inflated cells, appearingbead-like under the light microscope, cell contentsa uniform light bluish-green color, no distinctsheath surrounding the filaments - Nostochopsis(p.19)

8.b. Algal filament contained within a sheath, withcells more or less the same diameter (not bead-likeand rounded), although some may have slightconstrictions at cross walls - 9

9.a. Alga typically forming two false branches at thesame point - Scytonema (p.23)

9.b. Alga typically only forming a single falsebranch at any one point, if at all - 10

10.a. Filaments long, single false branchescommon, branching occurs adjacent to a larger,clearer cell (heterocyst) in the filament - Tolypothrix(p.25)

10.b. Single false branches rare, filaments quiteshort - Microchaete (p.16)

11.a. Chloroplasts a yellow-green, grass-green ordark green color - 12

11.b. Chloroplasts olive-gray, blue, pink, purple orred in color - 16

12.a. Alga branching only at the base, near thepoint of attachment - Basicladia (p.26)

12.b. Alga branching in regions other than just atthe base, near the point of attachment, or not atall (but possessing a multiseriate main axis) - 13

13.a. Chloroplasts dense and net-like, oftenseeming to fill the cell - Cladophora (p.29)

13.b. Chloroplast a plate-like band, especiallyevident in the main axis cells - 14

14.a. Alga multiseriate (multiple filamentscomposing the main axis) in the upper regions ofthe plant - Schizomeris (p.35)

14.b. Alga uniseriate throughout (only onefilament composing the axis) - 15

15.a. Alga forming a distinct colony, filamentsgradually tapering toward their ends -Chaetophora (p.27)

15.b. Alga a feathery tuft, cells of branches notmarkedly different in diameter from the main axis,tips of branches tapering to a point or ending in afine hair - Stigeoclonium (p.37)

15.c. Alga a feathery tuft, cells of the branchessmaller than those of the main axis, tips ofbranches not tapering to a point or ending in afine hair - Cloniophora (p.30)

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16.a. Alga composed of a main axis with whorls ofbranches emerging from it, gelatinous to the touch- Batrachospermum (p.40)

16.b. Alga either crustose or filamentous, but notgelatinous - 17

17.a. Alga crustose, resembling spots of red paint,usually on rock surfaces - Hildenbrandia (p.42)

17.b. Alga branched and filamentous, forming longbluish-green or bluish-gray strands, main axiswith a bead-like appearance that can be seenwithout a microscope - Compsopogon (p.41)

17.c. Alga filamentous and branched, chloroplastsbluish or reddish in color, round-shapedreproductive structures (monosporangia) commonat the tips of branches - Audouinella (p.39)

18.a. Cell contents blue-green, olive-green orpinkish in color, lacking a nucleus and chloroplast- 19

18.b. Cells with chloroplasts colored grass-green,yellow-green, or as in 18a, but containing at leastone nucleus and chloroplast - 25

19.a. Cells bead-like or barrel-shaped, heterocystspresent at various positions within the filaments,or only at the ends - 20

19.b. Cells otherwise - 21

20.a. Alga with a thick outer mucilage layer thatgives the organism a definite shape - Nostoc (p.18)

20.b. Alga without a thick outer mucilage layer,does not retain its shape when removed from thewater, heterocysts common at multiple positionswithin a filament - Anabaena (p.11)

20.c. Alga without a thick outer mucilage layer,does not retain its shape when removed from thewater, heterocysts only at the ends of the filaments- Cylindrospermum (p.13)

21.a. Filaments of the alga tapering in diameteralong their length, with a heterocyst at the base ofthe filament - Calothrix (p.12)

21.b. Filaments much the same diameter alongtheir length - 22

22.a. Only a single filament present within asurrounding sheath, if present at all - 23

22.b. Two or more filaments sometimes or alwaysseen within a single surrounding sheath - 24

23.a. Filaments not surrounded by a sheath -Oscillatoria (p.20)

23.b. Filaments usually surrounded by a sheath,entangled to form a definite mat-like structure that

6

is conspicuous at the macroscopic level -Phormidium (p.21)

23.c. Filaments surrounded by a sheath, can beentangled in small growths but not as large mats -Lyngbya (p.15)

24.a. Many filaments bundled together within asheath, entangled to form a mat that is usuallygreenish in color - Schizothrix (p.22)

24.b. Only a few filaments typically bundledtogether within a sheath, mat is usually bluish-purple or purplish-gray in color - Microcoleus(p.17)

25.a. Cells with grass-green chloroplasts andcontaining starch (positive stain with Lugol’sIodine Solution) - 26

25.b. Cells with yellow-green or brownchloroplasts, not containing true starch (alga doesnot positively stain with Lugol’s Iodine Solution) -30

26.a. Cells with round chloroplasts that appearflattened against one wall of the cell, chloroplastsdo not occupy majority of the cell - Klebsormidium(p.31)


27.a. Cells containing net-like chloroplasts - 28


28.a. Some cells with conspicuous rings at oneend, chloroplast usually not dense and net-likestructure can be easily discerned - Oedogonium(p.33)

28.b. Cells without rings at the ends, chloroplastsusually very dense and the net-like structuredifficult to see - Rhizoclonium (p.34)

29.a. Cells with one or more spiral-shapedchloroplasts - Spirogyra (p.36)

29.b. Cells with one plate-like chloroplast that maybe either lying in a flat plane or twisted once -Mougeotia (p.32)

29.c. Cells with two star-shaped chloroplasts -Zygnema (p.38)

30a. Cells with yellow-green chloroplasts, cell wallsin two sections that overlap in the central region,forming H-shaped sections - Tribonema (p.43)

30b. Cells with brown chloroplasts, cell wallshighly ornamented (diatoms) - 31

31a. Cells arranged in filaments such that all ormost of the adjacent cell surfaces are touching - 32

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31b. Cells in filaments such that only the cornersof the adjacent cells are touching (zig-zagfilaments) - 33

32a. Filaments constructed of cylindrical cellscomposed of overlapping pieces, ornamentationin the form of organized lines of holes (striae)along the two halves of the cylinder - Melosira(p.46)

32b. Cells of filament appear rectangular, whenindividually separated appear rounded with sixprotrusions equally spaced around cell perimeter- Hydrosera (p.45)

33a. Cells appear rectangular in filaments, butelliptical when seen in valve view - Pleurosira(p.47)

33b. Cells in filaments form appear rectangular,small “musical-note” shaped ornamentationsvisible on the cell wall - Terpsinöe (p.49)

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Classification: Cyanobacteria (Family Nostocaceae)

General habit: unbranched filaments in anentangled mass, often in clumps or mats,surrounding mucilage does not have a definiteshape that is retained when the alga is removedfrom the water

Species in Hawai‘i: A. catenula, Anabaena sp.

Island distribution: Kaua‘i, O‘ahu

Distinguishing features: bead or barrel-shapedcells in unbranched filaments, slightly larger andless pigmented cells (heterocysts; sites of nitrogenfixation; Fig. C) spaced along filaments, similar toNostoc but colony does not have a well-definedmucilage coating that retains its shape

Compare with: Cylindrospermum, Nostoc,Nostochopsis

Anabaena

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A. Piece of an epilithic Anabaena mat. Scale bar= 2mm. B. Filaments of Anabaena as seen withthe compound microscope. Scale bar = 20µm. C.Single filament with both vegetative cells (col-ored) and heterocysts (larger and less pig-mented). Scale bar = 15µm.

Classification: Cyanobacteria (FamilyRivulariaceae)

General habit: plants either growing individually orclustered in tufts or mats (sometimes in a star-shaped formation), can grow on rock surfaces orepiphytically on other algae or plants

Species in Hawai‘i: C. braunii, C. fusca

Island distribution: Necker, O‘ahu, Maui

Distinguishing features: Filaments taper from thebase (which usually ends in a heterocyst; Figs C, D)to a fine point at the distal end, cells shorter thanwide in the lower regions of the filament andgradually becoming longer than wide toward the tips

Compare with: Scytonema, Tolypothrix

Calothrix

10

A. An epilithic tuft of Calothrix. Scale bar = 1mm.B. View of several filaments under a compoundmicroscope. Scale bar = 25µm. C, D. Individualfilaments of Calothrix illustrating tapering of thefilaments and heterocysts at the ends. Scale bar =25µm.


General habit: a series of intertwined filaments in amucilage coat, forms dark green mats or patches onrocks in streams, occasionally on submergedvegetation

Species in Hawai‘i: C. catenatum, C. stagnale,Cylindrospermum sp.

Island distribution: Kaua‘i, O‘ahu, Maui, Hawai‘i

Distinguishing features: heterocysts present at oneor both ends of the filaments (Fig. D), cellscylindrical or barrel-shaped, cross walls defined byconstrictions, gonidia (reproductive bodies)occasionally visible at the ends of filaments adjacentto heterocysts

Compare with: Anabaena, Oscillatoria, Phormidium

Cylindrospermum

11

A. A piece of an epilithic mat of Cylindrospermum.Scale bar = 1mm. B. View under a compoundmicroscope of a Cylindrospermum mat, illustratingintertwined filaments. Scale bar = 25µm. C. Fila-ment with a gonidium and heterocyst at the end.Scale bar = 20µm. D. Filament with a terminalheterocyst. Scale bar = 10µm.

Classification: Cyanobacteria (FamilyRivulariaceae)

General habit: forming small mats or feathery tuftson a variety of surfaces in streams, sometimesgrowing only as solitary plants, yellowish-brown incolor

Species in Hawai‘i: D. baueriana, D. fusca

Island distribution: Maui, Hawai‘i

Distinguishing features: filaments tapering slightlyalong their length, heterocysts usually at the largerends of filaments (although they can be present inthe central areas of the filaments as well), usually 2-6 filaments contained within a single sheath for atleast part of their length

Compare with: Scytonema, Tolypothrix

Dichothrix

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A. A piece of an epilithic mat of Dichothrix. Scalebar = 2mm. B. Filaments enclosed in a singlesheath for part of their length. Scale bar = 20µm.C. Basal heterocysts on Dichothrix filaments.Scale bar = 10µm.

Classification: Cyanobacteria (FamilyOscillatoriaceae)

General habit: loose filaments that occasionallyaggregate macroscopically in mats or tufts, can beepiphytic on other vegetation or epilithic on rocksurfaces, color varies from bluish-green to reddishor purplish

Species in Hawai‘i: L. aestuarii, L. cladophorae, L.major, L. martensiana, L. putealis, Lyngbya sp.

Island distribution: O‘ahu, Hawai‘i

Distinguishing features: filaments unbranched,mostly cylindrical and tapering very little if at all,enclosed in a sheath (Figs B, C), heterocysts absent,filaments loosely entangled rather than forming adistinct mat-like structure (as in Phormidium)

Compare with: Oscillatoria, Phormidium

Lyngbya

13

A. Filaments of Lyngbya entwined on a branch.Scale bar = 1mm. B. Two individual filaments ofLyngbya illustrating the surrounding sheath.Scale bar = 30µm. C. A long sheath surroundinga Lyngbya filament. Scale bar = 30µm. D. Highmagnification view of a terminal region of a fila-ment. Scale bar = 20µm.

Classification: Cyanobacteria (FamilyMicrochaetaceae)

General habit: entangled filaments, macroscopicallyseen as small, stellate tufts or as mats on rocksurfaces or submerged vegetation in streams,usually brownish or gray in color

Species in Hawai‘i: M. uberrima, M. tenera

Island distribution: Kaua‘i, Hawai‘i

Distinguishing features: filaments not taperingalong their length, enclosed in a sheath, occasionalfalse branching present, heterocysts can be at theends of filaments (Fig. C) or along the length of thefilament

Compare with: Dichothrix, Scytonema, Tolypothrix

Microchaete

14

A. A piece of an epilithic mat formed byMicrochaete. Scale bar = 2mm. B. Compoundmicroscope view of intertwined Microchaete fila-ments from a mat formation. Scale bar = 70µm.C. High magnification view of a small filamentillustrating the basal heterocyst and uniformity offilament diameter along its length. Scale bar =15µm.

Classification: Cyanobacteria (FamilyPhormidiaceae)

General habit: forms dark blue-green patches ormats on submerged surfaces, composed of filamentsin confluent sheaths, usually a purplish-gray mass

Species in Hawai‘i: M. lacustris, M. vaginatus


Distinguishing features: parallel filamentsenclosed in a mucilaginous sheath, slight taperingtoward the end of the filament (Fig. B), cross wallssometimes have a granular appearance (Fig. B)

Compare with: Phormidium, Schizothrix

Microcoleus

15

A. A piece of an epilithic mat formed byMicrocoleus. Scale bar = 2mm. B. A compoundmicroscope view of a Microcoleus filament, illus-trating granular cross walls (some species). Scalebar = 10µm. C, D. Parallel trichomes enclosed in asheath. Scale bar = 15µm.


General habit: colonies can be membranous,globular or lobed, or dried in clumps, composed ofunbranched filaments of cells, enclosed in a thickmucilage that lends a definite shape to the colony(which retains its shape when removed from thewater)

Species in Hawai‘i: N. foliaceum, N. hatei, N. linckia,N. microscopicum, N. paludosum, N. pruniforme, N.sphaericum, N. verrucosum, Nostoc sp.


Distinguishing features: colonies surrounded by athick layer of mucilage which gives the alga adefinite shape, cells of filaments resemble those ofAnabaena (bead or barrel-shaped), heterocystsfrequent along length of filament (Fig. F)

Compare with: Anabaena, Cylindrospermum,Nostochopsis

Nostoc

16

A. View of an individual epilithic Nostoc colonyScale bar = 3mm. B. Numerous Nostoc coloniesattached to a rock. Scale bar = 5cm. C. Compound

microscope view of inside a colony, showing fila-ments with heterocysts (larger cells). Scale bar =20µm. D. Filaments with highly pigmentedsheaths. Scale bar = 20µm. E. Arrangement offilaments within a colony. Scale bar = 100µm. F.An individual filament with several heterocystsScale bar = 15µm.

Classification: Cyanobacteria (FamilyNostochopsaceae)

General habit: bright blue-green globular colonies,composed of filaments encased in mucilage, coloniesretaining their shape when removed from the water

Species in Hawai‘i: N. lobatus, N. radians

Island distribution: Kaua‘i, O‘ahu, Maui

Distinguishing features: macroscopically similar toNostoc, but filaments branching, appears as brightblue-green to grass-green colonies in streams,usually attached to rocks, heterocysts can be eitherapical, or both intercalary and apical (depending onthe species)

Compare with: Nostoc, Chaetophora

Nostochopsis

17

A. An individual colony of epilithic Nostochopsis.Scale bar = 2mm. B. Compound microscope viewof filaments arrranged in a colony. Scale bar =20µm. C. Branched filament with heterocysts.Scale bar = 20µm. D. Intertwined filaments ofNostochopsis. Scale bar = 15µm.

Classification: Cyanobacteria (FamilyOscillatoriaceae)

General habit: forming either an expanded plantmass or present as loose filaments, attached tosubmerged rocks or vegetation in a stream, colorcan range greatly from blue-green to dark red,brown or purple

Species in Hawai‘i: O. chalybea, O. curviceps, O.formosa, O. limosa, O. princeps, O. sancta, O.splendida, O. subbrevis, Oscillatoria sp.

Island distribution: Kaua‘i, O‘ahu, Hawai‘i

Distinguishing features: unbranched filamentslacking a sheath, filaments cylindrical and nottapering along their length, heterocysts absent, canbe either single filaments or aggregated in smallcolonies, when live, filaments often exhibit acharacteristic “oscillating” movement

Compare with: Lyngbya, Phormidium

Oscillatoria

18

A. A piece of an epilithic mat formed byOscillatoria filaments. Scale bar = 2mm. B. Com-pound microscope view of an Oscillatoria mat.Scale bar = 40µm. C. Filaments of a small speciesof Oscillatoria. Scale bar = 15µm. D, E. Filamentsof large species of Oscillatoria, demonstrating thelack of a surrounding sheath. Scale bar = 15µm(D), 10µm (E).

Classification: Cyanobacteria (FamilyPhormidiaceae)

General habit: masses of entangled filamentsforming mats that are attached to rocks orvegetation, or growing in sediments in slower-flowing stream areas, can range in color from lightblue-green to red/purple or black/gray

Species in Hawai‘i: P. ambiguum, P. amoenum, P.corium, P. favosum, P. formosum, P. foveolarum, P.inundatum, P. pachydermaticum, P. retzii, P.splendidum, P. stagnina, P. subfuscum, P.subincrustatum, P. tinctorium, P. uncinatum,Phormidium sp.


Distinguishing features: unbranched filamentsentangled and forming a mat, filaments not taperingalong their length, heterocysts absent, cells at theends of filaments with a variety of possiblemorphologies (Figs E-G)

Compare with: Lyngbya, Oscillatoria

Phormidium

19

A. A mat of Phormidium growing on a damp rockwall. Scale bar = 5cm. B. A Phormidium mat grow-ing in bottom sediment of a stream. Scale bar =5cm. C. A dissecting microscope view of aPhormidium mat. Scale bar = 2mm. D. Compoundmicroscope view of intertwined filaments in aPhormidium mat. Scale bar = 80µm. E, F, G. Indi-vidual filaments illustrating some of the variationin cell size and terminal cell morphology. Scalebar = 10µm.

Classification: Cyanobacteria (FamilySchizotrichaceae)

General habit: series of filaments enclosed in asheath of mucilage, forming broad mats that areattached to rock surfaces or lightly embedded insediment

Species in Hawai‘i: S. calcicola, S. friesii, S.lacustris, S. rivularis

Island distribution: Ni‘ihau, Kaua‘i, O‘ahu,Moloka‘i, Maui, Hawai‘i

Distinguishing features: several filaments enclosedin a sheath of mucilage, the sheath can either becolorless or yellowish, cells cylindrical in shape butwith the apical cell tapering

Compare with: Dichothrix, Microcoleus, Phormidium

Schizothrix

20

A. Dissecting microscope view of a mat formed bySchizothrix filaments. Scale bar = 2mm. B. Severalfilaments enclosed in a mucilage sheath. Scalebar = 10µm. C. India Ink preparation illustratingthe sheath surrounding Schizothrix filaments.Scale bar = 15µm.

Classification: Cyanobacteria (FamilyScytonemataceae)

General habit: a falsely branched cyanobacteriumthat forms thick mats or tufts than can beabundant in streams, often yellowish-brown in colorfrom pigmentation, most commonly attached to rocksurfaces

Species in Hawai‘i: S. archangelii, S. chiastum, S.coactile, S. crispum, S. figuratum, S. fritchii, S.guyanese, S. hofmannii, S. myochrous, S. ocellatum,S. rivulare, S. stuposum, S. tolypothricoides, S.varium, Scytonema sp.


Distinguishing features: false branches normallyoccur in pairs in this genus (Figs B, D, E), only asingle filament is contained within the surroundingsheath, sheath can be thick and layered inappearance and often highly pigmented in Hawaiianspecimens

Compare with: Dichothrix, Tolypothrix

Scytonema

21

A. A tuft of Scytonema as viewed under a dissect-ing microscope. Scale bar = 1cm. B. Filament ofScytonema under a compound microscope illus-trating double false branching. Scale bar = 25µm.C. A heterocyst of Scytonema. Scale bar = 25µm.D, E. Double false branching of Scytonema fila-ments. Scale bar = 25µm (D), 30µm (E).

Classification: Cyanobacteria (FamilyStigonemataceae)

General habit: filaments multiseriate (several cellsthick on the main axis), forming small clumps amidother filaments of algae, sometimes present as amat, specimens in Hawai‘i usually highly pigmenteda yellowish-brown color, epilithic or epiphytic

Species in Hawai‘i: S. mamillosum, S. minutum

Island distribution: Lana‘i, Maui, Hawai‘i

Distinguishing features: this is the only commonmultiseriate cyanobacterium in the Hawaiianstream algal flora, filaments branched with a firmmucilaginous sheath, can be highly pigmented,heterocysts present

Compare with: Scytonema

Stigonema

22

A. A piece of a mat formed by Stigonema fila-ments , viewed with a dissecting microscope.Scale bar = 5mm. B. Multiseriate filaments ofStigonema viewed under a compound micro-scope. Scale bar = 50µm.

Classification: Cyanobacteria (FamilyMicrochaetaceae)

General habit: a falsely branched cyanobacteriumthat forms fluffy tufts and expanded masses due tointertwined filaments, bluish-green to brown incolor, usually epilithic, can be several cm in length

Species in Hawai‘i: T. distorta, T. nodosa, T. tenuis


Distinguishing features: false branches occursingly, arising at a heterocyst (pale colored cell,larger than vegetative cells), filaments surroundedby a sheath that is usually thin and sometimeslayered

Compare with: Scytonema

Tolypothrix

23

A. An epilithic mat formed by Tolypothrix. Scalebar = 1mm. B. Compound microscope view ofintertwined Tolypothrix filaments. Scale bar =100µm. C. A single filament illustrating singlefalse branching at a heterocyst. Scale bar = 30µm.

Classification: Chlorophyta (FamilyCladophoraceae)

General habit: commonly reported in otherlocations as growing on the backs of turtles, inHawai‘i it has only been reported growing on rocksurfaces, bright green in color

Species in Hawai‘i: B. chelonum

Island distribution: O‘ahu

Distinguishing features: this distinctive green algais typically quite small, filaments have a coarseappearance and cells have thick walls, chloroplastusually a dense net and appearing to fill the cell,composed of a series of filaments that branch onlytoward the base of the plant

Compare with: Cladophora, Rhizoclonium

Basicladia

24

A. Basicladia plant viewed under a dissectingmicroscope. Scale bar = 1mm. B. Plant viewedunder a compound microscope, showing branch-ing near the base. Scale bar = 250µm. C, D.Empty cells near the apex of the filament indicat-ing zoospore production and release. Scale bar =

Classification: Chlorophyta (FamilyChaetophoraceae)

General habit: a series of branched filaments thatradiate from a common central point, filamentsencased in a soft mucilage, appearing as smallyellow-green globules in a stream, usually epilithicor epiphytic

Species in Hawai‘i: C. elegans

Island distribution: Kaua‘i, O‘ahu

Distinguishing features: composed of a series ofhighly branched filaments, colony surrounded bysoft mucilage that lends a distinctive shape to theorganism, filaments either tapering to a blunt pointor to a long hair, chloroplast band-shaped andencircling the wall of the cells (especially visible inmain axis cells)

Compare with: Cloniophora, Stigeoclonium

Chaetophora

25

A. Colony of epilithic Chaetophora as viewed un-der a dissecting microscope. Scale bar = 500µm.B. Arrangement of filaments within a Chaetophoracolony. Scale bar = 50µm. C. Tips of branchedfilaments showing band-like chloroplasts in cells.Scale bar = 25µm.

Classification: Chlorophyta (Family Characeae)

General habit: coarse plants, may be easilymistaken for a higher plant, composed of a mainaxis with unbranched branchlets extending fromnodes

Habitats found: generally floating or only mildlyembedded in substrate of slow-flowing or pooledareas, occasionally found in areas of moderate flow,yellowish-green to grass-green in color

Species in Hawai‘i: C. braunii, C. zeylanica


Distinguishing features: very long internodal cells,unbranched branchlets (Fig. C), plants quite largecompared with other macroalgae in Hawaiianstreams and may be easily mistaken for higherplants

Compare with: higher aquatic plants, may possiblybe confused with large clumps of Cladophora,Rhizoclonium or Compsopogon

Chara

26

A. A mat of Chara plants entangled with othervegetation in a small roadside stream. Scale bar =30cm. B. A single Chara plant. Scale bar = 10cm.C. A nodal region of Chara illustrating the un-branched branchlets. Scale bar = 250µm. D. Thefemale reproductive structure (oogonium). Scalebar = 50µm.


General habit: branched filaments forming featherytufts or coarse clusters, bright green to yellow-greenin color, can form large growths in slower flowingstream areas, less than 1cm to greater than 30cm inlength

Species in Hawai‘i: C. canalicularis, C. fracta, C.glomerata, C. longiarticulata, C. rivularis, C. sericea,C. vagabunda, Cladophora sp.

Island distribution: Necker, Kaua‘i, O‘ahu, Maui,Hawai‘i

Distinguishing features: branched, filamentousgreen alga, branches smaller in diameter than themain axis, chloroplast a net-like structure than candensely fill the cell in some cases

Compare with: Cloniophora, Oedogonium,Rhizoclonium, Vaucheria

Cladophora

27

A. A region of a stream overgrown with Cladophora.Scale bar = 30cm. B. A single Cladophora plantattached to a rock in a stream. Scale bar = 2cm. C,D. Individual plants viewed under a dissecting

microscope. Scale bar = 500µm (C, D). E.Branched filaments of Cladophora viewed under acompound microscope. Scale bar = 200µm. F.High magnification view of a filament showing thedense, reticulate chloroplast. Scale bar = 60µm.


General habit: plants forming grass-green orsometimes yellow-green tufts on rocks, composed ofbranched filaments, not as coarse to the touch asCladophora, often with a feathery appearance,usually epilithic

Species in Hawai‘i: C. macrocladia, C. plumosa, C.spicata, Cloniophora sp.


Distinguishing features: a filamentous, branchedalga, branches sometimes in whorl-like formation,main axis cells larger than cells of branches,chloroplast band-shaped, mostly encircling the cell(especially in the main axis cells)

Compare with: Chaetophora, Cladophora,Stigeoclonium

Cloniophora

28

A, B. A rock in a stream covered with Cloniophora.Scale bar = 10cm (A), 2cm (B). C. An individualCloniophora plant viewed under a dissecting micro-scope. Scale bar = 5mm. D. Main axis of a filament

showing the band-shaped chloroplasts. Scale bar= 50µm. E, F. Branched Cloniophora filamentshowing band-shaped chloroplasts. Scale bar =50µm.

Classification: Chlorophyta (FamilyKlebsormidiaceae)

General habit: unbranched filaments, a single cellin thickness, no differentation along the length ofthe filament, forming entangled mats on submergedsurfaces

Species in Hawai‘i: K. flaccidum, K. rivulare, K.subtile

Island distribution: O‘ahu, Moloka‘i, Hawai‘i

Distinguishing features: filaments unbranched,usually growing in unattached mats, chloroplastssingle within the cell, round and flattened againstthe cell wall

Compare with: Rhizoclonium

Klebsormidium

29

A. A piece of an epilithic mat formed byKlebsormidium filaments. Scale bar = 1cm. B. Asingle filament (unbranched), showing the chloro-plast flattened against one edge of the cell wall.Scale bar = 20µm.

Classification: Chlorophyta (FamilyZygnemataceae)

General habit: unbranched filaments, a single cellin thickness, forming growths around the edges ofponds and the slow-flowing areas of streams,yellow-green in color

Species in Hawai‘i: M. capucina, Mougeotia sp.


Distinguishing features: filaments unbranched,uniform diameter along the length of the filament,chloroplast a flat plate that is occasionally slightlytwisted in view (Fig. D), “lens-shaped” cross wallsevident (Figs D-E).

Compare with: Oedogonium, Rhizoclonium,Spirogyra, Tribonema, Zygnema

Mougeotia

30

A. A large growth of Mougeotia covering rock sur-faces on the bottom of a stream. Scale bar = 1m. B.Mougeotia filaments viewed under a dissectingmicroscope. Scale bar = 500µm. C, D, E. Filaments

of Mougeotia showing plate-like chloroplasts withpyrenoids suspended in the middle of the cell.Scale bar = 30µm (C), 20µm (D), 25µm (E).

Classification: Chlorophyta (Family Oedogoniaceae)

General habit: unbranched filaments of cylindricalcells, can form dense mats of coiled filaments,yellowish-green in color, epilithic or epiphytic onsubmerged surfaces in streams

Species in Hawai‘i: O. crispum, O. globosum, O.undulatum, Oedogonium sp.


Distinguishing features: filaments unbranched,chloroplast a reticulate network (Fig. E),characteristic “rings” present at one end of many ofthe cells (Fig. E, F) due to unequal cell divisions


Oedogonium

31

A. Large growth of Oedogonium attached to asubmerged branch in a stream. Scale bar = 5cm.B. Oedogonium filaments viewed under a dissect-ing microscope. Scale bar = 1mm C. Unbranchedfilaments. Scale bar = 40µm. D. Variation in cellshape in Oedogonium. Scale bar = 25µm. E. Highmagnification view of Oedogonium cells illustrat-ing the reticulate chloroplast. Scale bar = 30µm.F. View of rings formed at the ends of cells inOedogonium due to unequal cell division pro-cesses. Scale bar = 30µm.


General habit: unbranched filaments that resemblean unbranched Cladophora, yellow-green to grass-green or dark green in color, can form tufts or densemats, attached to rock or vegetation

Species in Hawai‘i: R. crassipellitum, R.hieroglyphicum, R. hookeri


Distinguishing features: filaments generallyunbranched, uniform in diameter along the lengthof the filament (except for the apical cell),chloroplast a dense network that often appears tofill the cell

Compare with: Cladophora, Oedogonium

Rhizoclonium

32

A. A mat of Rhizoclonium viewed under a dissect-ing microscope. Scale bar = 500µm. B. Un-branched filaments. Scale bar = 50µm. C, D. Cellsof Rhizoclonium illustrating the dense, reticulatechloroplast. Scale bar = 50µm (C), 30µm (D).

Classification: Chlorophyta (FamilySchizomeridaceae)

General habit: plants uniseriate in lowers regionsbut becoming multiseriate above, yellow-green tograss-green in color, loosely attached to rocksurfaces in streams

Species in Hawai‘i: S. leibleinii

Island distribution: O‘ahu, Maui

Distinguishing features: main axis composed ofonly a single filament in the lower areas, butbecoming multiseriate (composed of severalfilaments) in the upper regions, brick-like cells,chloroplast plate-like and often encircling and fillingthe cells, especially in mature regions

Compare with: not likely to be confused with othercommon stream algal genera

Schizomeris

33

A. Schizomeris plants viewed under a dissectingmicroscope. Scale bar = 500µm. B. Lugol’s IodineSolution-stained filament of Schizomeris showingthe surface of the filament. Scale bar = 25µm. C.Unstained view of filament. Scale bar = 20µm. D.A cross-section through a filament. Scale bar =40µm. E. High magnification view of a cross-section through a filament. Scale bar = 25µm.


General habit: unbranched filaments with one ormore spiralled chloroplasts, can form dense mats,clots or tufts, yellow-green to grass-green tobrownish in color, can grow rapidly into thedominant species of a stream region

Species in Hawai‘i: S. dictyospora, S. dubia, S.elegantissima, S. fallax, S. fluviatilis, S. plena, S.rivularis, Spirogyra spp.


Distinguishing features: filaments unbranched,uniform in diameter along their length, chloroplastone or more spiralled in a regular pattern throughthe cell, sexual reproduction occasionally observed(Fig. C - as conjugation of filaments)

Compare with: Mougeotia, Oedogonium,Rhizoclonium, Zygnema

Spirogyra

34

A. A patch of Spirogyra filaments growing on acement surface in a stream. Scale bar = 2cm. B.Filaments viewed under a dissecting microscope.Scale bar = 2mm. C. Conjugated filaments of Spiro-gyra with zygospores (right filament). Scale bar =

50µm. D-I. Some variation in chloroplast mor-phology in Hawaiian Spirogyra. Scale bar = 50µm(D, E), 30µm (F), 60µm (G), 40µm (H, I).


General habit: branched filaments forming featherytufts or expanses, yellow-green to grass-green incolor, not enclosed in mucilage, attached tosubmerged rock or vegetation in streams

Species in Hawai‘i: S. amoenum, S. falklandicum, S.fasciculare, S. flagelliferum, S. lubricum, S.nudiusculum, S. pachydermum, S. segarare, S.setigerum, S. stagnatile, S. subsecundem, S. tenue,S. variabile, Stigeoclonium sp.


Distinguishing features: branched filaments,branches can be arranged opposite, alternate, orsometimes dichotomously, filaments tapering to ablunt point or a long hair, chloroplast plate-like andencircling the cell (especially visible along the mainaxis), not as much distinction in the diameter of themain axis versus the branches (compared withCloniophora)

Compare with: Chaetophora, Cloniophora

Stigeoclonium

35

A. An epilithic tuft of Stigeoclonium as viewedunder a dissecting microscope. Scale bar = 0.5cm.B. Branched filaments viewed under a compoundmicroscope. Scale bar = 50µm. C. Main axis of aplant showing the plate-like chloroplasts. Scalebar = 30µm. D, E. Branching patterns of someStigeoclonium viewed under a compound micro-scope. Scale bar = 50µm (D), 80µm (E).


General habit: unbranched filaments, formingcottony masses or tufts of filaments, yellow-green tograss-green or slightly darker in color, can developinto large plant masses in slower-flowing areas ofstreams and ponds

Species in Hawai‘i: Zygnema sp.


Distinguishing features: unbranched filaments,filaments uniform in diameter along their length,each cell contains two axial, stellate chloroplasts,each with a pyrenoid (Figs D-E), sexualreproduction through conjugation of filaments andsubsequent development of zygospores (Fig. C)

Compare with: Mougeotia, Oedogonium,Rhizoclonium, Spirogyra

Zygnema

36

A. Zygnema viewed under a dissecting micro-scope. Scale bar = 3mm. B. Aggregation of un-branched Zygnema filaments viewed under acompound microscope. Scale bar = 100µm. C. Afilament (post conjugation) containing zygospores.Scale bar = 40µm. D, E. Chloroplast morphologiesin Hawaiian Zygnema. Scale bar = 30µm.

Classification: Rhodophyta (FamilyAcrochaetiaceae)

General habit: branched filaments, usually presentin tufts or a spreading, mat-like arrangement, canbe steel blue, gray, reddish, or purple in color,usually found in faster-flowing areas of streams,growing directly on rock surfaces or epiphytically onmosses

Species in Hawai‘i: A. chalybea, A. eugenea, A.pygmaea


Distinguishing features: branched filaments,branches only slightly smaller in diameter than themain axis, chloroplasts one to several per cell (plate-like or ribbon-like), reproduction through roundedspores (termed monospores) produced at the tips ofbranches

Compare with: Cladophora

Audouinella

37

A. Audouinella plants (purplish-red color) at-tached to mosses in a stream. Scale bar = 2cm. B.A single plant viewed under a dissecting micro-scope. Scale bar = 3mm. C. Branched filaments.Scale bar = 50µm. D. A series of monosporangiaproduced along a filament of Audouinella. Scalebar = 30µm. E. A high magnification view of thechloroplast morphology of Audouinella. Scale bar= 30µm.

Classification: Rhodophyta (FamilyBatrachospermaceae)

General habit: usually found in faster-flowing areasof streams, greenish-gray in color, plant bodyenclosed in a soft mucilage

Species in Hawai‘i: B. spermatiophorum,Batrachospermum spp.

Island distribution: O‘ahu, Maui, Hawai‘i

Distinguishing features: typically found in swifterflowing areas of streams, also in shadier streamregions, branched (whorled) filaments, attached,whorls present along the main axis of the plant,sexual reproduction through fertilization ofcarpogonia by spermatia (Fig. D)

Compare with: Chara, Cloniophora

Batrachospermum

38

A. Batrachospermum plant viewed under a dis-secting microscope. Scale bar = 1mm. B. Com-pound microscope view of the axis of a plant, withlateral whorls of filaments. Scale bar = 400µm. C.Closer view of a main axis showing the branchedfilaments of the whorls. Scale bar = 100µm. D. Afertilized carpogonium (female reproductive struc-ture) extending from the lower side of the centerwhorl. Scale bar = 50µm.

Classification: Rhodophyta (FamilyCompsopogonaceae)

General habit: branched filaments, becomingcorticated in mature regions, typically bluish-gray tolight greenish-gray in color, can form dense mats,attached to rocks or vegetation

Species in Hawai‘i: C. coeruleus (most previousreports as Compsopogonopsis leptoclados, which isnow in synonymy), Compsopogon sp.


Distinguishing features: branched filamentousalga, the main axis of mature plants has a “bead-like” appearance, main axis covered with corticalcells (Fig. F), reproduction through production ofmonospores (Fig. F)

Compare with: Cladophora

Compsopogon

39

A. A rock in a small stream covered with bluish-colored Compsopogon filaments. Scale bar = 20cm.B. Branched filaments of Compsopogon as viewedunder a dissecting microscope. Scale bar = 250µm.C. A mat of Compsopogon filaments viewed under adissecting microscope. Scale bar = 3mm. D.Branched filaments seen under a compound micro-

scope. Scale bar = 100µm. E. Cortication on thelarger filaments. Scale bar = 100µm. F. A corticalcell producing two monosporangia. Scale bar =50µm.

Classification: Rhodophyta (FamilyHildenbrandiaceae)

General habit: a crustose red alga that appears aspink to dark red splotches on rocks, usually growsin shadier areas of streams, can be small patchesunder 1cm in diameter up to expanses of 10’s of cm

Species in Hawai‘i: H. angolensis


Distinguishing features: this alga should bechecked using a microscope since Hawaiian streamsoften contain crusts of various algae that can easilybe confused with Hildenbrandia at the macroscopiclevel; Hildenbrandia is a filamentous alga that iscomposed of a series of branched vertical files ofcells, cells have a “honeycomb” appearance from thesurface of the crust

Compare with: periphyton growths, cyanobacterialcrusts

Hildenbrandia

40

A. Surface of a rock in a stream with patches ofHildenbrandia. Scale bar = 4cm. B. A piece ofHildenbrandia crust viewed with a dissecting micro-scope. Scale bar = 0.5cm. C. A surface view of the

crust viewed with a compound microscope. Scalebar = 20µm. D. A cross section through a piece ofcrust illustrating the vertical files of cells. Scalebar = 15µm.

Classification: Tribophyta (FamilyTribonemataceae)

General habit: unbranched filaments, light yellow-green in color, can form dense mats and expanses ofgrowth, often free-floating masses but sometimesattached to a substrate when immature

Species in Hawai‘i: T. aequale, T. affine, T. minus,Tribonema sp.


Distinguishing features: filaments unbranched,usually several chloroplasts within the cell, cellscomposed of overlapping “H-pieces” that areespecially evident at the ends of the filaments (FigsC, D), cell contents do not display a positive stainingreaction with Lugol’s Iodine Solution

Compare with: Mougeotia, Rhizoclonium,Oedogonium

Tribonema

41

A. A mat of Tribonema filaments viewed through adissecting microscope. Scale bar = 500µm. B.Several filaments (unbranched). Scale bar =30µm. C. Unbranched filament with one or sev-eral chloroplasts per cell. Scale bar = 10µm. D. H-shaped cell walls in overlapping pieces. Scale bar= 10µm.

Classification: Tribophyta (? incertae sedis) (FamilyVaucheriaceae)

General habit: forming green felty patches on dampsurfaces, or growing attached to surfaces within astream, usually a grass-green color, coarse intexture

Species in Hawai‘i: Vaucheria sp.


Distinguishing features: siphonous (multi-nucleate, lacking internal cell walls within afilament, or cross walls), identification of Vaucheriato species requires examination of morphologicalcharacters pertaining to sexual reproduction, thesecharacters are often absent in field-collectedmaterial, cell contents do not display a positivestaining reaction with Lugol’s Iodine Solution


Vaucheria

42

A. A mat of Vaucheria growing on a damp wall.Scale bar = 10cm. B. A mat of Vaucheria viewedthrough a dissecting microscope. Scale bar =700µm. C. A large, multi-nucleate cell. Scale bar =40µm. D. Branched filament. Scale bar = 60µm.

Classification: Bacillariophyta (FamilyBiddulphiaceae)

General habit: filamentous chains of cells, can beeither attached to a substrate or free-floating,appear as light brown masses of filaments that caneasily be broken apart when removed from thestream, growths can be up to many cm in length

Species in Hawai‘i: H. whampoensis


Distinguishing features: cells exhibit acharacteristic shape of overlapping triangles whenin valve view (Fig. D); material should be examinedin this view for positive identification

Compare with: Melosira, Pleurosira, Terpsinöe

Hydrosera

43

A. Epiphytic filaments of Hydrosera in a stream.Scale bar = 5cm. B. Chains of cells viewed undera dissecting microscope. Scale bar = 110µm. C.View under a compound microscope of aHydrosera chain. Scale bar = 50µm. D. Valve viewof a Hydrosera cell. Scale bar = 25µm.

Classification: Bacillariophyta (FamilyMelosiraceae)

General habit: filamentous chains of cells, can beeither attached to a substrate or free-floating,appear as light brown filaments, often entangledwith other filamentous algae, growths can be severalcm in length

Species in Hawai‘i: M. varians


Distinguishing features: chains of cells of uniformdiameter, cells appear cylindrical and have multiplegolden-colored chloroplasts (Fig. B, C)

Compare with: Hydrosera, Pleurosira, Terpsinöe

Melosira

44

A. Mat of Melosira chains viewed under a dis-secting microscope. Scale bar = 500µm. B, C.Unbranched chains of cells viewed under a com-pound microscope. Scale bar = 30µm.

Classification: Bacillariophyta (FamilyTriceratiaceae)

General habit: filamentous zig-zag-shaped chainsof cells, light brown in color, often entangled withother filamentous algae, growths can be several cmin length

Species in Hawai‘i: P. laevis


Distinguishing features: chains of cells in a zig-zagformation (Figs A, B), cells containing numerousgolden-colored chloroplasts, cells in valve view areelliptical with small ornamentations in the majorityof the valve surface (Fig. D)

Compare with: Hydrosera, Melosira, Terpsinöe

Pleurosira

45

A. A zig-zag shaped filament of Pleurosira cells.Scale bar = 100µm. B. A closer view of the chainof cells under a compound microscope. Scale bar= 45µm. C. Many chloroplasts within a single cell.Scale bar = 45µm. D. A Pleurosira cell in valveview. Scale bar = 15µm. E. A cell in girdle (side)view. Scale bar = 45µm.

Classification: Bacillariophyta (FamilyFragilariaceae)

General habit: radiating needle-like colonies, seenas small, light brown colored “balls”, usuallyepiphytic on mosses or algae

Species in Hawai‘i: S. ulna


Distinguishing features: cells formed into needle-like clusters, cells a golden color due to thepresence of multiple chloroplasts, cells cansometimes be stacked into vertical colonies (Fig. B)

Compare with: periphyton growth

Synedra

46

A. A mat of needle-like clusters of Synedra cellsseen under a dissecting microscope. Scale bar =500µm. B. A series of cells attached together.Scale bar = 25µm. C. A girdle (side) view of a cellshowing the chloroplasts. Scale bar = 50µm. D. Amount of diatoms showing a large Synedra cell inthe center. Scale bar = 50µm.

Classification: Bacillariophyta (FamilyBiddulphiaceae)

General habit: zig-zag-shaped filaments of cells,light brown in color, can form growths of up toseveral cm in length, usually attached to mosses orother algae, sometimes epilithic

Species in Hawai‘i: T. musica


Distinguishing features: filaments composed of zig-zag chains of cells (Figs B, C), cells containingmultiple golden-colored chloroplasts, cells viewedfrom the side have small ornamentations thatresemble musical notes (Fig. B) - hence the speciesepithet

Compare with: Hydrosera, Melosira, Pleurosira

Terpsinöe

47

A. A chain of cells viewed under a dissectingmicroscope. Scale bar = 200µm. B, C. A closerview of the chain of cells under a compound mi-croscope, showing the mucilage pad adhesion.Scale bar = 100µm. D. A cell viewed under a com-pound microscope. Scale bar = 25µm.

Index

AnabaenaAudouinella

BasicladiaBatrachospermum

CalothrixChaetophoraCharaCladophoraCloniophoraCompsopogonCylindrospermum

Dichothrix

HildenbrandiaHydrosera

Klebsormidium

Lyngbya

MelosiraMicrochaeteMicrocoleusMougeotia

NostocNostochopsis

OedogoniumOscillatoria

PhormidiumPleurosira

Rhizoclonium

SchizomerisSchizothrixScytonemaSpirogyraStigeocloniumStigonemaSynedra

TerpsinöeTribonemaTolypothrix

Vaucheria

Zygnema

48

937

2438

10252627283911

12

4043

29

13

44141530

1617

3118

1945

32

33202134352246

474123

42

36

stream macroalgae of hawai'i: an identification guide to the

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