Malcolm Potts

Colour Plates

Nitrogen FixationPleurocapsa

Plate 1

1 Diversity of habitat, a, b, c, d, e Aldabra Atoll, Indian Ocean (9° S): a Green silt dominated by Aphanocapsa and Pleurocapsa in intertidal region of lagoon, b Mollusc tracks in green silt, c Drier parts of terrestrial limestone are sometimes almost black due to Tolypothrix byssoidea with its dark brown sheaths, d Hemispherical colonies of Phormidium hendersonii on floor of shallow part of lagoon, e Section of P. hendersonii showing laminated structure due to daily differences in trichome orientation and consequent differences in particle trapping; colonies are eventually eaten by sea-slugs, f Stromatolites, Shark Bay, W. Australia, g Chamaesiphon fuscus colonies on rock from fast-flowing stretch of River Swale, England, h Phormidium in fast-flowing stream (Asir Mts, Saudi Arabia), showing pattern of many motile stream cyanobacterial populations under very high illumination: trichomes aggregate by day and disperse by night, i. Nostoc soup: N. flagelliforme harvested from the regions adjacent to the Gobi Desert is used widely in China for soups.

(Photos a,b,c B.A.Whitton & M. Potts; d B.A. Whitton & A. Donaldson; e-i B.A. Whitton; f DJ. Bellamy)

Plate 2

2 Diversity of form, a Chroococcus. b Merismopedia. c Gloeocapsa cf sanguínea, d Microcystis aeruginosa being consumed by amoeba, e Schizothrix. f Anabaena: planktonic form showing gas-vacuoles in vegetative cells, heterocysts and (in this species) akinetes developing either side of the heterocyst. g Tolypothrix tenuis, showing single 'false' branch;, h Scytonema myochrous, showing pairs of 'false' branches originating from main axis, i Stigonema mamillosum, with true branching.

(Photos a,h J. Davies & B.A. Whitton; b,c M. Potts; d H. W. Paerl; e,f,g,i P.N.G. Boulton & B. A. Whitton)

a

Plate 3

3 Comparison of modern and fossil cyanobacteria. A Modern Lyngbya sp. (Oscillatoriaceae), encompassed by a cylindrical mucilaginous sheath (arrow), from a mat-building stromatolitic community of northern Baja, Mexico (Schopf, 1994a). B Fossil Palaeolyngbya helva, similarly ensheathed (arrows), from siltstone of the ~ 950 Ma-old Lakhanda Formation of eastern Siberia, Russia (Hermann, 1981). (For references, see Chapter 2)

Plate 4

4 Comparison of modem and fossil cyanobacteria. A Modem Entophysalis sp. (Entophysalidaceae) from a mat-building stromatolitic community of northern Baja, Mexico (Schopf, 1994a). B Eoentophysalis belcherensis, an Entophysalis-lïke colonial cyanobacterium, from stromatolitic chert of the -2150 Ma-old Kasegalik Formation of the Belcher Islands in southeastern Hudson Bay, Northwest Territories, Canada (Hofmann, 1976). (For references, see Chapter 2)

Eoentophysalis Belcherensis

Plate 5

5 a, b, c Hunter's Hot Springs, Oregon: a One of >90°C sources showing the "V" of cooling to ~ 74° C, with green Synechococcus sp(p). followed at ~ 54° C by reddish-brown Oscillatoriacf. terebriformis mat; in some areas this mat has retracted, exposing undermat of Chloroflexus; b Edge ofpool, with thick mat of Oscillatoria where it replaces green Synechococcus mat at ~ 54°C; ostracods (Potamocypris sp.: white objects, true size ~ 0.5 mm long) have grazed Oscillatoria below ~ 48°C; c Ostracods grazing on grazer-resistant, grazer-dependent Pleurocapsa/Calothrix community; glistening spot in each animal is the eye. d, e, f Yellowstone National Park, d Adult ephydrid flies grazing cyanobacterial mat in Serendipity Meadows (~40°C); eggs are laid within the mat, which may be almost destroyed when larvae are numerous, e Yellow-green Synechococcus biofilm in Octopus Spring on siliceous sinter, beginning at- 74°C, as indicated by "V" shape inmain channel; source pool is 90-92° C. f Laminated Synechococcus matin Octopus Spring at 55 to ~ 50°C. (Photos D M. Ward & R.W.Castenholz)

Plate 6

6 a, b, c Octopus Spring, Yellowstone National Park: a Overview, with letters indicating approximate locations of cyanobacterial features in Plates 5e, 5f, 6b, 6c; b streamers in high flow; c conical structures in quiescent pools at approximately 50°C, containing Synechococcus and Phormidium. (Photos by D.M. Ward & R.W.Castenholz: b, c from Ward et al., 1992b)

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