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Freshwater planktic Chroococcales (Cyanoprokaryota) from North-Eastern Australia: a morphological evaluation by
Glenn B. McGregor*1,3, Larelle D. Fabbro2 and Jaye S. Lobegeiger1 1
2
Natural Resource Sciences, Queensland Department of Natural Resources and Water, 120 Meiers Road, Indooroopilly, QLD 4068, Australia
Centre for Environmental Management, AHS BLG 6, Central Queensland University, Rockhampto, QLD 4702, Australia 3
School of Integrative Biology, The University of Queensland, St Lucia, QLD 4072, Australia With 90 figures and 2 tables
McGregor, G.B., L.D. Fabbro & J.S. Lobegeiger (2007): Freshwater planktic Chroococcales (Cyanoprokaryota) from North-Eastern Australia: a morphological evaluation. - Nova Hedwigia 84: 299-331. Abstract: Planktic cyanoprokaryotes of the order Chroococcales are described from 192 sites in north-eastern Australia. Despite the diversity of freshwater biotopes, and increasing evidence of seasonal cyanoprokaryote dominance in planktic habitats, particularly man made reservoirs, this is the first detailed study documenting the cyanoprokaryote microflora from this region. Over five thousand samples were observed from which 54 Chroococcalean species were recorded representing four families. Sampling locations included natural lakes, man made reservoirs and weir pools, rivers and streams. The majority of the taxa could be regarded as cosmopolitan, followed by tropical/ subtropical taxa and temperate taxa. The most common genera recorded included Aphanocapsa, Cyanodictyon, Myxobaktron, Merismopedia, and Microcystis. The highest taxon richness occurred in man-made lakes and reservoirs, followed by natural lakes, and streams and rivers. Fifty three taxa including three newly described species (Aphanocapsa annulata sp. nova, Gloeothece lacustris sp. nova, Gloeocapsa planctonica sp. nova) are presented including information on their morphological variability, ecology and distribution. eschweizerbartxxx
Introduction The importance of cyanoprokaryotes in a vast array of biotopes across the biosphere cannot be underestimated. Their impact on potable water supplies has brought them to the national and international attention of researchers and water managers alike. e-mail:
[email protected] DOI: 10.1127/0029-5035/2007/0084-0299
0029-5035/07/0084-0299 $ 8.25 © 2007 J. Cramer in der Gebrüder Borntraeger Verlagsbuchhandlung, D-14129 Berlin · D-70176 Stuttgart
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Hence over the past decade there has been a considerable effort devoted to understanding the causes of cyanoprokaryote blooms in Australia. A keystone to this understanding has been the development of tools to facilitate accurate identification of the constituent fauna and flora of Australia’s unique aquatic ecosystems. The importance of developing a sound regional taxonomy based on stable morphological features, which can be easily and reliably interpreted, has been recognised as integral to the research effort (Scott et al. 1997, ACIL 2002). This will greatly assist the accurate identification and description of samples collected from diverse environments thus providing an essential basis for ecological and toxicological investigations. Australia’s tropical and sub-tropical freshwater cyanoprokaryotic microflora is relatively poorly known. The first references of cyanophytes from Queensland date back to the nineteenth century (Bailey 1893, 1895, 1898) and while a limited number of works have documented the microalgal flora of north-eastern Australia since then (eg. McLeod 1975, Ling & Tyler 1986, 2000, McGregor & Fabbro 2001), there still remains no comprehensive study of Australia’s freshwater cyanoprokaryotes. Recent studies have shown that the diversity of cyanoprokaryotes from tropical regions is considerably larger than is apparent from the literature (Komárek 1985a, 1985b, Komárek & Kaštovský 2003). It is clear that new data on cyanoprokaryotes from different natural habitats across Australia’s tropical and sub-tropical regions are urgently required to gain a better understanding of cyanoprokaryote diversity. The purpose of this paper is to describe the planktic Chroococcales from north-eastern Australia’s lentic habitats. We also present data on their distribution and morphological variability and contribute to an increased understanding of Australia’s cyanoprokaryote flora. The Chroococcales are a highly conspicuous order of cyanoprokaryotes in planktic communities throughout north-eastern Australia, both in terms of the number of taxa and their relative abundance. Taxonomically they are considered one of the more problematic cyanoprokaryotic orders due to the relatively simple morphology of the taxa (Anagnostidis & Komárek 1985) and the difficulty in determining precise and stable intergeneric features. This paper is the first step in refining a morphologybased classification by completing a comprehensive documentation of existing morphotypes from a large geographic coverage of north-eastern Australia including representatives from all lentic and slow-flowing lotic biotopes. We have focused on stable ecotypes that can be readily identified using well established character sets. These species will ultimately form the basis of a more detailed polyphasic assessment of Australia’s cyanoprokaryote diversity when consensus on a universally applicable species concept is reached. Three distinct morphotypes, which differ from known cyanoprokaryote taxa, are described as new species. eschweizerbartxxx
Materials and methods Samples were collected by phytoplankton nets (25 µm mesh), whole surface plankton grabs, or by a 5 m integrated tube sampler. Preserved material was fixed in situ using 3-4% calcium buffered formaldehyde or Lugol’s iodine solution to a final concentration of 1%. Material was examined by bright field, phase contrast and differential interference contrast (DIC) microscopy with Olympus BX51 and Zeiss Axioskop compound microscopes. Photomicrographs and drawings were made from freshly preserved material using an Olympus DP12 digital microscope camera and a Zeiss MC80 photographic unit and cell
300
Fig 1. Location of sampling sites.
measurements made from digital images of live or freshly preserved material using UTHSCHA Image Tool V 3.0 (Wilcox et al. 2002). The classification system for cyanoprokaryotes proposed by Anagnostidis & Komárek (1985) and Komárek & Anagnostidis (1986), and more specifically by Komárek & Anagnostidis (1999) for the Chroococcales has been followed for the delimitation of species. eschweizerbartxxx
Site descriptions Collections were made during the period 1997-2004 from 192 sites throughout north-eastern Australia (Fig. 1). The majority of the > 5000 samples were collected from lentic and slow flowing lotic habitats represented by natural lakes, man made reservoirs and weir pools, and river and stream pools. Man made reservoirs represent the most conspicuous permanent lentic environments in northeastern Australia. They are characteristically meso-eutrophic with long water residence times (2-7 years), and are thermally stratified for much of the year (McGregor & Everding 1998). Most of the natural freshwater lakes occur within the sandy coastal dune areas of south-east Queensland, notably on Fraser, Moreton and North Stradbroke Islands, within the Cooloola sand mass (Bowling 1988), and in the siliceous dunefields of Cape Flattery in tropical north Queensland (Timms 1986, Hawkins et al. 1988). Typically these lakes are small in comparison to man made reservoirs, acidic, of low conductivity dominated by Na+ and Cl- ions, vary from optically clear to strongly humic-stained, and are generally oligotrophic (Bayly 1964, Bayly & Williams 1972, Timms 1986, Bowling 1988). Much of the areas west of the Great Dividing Range which runs along the Queensland coast, with the exception of the wet tropics, Cape York Peninsula, and the northern parts of the Northern Territory, can be regarded as arid or semi arid. Most of the rivers in this region are subject to long periods of no flow (Thoms & Sheldon 2000), and for much of the time they exist as a network of dry channels and ephemeral to permanent waterholes. These rivers are characteristically turbid due to a combination of edaphic, aeolian and morphological features (Williams 1985). Consequently, reduction in light
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penetration due to high levels of abiogenic turbidity limits phytoplankton photosynthesis therefore restricting algal biomass development to the benthic littoral margins within the photic zone (Dokulil 1994, Bunn et al. 2003, McGregor et al. 2006). Mean physico-chemical data from selected water bodies representative of the sites sampled is given in Table 1.
Results and discussion Over five thousand samples were observed from which 54 Chroococcalean species were recorded representing four families (Table 2). The majority of the taxa could be regarded as cosmopolitan (56%), followed by tropical/subtropical taxa (23%) and temperate taxa (21%). Three new planktic species that corresponded to stable morphological types in the lentic populations studied and could not be identified from the current taxonomic literature are described for the first time. The highest species richness and overall biomass was recorded in man-made reservoirs. Reservoirs are highly homogeneous, unnatural aquatic biotopes and across the study area they represent the most conspicuous and persistent lentic habitats. The predominance of these water types may have contributed to the relatively high proportion of cosmopolitan taxa represented in the samples. Assemblages of colonial picoplanktic taxa such as Aphanocapsa holsatica, Cyanodictyon imperfectum, Myxobaktron plankticus, and Merismopedia tenuissima were the most commonly represented taxa in these reservoirs with seasonal blooms of Microcystis aeruginosa and Cylindrospermopsis raciborskii a common feature. Cyanoprokaryotes were underrepresented in the potamoplankton and only intermittently detected in natural lakes, which in the study area are generally dystrophic. Family Synechococcaceae Aphanothece clathrata W. & G.S.West 1906 eschweizerbartxxx
Figs 2, 52
Colonies microscopic, initially irregularly spherical, later irregular, elongate, more or less flat, often perforate (clathrate) with large numbers of irregularly ± densely arranged cells. Colonial mucilage fine, hyaline, indistinct, and diffluent at the margin. Cells small, rod-shaped, 2-4 times longer than broad, 1.0-3.0 µm long × 0.8-1.3 µm broad, without aerotopes. COMMENTS: The flattened shapes of the colonies in cross-section are less clear as the colonies age and grow in size. Older colonies tend to exhibit a complex three dimensional shape which is less flattened and has many holes and irregular perforations, however smaller colonies predominate the forms observed. A common species in reservoirs and weir pools throughout the study area. Baker (1992) reported A. clathrata present in high cell concentrations (up to 130 colonies mL-1) at several water supply reservoirs in southern Australia (Victoria). Aphanothece stagnina (Sprengel) A.Braun in Rabenhorst 1863
Figs 3, 55
Colonies planktic, benthic, or metaphytic, gelatinous, with distinct, firmly delimited margin, spherical or irregularly elongate and lobate, usually consisting of subcolonies, up to 4(6) cm in diameter. Cells oval to widely cylindrical with rounded ends, 3.8-9.0 µm long × 3-5 µm broad. 302
Reservoirs and weir pools Tinaroo Falls Dam Peter Faust Dam Kinchant Dam Fred Haigh Dam Bjelke-Petersen Dam Glenlyon Dam Bucca Weir Ned Churchward Weir Natural Lakes Blue Lake Brown Lake Rivers and streams Cooper Creek at Windorah Warrego River at Quilberry Mary River at Owanyilla Condamine River at Warwick
Total Depth (m)
303 142°43'E 145°55'E 152°37'E 152°02'E
-
11.0 8.0
27°32'S, 153°29'E 27°32'S, 153°29'E 25°25'S, 27°04'S, 28°38'S, 28°12'S,
41.8 39.6 18.1 43.0 26.5 47.4 12.5 14.0
145°32'E 148°23'E 148°53'E 151°51'E 151°58'E 151°27'E 152°04'E 152°06'E
17°09'S, 20°22'S, 21°12'S, 24°52'S, 26°18'S, 28°59'S, 24°51'S, 25°02'S,
Location
23 25 20 20
17 15
17 19 19 17 14 13 17 16
30 26 28 25
28 27
36 30 32 29 28 30 30 29
Temperature (oC) Min Max
7.3 7.4 8.0 7.9
5.1 4.7
7.5 7.9 7.8 7.6 8.4 7.2 7.5 7.4
pH
181 113 526 339
99 92
86 158 176 228 1390 149 365 497
Conductivity (µS cm-1)
Table 1. Mean physico-chemical data from selected water bodies representative of the sites sampled
eschweizerbartxxx
567 465 3 23
1 8
4 9 11 12 8 11 6 18
Turbidity (NTU)
1090 350 30 124
5 13
13 19 20 36 15 22
Total phosphorus (µg L-1)
3.40 0.83 0.27 0.50
0.11 0.45
0.05 0.54 0.31 1.14 0.68
Total nitrogen (mg L-1)
Table 2. Planktic Chroococcales of north-eastern Australia. Taxa
*Geographic distribution
*Habitat
Family Synechococcaceae Aphanothece clathrata W. & G.S.West 1906 Aphanothece stagnina (Sprengel) A.Braun in Rabenhorst 1863 Cyanodictyon imperfectum Cronberg & Weibull 1981 Cyanodictyon planctonicum B.Meyer 1994 Cyanonephron styloides B.Hickel 1985 Cyanogranis libera Hindák 2002 Cyanocatena planctonica Hindák 1975 Gloeothece lacustris spec. nova G.B.McGregor Myxobaktron plankticus G.B.McGregor 2001 Rhabdoderma lineare Schmidle & Lauterborn 1900 Rhabdoderma vermiculare Fott 1952 Rhabdoderma sp. Rhabdogloea cf. smithii (R. & F.Chodat) Komárek 1983 Synechococcus aff. nidulans (Pringsheim) Komárek in Bourrelly 1970
C C C C C? Te C? T T Te Te T Te C?
R, S L R L, R R R, S L, R R R, S R L L L R, S
Family Merismopediaceae Aphanocapsa annulata spec. nova G.B.McGregor Aphanocapsa delicatissima W. & G.S.West 1912 Aphanocapsa elachista W. & G.S.West 1894 Aphanocapsa holsatica (Lemmermann) Cronberg & Komárek 1994 Aphanocapsa incerta (Lemmermann) Cronberg & Komárek 1994 Aphanocapsa koordersii Strøm 1923 Aphanocapsa nubilum Komárek & H.J.Kling 1991 Coelomoron microcystoides Komárek 1988 Coelomoron pusillum (Van Goor) Komárek 1988 Coelomoron tropicale Senna, A.C.Peres & Komárek 1998 Coelosphaerium kuetzingianum Nägeli 1849 Coelosphaerium aff. natans Lemmermann 1900 Coelosphaerium punctiferum Komárek & Komárková-Legnerová 1992 Gomphosphaeria aponina Kützing 1836 Merismopedia elegans A.Braun in Kützing 1849 Merismopedia glauca (Ehrenberg) Kützing 1845 Merismopedia hyalina (Ehrenberg) Kützing 1845 Merismopedia marssonii Lemmermann 1900 Merismopedia punctata Meyen 1839 Merismopedia tenuissima Lemmermann 1898 Merismopedia warmingiana Lagerheim 1883 Snowella lacustris (Chodat) Komárek & Hindák 1988 Snowella litoralis (Häyrén) Komárek & Hindák 1988 Synechocystis sp.
T C C C C T T T C T C Te Te C C C C Te C C C C Te ?
R R L, R L, R, S L, R, S L, R R L, R R R R R R, S R L, R, S L, R, S L R R, S L, R, S L, R, S R R S
Family Chroococcaceae Chroococcus deltoides Komárek & Novelo 1994 Chroococcus limneticus Lemmermann 1898 Chroococcus microscopicus Komárková-Legnerová & Cronberg 1994 Chroococcus minimus (Keissler) Lemmermann 1904 Chroococcus minor (Kützing) Nägeli 1849 Chroococcus minutus (Kützing) Nägeli 1849 Chroococcus turgidus (Kützing) Nägeli 1849
T C Te C C C C
S L, S R R R R, S L, S
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Family Microcystaceae Eucapsis densa M.T.P. Azevedo et al. 2003 Eucapsis sp. Gloeocapsa planctonica spec. nova G.B.McGregor Microcystis aeruginosa (Kützing) Kützing 1846 Microcystis botrys Teiling 1942 Microcystis flos-aquae (Wittrock) Kirchner 1898 Microcystis ichthyoblabe Kützing 1843 Microcystis panniformis Komárek et al. 2002 Microcystis wesenbergii (Komárek) Komárek in N.V.Kondrateva 1968
T T T C Te C? Te T C
L L R, S L, R L, R L, R R L, R L, R
*Cosmopolitan (C), Temperate (Te), Tropical/sub-tropical (T); Habitat: Natural Lakes (L), Reservoirs (R), Rivers and streams (S).
COMMENTS: Uncommon in the plankton. Our records from the plankton have occurred following significant river inflows to reservoirs where benthic or epiphytic material has been disturbed and drawn into the water column. A widely distributed species throughout north-eastern Australia, particularly in swampy backwaters and ephemeral pools (McGregor unpublished data). It has also been reported as a significant component of the benthos in coastal lakes from southern Australia (Dasey et al. 2005). Our material corresponds well to descriptions of temperate populations (eg. Komárková-Legnerová & Cronberg 1994). Cyanodictyon imperfectum Cronberg & Weibull 1981
Fig. 4
Colonies microscopic, oval, later becoming elongate to irregular, with 2-8 celled irregular rows in small, loose, net-like formations; in older colonies irregularly arranged, forming short fragmented rows; sheaths fine, colourless, indistinct. Cells small, spherical, 0.5-0.8 (-1.0) µm in diameter, pale blue-green, without aerotopes. During cell division, ring-like ferric precipitates form between the daughter cells. These precipitations appear as dark double dots or thin dark bands between pairs of cells; more obvious in older fragments of colonial mucilage that lack cells. eschweizerbartxxx
COMMENTS: Often mistaken for smaller species of Aphanocapsa, as the ferric rings are usually only visible under high magnification or with the aid of phase contrast microscopy. Very common and widespread, known to form bloom populations during the early summer in alkaline mesotrophic reservoirs and lakes throughout Queensland. Cosmopolitan. Cyanodictyon planctonicum B.Meyer 1994
Figs 5, 60
Colonies spherical later elongate to irregular, reticulate, multicellular, composed of short 8-16 celled pseudofilaments forming net-like, three dimensional colonies up to 150 µm long; colonial mucilage colourless, fine. Cells oval to rod-shaped, straight or slightly curved, 1.5 µm long × 0.8-1.0 µm wide, pale blue-green, without aerotopes. COMMENTS: Common species in reservoirs and to a lesser extent in rivers and weir pools. Also recorded from two artificial ornamental lakes in south-east Queensland. Our material was easily discernable from C. imperfectum by virtue of the cell morphology, and the loose net-like arrangement of the pseudo-filaments within the colonies. 305
Cyanonephron styloides B.Hickel 1985
Figs 6, 57
Colonies irregularly spherical to ellipsoidal, 12-38 × 20-48 µm in diameter, sometimes composed of 2-3 subcolonies, with cells at the ends of very fine, indistinct, colourless stalked gelatinous mucilage, arranged in semicircular sub-groups of 4-6-8 cells. Colony organization and mucilage structure is indistinct, generally only visible after staining or under phase contrast microscopy. Cells cylindrical, rod-shaped to kidney-shaped, always slightly arcuate (with the convex side facing the outside of the colony), spherical after division, with homogeneous, grey or pale yellowish-green content, 2.0-4.5 (-6.2) × 0.8-1.2 µm, usually covered with a fine hyaline, colourless mucilage. COMMENTS: Generally uncommon in north-eastern Australia, however it has been observed forming dense, bloom populations during spring and early summer from a tropical reservoir. Small colonial units (ie. 4-8 cells) may be easily mistaken for Cyanodictyon if the interconnecting mucilaginous stalks between cells are not visible. Visualising these stalks can be aided by staining with methylene blue or with phase contrast. Our populations correspond to the original description, however many older colonies were observed to take on a distinctly elongated shape. Originally described from a brackish lake in North Germany (Hickel 1985), subsequent records from the Baltic, Africa (Lake Kariba, Zimbabwe, Cronberg 1997) and now tropical and subtropical Australia suggests a widespread and possibly cosmopolitan distribution. Cyanogranis libera Hindák 2002
Fig. 7
Colonies microscopic, gelatinous, spherical to oval or irregular, beginning as a small number of randomly arranged cells, later more, 8-15(-25) µm in diameter, in the centre an irregular to rounded brown ferric body. Cells spherical to oval, 0.8-1.8 µm in diameter, blue-green to pale blue-green in colour, arranged freely in an indistinct colonial mucilage, generally distant from ferric body, aerotopes lacking. Mucilage fine, hyaline, 0.5-1.7 µm wide. eschweizerbartxxx
COMMENTS: The cells in C. libera are not directly connected with the ferric bodies rather freely clustered around them and slightly distant. Ferric bodies are 1-7 µm in diameter and range from smooth, regularly shaped particles, to elongated and sharpedged irregularly shaped granules. Originally described from a Slovakian gravel pit lake in northern Europe, its distribution in Queensland is considered widespread in lentic environments. However, it is difficult to ascertain its exact extent given that it is easily confused with other small colonial Chroococcales such as Aphanocapsa which often have organic particles associated with the colonial mucilage, and consequently likely to be under reported. Cyanocatena planctonica Hindák 1975
Fig. 8
Colonies few to many-celled, irregularly spherical or oval to irregularly elongate, with fine, hyaline, homogeneous mucilage, up to 20 µm in diameter. Cells irregularly, sometimes densely arranged, cylindrical-oval or cylindrical with rounded ends, straight or slightly arcuate, sometimes with 1-3 ring-like ferric precipitates on the surface; grey or pale blue-green, with homogeneous contents, without aerotopes, 1.0-2.5(-5.0) × 0.5-1.2 µm, after division almost spherical. 306
COMMENTS: Ring-like ferric precipitates are often free within the mucilage, otherwise they are difficult to see at magnifications less than × 400. The position of the ferric rings is an important intergeneric diacritical feature. Hindák (2002) highlighted this when contrasting the pattern of Fe precipitation between Cyanocatena and Cyanodictyon imperfectum, the former characterised by cylindrical cells rather than spherical, and Fe rings that occur between neighbouring cells, not on or around the cells. Generally overlooked due to its small size, and largely indistinguishable cells, this species has been found in eight Queensland reservoirs (Atkinson, Leslie, Coolmunda, Moogerah, Eungella, and Corella Dams, and Neville Hewitt and Bucca Weirs) where it is most abundant during late summer and early autumn when the water column is warm and at its most stable, occurring at times at concentrations up to 170 000 cells mL-1. Gloeothece lacustris sp. nova G.B.McGregor
Figs 9, 56
DESCRIPTIO: Coloniae microscopicae, primo sphaerice complanatae, in coloniis vetustioribus irregulares usque elongatae, e cellulis vaginatis 2-4-6(-8) aggregatis compositae, intra involucrum incolor gelatinosum inclusis, interdum in mucilagine firma communi inclusis, in agglomerationibus dispositis. Cellularum divisione per fissionem binariam in plano uno, cellulis ad magnitudines suas originales ante divisionem proximam crescentibus. Cellulae late ovales usque baculiformes, finibus rotundatae, pallide caeruleo-virides, 1.5-3.0 × 0.8-1.0 µm, sine aerotopis. LOCUS CLASSICUS: Atkinson Dam. ICONOTYPUS: Figura nostra 9. HOLOTYPUS HIC DESIGNATUS: Herbrecs No. AQ695703, Deposited at the Queensland Herbarium (BRI).
Colonies microscopic, spherically flattened initially, irregular to elongate in older colonies, composed of sheathed cells in groups of 2-4-6(-8), enclosed within a colourless gelatinous envelope, sometimes surrounded by a firm common mucilage, arranged in agglomerations. Cells division by binary fission in one plane, with cells growing to their original size before next division. Cells widely oval to rod-shaped, rounded at the ends, pale blue-green, 1.5-3.0 µm long × 0.8-1.0 µm wide, without aerotopes. eschweizerbartxxx
COMMENTS: Uncommon species; sheaths around individual cells are often indistinct only generally visible at higher magnification, using phase contrast or after staining. Subsequently colonies may be confused with Aphanothece, which have cells imbedded in common mucilage, if the individual sheaths around each cell are not observed. The individual sheaths also confer a regular spacing between adjacent cells and a homogeneous distribution within the colony. This differs from the often tightly arranged cells of Aphanothece. Skuja’s (1964) original description of Gloeothece subtilis Skuja was from the benthos of a shallow Swedish lake and subsequent records from other shallow turbulent lakes (Komárková-Legnerová & Cronberg 1994) confirm their facultative appearance in the plankton. Myxobaktron plankticus G.B.McGregor 2001
Figs 10, 70
Cells solitary or in pairs after division, cylindrically fusiform, ends tapered and bluntly pointed, not attenuated, 2.5-5.0(-10.0) × 0.8-1.1 µm. Cell walls thin, hyaline, without mucilage, cell contents homogenous pale blue-green without aerotopes. Cell 307
division occurs perpendicular to the longitudinal axis of the cell, in the same plane in successive generations, occasionally forming four to eight celled pseudofilaments. COMMENTS: Common in impounded rivers and reservoirs throughout Queensland. It generally forms a minor component of the planktic cyanoprokaryote populations during spring and summer, and may persist year-round in the tropical regions of the state. As in the original description (McGregor 2001), the two and four-celled forms were the most commonly encountered in our samples. Rhabdoderma lineare Schmidle & Lauterborn 1900
Figs 11, 61-62
Colonies small, few celled, with cells oriented more or less in one direction, rarely irregularly arranged. Mucilage scarcely visible, fine, homogeneous, colourless, sometimes diffluent at the margin; single cells ± very fine individual hyaline envelopes. Cells long, cylindrical, rod-shaped, straight, slightly arcuate, rounded at the ends, often in pseudofilamentous rows of 4-8 cells, pale blue-green or grey-green, with fine granular contents, without aerotopes, (3-)4-10(-22) × (0.8-)1.0-3.0 (-3.5) µm. Cells occasionally divide asymmetrically. COMMENTS: Tropical and sub-tropical material compares closely with R. tenuissima Komárek & H.J.Kling 1991: rod-shaped cells (2.0-7.8 × 0.5-0.6 µm), described from east African lakes. A widespread species in reservoirs, although never in high concentrations (ca. < 3000 cells mL-1), it is most commonly observed in short 4-8 celled pseudo-filaments. Many-celled, compound colonies have been rarely observed from two low pH, soft water, oligotrophic Fraser Island perched lakes. Rhabdoderma vermiculare Fott 1952
Fig. 12
Colonies 60-80 µm in diameter, irregularly spherical, with solitary cells loosely dispersed in fine, colourless common mucilage. Cells long, cylindrical with rounded ends, straight to distinctly arcuate, (4-)8-15(-28) × 0.8-1.2 µm, contents homogeneous, without aerotopes. Cells divide transverse to the longitudinal axis of the cells. eschweizerbartxxx
COMMENTS: Occurs in acidic perched lakes on Fraser Island, south-east Queensland. Originally described from acidophilic bogs in central Europe, our observations are consistent with the ecological preference of this species from the northern hemisphere, however its occurrence in the plankton differs from its previously reported metaphytic habit. Rhabdoderma sp.
Figs 13, 58
Colonies generally small, initially few-celled loosely arranged, up to many-celled, compact, spherical to irregularly ellipsoid, cells irregularly arranged. Mucilage fine, hyaline, often not well defined. Cells cylindrical, irregularly curved to sigmoid in shape, ends rounded, (0.7-)1.2-1.5 µm broad × 5-10(-13) µm long, dark blue-green to grey-green with fine granular contents, without aerotopes. COMMENTS: Occupying similar coastal lentic habitats as R. vermiculare, it differs by virtue of the irregularly curved to sigmoid shaped cells, akin to R. irregulare (Naumann) Geitler and R. sancti-pauli M.T.P. Azevedo, Sant’Anna, Senna, Komárek 308
& Komárková, however the cells in our material were longer, far more irregularly contorted, and were often quite densely arranged in the colonial mucilage. Rhabdogloea cf. smithii (R. & F.Chodat) Komárek 1983
Fig. 14
Colonies microscopic, free-floating, more or less spherical when small, later elongate, irregular, with up to 40, widely separated cells, ± oriented in one direction within the colony. Mucilage colourless, homogeneous, diffluent. Cells spindle-shaped, often slightly curved or rarely sigmoid, tapering to acutely rounded ends, pale blue or grey-green, 3.5-5 × (1.0-)1.6-3.0 µm. COMMENTS: Our populations of R. cf. smithii from the alkaline oligotrophic dune barrage lake, Lake Wabby, Fraser Island (153°07E, 25°27S) had cells slightly smaller than the type description, although similar in all other respects. Synechococcus aff. nidulans (Pringsheim) Komárek in Bourrelly 1970
Fig. 15
Cells solitary or in pairs, cylindrical, rod-shaped, without mucilage, contents homogeneous blue-green, straight or slightly bent or sigmoid, 1.6-2.0 × 5.0-9.0 µm, without aerotopes. COMMENTS: Commonly present in small concentrations in slow flowing rivers, ponds and weir pools; rarely in lakes. The name Synechococcus nidulans has been ascribed variously to taxa from a broad range of biotopes and with a wide morphological range. Although we use the name here to represent material from various tropical and subtropical lentic habitats, we recognise that it is unlikely that it corresponds to S. nidulans known from a number of temperate freshwater environments. Family Merismopediaceae eschweizerbartxxx
Aphanocapsa annulata sp. nova G.B.McGregor
Figs 18, 54, 59
DESCRIPTIO: Coloniae microscopicae, libere natantes. Coloniae minores sphaericae usque ellipsoidales, postea irregulariter elongatae (raro aperturis praeditae), ovales vel distincte annulatae, usque ad 120 µm. longae. Mucilagines homogeneae, incoloratae, distinctae, saepe latae et clare delimitatae. Cellulae generatim dense et aequabiliter contiguae, sphaericae pallide caeruleo-virides, 2.2-3.1(-3.5) µm diam., absque aerotopis. LOCUS CLASSICUS: Lacus Kinchant, Queensland, Australia. ICONOTYPUS: Figura nostra 18. HOLOTYPUS HIC DESIGNATUS: Herbrecs No. AQ695702, Deposited at the Queensland Herbarium (BRI). ETYMOLOGIA: Annulatus; shaped like a ring.
Colonies microscopic, free-floating. Smaller colonies regularly spherical to ellipsoidal, later irregularly elongate (rarely with holes), oval, or distinctly annulate, up to ca. 120 µm long. Mucilage homogeneous, colourless, distinct, often wide and clearly delimited. Cells generally densely and evenly packed, spherical pale blue-green, 2.2-3.1(-3.5) µm in diameter, without aerotopes. COMMENTS: Recorded from a few mesotrophic reservoirs, most common in central and north Queensland; Lake MacDonald (152°55E, 26°25S), Lake Monduran 309
(151°51E, 24°52S), Peter Faust Reservoir (148°23E, 20°22S), Kinchant Reservoir (148°53E, 21°12S). The maturation cycle of the colonies is distinctive; colonies begin as small and irregularly spherical with cells densely arranged, over time elongating to many times longer than broad, before bending into a C-shaped arc and eventually closing full circle to form mature ring-shaped colonies with cells more evenly and widely spaced than in the immature colony. Spherical sub-colonies may bud off at the elongation phase when colonies may acutely narrow at various points. This species is most similar to A. koordersii with respect to cell size, however A. annulata differs markedly by the proximity of the cells to each other within the colony at all stages of its lifecycle, clearly delimited mucilage, and marked elongation and ultimate annulate shape of mature colonies. The specimens of A. koordersii observed from the study area corresponded well to the original description. Aphanocapsa delicatissima W. & G.S.West 1912
Figs 19, 67
Colonies regularly spherical to elliptical, often irregular in older colonies, up to 50 µm in diameter, with more or less loosely arranged, evenly dispersed cells; mucilage colourless homogeneous, diffluent. Cells small, spherical, grey or pale blue-green, without aerotopes, 0.5-1.0(-1.3) µm in diameter. COMMENTS: Common in meso-eutrophic lakes and reservoirs. Occurs in the plankton of lakes and reservoirs throughout the world, although more commonly reported from temperate regions. Our populations were mostly spherical or irregularly oval and corresponded well to the original description. Aphanocapsa elachista W. & G.S.West 1894
Figs 20, 64
Colonies microscopic, spherical to oval, up to 100 µm in diameter, with sparsely disposed solitary cells, in twos after division. Mucilage homogeneous, scarce, colourless, usually diffluent. Cells spherical, grey or pale blue-green, without aerotopes, 1.3-2.3 µm in diameter. eschweizerbartxxx
COMMENTS: Common in meso-eutrophic lakes and reservoirs. Occurs in the plankton of lakes and reservoirs throughout the world, although more commonly reported from tropical countries or warm temperate regions. Irregularly elongate colonies were rarely observed. Aphanocapsa holsatica (Lemmermann) Cronberg & Komárek 1994
Figs 21, 65
Colonies irregularly spherical in younger colonies, later irregular, lobate, elongate or clathrate usually embedded in clearly visible colourless mucilage. Cells more or less densely arranged, spherical, 0.8-1.2 µm in diameter, pale greyish blue-green, without aerotopes. COMMENTS: Extremely common component of the phytoplankton of lakes and reservoirs, with the majority of samples collected from reservoirs throughout the study area during lake stratification (October - May) containing this species; widespread throughout Australia. Differs from Aphanocapsa incerta by virtue of its irregular colony margin and having cells more widely dispersed within the colony.
310
Aphanocapsa incerta (Lemmermann) Cronberg & Komárek 1994
Figs 22, 66
Colonies microscopic, spherical, rarely irregular; mucilage colourless structureless, diffluent and indistinct at the margin. Cells very densely aggregated with spaces between adjacent cells less than the diameter of the cells, spherical 0.8-1.5(-1.9) µm in diameter, pale blue-grey, without aerotopes. COMMENTS: The occurrence of this species may have been over reported in Australia due to its confusion with the widely reported species previously known as Microcystis incerta (Lemmermann) Lemmermann 1907. Historically, Australian algal practitioners have included material that corresponds to both A. holsatica and A. incerta under this synonym. Aphanocapsa koordersii Strøm 1923
Fig. 23
Colonies microscopic, more or less spherical or irregular. Cells loosely arranged, spherical 2.0-2.8(-3) µm in diameter, without aerotopes. COMMENTS: Although reported as common in the tropics, it has been scarcely reported from tropical regions of Australia. The description of A. koordersii by Ling & Tyler (1986) from the Alligator River region of the Northern Territory corresponds to our populations and the original description. Komárek & Cronberg (2001) observed solitary aerotopes in the cells of South African populations. Aphanocapsa nubilum Komárek & H.J.Kling 1991
Fig. 24
Colonies microscopic, spherical to irregularly cloud-like, up to 60 µm in diameter, rarely composed of sub-colonies. Mucilage colourless, diffluent, following the colony margin, 1-3 µm wide around the marginal cells, often visible. Cells spherical, pale grey blue-green, 1.2-1.8 µm in diameter, without aerotopes, irregularly distributed within the colony, more or less densely arranged, more so in older colonies. eschweizerbartxxx
COMMENTS: Differs from A. elachista by the dense arrangement of cells and the irregular shape of the colonies; the two species often being present at the same time. Seasonally abundant, mostly in tropical reservoirs, largely during the warmer summer months. Our populations corresponded to the original description from African lakes. Coelomoron microcystoides Komárek 1988 (Fig. 84) Colonies spherical, with radially and densely arranged cells in one layer on the periphery, 50-80 µm in diameter. Mucilage fine, colourless, diffluent, almost indis-tinguishable. Cells widely oval, pale blue-green, without aerotopes, 2.0-3.0 × 1.6-2.5 µm. COMMENTS: A tropical species known from Cuba, Mexico and South Africa. Our populations were uncommon, occurring in shallow hypertrophic sub-tropical lakes in Central Queensland, however they generally corresponded to the original description. Coelomoron pusillum (Van Goor) Komárek 1988
Fig. 26
Colonies microscopic, ± spherical to irregularly oval, often compound, 12-30 µm in diameter, cells more or less radially arranged at the periphery, slightly distant and displaced from one another, sometimes in groups of 2-4, later aggregated, younger 311
colonies often with only 10-30 cells. Mucilaginous envelope colourless, diffluent, extending 1.2-2.5 µm beyond the cell margin; mucilage in the centre of young colonies dense, radiating out in barely visible stands. Cells widely oval or obovoid, pale bluegreen, granulate, without aerotopes, 2.2-4.5(-5.5) × 1.8-4.0 µm. COMMENTS: A widespread species known from both the temperate and tropical regions. Commonly present in small numbers in tropical and sub-tropical reservoirs. Compound colonies rarely observed. Ling & Tyler (2000) reported this species from the Northern Territory as Coelosphaerium pusillum van Goor and described irregular to globose colonies 20-30 µm in diameter. Coelomoron tropicale Senna, A.C.Peres & Komárek 1998
Figs 27, 83
Colonies irregularly spherical or oval to elongate, with radially arranged cells in one layer on the periphery, slightly distant from each other in younger colonies, later densely arranged, 12-17 µm long × 9-14 µm wide. Mucilage fine, colourless, diffluent, not easily distinguished. Cells widely obovoid or rounded triangular, pale blue-green, contents homogeneous, without aerotopes, 2.8-3.0 × 2.3-2.8 µm. COMMENTS: Uncommon species. Populations from Queensland closely match the description of the Brazilian type material, and records from southern African Lakes (Komarek & Cronberg 2001). Recorded sporadically as planktic in a shallow, mesotrophic off-stream reservoir (149°58E, 24°36S), and in eutrophic to hypertrophic billabongs along the Fitzroy River, Central Queensland. Coelosphaerium kuetzingianum Nägeli 1849
Figs 28, 69
Colonies microscopic, spherical or widely oval, 20-50(-100) µm in diameter, sometimes consisting of two sub-colonies, with relatively densely arranged cells in one or two layers close to the colony surface. Mucilage colourless, indistinct. Cells spherical or hemispherical after division, 1.8-3.0 µm in diameter, pale blue-green or olivegreen, slightly granular, without aerotopes. eschweizerbartxxx
COMMENTS: Coelosphaerium pallidum Lemmermann, recorded from the Northern Territory (Ling & Tyler 1986) appears sufficiently similar to the description of C. kuetzingianum as to be considered synonymous. Coelosphaerium aff. natans Lemmermann 1900
Fig. 29
Colonies spherical with cells relatively densely arranged in up to 3 layers around the surface of the colony. Fine colourless mucilage extending up to 4 µm from the surface of the colony. Cells spherical 1.3-2.0(-2.5) µm diameter with aerotopes. COMMENTS: The material differs from Coelosphaerium natans Lemmermann in the extent of the gelatinous envelope and mainly tropical distribution. Baker (1992) noted that Lugol’s preserved material from south-eastern Australia is also very similar in dimensions to C. natans. Our populations show almost a continuum between C. aff. natans, C. aff. kuetzingianum, C. confertum W. & G.S.West and Coelomoron microcystoides like forms suggesting these morphotypes may represent environmentally induced forms of the same species. 312
Coelosphaerium punctiferum Komárek & Komárková-Legnerová 1992 Figs 30, 68 Colonies spherical to oval (rarely), 30-80 µm in diameter, with cells ± regularly and sparsely distributed just beneath the periphery of the fine, hyaline colonial mucilage, distant from one another, sometimes in small loose groups. Cells small, spherical 1.0-1.2 µm in diameter, with pale blue-green homogeneous content, without aerotopes. COMMENTS: May appear similar to Aphanocapsa delicatissima due to comparable cell size and colony shape. However A. delicatissima can be distinguished from C. punctiferum by virtue of its cells being disposed throughout the colony, not just restricted to the periphery. Gomphosphaeria aponina Kützing 1836
Fig. 31
Colonies microscopic, irregularly spherical or oval, sometimes compound, with sparsely or densely arranged cells; mucilaginous envelopes colourless, thick, homogeneous, mucilaginous stalks more or less thick. Cells obovoid or slightly clubshaped, during division cordiform, pale blue-green, with homogeneous or finely granulate contents, without aerotopes, 8-12 × 4.0-6.5 µm. COMMENTS: Uncommon in the plankton. Like Aphanothece stagnina, our records of G. aponina from the plankton have occurred following significant river inflows to reservoirs where benthic or epiphytic material has been disturbed and drawn into the water column. Reported sporadically from Lake Monduran, Central Queensland. Merismopedia elegans A.Braun in Kützing 1849
Figs 32, 71
eschweizerbartxxx
Colonies generally large (up to 4000 celled), tabular, rectangular, with cells regularly and closely arranged in perpendicular rows. Mucilage thick, distinct, sometimes slightly layered, forming a distinct 2-10 µm margin around colonies. Cells spherical or broadly oval before division, sub-spherical after division, 5-8(-9) µm wide, bluegreen, without aerotopes. COMMENTS: Widespread and common species, particularly in small eutrophic water bodies including artificial ponds and waterholes. Merismopedia glauca (Ehrenberg) Kützing 1845
Fig. 33
Colonies flat, rectangular or irregular, usually 64 celled (rarely more), with more or less densely and regularly arranged cells, sometimes consisting of subcolonies. Mucilage colourless, sometimes diffluent, but usually distinct, slightly extending beyond the marginal cells (2-4 µm). Cells spherical or widely oval before division, hemispherical after division, homogeneous pale blue-green, without aerotopes (2.8-)3-5(-6) µm in diameter. COMMENTS: Commonly metaphytic, secondarily planktic. Most of our material was observed from temporary pools and ponds, associated with aquatic macrophytes. 313
Merismopedia hyalina (Ehrenberg) Kützing 1845 Colonies small, flat, and often irregular, 4-8(-16) celled, rarely more, most often with cells in short rows, more or less loosely arranged, rarely composed of sub-colonies. Mucilage colourless, but often distinct, overlapping the cells up to 4 µm; individual envelopes around cells rarely visible. Cells spherical, hemispherical after division, with pale greyish or blue-green content (1-)2-3(-3.5?) µm in diameter, without aerotopes. COMMENTS: Present in shallow reservoirs and eutrophic billabongs in Cental Queensland. Some coastal sites are brackish at various times of the year. Merismopedia marssonii Lemmermann 1900
Figs 34, 72
Colonies generally small, 8-16(-32) celled, flat or slightly curved with cells densely arranged. Mucilage fine, diffluent, hyaline 1-3 µm broad. Cells spherical or subspherical after division, 1.8-2.1 µm wide, blue-green in colour, with much of the central area of the cell occupied by several large aerotopes ± finger-like protuberances. COMMENTS: An uncommon species, records for Australia appear restricted to two sub-tropical meso-eutrophic reservoirs, Lake Monduran (151°51E, 24°52S) and Cania Dam (150°59E, 24°39S), Central Queensland. Has occasionally been observed as occurring in high concentrations (ca. 30 000-50 000 cells mL-1) during summer blooms of Cylindrospermopsis raciborskii. The Queensland material generally differs from the description of M. marssonii from European lakes by Hindák (1992) by virtue of its regular occurrence in smaller colonial units, which is possibly related to the faster growth rates experienced by tropical populations. Merismopedia punctata Meyen 1839
Figs 35, 73
Colonies tabular, flat, small, 2-16 up to 64 celled (rarely more), usually in regular rows with more or less loosely arranged cells, rarely composed of subcolonies. Mucilage distinct or diffluent, colourless. Cells spherical or sub-spherical after division, widely oval or hemispherical before division, pale blue-green, without aerotopes (2-)2.5-3.5 µm in diameter. eschweizerbartxxx
COMMENTS: Common component of the phytoplankton in lakes and reservoirs and possibly the most common species of Merismopedia across the study area. Our populations corresponded well to the original description. Merismopedia tenuissima Lemmermann 1898
Figs 36, 74
Colonies flat, usually rectangular, sometimes slightly rolled or bent, 16 up to 100 more or less densely aggregated cells. Cells small, spherical to oval, hemispherical after division, 0.8-1.6(-2.0) µm in diameter, in groups of 2-4, pale grey-blue or blue-green, with more or less visible individual mucilaginous sheaths around the cells, without aerotopes. COMMENTS: Common; has been recorded as a summer bloom forming species in eutrophic reservoirs at concentrations > 800 000 cells mL-1. We observed many populations from turbulent, well mixed shallow lakes where the tabular morphology of the colonies had collapsed forming loosely to densely compact Aphanocapsa-like 314
agglomerations. Only on closer observation was the arrangement of cells within the agglomerations into groups of four evident. Merismopedia warmingiana Lagerheim 1883
Figs 37, 75
Colonies small, free-floating, quadrate, 4-32 celled, with more or less densely arranged cells. Larger colonies composed of multiple sub-colonies of 16-64 cells. Mucilage hyaline, up to 2 µm broad and generally indistinct. Cells small, spherical, greyish or pale blue-green, rarely with individual gelatinous envelopes, 0.6-0.8(-1.2) µm in diameter, without aerotopes. COMMENTS: Often incorrectly cited as M. minima, which refers to subaerophytic or metaphytic rather than planktic populations. Commonly a constituent of cyanoprokaryote blooms in eutrophic lakes and reservoirs. Snowella lacustris (Chodat) Komárek & Hindák 1988
Figs 16, 63
Colonies microscopic, spherical or ellipsoidal, rarely irregular, sometimes compound, up to 80 µm in diameter, with cells disposed sparsely initially, more densely in older colonies. Mucilaginous envelope fine, diffluent, stalks thin, usually clearly visible. Cells elliptical or obovoid, pale grey- or blue-green, without aerotopes, 2-4 × 1.5-3.5 µm. Snowella litoralis (Häyrén) Komárek & Hindák 1988
Fig. 17
Colonies spherical to sub-spherical, 20-40 µm in diameter. Mucilage distinct, wide, colourless. Cells at the ends of fine gelatinous stalks, spherical, 2-3(-4) µm in diameter, pale blue-green, without aerotopes, always arranged distant from one another around the colony periphery. COMMENTS: Both species of Snowella described here maybe easily confused with other planktic gomphosphaerioid taxa if the mucilaginous stalks within the colony are not observed. These stalks are more readily seen with phase-contrast microscopy or after staining. The two Snowella species are easily distinguished from each other by their distinctive cells shapes, S. lacustris drop-shaped or obovoid, S. litoralis spherical. Both species were never observed forming large populations, but rather occurred infrequently in the plankton of reservoirs throughout the study area, principally in the tropical regions during the warmer summer months. eschweizerbartxxx
Synechocystis sp.
Fig. 25
Cells spherical, solitary or often in pairs following division, 1.8-2.0(-2.4) µm in diameter, green to blue-green in colour, without aerotopes. Individual cells surrounded by a fine, diffluent, and indistinct mucilaginous sheath. COMMENTS: Planktic in blooms dominated by various coiled and straight Anabaena species in the Fitzroy River, Central Queensland. Despite various species of Synechocystis being known to produce microcystins (ie. Synechocystis aquatilis f. salina (Wislouch) Komárek, a brackish water nanoplanktic species from Brazilian coastal lagoons; (Nascimento & Azevedo 1999), little is known about the presence, distribution, taxonomic position or toxin producing potential of Synechocystis species from Australian freshwaters. 315
Family Chroococcaceae Chroococcus deltoides Komárek & Novelo 1994
Figs 38, 82
Colonies microscopic, containing few cells (up to 6), freely separated in fine homogeneous common mucilage (only visible with phase contrast or Normarski DIC microscopy). Cells 15-20 µm in diameter, spherical or remaining distinctively hemispherical or triangular-rounded for some time after division, pale grey-blue, or olive-green, without aerotopes. COMMENTS : Pantropical. Originally described from coastal Caribbean swamps (Komárek & Novelo 1994), this species has been found in similar metaphytic or periphytic habitats in coastal north-eastern Australia; occurring infrequently in the plankton. Rarely we observed mature colonies with firm mucilage, which was indistinctly stratified. This was evident only with the aid of DIC. Chroococcus limneticus Lemmermann 1898
Fig. 39
Colonies oval or irregular and lobate, 4-40 celled. Cells in small groups, spherical or hemispherical after division, pale blue-green, without aerotopes, 6-13(-22) µm in diameter, situated irregularly in fine homogeneous, diffluent, colourless mucilage, sometimes with narrow individual not lamellated sheaths. COMMENTS: Uncommon; known only from two small natural lakes in south-east Queensland, where it constitutes a small component of the cyanoprokaryote phytoplankton during early autumn. Chroococcus microscopicus Komárková-Legnerová & Cronberg 1994 Figs 40, 78 eschweizerbartxxx
Colonies microscopic, irregularly cloud-like, up to 100 µm in diameter, with numerous densely packed groups of 4-8 cells surrounded by a common sheath. Mucilage colourless, fine, clearly delimited or diffluent, structureless (generally visible after staining or with phase contrast). Cells spherical, 0.7-1.0 µm in diameter, with homogeneous, pale blue-green contents. COMMENTS: Uncommon. Forms many celled Aphanocapsa-like colonies, which can be distinguished on the basis of the 4-8 celled subunits with their own mucilaginous envelope. Our material agrees well with the original description of C. microscopicus (Komárková-Legnerová & Cronberg 1994) from Swedish lakes. Its record here from Australia confers a wider, possibly cosmopolitan distribution including other tropical and sub-tropical regions (eg. Komárková-Legnerová & Tavera 2003). Chroococcus minimus (Keissler) Lemmermann 1904
Figs 41, 79
Colonies mucilaginous, microscopic, spherical or irregularly spherical, with 3-6(-8) cells which are more or less regularly arranged in twos or small groups situated within colourless, homogeneous mucilage, diffluent at the margin. Cells spherical, hemispherical after division, pale blue-green or greyish-blue, 1.7-3.0 µm in diameter, without aerotopes. 316
COMMENTS: Common component of the plankton in meso-eutrophic reservoirs. 4-6 celled packets of cells are most commonly observed. The mucilage is often not evident without staining, or with the aid of phase contrast microscopy. Chroococcus minor (Kützing) Nägeli 1849 Colonies microscopic, irregular, gelatinous, rarely larger, with irregularly arranged clustered cells, often in 2-4 celled groups, rarely more. Mucilage delicate, wide, diffluent, colourless, not lamellated, often scarcely visible. Cells spherical or hemispherical after division, 3-4 µm in diameter, pale blue-green. Chroococcus minutus (Kützing) Nägeli 1849
Figs 42, 80
Cells solitary or in few-celled colonies (usually 2-4 cells), enclosed in a wide, more or less spherical or oval, homogeneous or slightly lamellate, delimited gelatinous mucilage. Cells spherical or hemispherical after division, pale blue-green or grey, homogeneous or granulose, (4-)5-10(-12) µm in diameter. COMMENTS: This polymorphic species is widely reported from various biotopes throughout the world including saline mangrove habitats, aerophytic and metaphytic habitats, thermal springs, and alkaline sub-tropical and tropical swamps, springs, creeks and lakes. Our planktic populations were common in reservoirs, particularly during the later summer months, and corresponded to the original description. Two celled colonial units were the most frequently observed form. Chroococcus turgidus (Kützing) Nägeli 1849
Figs 43, 81
Colonies microscopic composed of cells in groups of 2-4(-8) seldom more, rarely solitary. Common colonial mucilage generally lacking, often present as firm clearly delimited mucilaginous envelope in older colonies, colourless, ± indistinctly striated, up to 10 µm wide. Cells spherical or ellipsoidal, hemispherical after division, bluegreen, olive-green, homogeneous or finely granular, without sheaths 8-32 µm in diameter. eschweizerbartxxx
COMMENTS: Uncommon in the plankton, usually metaphytic; associated with detritus, rocks, logs, and submerged vegetation in the littoral zone of lakes, rivers and swamps. Family Microcystaceae Eucapsis densa M.T.P. Azevedo, Sant’Anna, Senna, Komárek & Komárková 2003 Figs 44, 77 Colonies with 30-64 cells, arranged in cubic formation, less regularly so in mature colonies; sometimes composed of sub-colonies; mucilage fine, colourless, diffuse at the edge, usually 2-4 µm wide. Cells spherical, hemispherical after division, 2.6-3.4 µm in diameter, contents pale blue-green, without aerotopes. COMMENTS: Originally described from the metaphyton of warm, alkaline Brazilian swamps (Azevedo et al. 2003), but also know from other tropical areas including Iran and West Africa, and warm areas of the temperate zone (as Eucapsis sp. [Komárek & Hindák 1989]), E. densa has only been found in a few oligotrophic 317
coastal dune lakes in south-eastern Queensland. This genus has not been previously reported from Australian freshwaters. The cubic alignment of cells within the colony is often only apparent in younger colonies, with cells in older colonies more irregularly and densely arranged. Eucapsis sp.
Figs 45, 76
Colonies microscopic, composed of 8-32(-64) cells, arranged in cubic formations; sometimes composed of sub-colonies; mucilage fine, colourless, diffuse at the margins. Cells spherical, hemispherical after division, 1.4-2.6 µm in diameter, contents pale blue-green, without aerotopes. COMMENTS: This species is similar in cell size to E. starmachii Komárek & Hindák, and E. minuta Fritsch, however it differs from both with respect to cell arrangement within the colony and habit. The cubic arrangement of cells is often less clearly defined in older colonies. Found infrequently in slightly acidic coastal lakes and lagoons. Gloeocapsa planctonica sp. nova G.B.McGregor
Figs 46, 53
DIAGNOSIS: Coloniae microscopicae, libere natantes, cellulis (1-)2-6(-8) irregulariter dispositis. Cellulae sphaericae, ovales ante divisionem, 3.0-4.5 µm diam., pallide luteo-virides absque aerotopis, involucris latis rotundatis inclusae. Cellularum divisio per fissionem binariam in planis ternis intra involucra gelatina, cellulis ad magnitudines suas originales ante divisionem proximam crescentibus. Involucra mucilaginea concentrice lamellata, tenuia, ochracea, peripheriam versus intensius colorata. LOCUS CLASSICUS: Kirar Weir, Central Queensland, Australia. ICONOTYPUS: Figura nostra 46. HOLOTYPUS HIC DESIGNATUS: Herbrecs No. AQ695701, Deposited at the Queensland Herbarium (BRI). eschweizerbartxxx
ETYMOLOGIA: Planctonica, planktic.
Colonies microscopic, free floating, with (1-)2-6(-8) irregularly arranged cells. Cells spherical, oval before division, 3.0-4.5 µm in diameter, pale blue-green without aerotopes, surrounded by wide, rounded envelopes. Cells division by binary fission in three planes within the gelatinous envelopes, with cells growing to their original size before next division. Mucilaginous envelopes concentrically lamellate, fine, yellowish-brown, more intensely coloured towards the periphery. COMMENTS: Gloeocapsa siderochlamys (Skuja) Stamarch is the only other species of Gloeocapsa known to be truly planktic, most are epilithic or epiphytic; subaerophytic or aerophytic forms are the most common. The colonial form and arrangement of cells of G. planctonica is similar to G. siderochlamys however none of the populations observed from reservoirs throughout Queensland had cells with aerotopes. The mucilaginous envelope of G. planctonica is clearly delimited and the lamellations evident under phase contrast microscopy. Following division, daughter cells bud off in three planes rapidly forming new individual envelopes. This leads to older colonies being comprised of many irregularly arranged packet-like sub-colonies of 2-4 cells, which eventually separate. This planktic species is mostly restricted to eutrophic reservoirs and weir pools where it has been collected from still surface waters, 318
confirming its planktic origin. It has only rarely been found in coastal lowland slowflowing rivers. Microcystis aeruginosa (Kützing) Kützing 1846
Figs 47, 85
Colonies mucilaginous, microscopic to macroscopic, the former more or less spherical or elongate, the later irregularly lobate, elongated or clathrate (net-like) or composed of sub-colonies with irregular outline and large numbers of irregularly arranged ± densely packed cells. Mucilage colourless, structureless, diffluent, often indistinctly defined, margin around the colony (usually 5-10 µm wide). Cells spherical, slightly elongated during division, or hemispherical after division, generally 4-7 µm in diameter with numerous and conspicuous aerotopes. COMMENTS: Young colonies may be confused with M. flos-aquae. Distinction lies in the colony margin, extent of colonial mucilage, and the cell proximity within the colony. Common cosmopolitan species commonly forming blooms in eutrophic lakes and reservoirs. Microcystis botrys Teiling 1942
Figs 48, 87
Colonies mucilaginous, microscopic to macroscopic, essentially spherical and sometimes composed of sub-colonies with densely packed cells. Mucilage wide, colourless, often indistinct, yet structured and forming a broad margin around the colony. Gelatinous processes, which may be observable under phase contrast microscopy, protrude radially from the colony. Cells spherical generally 6–7 µm in diameter with aerotopes. COMMENTS: Often observed as mixed populations with M. aeruginosa, with which it may be confused. Distinction lies in the spherical shape of the colony, often larger cell size, and gelatinous protuberances within the mucilage. These protuberances may not always be visible without staining, phase contrast or DIC. Older colonies form complex net-like spherical colonies. eschweizerbartxxx
Microcystis flos-aquae (Wittrock) Kirchner 1898
Figs 49, 89
Colonies microscopic, compact, more or less spherical, globose, obovoid, ellipsoidal or irregular in outline, not lobate, with very densely aggregated cells, only rarely with indistinct holes in older colonies. Mucilage indistinct, fine, hyaline, colourless, diffluent. Mucilaginous envelopes not exceeding the margin of the colony by more than 1 µm. Cells spherical or hemispherical when dividing, with aerotopes (2.5-) 3.5-4.8(-5.6?) µm in diameter. COMMENTS: May be confused with young colonies of M. aeruginosa. It differs with respect to its smaller cell size and more compact arrangement of cells without holes in mature colonies and propagation of colonies. Common and widespread species, often co-occurring with blooms of M. aeruginosa. Microcystis ichthyoblabe Kützing 1843
Fig. 86
Colonies compound, composed of more or less spherical sub-colonies situated in a wide mucilaginous envelope. Cells spherical with aerotopes, 2.5-3.0 µm in diameter. 319
COMMENTS: Rare, as a sub-dominant in Microcystis panniformis blooms in Central Queensland. Microcystis panniformis Komárek, Komárková-Legnerová, Sant’Anna, M.T.P. Azevedo & Senna 2002 Figs 50, 88 Colonies in the shape of a thickened disc or forming a thin often folded film. Colonies may be regular in shape or irregular with cells disintegrating apart from the colony (? older colonies). Mucilage wide, colourless. Cells spherical with distinct aerotopes, 3-5 µm in diameter. Cells may be evenly distributed throughout the colony or form slight aggregations in a pattern similar to that of M. ichthyoblabe. COMMENTS: A tropical species originally described from a eutrophic Brazilian reservoir and associated with a number of fatal human intoxications (Komárek et al. 2001). Associated with the production of the cyanotoxin microcystin, it is sporadically reported forming blooms in tropical regions of Australia (eg. White et al. 2003). Its distribution is possibly underestimated in tropical and sub-tropical Australia due to its common misinterpretation with M. aeruginosa. Our populations corresponded to the original description and were distinguishable from M. aeruginosa on the basis of the flattened colony morphology, cell size and arrangement, and the irregular colony outline. Microcystis wesenbergii (Komárek) Komárek in N.V.Kondrateva 1968 Figs 51, 90 Colonies initially spherical, later becoming elongate and intensely lobate, often with distinct holes (clathrate), sometimes composed of sub-colonies; cells arranged randomly rarely densely, in young colonies near the colony surface. Mucilage colourless, smooth, firm, distinctly delimited, not diffluent but with a refractive outline. Gelatinous margin extends 3-6 µm beyond the cell aggregations. Cells spherical with distinct aerotopes, 4.0-7.5 µm in diameter. eschweizerbartxxx
COMMENTS: Uncommon in tropical and sub-tropical Australia. Recorded by Baker (1992) as forming bloom populations in lagoons adjacent to the River Murray, southern Australia (Victoria). In Central Queensland it occupies similar habitats such as eutrophic billabongs and farm dams.
Acknowledgements The preparation of this paper would not have been possible without the assistance and support of many colleagues and friends. We would like to make special mention of the following individuals who have greatly assisted us along the way: Heather Smyth, Central Queensland University, for assistance with preparation of drawings and compilation of photomicrographs; Prof. Jiøí Komárek and Dr Jaroslava Komárková-Legnerová University of Southern Bohemia, Czech Republic, Assoc Prof. Gertrud Cronberg University of Lund, Sweden, and Hedy Kling, Algal Taxonomy and Ecology Inc, Winnipeg, Canada for editorial and taxonomic advice, and SunWater, Queensland for availing the data from their ongoing cyanoprokaryote monitoring program. Peter Bostock, Queensland Herbarium kindly provided the translation of the Latin descriptions.
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Figs 2-9. 2. Aphanothece clathrata; 3. Aphanothece stagnina; 4. Cyanodictyon imperfectum; 5. Cyanodictyon planctonicum; 6. Cyanonephron styloides; 7. Cyanogranis libera; 8. Cyanocatena planctonica; 9. Gloeothece lacustris. [Scale bars = 10 µm]
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Figs 10-17. 10. Myxobaktron plankticus; 11. Rhabdoderma lineare; 12. Rhabdoderma vermiculare; 13. Rhabdoderma sp.; 14. Rhabdogloea cf. smithii; 15. Synechococcus aff. nidulans; 16. Snowella lacustris; 17. Snowella litoralis. [Scale bars = 10 µm]
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Figs 18-25. 18. Aphanocapsa annulata; 19. Aphanocapsa delicatissima; 20. Aphanocapsa elachista; 21. Aphanocapsa holsatica; 22. Aphanocapsa incerta; 23. Aphanocapsa koordersii; 24. Aphanocapsa nubilum; 25. Synechocystis sp. [Scale bars = 10 µm]
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Figs 26-37. 26. Coelomoron pusillum; 27. Coelomoron tropicalis; 28. Coelosphaerium kuetzingianum; 29. Coelosphaerium aff. natans; 30. Coelosphaerium punctiferum; 31. Gomphosphaeria aponina; 32. Merismopedia elegans; 33. Merismopedia glauca; 34. Merismopedia marssonii; 35. Merismopedia punctata; 36. Merismopedia tenuissima; 37. Merismopedia warmingiana. [Scale bars = 10 µm]
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Figs 38-51. 38. Chroococcus deltoides; 39. Chroococcus limneticus; 40. Chroococcus microscopicus; 41. Chroococcus minimus; 42. Chroococcus minutus; 43. Chroococcus turgidus; 44. Eucapsis densa; 45. Eucapsis sp.; 46. Gloeocapsa planctonica; 47. Microcystis aeruginosa; 48. Microcystis botrys; 49. Microcystis flos-aquae; 50. Microcystis panniformis; 51. Microcystis wesenbergii. [Figs 38-46 scale bars = 10 µm; Figs 47-51 scale bars = 20 µm]
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Figs 52-62. 52. Aphanothece clathrata; 53. Gloeocapsa planctonica; 54. Aphanocapsa annulata; 55. Aphanothece stagnina; 56. Gloeothece lacustris; 57. Cyanonephron styloides; 58. Rhabdoderma sp.; 59. Aphanocapsa annulata; 60. Cyanodictyon planctonicum; 61-62. Rhabdoderma lineare. [Scale bars = 10 µm]
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Figs 63-75. 63. Snowella lacustris; 64. Aphanocapsa elachista; 65. Aphanocapsa holsatica; 66. Aphanocapsa incerta; 67. Aphanocapsa delicatissima; 68. Coelosphaerium punctiferum; 69. Coelosphaerium kuetzingianum; 70. Myxobaktron plankticus; 71. Merismopedia elegans; 72. Merismopedia marssonii; 73. Merismopedia punctata; 74. Merismopedia tenuissima; 75. Merismopedia warmingiana. [Scale bars = 10 µm]
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Figs 76-90. 76. Eucapsis sp.; 77. Eucapsis densa; 78. Chroococcus microscopicus; 79. Chroococcus minimus; 80. Chroococcus minutus; 81. Chroococcus turgidus; 82. Chroococcus deltoides; 83. Coelomoron tropicalis; 84. Coelomoron microcystoides; 85. Microcystis aeruginosa; 86. Microcystis ichthyoblabe; 87. Microcystis botrys; 88. Microcystis panniformis; 89. Microcystis flos-aquae; 90. Microcystis wesenbergii. [Figs 76-84 scale bars = 10 µm, Figs 85-90 scale bar = 20 µm]
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Received 7 July 2005, accepted in revised form 3 July 2006.
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