PHYSIOLOGICAL ECOLOGY OF NITROGEN FIXING BLUE-GREEN ALGAL CRUSTS IN THE UPPER-SUBALPINE LIFE ZONE1

Blue-green algal (cyanobacterial) crusts composed of nitrogen fixing Nostoc commune Voucher ex Born. et Flah. and Tolypothrix conglutinata var. colorata Ghose were studied in the upper-subalpine life zone, Mission Mountain Wilderness, Montana. Rates of ethylene production were highest in the submerged shoreline crusts, lower for exposed crusts pioneering rocky shorelines and lowest in the Carex meadow. Nitrogenase activity (acetylene reduction technique) was constant between 200–285% crust moisture content (wet/dry weight) and then rapidly declined to 0 between 200–140%. Optimal temperatures for ethylene production by illuminated cells was between 20–30° C for T. conglutinata, 20° C for N. commune and about 25° C in darkness for both species. Nitrogenase activity by T. conglutinata in culture was unaffected by repeated freeze-thaw treatments whereas N. commune was severely inhibited. In contrast, N₂-ase activity of these two species in an intact crust was unaffected by repeated freeze-thaw treatments. Application of nitrogen-free growth medium to intact crusts increased nitrogenase activity by 3.7 times implying that these were mineral deficient under field conditions. Photosynthesis was light saturated at 125 μmol-m^?2.s^?1 whereas nitrogenase activity was light independent for cells with carbohydrate reserves. When carbohydrate reserves were reduced by 8 h incubation in darkness, between 1–3 h of illumination were required to restore nitrogenase activity to 80% of the maximum rate. Biochemical pathway inhibitor studies employing DCMU, MFA, and CCCP showed that oxidative metabolism was the source of reductant for acetylene reduction. Tetrazolium precipitation in heterocysts paralleled acetylene reduction activity in the inhibitor treated cells.     

A COMPARISON OF THE ATTACHED ALGAL COMMUNITIES OF A NATURAL AND AN ARTIFICIAL SUBSTRATE1

A study of communities of attached algae in Lake Mize Florida, wax made during July 1969, July-August 1970 and April 1971. The substrates exposed during the study included glass slides mid the terrestrial form of the amphibious sedge, Eleocharis baldwinii (Torr.) Chapman. Counts were used to determine the relative abundance and densities of the species present on the 2 substrates under different environmental conditions. Such analyses indicated that at any given lime and place, a number of factors influenced the composition of the periphyton. Generally, lightly adhering, resupinate species attained higher densities on glass slides than filamentous and loosely associated metaphytonic species. The epiphytic flora of E. baldwinii contained a large number of both strong attachers and the metaphyton. The vertical range of many attached species was also greater on E. baldwinii than on glass slides.     

SEDIMENTATION STUDIES OF RED ALGAL SPORES1

More than 1000 spores from 11 species of red algae were collected; their differences in size and sinking rates were measured using a new micro-video technique. A relationship between size and sinking rate was shown with larger spores generally sinking faster than smaller ones. Variability in spore size, or lack thereof, is a species characteristic. Cryptopleura violacea (J. G. Ag.) Kylin and Neoagardhiella baileyi (Kutz.) Wynne and Taylor were found to produce a wide range of spore sizes. Such variability in size may be related to differences in spore formation. Centrifugation was used to separate the contents of spores to show differences in them. The ecological implications of these observations are considered.     

ESTABLISHMENT,PERSISTENCE AND DOMINANCE OF CORALLINA (RHODOPHYTA) IN ALGAL TURF1

The dominance of Corallina thalli in an intertidal algal assemblage was examined by a series of algal removal experiments to test the hypothesis that other tam are competitively excluded from rock substrate. An alternate explanation, that environmental factors seasonally filter out taxa leaving Corallina as the only alga adapted for year to year survival, was considered. Development of vegetation on patches of naturally exposed bare rock was monitored and compared with manipulated surfaces. Thalli of several species were selectively removed from exposed surfaces and intact turf;. changes in tam occupying primary substrate were recorded over more than three years. No significant differences in mean percent cover for Corallina, Lithothrix, bare rock, or algal crusts were found among treatments. Except for initial growth of colonizing species, abundances of other species dad not increase in the absence of Corallina. Large amounts of rock remained bare or intermittently covered by transient populations of short-lived algae. Data from single quad-rats, where individual clumps of Lithothrix were followed from month to month, indicated that the continued presence of this co-occurring and often abundant species depended on turnover of short-lived thalli rather than persistence of the same clumps. No interactions were found among the several categories of species that appeared after rock substrate was cleared. Most species were the same ones that grew, epiphytically in intact turf at the same time. In control quadrats Corallina maintained 59-95% cover while slowly increasing on surfaces earlier exposed. I predict that Corallina species will regain their dominance in the absence of competitors for primary substrate if the slowly spreading basal crusts remain undisturbed. Morphological and life history characteristics are identified that adapt Corallina to its dominant role in this habitat.     

柴达木盆地荒漠土壤蓝藻群落的初步研究

本文分析了柴达木盆地东部和中部具有代表性地区的丘陵、戈壁和沙丘的蓝藻种类组成、生物量及主要的土壤化学成分;采用了模糊聚类、系统聚类及多元线性回归等方法分析藻类的群落及其与环境因子的关系。共鉴定出21种蓝藻,其中6种为国内首次报道。研究表明:土壤含磷量、总盐量及与粘性和湿度有关的土壤结构是决定柴达木盆地蓝藻群落组成的重要因素。     

TOXIN EXTRACTION FROM THE BLUE-GREEN ALGA MICROCYSTIS AERUGINOSA BY DIFFERENT EXTRACTION MEDIA

SUMMARY

The extractability of toxin from Microcystis aeruginosa isolate UV-006 by different extraction media such as O, 1N HC1, 2N CH₃COOH, Triton X-100 and water at different pH levels was investigated. The best recovery of toxin was achieved with water at a pH of 10 while the recoveries with the more acidic media tended to be lower.     

A NUMERICAL TAXONOMIC STUDY OF NOSTOC AND ANABAENA1

Thirty characteristics of 14 Nostoc and 10 Anabaena species were analyzed from previously published data. Using standard numerical taxonomic methods, simple matching coefficients were calculated and a phenogram drawn. The analysis revealed that some of the central characteristics of Nostoc are: a punctiforme stage; motile reproductive stage; plant mass with a dull to shiny luster, non-veined surface, and nonfimbriate margin; some spherical vegetative cells; no cylindrical heterocysts; and some spherical, but no cylindrical akinetes. Some of the central characteristics of Anabaena that were revealed are: no punctiforme stage; a motile vegetative stage; plant mass with a shiny luster, veined surface, and fimbriate margin; no spherical vegetative cells; some cylindrical heterocysts; and some cylindrical, but no spherical, akinetes. In general, Anabaena has larger akinetes and vegetative cells than Nostoc. Based on 30 morphological characteristics and the clustering data of the phenogram, keys were constructed for the Nostoc and Anabaena species studied. The data clearly support two separate and distinct, though similar genera and, less sharply, the separation of the 24 species. The more useful characteristics for separation of the species are size and shape of akinetes, vegetative cells, and heterocysts; color and luster of plant mass; veined plant mass surface; margin fimbriate; and shape of plant mass in nature.     

THE ULTRASTRUCTURE OF MEIOSPORES OF COLEOCHAETE PULVINATA (CHAROPHYCEAE)1

In view of the relative importance of reproductive cell ultrastructure in phylogenetic and systematic studies of green algae, we investigated the fine structure of germinating zygotes and meiospores of Coleochaete pulvinata Braun. Meiospores have a flagellar apparatus very similar to that of zoospores and spermatozoids of the same species. Meiospores differ from zoospores and spermatozoids of C. pulvinata in having pyramidal body scales similar to those present on zoospores of C. scutata. Meiospores of C. pulvinata had as many as twice the number of spline microtubules as zoospores, and four times the number present in splines of spermatozoids of the same species. Developing meiospores of C.pulvinata, like those of other Coleochaete species, are individually surrounded by chamber walls. These differed from vegetative cell walls in lacking plasmodesmata. Moreover, the chamber walls in germinating zygotes of C.pulvinata stained a cobalt blue color with resorcinal blue, and fluoresced yellow in the presence of aniline blue, thus exhibiting the staining characteristics of callose. In location, morphology and presence of callose, chamberwalls resemble “special walls” of land plants, they may represent a charophycean spore development preadaptation useful in the evolution of walled spores characteristic of land     

STRONG PROBABILITY OF LETHAL TOXICITY IN THE BLUE-GREEN ALGA MICROCYSTIS VIRIDIS LEMMERMANN1

Lethal toxicity (intraperitoneal, mouse) was examined in relation to Species composition of samples containing bloom-forming Microcystis populations from natural waters and correlated with toxicity of laboratory strains of four Microcystis formas and species. Toxicity was not always associated with the presence of M. aeruginosa f . aeruginosa Elenkin. A sample with almost all cells of M. aeruginosa f . aeruginosa showed no toxicity, However samples comprised of a high percentage of M. viridis Lemmermann often showed lethal toxicity. Toxicity tests were done on culture strains M. aeruginosa f aeruginosa, M. aeruginosa f flos-aquae Elenkin , M. viridis and M. wesenbergii Kamárek. All five cultured strains of M. viridis were found to be toxic, while only one out of nine strains of M. aeruginosa f . aeruginosa was toxic. Six strains of M. wesenbergii showed no toxicity, It is recommended that attention should be paid to the occurrences and possibility of toxic bloom of M. viridis from the standpoint of water management and public health .     

EFFECTS OF HYDROXAMATE SIDEROPHORES (STRONG Fe (III) CHELATORS) ON THE GROWTH OF ALGAE1

Varying concentrations of Fe were tested with three hydroxamate siderophores to demonstrate the interactions affecting growth of Chlamydomonas reinhardtii and Chlorella vulgaris. Schizokinen was purified from the excretions of the blue-green alga Anabaena sp. grown in low-Fe medium. Chlamydomonas reinhardtii was inhibited by schizokinen when in molar excess of the Fe concentration; the inhibition was overcome with excess Fe. The growth of C. vulgaris was not affected by this chelator. Results with desferrioxamine were similar. A weaker chelator, rhodorulic acid, did not inhibit the growth of either alga. Low concentrations of the chelators may stimulate algal growth when Fe precipitates are hydrolyzed. Since different algae respond differently to the presence of the chelators, the observed interactions could be important in determining competitive relationships when Fe is limiting. If an alga can excrete a strong chelating agent, as does Anabaena, algae lacking the ability to compete with the chelator may not grow.     

Estimation of soil algal biomass in salinized irrigation land: a comparison of culture dilution and chlorophyll a extraction methods

Two representative methods for quantitative estimation of soil algae, the culture dilution method and chlorophyll a extraction, were compared using soil samples collected from irrigation land in the flood plain of the River Ili, Kazakhstan, where the distribution of soil algae had been studied in the previous year. The estimate by the culture dilution method was almost the same as in the previous year, except for one site, which was enclosed by shrubs of sakusaul, Haloxylon aphyllum (Minkw.) Iljin. The important role of wind in transport of airborne algal cells was pointed out. There was a significant correlation (p<0.001) between the logarithm of the number of colonies by the culture dilution method andthe logarithm of the concentration of chlorophyll a, when data from all samples were analyzed. However, no significant correlation was observed with the data of cropland sites alone. Furthermore, the seasonal variations of both values at each site did not necessarily agree with each other. One reason for the inconsistency may have been the over estimation of chlorophyll a caused by inclusion of litter from vascular plants. Other reasons may relate to differences between the methodologies. The density of soil algae estimated by culture dilution reflects the algal biomass in a certain previous period of time. Therefore, it is suggested that the method is suitable for spatial, but not for seasonal studies. This revised version was published online in August 2006 with corrections to the Cover Date.     

FACTORS REGULATING THE SPATIAL DISTRIBUTION OF THE FILAMENTOUS ALGA PITHOPHORA OEDOGONIA (CHLOROPHYCEAE) IN AN INDIANA LAKE1

Pithophora oedogonia (Mont.) Wittr. biomass in Surrey Lake, Indiana was greater in the littoral than in the pelagial region. Although mean soluble reactive phosphorus concentrations did not differ between the two areas, nitrate concentrations were almost six times higher in the cove than in the open water. Using laboratory cultures of Pithophora, the half saturation constant (K_s at 20° C relating filament growth to external concentrations of nitrate-nitrogen was determined to be 1.23 mg L^?1 (=88 μM)and for phosphate-phosphorus, 0.1 mg L^?1 (=3.22 μM). These values were used to calculate a NO₃-N/PO₄-P atomic ratio of 27.6. Comparison of this value with NO₃-N/PO₄-P ratios in Surrey Lake showed that nitrogen limiting conditions were prevalent in the open water section of the lake. Alkaline phosphatase and dark ammonia uptake analyses on field collected filaments from the shallow and deep water sections confirmed the hypothesis that nitrate is the major factor limiting growth of Pithophora in Surrey Lake.     

PHOTOSYNTHESIS OF THE RED ALGA GASTROCLONIUM COULTERI (RHODOPHYTA) IN RESPONSE TO CHANGES IN TEMPERATURE,LIGHT INTENSITY,AND DESICCATION1

Previously reported transplantation experiments in the field showed that Gastroclonium coulteri (Harvey) Kylin could survive above its normal intertidal range (0.0–0.5 m above MLLW), except during periods of daytime low tides in spring. Net photosynthetic rate measurements in the laboratory were performed to determine which physical factors might determine the upper boundary for this species in the intertidal zone. Maximum net photosynthesis occurred between 15 and 20° C, but remained positive between 4 and 35° C. The air temperature extremes observed in the field were 2° C (only seen once) and 26° C. Net photosynthesis increased as expected with light intensity to the highest value obtainable in the laboratory, 1400 μEin m^?2 s^?1. Plants collected from the field under higher light intensity (up to 2000 μEin m^?2 s^?2) also showed high rates of photosynthesis. Neither the temperature nor light levels observed in the field were directly damaging to photosynthesis. Desiccation, however, resulted in a sharp decrease in both photosynthesis and respiration. G. coulteri fully recovered from successive daily treatments of about 35% desiccation, but not from successive treatments of 50% desiccation. One exposure to 70% desiccation allowed no recovery of photosynthetic capacity.     

POLYSACCHARIDES FROM THE ENVELOPES OF HETEROCYSTS AND SPORES OF THE BLUE-GREEN ALGAE ANABAENA VARIABILIS AND CYLINDROSPERMUM LICHENIFORME1

The polysaccharides from the envelopes of heterocysts of Cylindrospermum licheniforme Kütz., and of heterocysts and spores of Anabaena variabilis Kütz., like those from the differentiated cells of Anabaena cylindrica Lemm., have a 1,3-linked backbone consisting of glucosyl and mannosyl residues in a molar ratio of approximately 3:1. As is the case with A. cylindrica the polysaccharides from A. variabilis and from the heterocysts of C. licheniforme have terminal xylosyl and galactosyl residues as side branches. In addition, the polysaccharide from C. licheniforme resembles that from A. cylindrica in having terminal mannosyl residues as side branches (absent from A. variabilis). The polysaccharides from A. variabilis resemble that from A. cylindrica in having glucose-containing side branches (absent from the heterocyst polysaccharide from C. licheniforme), but in contrast to the polysaccharides from the other two species they also have terminal arabinosyl residues as side branches. All of the polysaccharides mentioned appear to be structurally related; we present tentative structures for those not previously investigated. In contrast, the envelope of spores of C. licheniforme contains only a largely 4-linked galactan. The bulk of this envelope is not polysaccharide in nature, and contains aromatic groups.     

OPTICAL PROPERTIES OF DENSE ALGAL CULTURES OUTDOORS AND THEIR APPLICATION TO REMOTE ESTIMATION OF BIOMASS AND PIGMENT CONCENTRATION IN SPIRULINA PLATENSIS (CYANOBACTERIA)1

Reflectance and vertical attenuation coefficient spectra from 400 to 1100 nm were investigated in detail on dense algal cultures of Spirulina in order to create algorithms for remote estimation of pigment and biomass concentration. Reflectance and the vertical attenuation coefficients were compared with biomass and pigment concentration in outdoor algal cultures. For assessing biomass concentration, the sum of reflectance above the base line from 670 to 950 nm was used. This allows the estimation of biomass with an error of less than 0.06 g·L^?1 For chlorophyll a and phycocyanin estimation, vertical attenuation coefficients at the wavelengths 440 nm (or 676 nm) and 624 nm, respectively, were employed. The developed algorithms were tested by using independent data sets in the range of chlorophyll a from 0.2 to 20mg·L^?1 and biomass from 0.15 to 1.1 g·L^?1. An error of pigment estimation of less than 0.80 mg·L^?1 was achieved. The potential use of the algorithms in algal biotechnology is further discussed.     

ANNUAL PRODUCTIVITY AND EXTRACELLULAR RELEASE OF DISSOLVED ORGANIC COMPOUNDS BY THE EPIBENTHIC ALGAL COMMUNITY OF A BRACKISH MARSH1

Annual productivity and excretion of organic compounds by epibenthic algae in a coastal Texas marsh were investigated using ¹⁴C techniques. Over the course of two years, productivity and extracellular release were measured bimonthly to assess the environmental factors affecting seasonal patterns. Annual productivity was estimated to be 71 gc·m^?2, approximately 10% of the estimated net aerial productivity of the grass canopy in this area. The percentage of photoassimilated carbon released was fairly constant, and the rate of excretion appeared to be primarily dependent upon the rate of carbon fixation. Greater rates of release were observed with high salinity, low soil moisture conditions. It was estimated that up to 10% of the DOC in adjacent tidal creek water could be produced by this community and could represent an important source of nutrients for consumers in the system.     

THE MARINE AND TERRESTRIAL PRASIOLALES (CHLOROPHYTA) OF GALWAY CITY, IRELAND: A MORPHOLOGICAL AND ECOLOGICAL STUDY

Green algae belonging to the order Prasiolales have been reported frequently in terrestrial, freshwater, and marine habitats, generally in situations in which they are not submerged continuously and often in association with deposits of avian feces or other rich sources of nitrogenous compounds. Terrestrial habitats in Galway City on the west coast of Ireland have large populations of four such algae: Rosenvingiella polyrhiza (Rosenvinge) P. C. Silva, Prasiola calophylla (Carmichael ex Greville) Kützing, P. crispa (Lightfoot) Kützing, and P. stipitata Suhr ex Jessen, of which only the last is in any way fully associated with a tidal regime. The other species are found in an extraordinary range of nonmarine terrestrial habitats in the center of Galway, a city that still retains its narrow, medieval street plan. Width of the streets, proportion of residences, substratum type, and aspect are shown to be the main factors affecting the distribution of these algae, although a combination of consistent dampness and nitrogenous-compound availability from animal wastes is likely to be the primary determining factor. Morphological and phenological data are presented for each entity, and it is concluded from field observations that R. polyrhiza should continue to be recognized as a separate entity, even though a close relationship with Schizogonium murale Kützing is probable.     

ULTRASTRUCTURE OF THE ZOOSPORES AND VEGETATIVE CELLS OF TETRAEDRON AND CHLOROTETRAEDRON (CHLOROPHYCEAE)1

The flagellar apparatus of the zoospores of Tetraedron bitridens Beck-Mannagetta and Chlorotetraedron polymorphum MacEntee, Bold et Archibald includes directly opposed basal bodies, a distal fiber that is elaborated into a ribbed structure to which the continuous striated microtubule-associated component (SMAC) is connected, and partial caps over the proximal end of each basal body. The angle between basal bodies ranges from approximately 25° to 150°. Basal bodies at wider angles are interconnected via their cores. A septum is present in the B-tubule of one basal body triplet in C. polymorphum. Both organisms have four microtubular rootlets arranged in a cruciate pattern. The two X-membered rootlets in a single cell have dissimilar numbers of microtubules. In C. polymorphum there are 5 and 6 microtubules in a 4/1 and 5/1 arrangement. 3/1 and 4/1 rootlets are present in T. bitridens. Zoospores of T. bitridens have a fuzzy coat whereas those of C. polymorphum are naked. Pyrenoids in both species are covered by a continuous starch sheath. Vegetative, interphase cells of C. polymorphum have two centrioles connected by a fiber that are located in depressions in the nuclear envelope. We propose that these two genera may be closely related to Neochloris, and that the coenobial genera Hydrodictyon, Pediastrum and Sorastrum are derived from a Tetraedron-like alga.