Showing papers in "European Journal of Phycology in 1981"
TL;DR: Comparison of the diel variations of the wind intensity and the division rate (DR) of Peridinium cinctum forma westii (Lemm.) Lefevre in situ reveals that the intensity of theWind blowing throughout the whole day does not affect the DR.
Abstract: Comparison of the diel variations of the wind intensity and the division rate (DR) of Peridinium cinctum forma westii (Lemm.) Lefevre in situ reveals that the intensity of the wind blowing throughout the whole day does not affect the DR. On the other hand, a strong inhibitory effect is noticed when the wind episodes occur during the time period 18.00–02.00 h. Systematic hourly sampling and staining of Peridinium cells showed that nuclear division takes place between 23.00 and 02.00 h and is completed before cytokinesis begins. Thus the time period 18.00–02.00 h corresponds to the premitotic and mitotic phases of cell division, and the turbulence generated by the wind affects the process of nuclear division. The relationship between water turbulence and the DR of Peridinium which was observed in Lake Kinneret (Israel) has been checked under experimental conditions. Peridinium was grown without shaking, with continuous rotary shaking and with intermittent shaking at 100 r min-1. The specific growth rate (k)...
121 citations
86 citations
TL;DR: Estimation showed sublithic algal growths to be considerably more abundant than growths in adjacent exposed soil surfaces but less abundant than superficial algal Growths in favourable wet microenvironments.
Abstract: Sublithic (hypolithic) algae were found to be widely distributed under quartz stones at the Vestfold Hills, Antarctica. More than 17 taxa were recognized but four were dominant: Chroococcidiopsis sp. and Plectonema sp. (Cyanophyta), cf. Desmococcus sp. A and Prasiococcus calcarius (Boye Pet.) Vischer (Chlorophyta). Niche selection by the different algae resulted in Chroococcidiopsis and cf. Desmococcus sp. A favouring dry, raw mineral soils, Plectonema sp moist, raw mineral soils and P. calcarius seal and bird-influenced soils. Chlorophyll a estimations showed sublithic algal growths to be considerably more abundant than growths in adjacent exposed soil surfaces but less abundant than superficial algal growths in favourable wet microenvironments. In an area of typical dry mineral soil there was a mean area of 66 cm2 of sublithic algal growth m-2 of the site. Most stones with algal growths were less than 30 g in weight. Algae were found at a maximum depth of 61 mm below the soil surface and under a maximum...
71 citations
TL;DR: In gametophytes cultivated in continuous white fluorescent light eggs are also released from day 8–10, so in this case no inhibiting activity of light is apparent, and the inhibiting effects of light during the light cycle of 16 h per day is also apparent.
Abstract: Gametophytes of Laminaria saccharina cultivated from zoospores in a light-dark regime (16:8), release eggs exclusively during the dark cycles, 8–10 days after seeding of the zoospores, and mainly during the first 30 min of darkness. The inhibiting effects of light during the light cycle of 16 h per day is also apparent in gametophytes which have experienced only two dark cycles prior to day 8, when egg release begins. Egg release can be shifted to any time during the light cycle by prolonging the irradiation with white fluorescent light and by subsequent darkening for 1 h. In gametophytes cultivated in continuous white fluorescent light eggs are also released from day 8–10, so in this case no inhibiting activity of light is apparent. Egg release is inhibited by blue light and u.v., with peak wavelengths for inhibition at 372, 413, 438 and 481 nm. No inhibition occurs at wavelengths above 513 nm. The light requirement for inhibition is very low. A photon fluence rate of 1·4 μE m-2s-1, given for 45 min at 4...
68 citations
TL;DR: Five Ulva species were distinguished, and described for the Netherlands coast, namely U. pseudocurvata nov. spec.
Abstract: On the basis of 160 living samples from 26 different stations five Ulva species were distinguished, and described for the Netherlands coast, namely U. pseudocurvata nov. spec., U. curvata (Kutz.) De Toni, U. lactuca L., U. rigida C.Ag. and U. scandinavica Bliding. Unialgal cultures were isolated from these samples in order to test the validity of the taxonomic criteria and to test the growth response of germlings and young blades to varying salinities. The following criteria appeared to be taxonomically valid, though most of them are subject to wide variation: (1) macroscopic morphology (including colour and texture); (2) form and arrangement of the cells in surface view; (3) the structure of the basal region (form and size of rhizoidal cells; the presence or absence of small-celled marginal wings; the presence or absence of longitudinal rhizoidal ribs; and the presence or absence of a flat central cavity in the lower basal region and the stipe); (4) the number of pyrenoids in a vegetative cell; (5) the a...
67 citations
TL;DR: The extent of CO2-depletion, and pH rise, was greater in later cycles, indicative of some cellular adaptation, and the primary limitation of CO1uptake and growth was probably related to the concentra...
Abstract: Growth in relation to CO2-depletion and CO2-enrichment was investigated for the freshwater diatoms Asterionella formosa and Fragilaria crotonensis in batch cultures. Algal concentration and pH were measured during growth cycles, and inorganic carbon quantities determined by potentiometric Gran titrations and from pH-alkalinity relationships. After the primary growth with CO2-depletion and pH increase, successive CO2-enrichments induced further such cycles and produced a final three- to fivefold increase in algal biomass over that of unenriched controls. The extent of CO2-depletion, and pH rise, was greater in later cycles, indicative of some cellular adaptation. Values of pH reached 9·7 for Asterionella and 9·9 for Fragilaria. The lowest residual quantities of free CO2 were 0·1 and 0·03 μmol 1-1 for Asterionella and Fragilaria respectively, which were less than 0·05% of the corresponding residual quantities of total CO2. The primary limitation of CO2-uptake and growth was probably related to the concentra...
50 citations
TL;DR: Water chemistry, phytoplankton populations and periphyton populations on Potamogeton pectinatus, have been compared in a shallow, brackish lake and in two enclosed, 20 m diameter butyl rubber reservoirs, placed in it.
Abstract: Water chemistry, phytoplankton populations and periphyton populations on Potamogeton pectinatus, have been compared in a shallow, brackish lake, Hickling Broad, and in two enclosed, 20 m diameter butyl rubber reservoirs, placed in it. The seasonal changes of periphyton on Hippuris vulgaris and Myriophyllum spicatum in the lake have also been examined. The lake has been made more eutrophic by agricultural land drainage and roosting gull populations, the tubes to a greater extent by gulls perching on their rims. The water in the tubes became persistently dominated by colonial blue-green algae, a spring diatom pulse was absent, and severe nitrogen limitation was found. Periphyton on P. pectinatus in the tubes was scanty. In the lake, however, though phytoplankton chlorophyll a levels were lower, an alternation of spring diatom and summer colonial blue-green algae was recorded. Nitrogen limitation was less severe in the lake and abundant periphyton crops, mainly of diatoms, developed on P. pectinatus and to a...
49 citations
TL;DR: The absence of HCO3 - use is discussed in relation to the “bipolar band growth” of florideophytes, and to the relative availability of C, N and P and light in these haptophytic algae.
Abstract: Rates of photosynthesis at light saturation as a function of CO2 concentration and rates of dark respiration, are reported for the freshwater red algae Lemanea mamillosa and Batrachospermum sp., and are related to their ecological strategies. The CO2 compensation concentration in these two algae is pH-independent in the range pH 6·5–8·9, and is of a magnitude which suggests that these algae are unable to use HCO3 - in photosynthesis, and lack a “CO2 concentrating mechanism”. This is related to the relatively high CO2/HCO3 - ratio in the natural habitats of the algae, in contrast with the seawater in which most rhodophytes live and in which some red algae exhibit characteristics of HCO3 - use. The absence of HCO3 - use is also discussed in relation to the “bipolar band growth” of florideophytes, and to the relative availability of C, N and P and light in these haptophytic algae.
47 citations
TL;DR: It proved to be difficult to find optima for the different parameters tested because of their integrated effects within the plant cell; for instance the temperature optimum was higher at high light intensity than at lower intensities.
Abstract: The growth rate of several Dunaliella strains was measured as a function of several environmental parameters. The strains tested fell into two groups, the halotolerant capable of growing at 0·5 m NaCl and above, and the halophilic which cannot grow in media containing less than 2 m NaCl. It proved to be difficult to find optima for the different parameters tested because of their integrated effects within the plant cell; for instance the temperature optimum was higher at high light intensity than at lower intensities. Similarly, higher concentrations of NaCl were tolerated when the light intensity was high and carbon plentiful.
40 citations
TL;DR: Heating at 80°C for 15 min, followed by 30 s vortex-mixing, was found to completely reduce the colonies to a suspension of single cells, and the heating method was preferred for reasons of simplicity and the absence of associated cell losses.
Abstract: Three published methods for the reduction of colonies of Microcystis aeruginosa Kutz. emend. Elenkin to single cells were investigated using a laboratory culture. Alkaline hydrolysis in 0·01, 0·1 or 1·0 m KOH was ineffective at room temperature; hydrolysis at 80°C using 0·01 m KOH reduced the colonies to single cells, but the use of higher KOH molarities resulted in cell loss. Sonication (20 kHz, c. 50 W) did not always completely reduce the colonies to single cells and it was found that cell losses occurred on some occasions. Heating at 80°C for 15 min, followed by 30 s vortex-mixing, was found to completely reduce the colonies to a suspension of single cells. Published results and experimental evidence suggest that the ability of each method to reduce colonies of M. aeruginosa to single cells without cell loss appears to depend on the particular strain used. The heating method was preferred for reasons of simplicity and the absence of associated cell losses; the technique was characterized with respect ...
40 citations
TL;DR: The growth and buoyancy of the planktonic blue-green alga Anabaena flos-aquae Breb.
Abstract: The growth and buoyancy of the planktonic blue-green alga Anabaena flos-aquae Breb. was studied under different nutrient conditions in small batch cultures and in a thermally stratified water column. When conditions permitted the development of high algal concentrations, the diffusion of CO2 into the culture limited the photosynthetically driven buoyancy-regulating response and the filaments became buoyant. Under similar conditions in the water column CO2 again became limiting and the alga floated up to form a waterbloom at the surface, even though the incident light intensity there was 10 klx (200 μE s-1 m-2). When growth of the alga in culture was limited by reducing the concentration of K2HPO4 the alga sank, even when the light intensity was only 1·7 klx. The alga no longer formed a surface water bloom in the column when the K2HPO4 concentration was reduced to 10 μm, but instead it stratified at a depth of about 1 m, where the light intensity was about 1·2 klx. The behaviour of the alga in the column i...
TL;DR: Subaerial epilithic algae were encountered for the first time at locations in Princess Elizabeth Land and Mac.Robertson Land, Antarctica where late-lying snow drifts persisted during summer and in areas which were not affected by salt spray.
Abstract: Subaerial epilithic algae were encountered for the first time at locations in Princess Elizabeth Land and Mac.Robertson Land, Antarctica. The flora was predominantly of cyanophytes, particularly from the genera Chroococcidiopsis, Gloeocapsa, Myxosarcina and Calothrix with frequently associated oscillatoriacean algae. The black to dark-brown epilithic growths developed where thin films of water percolated over rock surfaces for a sufficiently prolonged period during summer. They were only found where late-lying snow drifts persisted during summer and in areas which were not affected by salt spray. The majority of these growths were on lee-slopes protected from the prevailing winds.
TL;DR: Rings of dense tissue found in the base of the stipe of a long stiped variety of the perennial laminarian Ecklonia radiata in New Zealand result from a cycle of slow and rapid growth with periodic haptera production, and can be used to estimate the age of the plant.
Abstract: Rings of dense tissue found in the base of the stipe of a long stiped variety of the perennial laminarian Ecklonia radiata in New Zealand result from a cycle of slow and rapid growth with periodic haptera production. These rings can be used to estimate the age of the plant. The diameter of the rings and their relationship to the medulla are affected by depth and wave exposure. The environment from which the plant was taken must therefore be known before the rings can be correctly interpreted. The number of layers of haptera gives a less precise indication of age, but haptera rot away in old plants. Ecklonia can live for at least 10 years.
TL;DR: Algal remains recovered from sediment traps in Rostherne Mere, Cheshire, broadly reflected the phytoplankton periodicity and suggested that the turbulent resuspension of sedimented material occurs infrequently.
Abstract: Algal remains recovered from sediment traps in Rostherne Mere, Cheshire, broadly reflected the phytoplankton periodicity and suggested that the turbulent resuspension of sedimented material occurs infrequently. Quantitative comparisons between the standing crops and the algal fluxes intercepted by sediment traps indicated that the cylindrical traps yielded accurate estimates when operated in weakly turbulent waters but apparently exaggerated the fluxes when operated in turbulent conditions.
TL;DR: Ten taxa of nanoplanktonic coccolithophorids are reported from West Greenland on the basis of material collected in the vicinity of Godhavn (Disko Island) in July and August 1977, with considerable variation within the area investigated with regard to the number of species present in each sample.
Abstract: Eleven taxa of nanoplanktonic coccolithophorids are reported from West Greenland on the basis of material collected in the vicinity of Godhavn (Disko Island) in July and August 1977. Pappomonas flabellifera var. flabellifera is a new record for the northern hemisphere. Five of the species are new recordings for the Disko Bay area (Papposphaera sagittifera, Balaniger balticus, Calciarcus alaskensis, Wigwamma annulifera, and Turrisphaera arctica). A new species, Papposphaera sarion sp.nov., is described on the basis of transmission electron microscopy. It is distinguished from the two other Papposphaera species by a different type of appendage head. A summary of all the coccolithophorid data from 1977 show considerable variation within the area investigated with regard to the number of species present in each sample, as well as regarding the local distribution of certain species. The biogeography of the species recorded from West Greenland is considered. The inclusion of several records from nanoplankton in...
TL;DR: Experimental evidence indicates the presence of a hormonal factor secreted by the eggs, which is responsible for discharge and subsequent attraction of spermatozoids to the egg, as well as the strong resemblance with the respective processes in Laminaria.
Abstract: Male and female gametophytes of Desmarestia aculeata have been grown as clonal cultures. Red light permits vegetative growth only. Differentiation of oogonia and antheridia takes place under illumination with blue light as has been previously reported for several species of Laminaria. Morphological details for differentiation of oogonia and antheridia are presented, stressing the strong resemblance with the respective processes in Laminaria. Experimental evidence indicates the presence of a hormonal factor secreted by the eggs, which is responsible for discharge and subsequent attraction of spermatozoids to the egg.
TL;DR: It is suggested that the understanding of environmental factors which influence or control species distribution and abundance should be improved if the occurrence of living taxa only is considered.
Abstract: An analysis of diatoms in estuarine sediment samples has revealed that: (1) the percentage of dead diatoms can be large, (2) ratios of living to dead diatoms vary between sediment habitats, and (3) measurements of “live” species richness and diversity are lower than measurements which include live and dead members of the assemblage. Also, the reliability of the dioxane and dioxane-xylene preparation methods for observing the live component of sediment diatom communities has been demonstrated. We suggest that the understanding of environmental factors which influence or control species distribution and abundance should be improved if the occurrence of living taxa only is considered.
TL;DR: Three new generic names are proposed for marine dinoflagellates because the organisms cannot remain in the original genera because they are not naked but have a tough theca or periplast.
Abstract: Three new generic names are proposed for marine dinoflagellates. Herdmania gen. nov. is suggested for some organisms currently placed in Gymnodinium, and Sclerodinium gen. nov. for Gyrodinium calyptroglyphe and an entirely new species, S. striatum. In all cases the organisms cannot remain in the original genera because they are not naked but have a tough theca or periplast. Triadinium gen. nov. is proposed to replace Goniodoma Stein and Heteraulacus Diesing, both of which are invalid names. New combinations are put forward for several other species of Triadinium.
TL;DR: The excystment and development of cells of Ceratium hirundinella (O. F. Mull.) Bergh has been studied in the laboratory using transmission and scanning electron microscopy and the occurrence of an exit slit through which excyStment takes place has been confirmed.
Abstract: The excystment and development of cells of Ceratium hirundinella (O. F. Mull.) Bergh. has been studied in the laboratory using transmission and scanning electron microscopy. The occurrence of an exit slit through which excystment takes place has been confirmed. The emergent cell, or gymnoceratium, is shown to lack thecal plates but has thecal vesicles with extensive microtubules lying beneath. Thecal plates rapidly form within the vesicles except in the ventral region adjacent to the chamber. The flagellar apparatus is present at the gymnoceratium stage prior to excystment, but the more extensive chamber develops with cell growth. Starch and lipid reserves are present in the gymnoceratium and throughout the cell's development, and they have distinct locations within the cell. The occurrence of a pusule has been confirmed. This opens near the base of the longitudinal flagellum. The ultrastructure of the orange pigmented bodies, observed with the light microscope, is described and these are compared with th...
TL;DR: The benthic centric diatom Melosira nummuloides dominated sites of heavy pollution on the Clyde Estuary, occurring in conditions conducive to heterotrophic growth—positive correlation with BOD and suspended solids and negative correlation against light penetration of the water.
Abstract: The benthic centric diatom Melosira nummuloides dominated sites of heavy pollution on the Clyde Estuary, occurring in conditions conducive to heterotrophic growth—positive correlation with BOD and suspended solids and negative correlation against light penetration of the water. A clone (Renf-1) of the organism, isolated from a polluted site and rendered axenic grew in culture through a range of light intensities, with compensating light below 150 lx. Some initial growth occurred in the dark on medium enriched with site water. Growth was best at a salinity of 10‰. for samples adapted to 4, 10 and 12‰.. Addition of certain amino acids to the medium caused significant enhancement of growth, due to leucine, arginine and serine at 0 klx, leucine, arginine and glutamic acid at 0·1 klx and glutamic acid at 3·3 klx. Eight amino acids were accumulated by carrier mediated methods in the dark. Kinetics for arginine uptake were best (low K m) in the dark and at a salinity of 10‰, with a corresponding greater growth e...
TL;DR: It is shown that Pyrocystis margalefii from the Mediterranean Sea is probably identical with the resting stages of D. pseudolunula, and possible affinity to the fossil Palaeocystodinium golzowense is discussed.
Abstract: Previously unknown dinoflagellate resting spores found in the North Sea were germinated in culture. The emerging dinospores proved to be identical with those of an ectoparasite, Dissodinium pseudolunula. Hence, the resting spores are interpreted as an integral stage in the life cycle of this species. It is shown that Pyrocystis margalefii from the Mediterranean Sea is probably identical with the resting stages of D. pseudolunula. Possible affinity to the fossil Palaeocystodinium golzowense is discussed.
TL;DR: The behaviour of contractile vacuole complexes of representatives of the Cryptophycean genera Chilomonas, Cryptomona, Cyathomonas and Rhodomonas is described using light and electron microscopy and two types of vesicles have been identified in the spongiome.
Abstract: The behaviour of contractile vacuole complexes of representatives of the Cryptophycean genera Chilomonas, Cryptomonas, Cyathomonas and Rhodomonas is described using light and electron microscopy. The contractile vacuole occupies a fixed position in the cell, lying adjacent to the flagellar pocket/groove. A small region of the flagellar pocket is invaginated so that the plasma membrane lies close to the membrane of the contractile vacuole. This region acts as the pore through which the contents of the contractile vacuole are discharged. Discharge follows the fusion of the contractile vacuole membrane with the plasma membrane of the pore. Filling initially involves the fusion of small vacuoles which appear around the contractile vacuole shortly before the discharge of its contents. After these vacuoles have fused, filling may continue by the accretion of small vesicles which form the spongiome surrounding the contractile vacuole. Two types of vesicles have been identified in the spongiome. One type is invol...
TL;DR: A new species, Actinocyclus exiguus, a small centric diatom, is described from the southern Indian and Atlantic Oceans and the pseudonodulus is not seen in the light microscope and is more easily seen on the inside of eroded valves with the aid of the scanning electron microscope.
Abstract: A new species, Actinocyclus exiguus, a small centric diatom, is described from the southern Indian and Atlantic Oceans. The pseudonodulus, a diagnostic feature of the genus and family, has not been seen in the light microscope and is more easily seen on the inside of eroded valves with the aid of the scanning electron microscope. A. exiguus is compared to closely related species.
TL;DR: It is shown that filamentous blue-green algae of average size tend to have isodiametric cells, while the very narrow ones often have cylindrical cells and the very large forms have only discoid cells.
Abstract: Observations on infralittoral blue-green algae and a literature survey show that filamentous blue-green algae of average size tend to have isodiametric cells, while the very narrow ones often have cylindrical cells and the very large forms have only discoid cells. A possible interpretation of this phenomenon is presented, based on the short life of prokaryotic messenger RNAs.
TL;DR: The fate of eyespot lipid globules after zoospore settlement in the green alga Pleurastrum terrestre Fritsch et John was investigated in detail and it is suggested that by incorporation into the pyrenoid the eyespot globules add to the lipid store of the growing vegetative cell.
Abstract: The fate of eyespot lipid globules after zoospore settlement in the green alga Pleurastrum terrestre Fritsch et John was investigated in detail. After retraction of flagella the close association between the outer chloroplast envelope membrane and the plasmalemma in the eyespot region is lost. The intact eyespot plate (with approximately 60 eyespot globules) then starts to change position inside the chloroplast. While staying in a peripheral position below the chloroplast envelope membranes, the eyespot plate moves around half of the chloroplast to the cell interior, where it comes to lie close to a mitochondrion. Later the eyespot plate curves around into the chloroplast interior and single eyespot globules enter the pyrenoid matrix of the chloroplast to join the pyrenoglobules, which characterize the pyrenoid of this alga. It is suggested that by incorporation into the pyrenoid the eyespot globules add to the lipid store of the growing vegetative cell. During zoosporogenesis pyrenoglobules may be drawn ...
TL;DR: The polymorphous trichome apices of Oscillatoria redekei are described and Transmission electron microscopy shows that the fine structure of cell walls resembles that of Pseudanabaena galeata.
Abstract: The polymorphous trichome apices of Oscillatoria redekei are described with respect to their shape and size. Breakage of trichomes may occur either trans- or intercellularly. The development and localization of intercellular trichome breakage were observed. Transmission electron microscopy shows that the fine structure of cell walls resembles that of Pseudanabaena galeata. Longitudinal walls consist of three or four layers and lack a sheath, while the cross walls are composed of three layers with a dominating L2-layer. In contrast to P. galeata, the centroplasm and most of the thylakoidal region of adjacent cells of O. redekei are connected by the cross walls forming obtuse angles at the site of the longitudinal walls. The main characteristics of O. redekei and of Pseudanabaena species are discussed.
TL;DR: Strains of several forms of Micrasterias thomasiana, isolated in Tasmania and Victoria, conjugated when mixed in all combinations, but homothallism was not detected and rarely were both mating strains present in one locality.
Abstract: Strains of several forms of Micrasterias thomasiana, isolated in Tasmania and Victoria, conjugated when mixed in all combinations. Homothallism was not detected and rarely were both mating strains present in one locality. Conjugation, preceded by an initial pairing and subsequent cell division, takes place between offspring of this division, either within or between parental groups. Conjugants, invested by a mucilage envelope, secrete a pinkish mucilage medially, in which a conjugation cylinder differentiates. Its relationship to conjugation structures in other species is discussed. Conjugation is anisogamous. The spiny zygospore has at least three walls and an undifferentiated operculum of the exospore facilitates germination. Only one gone is produced. Meiosis occurs at or immediately preceding germination. Most chromosomes are too small to reveal details of centromeric organization but two longer chromosomes are apparently sub-telocentric. Meiosis is at least partially asynchronous. A presumably haploi...
TL;DR: Ten sexually reproducing strains of Callithamnion have been used in a comparison of phycoerythrin, interfertility and morphology and all cultures showed very similar mobilities in SDS gels.
Abstract: Ten sexually reproducing strains of Callithamnion have been used in a comparison of phycoerythrin, interfertility and morphology. Four isolates of C. byssoides Harvey from North America (Massachusetts, New York, North Carolina and Georgia) are all interfertile and they also hybridize with C. halliae Collins (UTEX LB1411) from Texas. Norwegian C. byssoides and C. roseum (Roth) Lyngbye (sensu Harvey) isolates are not interfertile with any North American strain. Phycoerythrins were compared by absorption spectroscopy, SDS gel electrophoresis and Ouchterlony double diffusion techniques. The absorption spectrum of phycoerythrin from the Massachusetts C. roseum is different from that of the R-phycoerythrin typical of all other strains. The subunits of phycoerythrin from all cultures showed very similar mobilities in SDS gels. Phycoerythrin from all C. byssoides and C. halliae reacted identically in Ouchterlony plates. Antigenic identity with C. byssoides was also seen with one strain (an unidentified species fr...
TL;DR: Distinctive granular inclusions have been observed in the cells of the filamentous desmids Bambusina and Gonatozygon which do not appear to have been previously recorded.
Abstract: Distinctive granular inclusions have been observed in the cells of the filamentous desmids Bambusina and Gonatozygon which do not appear to have been previously recorded. X-ray analysis of those of B. brebissonii and G. brebissonii indicates that they are of calcium sulphate. Those of G. kinahani, like the crystalline inclusions of so many other desmid genera, would appear to be of barium sulphate.
TL;DR: Testing the hypothesis that surface electrical charge influences buoyancy in Asterionella formosa colonies found that appreciable differences in sinking rate were related to the physiological condition of the algae but were not accompanied by significant changes in electrophoretic mobility.
Abstract: Sinking rate and electrophoretic mobility were measured on individual colonies of Asterionella formosa, in order to test the hypothesis that surface electrical charge influences buoyancy. Although appreciable differences in sinking rate were related to the physiological condition of the algae, they were not accompanied by significant changes in electrophoretic mobility.