Schizothrix Calcicola Research Articles

Changes in subtidal assemblages in a scenario of warming: Proliferations of ephemeral benthic algae in the Canary Islands (eastern Atlantic Ocean)

The present work analysed the main changes in subtidal algal assemblages in the last decade in an oceanic archipelago (Canary Islands – eastern Atlantic Ocean). Changes result from increases in cover of ephemeral benthic algae, such as the non-native chlorophyte Pseudotetraspora marina and the native cyanophytes Blennothrix lyngbyacea, Schizothrix calcicola and Schizothrix mexicana. Ephemeral algae overgrow subtidal assemblages which are extensively dominated by Lobophora variegata, but competitively do not exclude other species. Increases in the abundance of species coincided with a warming of about 2 °C in surface seawater temperature (SST) linked to the weakening of the Cold Canary Current and the Northwestern African upwelling. Shifts in the distribution and cover of ephemeral species follow the SST gradient from warmer waters in the western islands to colder waters in the eastern ones. While in the warmest western islands, species have spread quickly colonizing all type of substrates in just a few years (2005–2008), the occurrence of ephemerals towards the coldest eastern islands is yet inconspicuous.

Trends and explanatory variables for the major phytoplankton groups of two southwestern Florida estuaries, U.S.A.

Multi-year phytoplankton abundance data from two estuaries in southwest Florida were combined into taxonomic groups, assessed for trend, and compared with water quality data using multivariate techniques. Interannual flow variations were linked to climatic indices and were relatively large. Trends in water quality included declining biomass, N and P signals in Tampa Bay, and declining P and a complex but slightly increasing N in Charlotte Harbor. Trends were superimposed on flow-dominated seasonal and annual variations in nutrient loads. Trends in phytoplankton abundance were both gradual and abrupt, were not always monotonic, and were most noted for cyanobacteria. One species of cyanobacteria, Schizothrix calcicola sensu Drouet could be considered an indicator species. At specific stations, nutrient concentrations and seasonal parameters were significant explanatory variables for variations in community structure. Clustering of community structure by taxonomic groups did not align well with known trends in nutrient loadings or biomass.

Benthic Algae Taxa (Exclusive of Diatoms) of the Little River Basin, Western Kentucky, 2000–2003

ABSTRACT The Little River is a highly disturbed system, heavily impacted by non-point source pollution from agricultural runoff in the form of excessive siltation, nitrogen and phosphorus, and organic pollution. Sixty-seven taxa of non-diatom benthic algae were documented for 16 sites in the Little River basin of western Kentucky during four sampling periods in 2000 and 2003. Algal taxa most often encountered included members of the Cyanophyta: Oscillatoria lutea (15 of 16 sites), O. subbrevis (13 of 16 sites), and Schizothrix calcicola (15 of 16 sites). Chlorophyta taxa most often encountered included Oedogonium sp. and Rhizoclonium hieroglyphicum, both at 10 of 16 sites. No trends were found between the algal taxa and areas of nutrient enrichment in the Little River basin. Because little is known of the benthic algal flora in the Little River, this report represents information complementary to that published previously on the benthic diatom taxa found at the same sites during the same study period.

Development of immobilized cyanobacterial amendments for reclamation of microbiotic soil crusts

Cyanobacteria were immobilized on hemp cloth, which was subsequently cut into fine pieces for use as a soil amendment. The amendment is intended for speeding recovery of microbiotic soil crusts in semi-arid and arid lands where such crusts have been destroyed by anthropogenic activities. Microcoleus vaginatus, Schizothrix calcicola, and Nostoc were used to create amendments, but most of the experiments in this study utilized the Microcoleus amendment, as it is the most cosmopolitan and ecologically important cyanobacterial taxon in desert soil crusts. The amendment was found to retain its viability in storage for at least 18 months. M. vaginatus grew best in CT and Z8+ (plus vitamins) media with aeration and addition of KHCO 3 . A field test of Fort Irwin National Training Center, Mojave Desert, California, showed significant increases in phototrophic biomass 6 and 12 months after inoculation, but the stimulans was not evident at 18 months. Four other field tests did not show significant gains. We suspect the failure of the field tests is due to a loss of cyanobacterial viability after inoculation but before favorable growth conditions. Cyanobacteria were possibly killed by UV irradiation or photo-oxidation in the hot desert environment M. vaginatus is known to live below the surface in desert soils, and so likely is sensitive to full sunlight. Laboratory experiments in full sunlight verified this hypothesis.

Nutrients, phytoplankton and harmful algal blooms in shrimp ponds: a review with special reference to the situation in the Gulf of California

The present work is a first attempt to document the latest reports on the occurrence of algal blooms in shrimp farm ponds worldwide. Particular emphasis is placed on discussing the relation of algal blooms with nutrients, with special reference to the northwest of Mexico. Typically, shrimp pond waters are enriched with organic matter and nutrients whose concentrations depend mostly on the management (i.e. higher stocking densities, water use, food and fertilizers). Generally, more intensive culture systems produce higher loads of nutrients in their discharge (e.g. N and P). Nitrogen and P concentrations vary in pond waters; N/P ratio ranges from 1.1 to 67 with values being more frequently between 1.1 and 6.8. Such variations are closely related with the cycling and supply of nutrients in the ponds. In shrimp farms located in NW Mexico, phytoplankton abundance varies widely, having a higher abundance in advanced stages of the culture cycle. In the most common pond types (intensive and semi-intensive), Synechocystis diplococcus (cyanobacteria) was the dominant species (>88.9%), followed by Peridinium trochoideum ( Scrippsiella trochoidea) and eventually Prorocentrum minimum and Gymnodinium spp. (dinoflagellates). The numerous occurrences of large blooms of dinoflagellates and other functional groups such as cyanobacteria, diatoms, chlorophytes and flagellates mean economic losses for farm industry on account of shrimp mortality or growth diminution due to poisoning, anoxic or mucus production effects, in which shrimp were mortality provoked in different regions: in China, the dinoflagellates Alexandrium tamarense ( Gonyaulax tamarensis) and Gymnodinium; in Malaysia, the raphidophyte Hornellia ( Chattonella) and the dinoflagellate Pyrodinium bahamense var. compressum; in Vietnam, the diatom Nitzchia navis- varingica; in Ecuador, the dinoflagellate Gyrodinium instriatum; and in NW Mexico the cyanobacteria S. diplococcus, Schizothrix calcicola, and the dinoflagellates P. minimum, and lastly Gymnodinium catenatum from supply waters.

Kinetics and uptake mechanisms for monomethylmercury between freshwater algae and water.

Uptake kinetics of monomethylmercury chloride (MeHgCl) were measured for two species of green algae (Selenastrum capricomutum and Cosmarium botrytis), one blue-green algae (Schizothrix calcicola), and one diatom (Thalassiosira weissflogii), algal species that are commonly found in natural surface waters. Species differences were found with the two green algae giving the highest uptake rates, and one of them (Cosmarium) showing differences between cultures having widely different cell age (exponential versus stationary), where increases in uptake rate for cells 30 days old were about 25 times greater than cells only 3 days old when weights of cells were considered. Both Schizothrix and Thalassiosira exhibited nearly the same lower uptake rates, approximately 20 times lower than the two green algal species. Experiments with photosystem inhibitors, uncouplers, gamma-radiation, light deprivation, and extended range uptake all point to an active transport mechanism for MeHgCl.

THE CYANOBACTERIAL FLORA OF MICROBIOTIC CRUSTS OF NATURAL BRIDGES NATIONAL MONUMENT, UTAH

Nagy, M. L. & Johansen, J. R.Department of Biology, John Carroll University, University Heights, OH 44118 USAWe examined the cyanobacterial flora of microbiotic crusts in two sites of Natural Bridges national Monument. Composite soil samples were subsampled, dilution plated on Z8 media, and incubated 3‐5 weeks. Cyanobacteria were characterized directly from plates, and isolations were made of all morphologically distinct strains. The cyanobacterial flora of soils of this site differed markedly from cyanobacterial floras observed elsewhere in the soils of the Colorado Plateau. Oscillatoriales were well represented, with Leptolyngbya (4 spp.), Microcoleus (3 spp.), Schizothrix calcicola, Phormidium rubroterricola, and Oscillatoria coerulescens all present. Coccoid cyanobacteria were notably absent, and heterocystous species were limited in number (only Scytonema javanicum and Calothrix elenkinii) and very rare. Nostoc species were unusually rare, and seen only in moistened soil samples. Tolypothrix was also seen in the moistened soils. Two especially interesting strains are likely new taxa. A Schizothrix morphospecies was recovered with distinctively constricted cells and a yellow‐brown calyptra that fits no description of Schizothrix or Leptolyngbya. An especially large form of Microcoleus vaginatus was found with a trichome width of 5‐9.6 m. Sequence of the 16S rRNA provides some evidence that both of these morphospecies may be distinct from other members in their genera.

EFFECTS OF INCREASING UV‐B RADIATION DUE TO OZONE DEPLETION ON PHOTOSYNTHESIS OF ANTARCTIC CYANOBACTERIA

Ground level ultraviolet‐B (UV‐B; 290–320 nm) fluxes in Antarctica have been increasing due to stratospheric ozone depletion. Although mat‐forming cyanobacteria are major component of freshwater algal biomass in Antarctica, little is known about their response to increasing ultraviolet radiation (UVR). The present study evaluated the sensitivity to UVR of two strains of mat‐forming cyanobacteria with different cell size, Phormidium murrayi (6.0 x 3.2 μm) and Schizothrix calcicola (2.2 x 2.3 μm). Cyanobacterial photosynthesis was measured under different UV spectral quality and quantity achieved by polychromatic filters with different cutoff wavelengths and neutral density screens. The productivity and irradiance data were used to generate biological weighting functions (BWF) for the assessment of UV inhibition on photosynthesis. The kinetics of UV inhibition, as determined by PAM fluorometry, differed between the two species so that inhibition of P. murrayi and S. calcicola were modeled based on UV‐irradiance and cumulative exposure, respectively. After a one hour exposure, BWF's did not differ between the two isolates of cyanobacteria despite their differences in cell size. To evaluate the negative impact of increased UV‐B exposure due to ozone depletion on cyanobacteria, the BWF's were applied to two solar spectra obtained from McMurdo Station, one on a day when the ozone hole was prominent (O3 = 170 Dobson units; DU = 10‐3 cm O3), and the other on a day with high ozone concentration (O3 = 328 DU). The decrease in ozone level would reduce productivity by 3–8%. Seasonal variation of UVR has a bigger impact on cyanobacterial productivity than ozone depletion.

ECOLOGICAL STUDIES ON THE SOIL ALGAE OF WADI ALLAQI BIOSPHERE RESERVE AREA IN SOUTH EASTERN DESERT, EGYPT.

First comprehensive data on the floristic composition of the soil algae in relation to edaphic factors in Wadi Allaqi Biosphere Reserve were recorded during 1996-7. Twenty-four species of soil algae belonging to 15 genera and three divisions viz., Cyanophyta (15 species), Chlorophyta (six species) and Bacillariophyta (three species) were isolated and identified. Among them, 13 species; Lyngbya allorgei , Oscillatoria pseudogeminata, Phormidium foveolarum, Phormidium subfuscum, Schizothrix calcicola (Cyanophyta); Bracteacoccus cohaerens, Gloeococcus minutissimus, Keratococcus bicaudatus,Muriella terrstris , Pseudococcomyxa simplex (Chlorophyta); Navicula cincta and Navicula rhyncocephala (Bacillariophyta) were recorded for the first time in the soils of Upper Egypt. Some physico-chemical characteristics of the soil correlated significantly with the number of species and total counts of soil algae. However, no significant correlation were noticed between the soil algae and soil texture.

Effects of daylength and temperature on the growth and photosynthesis of an Arctic cyanobacterium, Schizothrix calcicola (Oscillatoriaceae)

Cyanobacteria are often the dominant phototrophs in high-latitude lakes and streams where they must experience continuously low temperature and extreme variations in daylength. The present study examined the interaction between these two variables for the growth and physiology of an Arctic isolate of the mat-forming species Schizothrix calcicola (Agardh) Gomont. Growth rates (μ), photosynthesis (P), respiration (R), pigment composition and in vivo absorption characteristics were measured under 15 combinations of daylengths (8:16, 12:12, 16:8, 20:4 and 24:0 L/D) and temperatures (5, 15 and 25 °C). μ increased with increasing temperature (μmax at 5 °C = 0.12 d−1, μmax at 25 °C = 0.28 d−1) and a similar trend was observed in photosynthetic capacity (average P B max at 5 °C = 4.42 mg C (mg Chl a)−1 h−1, average P B max at 25 °C = 5.74 mg C (mg Chl a)−1 h−1), pigment content and absorbance. Daylength had a positive effect on μ and pigment absorption, but not pigment content. The shape of the μ–daylength curve varied with temperature: μ was a linear function of daylength at 5 °C, but at 15 and 25 °C the relationship resembled a rectangular hyperbola and μ saturated at 16:8 and 12:12 L/D, respectively. The non-linear relationship between μ and daylength at high temperature was related to a reduction in net photosynthesis under extended daylength; at 25 °C, net P under 24:0 L/D was 0.82 ± 0.37 mg O2 (mg Chl a)−1 h−1, while under 8:16 L/D, it was 6.54 ± 0.69 mg O2 (mg Chl a)−1 h−1. The constant increase in growth with increasing daylength at low temperature may reflect an adaptive tolerance to the combination of cold temperature and continuous daylight during the Arctic summer.

Effects of daylength and temperature on the growth and photosynthesis of an Arctic cyanobacterium, Schizothrix calcicola (Oscillatoriaceae)

Cyanobacteria are often the dominant phototrophs in high-latitude lakes and streams where they must experience continuously low temperature and extreme variations in daylength. The present study examined the interaction between these two variables for the growth and physiology of an Arctic isolate of the mat-forming species Schizothrix calcicola (Agardh) Gomont. Growth rates (μ), photosynthesis (P), respiration (R), pigment composition and in vivo absorption characteristics were measured under 15 combinations of daylengths (8:16, 12:12, 16:8, 20:4 and 24:0 L/D) and temperatures (5, 15 and 25 °C). μ increased with increasing temperature (μmax at 5 °C = 0.12 d−1, μmax at 25 °C = 0.28 d−1) and a similar trend was observed in photosynthetic capacity (average P B max at 5 °C = 4.42 mg C (mg Chl a)−1 h−1, average P B max at 25 °C = 5.74 mg C (mg Chl a)−1 h−1), pigment content and absorbance. Daylength had a positive effect on μ and pigment absorption, but not pigment content. The shape of the μ–daylength curve varied with temperature: μ was a linear function of daylength at 5 °C, but at 15 and 25 °C the relationship resembled a rectangular hyperbola and μ saturated at 16:8 and 12:12 L/D, respectively. The non-linear relationship between μ and daylength at high temperature was related to a reduction in net photosynthesis under extended daylength; at 25 °C, net P under 24:0 L/D was 0.82 ± 0.37 mg O2 (mg Chl a)−1 h−1, while under 8:16 L/D, it was 6.54 ± 0.69 mg O2 (mg Chl a)−1 h−1. The constant increase in growth with increasing daylength at low temperature may reflect an adaptive tolerance to the combination of cold temperature and continuous daylight during the Arctic summer.

COLONIZATION OF PERIPHYTIC ALGAE ON ARTIFICIAL SUBSTRATES IN A TROPICAL STREAM

Standard periphyton samplers were used to examine the colonization pattern of periphytic algae on an artificial substrate (glass slides) in the Lam Tsuen River, Hong Kong, between October 1995 and August 1996. Changes in the taxonomic composition, species diversity (Shannon-Wiener diversity index), total standing crop, as well as the abundance of individual algal species were monitored over a six-week period in each season. Diatoms were most dominant in terms of cell density and biovolume, while green algae were important in terms of cell biovolume in autumn and summer. Of the 81 algal species observed, the pennate diatoms were most abundant. Dominant algal species included Achnanthes minutissima, Gomphonema parvulum, G. angustatum, G. rhombicum, Synedra rumpens var. familiaris, Nitzschia palea, Cocconeis placentula, Mougeotia spp., Spirogyra spp., Stigeoclonium aestivale and Schizothrix calcicola. A maximum algal density of 3.45 × 106 cells per cm2 was observed after a 4-week field incubation in spring (April and May), while maximum algal biovolume (1.20 × 106 μm3 cm−2) was recorded after a 6-week field incubation in summer (July and August). In general, the standing crop reached its maximum at week 4. Seasonal variations in the succession patterns of the periphytic algal communities are described.

Chemical defense of a marine cyanobacterial bloom

A popular Guam beach experienced a temporary closure in May 1994 due to the simultaneous occurrence of a blue-green algal bloom and a massive die-off of juvenile rabbitfishes ( Siganus argenteus (Quoy and Gaimard) and Siganus spinus (Linnaeus). The microbial assemblage was composed primarily of the marine cyanobacterium Schizothrix calcicola (Ag.) Gomont with sparsely distributed strands of Lyngbya majuscula Gomont. Palatability of the crude organic extract of this mixed cyanobacterial assemblage was evaluated in feeding assays using the parrotfish Scarus schlegeli (Bleeker) and the sea urchin Echinometra mathaei (Blainville) in outdoor tanks on Guam. Bioassay-guided fractionation resulted in the isolation of ypaoamide, a new broadly-acting feeding deterrent compound. At natural concentrations, ypaoamide deters feeding by juvenile rabbitfishes ( S. spinus and S. argenteus), the parrotfish S. schlegeli, and the sea urchin E. mathaei. We propose that the production of deterrent secondary metabolites by this benthic cyanobacterial assemblage and other similar microbial assemblages facilitates the formation of cyanobacterial blooms on coral reefs surrounding Guam.

Ypaoamide, a new broadly acting feeding deterrent from the marine cyanobacterium Lyngbya majuscula

Ypaoamide, a new herbivore antifeedent metabolite, was isolated from the extract of a mixed cyanobacteria assemblage which was composed of Schizothrix calcicola and Lyngbya majuscula. The structure was determined spectroscopically by interpretation of 2D-NMR experiments, including HMBC and NOESY, and by comparison with model compounds. Isolated cells of the L. majuscula produced ypaoamide in laboratory culture.

Grazing patterns in Siphonaria gigas (Mollusca, Pulmonata) on the rocky Pacific coast of Panama.

The pulmonate limpet Siphonaria gigas is the most abundant molluscan grazer in the mid zone on rocky, wave-exposed shores of the Pacific coast of Panama. Erect macroalgae and sessile invertebrates are rare; crustose algae cover ∼90% of the rock. The relative abundance of a common blue-green algal crust (Schizothrix calcicola?) is negatively correlated with Siphonaria's abundance. Large-scale removals of the limpet cause rapid increases in percent cover of Schizothrix and concomitant decreases in other crusts, but no changes in the abundance of erect algae or sessile invertebrates. Removing Siphonaria also (1) increases recruitment of crustose algae and barnacles onto new rock and plexiglass substrata, and (2) decreases the abundance of a calcified form of Schizothrix.Harsh conditions during daytime low tides and foraging by fishes at high tide control the microdistribution of most of this region's mobile and sessile benthic organisms. Wave action and substratum heterogeneity modify these constraints: Siphonaria is rare or absent in sheltered areas, especially on homogeneous surfaces, and is most abundant at wave-exposed sites. However, at extremely wave-beaten sites, Siphonaria and other benthic consumers are rare and ineffective. Crustose algae are reduced in abundance and space is dominated by erect macroalgae and/or barnacles. These normally rare species can outcompete crusts only when thermal or desiccation stress and the effects of benthic consumers and fishes are drastically reduced.

Small‐scale nutrient patchiness: Some consequences and a new encounter mechanism1

Semicontinuous cultures of Lake Michigan algal assemblages were run at 0.15·day‒1 dilution rates under P limitation for 41 days. In control cultures, nutrients were supplied to the entire culture once per day. In patch cultures, 10% of the cultures received a high concentration 10‐min pulse each day. Patch and control cultures received equal nutrient flux and achieved equal biomass levels; however, their species composition was different. Patch cultures were dominated by the filamentous blue‐green alga Schizothrix calcicola and control cultures were dominated equally by S. calcicola, Nitzschia acicularis, and a group of phytoflagellates. These results, as well as shifts in subdominants, demonstrate the effect of small‐scale, short term nutrient patches on species composition. Similar patch and control unialgal cultures revealed lower cell nutrient quotas for patchy cultures.Microvideographic observations of Daphnia magna suspended in three concentrations of Chlamydomonas sp. allowed quantification of rates at which algal cells were collected, swept close by, and released via bolus rejection or outwashing of unpacked cells. Outwashing release rates of presumably unharmed cells increased from 31 to 71% of the collection rate as food concentration increased. It appears that algal outwashing is a significant mechanism for eliminating excess food. An important implication is the potential algal nutritional consequence of this very close nondestructive encounter.

A quantitative study of calcareous stream and Tintenstriche algae from the Malham district, Northern England

The algal floras of two limestone streams and two calcareous Tintenstrichen are described and compared. The most important factor governing the distribution and abundance of species was the availability of water. Permanently wet stands, dominated by filamentous blue-green algae (Schizothrix calcicola and Phormidium incrustatum) had a greater species diversity than stands subject to frequent drying which were dominated by coccoid blue-green algae (Gloeocapsa spp.). Significant correlations were found between S. calcicola and water pH (+ve), total species numbers and pH (+ve), filamentous blue-green algae and aufwuchs thickness (+ve) and Calothrix numbers and rock mass colonized (+ve). The algal flora of the Tintenstrichen and the streams differed, although both developed upon the same limestone formation. The results are discussed with reference to previous work, substratum stability, aufwuchs structure, water chemistry, light and temperature.

Recent freshwater oscillatoriacean analogue of the Lower Palaeozoic calcareous alga Angulocellularia

Recent freshwater cyanophyte oncoids from Canandaigua Lake, New York, consist almost entirely of minute irregular, bush-like, micritic masses comparable with the calcareous alga Angulocellularia Vologdin from Lower Cambrian algal-arehaeocyathan bioherms and biostromes of the Siberian Platform and western Mongolia. The Recent specimens arc radially orientated within the oncoids and occasionally contain moulds of axial filaments 15 μm in diameter. Acid-residues of the oncoids yield abundant Schizothrix calcicola. The micritic bush-like masses are interpreted to have formed by the calcification of the sheaths of these cyanophytes. This analogue allows Angulocellularia to be reinterpreted as a calcified oscillatoriacean cyanophyte, rather than a rhodophyte as previously suggested. It indicates that filamentous cyanophytes can produce apparently solid calcareous fossils, not only porostromatc tubes. The occurrence of Angulocellularia has been overlooked in some previous studies of Cambrian and Ordovician bioherms. The generic diagnosis is emended.

Hydrogen metabolism by filamentous cyanobacteria

Apparent discrepancies in the literature concerning the amounts of H 2 produced by strains of Anabaena cylindrica are explained. These are not due to differences in strains used by different workers nor to differences in growth conditions, but rather appear to be due to the fact that cultures show an increasing dependence with age on CO 2 for sustained H 2 production. Two distinct hydrogenase activities were measured and characterized, both in vivo and in vitro in A. cylindrica B629; these were H 2 uptake activity and H 2 evolution from reduced methyl viologen. Gentle cell disruption techniques were used to gain further evidence that the latter activity was soluble. H 2 uptake was strongly inhibited by acetylene in vivo in the light or in the dark with phenazine methosulfate added, but only after a prolonged lag period. In extracts this lag did not occur. A detailed study of the nitrogenase and hydrogen uptake activities and their interrelationship both in the light and in the dark in A. cylindrica B629 showed that only in the dark in the presence of O 2 did H 2 uptake support C 2H 2 reduction significantly. Under several conditions in which nitrogenase activity was inhibited H 2 uptake was unaffected. H 2 metabolism was tested in three nonheterocystous filamentous cyanobacteria under different growth and incubation conditions. These were Plectonema boryanum, Schizothrix calcicola, and Oscillatoria brevis. Myxosarcina chroococcoides and Fischerella muscicola were also investigated. Cyanobacterial species vary markedly in their hydrogen metabolism and in the composition of the three H 2 metabolizing enzymes.

Endotoxins, algae and Limulus amoebocyte lysate test in drinking water

Field and laboratory studies were conducted to determine the distribution of algae and bacteria, and investigate sources of endotoxins (lipopolysaccharides) in drinking water. The field survey was performed on five drinking water systems located in Allegheny County, Pennsylvania during the spring and summer of 1978. The highest concentrations of phytoplankton were found in uncovered finished water reservoirs. The major source of “endotoxic” response as measured by the Limulus amoebocyte lysate (LAL) gelation test was a non-specific reaction caused by algae. This was documented by a highly positive correlation of phytoplankton concentrations occurring in the reservoirs with respective LAL titers. Chlorella vulgaris (Chlorophyta) was the most common alga, whereas Schizothrix calcicola was the most dominant Cyanobacterium found in the five water systems. LAL gelation test with C. vulgaris grown in the laboratory verified the phenomenon observed on samples collected in the field and indicated a non-specific reaction, whereas S. calcicola cultures under identical conditions produced a specific response. Alkali and lysozyme treatments were successful in distinguishing specific and non-specific LAL reactions. These two techniques in conjunction with LAL test are recommended for drinking water quality assessment.