Oscillatoria Princeps Research Articles

The Effect of Polyethylene Microplastics on Growth and Antioxydant Response of Oscillatoria Princeps and Chlorella Pyrenoidosa.

This study investigated the impacts of polyethylene microplastics (PE-MPs) with varying particle sizes (13μm and 6.5μm) on the growth and antioxidant responses of two freshwater algae species, Oscillatoria princeps (O. princeps) and Chlorella pyrenoidosa (C. pyrenoidosa). The results revealed a significant reduction in chlorophyll a content in both algal species upon exposure to PE-MPs, indicating a disruption of photosynthesis. Furthermore, Superoxide Dismutase (SOD) activity decreased in O. princeps, while Catalase (CAT) activity increased in both species, indicating complex physiological responses to microplastic stress. Notably, phycotoxin levels in O. princeps decreased with PE-MP exposure, while those in C. pyrenoidosa increased, particularly with 6.5μm PE-MPs. These findings underscore the potential toxic effects of PE-MPs on freshwater algal growth and metabolism, as well as their influence on toxin production. This study contributes valuable insights into the ecotoxicological impacts of microplastics in freshwater environments, highlighting the need for further research on their biological effects and environmental health implications.

Analisis Jenis dan Kandungan Makanan Oreochromis mossambicus dan Oreochromis nilotica asal Danau Lindu

The purpose of this study was to describe the type and content of food for Mujair and tilapia fish from Lake Lindu by means of a section and taking gastric contents and observing and analyzing them. The stages of the research were fish sampling, surgery (section), research in the laboratory and testing the nutritional content of food (carbohydrates, protein and fat). The research samples were Mujair fish (Oreochromis mossambicus) and Tilapia (Oreochromis nilotica) from Lake Lindu. Based on research obtained by the types of fish food O. mossambicus obtained two groups of Phytoplankton namely, Oedogonium sp, Anabaena sp, Nostoc sp, Oscillatoria princeps, Diatomae sp, Navicula gysingen, Rivularia sp, Coelastrum sphaericum, and Zooplankton namely Chironomus sp, Dugesia tigrina. There were eight types of food for O. nilotica, consisting of six types of phytoplankton, namely Oedogonium sp, Anabaena sp, Nostoc sp, Oscillatoria princeps, Rivularia sp, Coelastrum sphaericum and 2 types of zooplankton feed, namely Chironomus sp and Dugesia tigrina. The nutritional content of fish food/feed is protein (15.18%), fat (19.20%), and carbohydrates (1.9%).

Cyanobacterial strains reclaimed induced-salinity stress attributes and improved the physicochemical properties of induced-saline soil

Saline soils with complex ecosystems limit biotic activities, and the reclamation of these soils can be favorable for soil health. A pot experiment was conducted in a completely randomized design with three replications to reclaim artificially induced salinity-related attributes in soil (7.0 dS m−1) using various cyanobacteria strains. For this purpose, six treatments were used, control, Oscillatory-MMF-1 (Oscillatoria princeps), Leptolyngbaya-MMF-2 (Lyngbya mucicola), Leptolyngbaya-MMF-3 (Lyngbya Phormidium), Gloeobacter-MMF-4 (Gloeocapsa) and Microcoleus-MMF-5 (Cryophilus). The salinity-induced soil was treated with the appropriate treatments before the transplantation of rice seedlings to each pot. The rice crop was grown for 100 days and monitored for growth attributes. Similarly, the soil was monitored for physicochemical properties. The experimental results revealed a significant reduction in soil pH from 8.32 to 7.20, EC from 7 to 5.2 dS m−1, Na+ from 2552 to 1146 mg kg−1, soil bulk density from 1.37 to 1.31 g cm−3 by the cyanobacterial strain MMF-4 Gloeobacter (Gloeocapsa), showing 13.5%, 25.7%, 55% and 4.38% decrease respectively. Whereas the cyanobacterial strain (Gloeobacter) significantly enhanced the concentration level of Ca++ (944 mg kg−1), Mg++ (358 mg kg−1) and increased the porosity up to 50.69% and saturation percentage (35.50) in the induced saline soils. It can be concluded from the findings that all the strains of cyanobacteria reclaimed soil salinity by reducing soil EC, pH, SAR, and soil bulk density and increased Ca++, Mg++, porosity, and saturation percentage (SP) in the saline soil. However, the best performance was recorded for MMF-4 (Gloeobacter) and MMF-5 (Microcoleus) strains and recommended for further research.

A comparative study on biomass processing methods for oil production from Oscillatoria princeps

A comparative study on biomass processing methods for oil production from Oscillatoria princeps

Antibacterial assay of cyanobacteria in invitro conditions and its valuable applications

Cyanobacteria are aquatic and photosynthetic they survive in fresh water ponds and sewage water. Since these cyanobacteria are quite small and unicellular, they often grow in large colonies more enough to see by naked eye. Cyanobacteria they produce bluish green colour pigments as they are phycocyanin, phycobiliproteins and carotenoids. It may surprise you to know that cyanobacteria are still around they are one of the largest and most important groups of bacteria on earth. The cyanobacterial ethanolic extracts of Oscillatoria formosa, Oscillatoria subbrevis, Oscillatoria princeps, Oscillatoria sancta and Oscillatoria fischeri showed effective antibacterial activity against pathogenic microorganisms like Streptococcus pyogenes, Streptococcus pneumoniae, Clostridium perfringes, Salmonella typhi and Vibrio cholerae. Cyanobacteria like Oscillatoria curviceps, Lyngbya majuscula and Spirulina subsalsa are rich source of bioactive compounds with antibacterial, antifungal, antialgal and antiviral properties. Some cyanobacteria like Synechococcus elongatus have ability to accumulate polyhydroxyalkanoates which may be used as bioplastics. In addition to these applications the Cyanobacteria are also useful in agricultural practices like Nostoc commune and Anabaena aequalis as biofertilizers. Some eukaryotic green algae like Chlorella vulgaris, Botryococcus braunii and Schizochytrium limacinum produce more oil content for ecofriendly production of more biodiesel.

Extraction of phycobiliprotein pigments from Oscillatoria princeps by using different methods

In the current study, one isolation was obtained from the Cyanophyta Oscillatoria princeps which was collected from pond water located in Khor Al-Zubair/Basrah during August 2018. The current study aims at extracting and purifying of some effective pigments from the above isolate, test them chemically. Allophycocyanin (APC) pigments were highest among other pigments in sample removal-oil compared to the quantities of concentrations of phycoerythrin (PE) and phycocyanin (PC) pigments. The stationary phase in the industrial media have produced the largest amount of pigments. Phycobiliproteins were observed through the UV-Visible peaks. Freeze-dried samples or removal-oil showed that phycobiliproteins aren't affected by increasing or decreasing the sonication period. The study showed that it’s possible to use different media for pigments extraction as buffers and acetate buffer has been mastered. The freezing-thawing method is the best compared with other methods, the concentration of phycoerythrin (PE) pigments began to increase gradually from 6-12 days at PC and PE pigments extract, respectively. According to the statistical analysis, there are significance differences in Phycoerythrin. pigments concentration from 9th day to the 12th day.

Antimicrobial, antibiofilm potential, and anti-quorum sensing activity of silver nanoparticles synthesized from Cyanobacteria Oscillatoria princeps.

Cyanobacteria are among the beneficial and environmentally friendly natural candidates used in the biosynthesis of nanoparticles, with their ability to accumulate heavy metals from their environment, thanks to their biologically active compounds. In the current study, an aqueous extract of Oscillatoria princeps fresh biomass was used for the green synthesis of AgNPs. UV-vis spectrum, Fourier transforms infrared, scanning electron microscopy, and energy-dispersive spectroscopy were used to validate and characterize biosynthesized of OSC-AgNPs. The biosynthesis of AgNPs was visually verified in terms of the change in the color of the AgNO3 solution from yellowish brown to brown colors from 72h onwards. An absorption peak of approximately 420nm was detected in the UV-vis spectrum, corresponding to the plasmon resonance of AgNPs. FT-IR analysis showed the presence of free amino groups in addition to sulfur-containing amino acid derivatives that act as stabilizing agents. SEM images detected the roughly spherical shape of OSC-AgNPs with an average size of 38nm. The pathogens tested were all susceptible to OSC-AgNPs showing varying antimicrobial effects on pathogenic microorganisms. E. coli and C. albicans displayed the maximum susceptibility, with zones of inhibition of 14.6 and 13.8mm at 3-mM concentration, respectively, while B. cereus had the lowest zone of inhibition (10.6mm) at 3-mM OSC-AgN03 concentration. In conclusion, AgNPs synthesized from Oscillatoria princeps inhibit biofilm formation, suggesting that AgNPs may be a promising candidate for the prevention and treatment of biofilm-associated infections caused by bacteria and yeasts.

Preparation of effective green sorbents using O. Princeps alga biomass with different composition of amine groups: Comparison to adsorption performances for removal of a model acid dye

In the present study, various green biosorbents based on Oscillatoria princeps biomass were developed for removal of dyes from wastewaters. For this, alga biomass was modified with three different amine containing ligands [i.e., tetraethylene tetramine (TETA), para-amino benzamidine (PAB) and polydopamine (PDA)]. These modified algal biomasses were used for removal of Reactive Red 120 dye (RR-120). The prepared biosorbents were characterized using Fourier transform infrared spectroscopy, zeta seizer, and contact angles studies. The zeta potential values of the TETA, PAB and PDA modified biosorbents were varied from 42.3 to −18.4 mV, 36.7 to −14.8 mV and 30.7 to −12.6 mV, in the pH range of 2.0–11.0, respectively. Batch experiments were performed to determine the effect of operational parameters on the biosorption of RR-120 dye on the biosorbents (i.e., pH: 2.0–8.0, biosorbent dose: 0.1–1.0 g/L, initial dye concentration: 25–500 mg/L, temperature: 15–35 °C, and contact time: 0–120 min). The biosorption capacities of the native, TETA, PAB, and PDA modified algal biomasses for RR-120 dye were found to be 148.7, 687.1, 451.8, and 260.3 mg/g, respectively, at pH 3.0, at 25 °C in 120 min. These results showed that the biosorption of the RR-120 dye on the algal biomass preparations was achieved by hydrogen bonding, ion-exchange, electrostatic, and π-π interactions. The biosorption process of the RR-120 by algal biomasses was well described by the Langmuir isotherm model and pseudo-second-order kinetic model. The adsorption enthalpies for the biosorption of dye on the biomass preparations had been found to be between 21.5 and 90.3 kJ/mol. Furthermore, the modified algal biomasses displayed good regeneration capabilities, and the modification of the algal biomass with different ligands remarkably increased the RR-120 dye biosorption performances compared to native algal biomass.

Antimicrobial Activity, Cytotoxicity and Chemical Constituents of the Freshwater Microalga Oscillatoria princeps

The microalgae Oscillatoria sp. are promising sources of bioactive metabolites used in both pharmaceutical and nutraceutical applications. The main objective of present study is to determine the antimicrobial activity, cytotoxicity, and chemical profile of Oscillatoria princeps r extracts and its fractions. O. princeps extracts were prepared by successive extraction method, and chemical constituents were identified using GC-MS. Diethyl ether extract (DEE) had antimicrobial activity against all tested microorganisms and the highest inhibition zones 20.7 and 20.2 mm was observed against P. aeruginosa and A. flavus, respectively. Also, DEE showed an anticancer activity with IC50 values of 35.18, 46.6, and 79.18 µg ml-1 against breast cancer (MCF7), colon cancer (HCT116), and hepatocellular carcinoma (HePG2) cell lines, respectively. By DEE fractionation, fraction F7 showed the highest antimicrobial activity followed by fraction F4 with minimum inhibitory concentration (MIC) values ranged between 0.5 and 1.9 mg ml-1. Fraction F4 recorded anticancer activity against HCT116, MCF7, and HePG2 with IC50 of 22.62, 24.43, and 102.52 µg ml-1, respectively. While fraction F7 had anticancer activity against HCT116 and MCF7 without any effect on the HePG2 cell line. GC-MS analysis of fractions F4 and F7 represented that the main compounds responsible for the bioactivity were Pentadeconic acid,4-hexadecyl ester, and 9-Octadecenoic acid in F4, while the main compounds in F7 were Quercetin 7,3',4'-trimethoxy and Methyl tetradecanoate. The study concluded that O. princeps DEE extract and fractions had a sufficient amount of bioactive compounds that possess antimicrobial and anticancer activity, which could be a promising source for pharmaceutical and nutraceutical ingredients.

Bio-synthesis of silver nanoparticles with the brackish water blue-green alga Oscillatoria princeps and antibacterial assessment

This study describes the morphology of a filamentous non-heterocystous blue-green alga (cyanobacterium) Oscillatoria princeps isolated from the Bhabakundalswara sea mouth, its use in biogenic synthesis of silver nanoparticles (AgNPs), along with antimicrobial studies using multidrug resistant (MDR) methicillin-resistant strains of Staphylococcus aureus (MRSA), Streptococcus pyogenes and Escherichia coli, isolated from clinical samples. The synthesized O. princeps -AgNPs were characterized with UV–visible spectrometry, scanning electron microscopy (SEM), X-ray diffraction (XRD), dynamic light scattering analysis (DLS) and Fourier transform infrared spectroscopy (FT-IR) analyses. The synthesized AgNPs had remarkable antibacterial activities against MDR strains of MRSA, S. pyogenes and E. coli with the inhibitory zone sizes, 14–16 mm as recorded from agar well diffusion method, while MIC values were 100, 80, 60 µg/ml, for the respective cited bacterial species. Thus, O. princeps -AgNPs in future would be druggable antibacterials.

Stomach Content Analysis of Tilapia Fish (Oreochromis mossambicus) in Talaga Lake Waters Donggala Regency

Tilapia fish (Oreochromis mossambicus) is a type of freshwater consumption fish, flat body shape with grey, brown or black colour. The purpose of this study was to describe the types of food found in the stomach of tilapia fish (Oreochromis mossambicus) in Talaga Lake, Donggala Regency. This research was conducted in April 2019. The method used in this study was a volumetric occurrence frequency method by a surgical sampling of fish to extract the stomach and analyze it. Based on the results of the analysis of the stomach contents of the Mujair fish (Oreochromis mossambicus), two groups of feed were obtained, namely Vegetable food (Fitoplaknton) in the form of Navicula placentula, Schroederia segitera, Schoroederia anchora, Zignemopsis circumcaniratum, Anabaena sp, Oscillatoria princeps, Spirogyra protifica, Bacillaria sp, Nitzschia aetinastroides, Oedogonium sp, Coelastrum chodati, and animal feed (Zooplankton) in the form of Tubipex sp, Brachionus havanaensis, Cyclops sp, Carcinus sp, Arcella sp, Acetes sp.

Response of some cyanobacterial species for adsorption of manganese, cobalt and nickel from untreated tannery effluent in Kano, Nigeria

The research was conducted to monitor the performance of some endogenous species of Cyanobacteria for the adsorption of Manganese (Mn), Cobalt (Co) and Nickel (Ni) from untreated effluents of Fata Tanning Limited (FTL) in Kano between July 2014-June, 2015. Primary field investigation and laboratory analysis were the main sources of data in the study. The study areas were divided into three strata within which samples were collected using stratified sampling techniques from a depth of 0 30cm.The study assessed the adsorption capacity of some heavy metals namely; Mn., Co. and Ni using Atomic Absorbance Spectrophotometer (AAS). Indigenous cyanobacteria species identified and isolated were Anabaena variabilis, Lyngbya majusculata and Oscillatoria princeps using microscopy and standard phycological chart as described by Komerak and Anagnostidis, (1989). Bioremediation Bioassay was conducted to evaluate the adsorption capacity of the isolated organisms. The results showed that, tested organisms reduced the concentration level of heavy metals in the effluents to the standard limit proposed by FEPA (1997), WHO (1999) and (ICLARM, 1997). Anabaen was found to remove more Ni (4.13%) followed by Lyngbya (3.78%) all at 9 weeks after inoculation. Higher concentration of Mn (3.85%) and Co of (4.04%) were removed by Lyngbya and Oscillatoria at 9 weeks after inoculation. These findings indicated that all the tested organisms possessed great potential in removin heavy metals from untreated tannery effluents. These findings also showed that adsorption of heavy metals by the tested organisms increased with time from 3-9 weeks of inoculation and adsorption was significantly higher at 9 weeks after inoculation and some decline at 9 WAI.Keywords: Cyanobacterial species, Effluent, FTL and Heavy metals

Phytoplankton dynamics and species diversity in a shallow eutrophic, natural mid-altitude lake in Himachal Pradesh (India): role of physicochemical factors

Rewalsar Lake, a mid-altitude, shallow and recreational water body located in the north-western Himalayas, Himachal Pradesh (India) was studied through monthly surveys in two consecutive years (March 2008 to February 2010). Forty-seven species belonging to seven groups of phytoplankton were identified from the lake. Microcystis aeruginosa and Synedra ulna exhibited a perennial habit. Ankistrodesmus falcatus, Chlorella vulgaris, Scenedesmus bijugatus, Chlamydomonas reinhardi, Eudorina elegans, Navicula cuspidate, Synedra ulna, Euglena acus, Euglena oxyuris, Spirulina gomontii, Oscillatoria princeps and Arthrospira khannae were abundant, and Oscillatoria limosa and Microcystis aeruginosa were highly abundant. Twenty-one important criteria were studied, for example, temperature, free carbon dioxide, biochemical oxygen demand, total alkalinity, nitrate, silicate and phosphate, which provide an idea of the portability of water for irrigation and drinking purposes as per the permissible limits given in World Health Organization, Indian Council of Medical Research and Indian Standards Institute standards. Pearson's correlation revealed a significant relationship between physicochemical parameters and different algal groups. Both plankton and chlorophyll a showed a bimodal pattern of fluctuation. High annual mean concentrations of chlorophyll a (mg L−1) were recorded as 11.44 in 2008–09, and 11.04 in 2009–10. As per the Palmer pollution index, 13 pollution-tolerant algal species with a pollution score of 37 were observed. The Central Pollution Control Board categorised the water at Rewalsar Lake as ‘D–E’.

The algal community structure and seasonal variation in Taizi River catchment,Liaohe River basin

2010年9月到2011年9月分4次对太子河流域的藻类植物群落组成、丰度及优势种进行调查分析.共设置17个采样点,经鉴定共有藻类植物8门120属328种(包括21种变种).藻类植物群落以硅藻最多,有36属144种,占总体的43.77%;其次是绿藻,有49属117种,占总体的35.56%;蓝藻居第3位,有22属38种,占总体的11.85%.调查期间,太子河流域藻类植物细胞丰度在夏、秋季较高,丰度平均值分别为6.80×10⁷和3.29×10⁷cells/L;在春季较低,丰度平均值为1.36×10⁷cells/L.优势度分析显示,太子河流域各季节的藻类植物优势种都在5种以上,主要优势种有巨颤藻(Oscillatoria princeps Vauch.)、链丝藻(Hormidium flaccidum(Kütz.)Br.)、偏生毛枝藻(Stigeoclonium subsecundum(Kütz.)Haz.)等.藻类植物的Jaccard种类相似性指数在0.19~0.46之间.太子河流域藻类植物种类组成及细胞丰度均有明显的季节变化.;To understand the algal community structure,cell abundance and dominant species,Taizi River catchment,Liaohe River basin were investigated four times,from September 2010 to September 2011.Algae,including 8 phyla,120 genera,328 species (including 21 varieties) were identified from 17 sampling sites.Bacillariophyta were the dominant algae and included 36 genera,144 species,accounting for 43.77% of the algae.Chlorophyta,with 49 genera,117 species,accounted for 35.56% of the algae.Cyanophyta,included 22 genera,38 species and accounted for 11.85% of the algae.The cell abundance of algae was higher in summer and autumn,which were 6.80×10⁷ and 3.29×10⁷ cells/L,respectively.However,it was lower in spring with 1.36×10⁷ cells/L.This study also demonstrated that the dominant species of algae in Taizi River catchment were more than five, including Oscillatoria princeps Vauch.,Hormidium flaccidum (Kütz.) Br.and Stigeoclonium subsecundum (Kütz.) Haz.ect.Species Jaccard index of the algae varied from 0.19 to 0.46.Both algal community structure and cell abundance have obvious seasonal variation in Taizi River catchment.

Characterization of Roseofilum reptotaenium (Oscillatoriales, Cyanobacteria) gen. et sp. nov. isolated from Caribbean black band disease

Casamatta D., Stanić D., Gantar M. and Richardson L.L. 2012. Characterization of Roseofilum reptotaenium (Oscillatoriales, Cyanobacteria) gen. et sp. nov. isolated from Caribbean black band disease. Phycologia 51: 489–499. DOI: 10.2216/11-10.1Black band disease (BBD) is a pathogenic microbial consortium dominated in terms of biomass by phycoerythrin-rich, gliding, filamentous cyanobacteria. Studies of BBD using molecular methods have shown that the 16S rRNA gene sequence of ‘Oscillatoria’ sp. is consistently found in BBD samples worldwide. The purpose of this study is to erect a new genus, Roseofilum gen. et sp. nov., encompassing these and other previously reported strains. Using a polyphasic approach we characterized two strains of BBD Oscillatoria isolated from BBD infected corals in the Caribbean. These strains have the ability to tolerate sulphide, anoxia, and pH values in the range from 4.5 to 10, with optimal growth at pH 6 to 8. Growth occurs by photoautotrophy, including sulphide-insensitive oxygenic photosynthesis, and mixotrophy but not by heterotrophy under dark aerobic or anaerobic conditions. Both strains synthesize microcystin-LR. Results of infectivity experiments carried out under controlled laboratory conditions showed that both strains are capable of initiating an infection on healthy coral that resembles in situ BBD. 16S rRNA gene sequence data place these strains into a highly supported clade with other strains identified as Oscillatoria sensu lato, yet clearly genetically distinct from the type, Oscillatoria princeps. Further, while the BBD strains share more morphological similarity with members of Phormidium, they are also distinct from this genus based on sequence data. Based on morphology, ecology, physiology, and phylogenetic distinctiveness, we propose the novel epithet Roseofilum reptotaenium.

Biodiversity of Microalgae in Western and Eastern Ghats, India

The systematic study was conducted on the microalgal flora of Western Ghats and other parts of Eastern Ghats revealed a rich wetland algal resource for biotechnological exploration. The present study reveals with the diversity of microalgal flora in the region of Kodaikanal (10 degrees 14' N, 77 degrees 28' E), Gudalur (9 degrees 19'N 77 degrees 12'E), Agasthiyar falls (9 degrees 58'N, 78 degrees 10'E) and Kolli hills (10 degrees 12'N, 77 degrees 56'E) located in Western and Eastern Ghats of Tamilnadu, India collected in May 2011. In total, 97 species of micro algae belonging to three taxonomic groups were identified, of which 41 species belonging to Cyanophyceae, 38 species from Chlorophyceae and 18 species from Bacillariophyceae. The predominant species in Cyanophyceae were Aphanothece microscopica, Chroococcus minutus, Coelospharium dubium, Hydrococcus rivularism, Oscillatoria princeps, Nostoc muscorum, Nostoc puncteforme, Nostoc commune, Gleotricha gausii, Calothrix braunii, Rivellaria sp., Tolypothrix tenuis, Scytonema schmidtii, whereas in Chlorophyceae, Chlorella sp., Scenedesmus sp., Pediastrum duplex, Cosmarium consperum, Euastrum elagans, Micrasterias americana and in Bacillariophyceae, Navicula hallophyla, Rhophaldia gebrella, Fragellaria intermedia, Pinnularia virdis, Nitzchia palliate. Physicochemical nature of water samples were analyzed and correlated with the total microalgal diversity. Based on the correlation coefficient data, the micro algae showed positive relationship with dissolved oxygen, salinity, nutrients and negative relationship with temperature and turbidity. The species diversity index (H'), Species Richness (SR) and species evenness (J') were calculated and analyzed for microalgal population dynamic variation in the Western and Eastern Ghats.

Seasonal distribution of phytoplankton in the Aby lagoon system, Ivory Coast, West Africa

Seasonal variability of phytoplankton species composition, abundance and physical and chemical factors influencing phytoplankton dynamics were investigated in the Aby lagoon system, south-eastern Ivory Coast, covering the main climatic seasons in 2006–2007. Seasonal and spatial variability of nutrient concentrations in the system were influenced by freshwater inflow from the Bia and Tanoé rivers. The decrease in the salinity gradient in Aby Lagoon, which is permanently stratified during the long dry season, increased the bottom inputs of soluble reactive phosphate and soluble reactive silicate which, in combination with good light penetration during the long dry season, enhanced phytoplankton production in the system. During the rainy seasons, water discharges into the system washed phytoplankton biomass out, preventing the development of blooms. Overall, 192 taxa from eight phyla were recorded: Bacillariophyta (32%), Chlorophyta (31%), Cyanobacteria (23%), Euglenophyta (12%), Dinophyta (0.5%), Xanthophyta (0.5%), Chrysophyta (0.5%) and Rhodophyta (0.5%). During the long dry season, Cyanobacteria cells comprised >50% of the phytoplankton abundance. The main phytoplankton taxa responsible for this high abundance were Microcystis aeruginosa, Oscillatoria princeps, Pseudanabaena limnetica, Aphanizomenon sp. 2 and Anabaena planctonica.

Occurrence of phytoplankton in the water and gut of the volta clam (Galatea paradoxa born 1778) from the lower volta estuary, Ghana

The Volta Clam, Galatea paradoxa Born 1778 (= Egeria radiata) occurs in the waters of the Lower Volta Estuary. It is an important source of protein for the inhabitants and fishing for clams is done to supplement income. The clam is eaten whole after frying, boiling, steaming or roasting. The gut contains many microalgae that are resident in the enclosing riverine water. This paper reports the incidence of microalgae (phytoplankton) in the surrounding water and in the gut of the clam with the view to identifying potential toxin-producing ones which constitute the phytoplankton population. The phytoplankton content of the riverine water and in the gut ofthe clam was determined using standard and prescribed methods. Out of the 826 single microscopic phytoplanktons counted from the surface and bottom layers of water, 63.8% belonged to the Chlorophyta, 22.9% to the Bacillariophyta and the remaining 13.3% were Cyanophyta. The Chlorophyta population was made up of seventeen (17) species belonging to seven (17) genera. Actinastrum, Pediastrum, Phacus and Phytoconia species were detected only in the bottom water whilst Ankistrodesmus, Coelastrum, Chlorella, Euglena, Microspora, Mougeota, Scenedesmus, Spirogyra, Straurastrum and Ulothrix were found in both layers. Spirogyra was the most predominant amongst the Chlorophyta in the surface water consisting 70.6% at this layer and 44.3% of the Chlorophyta population of the bottom water. Cyanophyta belonging to nine genera (Anabaena, Anacystis, Chroococcus, Gomphosphaeria, Lyngbya, Nodularia, Oscillatoria, Phormidium and Stignonema) were isolated in the water. Oscillatoria princeps was the most predominant Cyanophyta at the surface (36.1%) and bottom (52.6%) waters. Members of the Bacillariophyta found at the surface and bottom layers belonged to six (6) genera (Asterionella, Diatoma, Fragilaria, Melosira, Navicula, and Synedra). Members of the Cyanophyta which were isolated from the gut only were Merismopedia elegans, Oscillatoria tenius and Planktothrix agardhii. Practical implications of the findings are discussed.

Periphyton as a potential phosphorus sink in the Everglades Nutrient Removal Project

Phosphorus uptake and release by periphyton mats were quantified in the Everglades Nutrient Removal Project (ENRP) to evaluate the potential for periphyton P removal. Short-term P uptake rates were determined by incubating cyanobacteria ( Oscillatoria princeps and Shizothrix calcicola) and Chlorophycean (primarily Rhizoclonium spp.) algal mat samples for 0.5–2 h under ambient conditions in BOD bottles spiked with soluble reactive P (SRP). Cyanobacterial mats removed P more than twice as fast (80–164 μg P h −1 g −1 AFDM) as Chlorophycean mats (33–61 μg P h −1 g −1 AFDM) during these incubations. In a longer term study, fiberglass cylinders were used to enclose 1.8 m 2 plots within the wetland and were dosed weekly for 7 weeks with: (1) no nutrients; (2) SRP (0.25 g P m −2 week −1); or (3) SRP plus nitrate (0.42 g N m −2 week −1) and ammonium (0.83 g N m −2 week −1). Phosphorus uptake rates by this periphyton assemblage, which was dominated by the chlorophytes Stigeoclonium spp. and Oedogonium spp., were measured weekly and were similar among nutrient treatments on most dates, indicating that the algal storage compartment for P was not saturated despite repeated P additions. Decomposition rates and P loss by cyanobacteria and Chlorophycean mats were determined by measuring biomass loss and SRP release in darkened BOD bottles over 28–42 day periods under anaerobic and aerobic conditions. First-order aerobic and anaerobic decomposition rates for cyanobacterial mats ( k = 0.1095 and 0.1408 day −1, respectively) were 4–20-fold higher than rates for Chlorophycean mats ( k = 0.0066 and 0.0250 day −1, respectively) and cyanobacteria released considerably more P back to the water column. Our findings suggest that periphyton can be an important short-term sink for P in treatment wetlands and that retention is strongly affected by the taxonomic composition of the periphyton assemblage.

Impactos da construção do Porto de Suape sobre a comunidade fitoplanctônica no estuário do rio Ipojuca (Pernambuco-Brasil)

A construção do Complexo Industrial Portuário de Suape, entre os anos de 1979/84, modificou as características ecológicas da área, sendo os maiores impactos observados no estuário do rio Ipojuca. Visando avaliar a ação desses impactos sobre a comunidade fitoplanctônica através da comparação com estudos realizados antes na área, foram analisadas amostras de plâncton coletadas em uma estação, durante um ciclo de 24 horas, nos períodos chuvoso (agosto/90) e seco (janeiro/91). As amostras foram coletadas pela técnica do fracionamento e com rede de plâncton de 65µm de abertura de malha. Coletas de parâmetros hidrológicos foram realizadas concomitantemente. Foram identificados 97 táxons, destacando-se como espécies muito freqüentes nos períodos chuvoso e seco: Gyrosigma balticum, Oscillatoria princeps, Chaetoceros lorenzianus, Climacosphenia moniligera e Licmophora abbreviata. A densidade fitoplanctônica variou entre 142.000 cels.l-1 a 1.789.000 cels.l-1 predominando a fração do nanofitoplâncton. O maior florescimento ocorreu no período seco, nos horários de maior insolação e maré enchente. A diversidade específica foi alta (> 3 bits.cel.l-1) explicada pela heterogeneidade ambiental. A comunidade fitoplanctônica apresentou mudanças quali-quantitativas após a implantação do Porto. Agora, predominam espécies marinhas litorais, devido à pequena profundidade e elevado hidrodinamismo na área e um decréscimo de 70% na densidade celular, ao contrário do que ocorria antes da construção do Porto, quando foi detectado a maior ocorrência de espécies marinhas planctônicas e maior número de células/litro.