Complex dynamics of toxin producing algal species and primary productivity in two water ponds of Faizabad

In order to develop a method of predicting and assessing pond eutrophication, which is a serious environmental problem, and to propose effective measure of improvement of water quality. The present study was performed to measure water quality variables, primary productivity, chl-a and biomass of toxin producing algal species and fish production. High nutrient influx and toxin producing algal species have been observed during June 1999 to May 2000 in two water bodies [Girija Kund (A) and Maqubara pond (B)] of Faizabad. The maximum chl-a concentration, toxins producing algal species biomass were found to be 415.00 and 515.00 in pond A, while 451.00 microg/l and 541.22 mg/l in pond B, respectively in the case of Microcystis aeruginosa. Ecological parameters to evaluate GPP, NPP and CR were found to be 297.00, 134.000 and 182.00 mgCm3/h in summer season in pond B, respectively which is higher than pond A. A poor association existed between chl-a and GPP. Temporal variation (Photosynthetic rate) in A(max) & P(max) was also observed to evaluate the productivity of pond. Annual fish production potential of the ponds A and B has been estimated to be around 342.00 Kg and 204. 00 Kg, respectively which may be due to the presence of toxin producing algal species.

Parasites as biological tags in population studies of marine organisms: an update

This paper reviews the work published over the past decade on the use of parasites as biological tags in population studies of marine fish, mammals and invertebrates. Fish hosts are considered in taxonomic and ecological groups as follows: demersal, anadromous, small pelagic, large pelagic and elasmobranch. Most studies were carried out on demersal fish, particularly on members of the genera Merluccius (hake), Sebastes (rockfish) and on Atlantic cod Gadus morhua L., but Pacific salmonids and small pelagic fish of the genus Trachurus are also well-represented. A current multidisciplinary study of the population biology of horse mackerel Trachurus trachurus in European waters, which includes the use of parasites as tags, is described. Two studies recognize the potential for using parasites as tags for cetaceans but, in spite of the considerable potential for this approach in population studies of elasmobranchs, no original study has been carried out on this group for over ten years. Studies of parasites as tags for marine invertebrates have concentrated on squid. Recent trends in the use of parasites as biological tags for marine hosts are discussed.

Continuous in vitro culture of the carpet shell clam Tapes decussatus protozoan parasite Perkinsus atlanticus

Continuous in vitro cultures of the clam Tapes decussatus parasite Perkinsus atlanticus were established from infected gill fragments, infected haemolymph and parasite hypnospores isolated from infected gill fragments following incubation in Ray's fluid thioglycollate medium (RFTM). No continuous cultures could be initiated from P. atlanticus zoospores. Cultures initiated from hypnospores yielded the highest percentage of continuous cultures (100%, 6/6), followed by cultures initiated from gill fragments (93%, 43/46) and from haemolymph (30%, 3/10). Failures to establish continuous cultures were due to microbial contamination. The source of parasite influenced the success rate, the time taken to establish cultures and the size of cultured cells. In vitro proliferation of parasite cells was mainly by vegetative multiplication. Zoosporulation, yielding motile biflagellated zoospores, was observed at a low frequency (< 1% of dividing cells) in every culture. Morphology of cultured cells examined with light and transmission electron microscopy corresponded to that of P. atlanticus found in clam tissues. Cultured cells enlarged in RFTM and stained blue-black with Lugol's solution, which are characteristics of the Perkinsus species cells. DNA sequences of the internal transcribed spacer (ITS) region of the ribosomal RNA gene complex matched those of P. atlanticus. All cultures were established in a medium designated JL-ODRP-2A that was similar in composition to the culture medium JL-ODRP-1 originally used to propagate Perkinsus marinus in vitro. Proliferation of P. atlanticus in vitro could be supported by the commercial culture medium (1:2 v/v) DME:Ham's F-12 with fetuin.

Impact of protozoan grazing on bacterial community structure in soil microcosms

The influence of grazing by a mixed assemblage of soil protozoa (seven flagellates and one amoeba) on bacterial community structure was studied in soil microcosms amended with a particulate resource (sterile wheat roots) or a soluble resource (a solution of various organic compounds). Sterilized soil was reinoculated with mixed soil bacteria (obtained by filtering and dilution) or with bacteria and protozoa. Denaturing gradient gel electrophoresis (DGGE) of PCR amplifications of 16S rRNA gene fragments, as well as community level physiological profiling (Biolog plates), suggested that the mixed protozoan community had significant effects on the bacterial community structure. Excising and sequencing of bands from the DGGE gels indicated that high-G+C gram-positive bacteria closely related to Arthrobacter spp. were favored by grazing, whereas the excised bands that decreased in intensity were related to gram-negative bacteria. The percentages of intensity found in bands related to high G+C gram positives increased from 4.5 and 12.6% in the ungrazed microcosms amended with roots and nutrient solution, respectively, to 19.3 and 32.9% in the grazed microcosms. Protozoa reduced the average bacterial cell size in microcosms amended with nutrient solution but not in the treatment amended with roots. Hence, size-selective feeding may explain some but not all of the changes in bacterial community structure. Five different protozoan isolates (Acanthamoeba sp., two species of Cercomonas, Thaumatomonas sp., and Spumella sp.) had different effects on the bacterial communities. This suggests that the composition of protozoan communities is important for the effect of protozoan grazing on bacterial communities.

Biotechnological potential of immobilized algae for wastewater N, P and metal removal: a review

This presentation comprises a review on the use of immobilized algae for wastewater nitrogen, phosphorus and metal removal purposes. Details of the use of immobilized algae, the techniques of immobilization and the effects of immobilization on cell function are included. Particularly relevant in their use for heavy metal removal from wastewaters; upon enriching the biomass in metal, can be recoverd, thereby providing economic advantages. The use of immobilized microalgae in these processes is very adequate and offers significant advantages in bioreactors. The future of this area of algal cell biotechnology is considered.

Development and release of a malacosporean (Myxozoa) from Plumatella repens (Bryozoa: Phylactolaemata)

During an experiment to transmit Tetracapsula bryosalmonae Canning, Curry, Feist, Longshaw et Okamura, 1999 to a laboratory-cultured bryozoan, Plumatella repens L. a previously undescribed malacosporean species was noted. This parasite produced sacs of spores in the host that reached 1.2 mm in length. The spores released from the sacs appeared similar in size to the two species of Tetracapsula previously described although slight differences in form were noted. Release of spores from the bryozoans was observed associated with the lophophore of the host. The use of experimental bryozoan cultures for the examination of malacosporeans is described and discussed.

Site preference of myxosporean spp. on the fins of some Hungarian fish species

Some species of the known fish myxosporeans select fins as type location for their development. During the plasmodial development of Myxobolus, Henneguya and Thelohanellus species in cyprinid fishes and eels, 3 main locations of plasmodial development were distinguished inside the fins. M. portucalensis, M. alburni, M. caudatus and a Myxobolus sp. formed plasmodia in the dermis of the skin doublets between finrays, while plasmodia of M. diversus and H. cutanea developed inside the lumen of the cartilaginous finrays. The third type of development was represented by T. nikolskii, which started its development on the outer surface of the finrays. Plasmodia both in the lumen and on the surface of the finrays were surrounded by a cartilaginous capsule, but plasmodia of T. nikolskii also had a thick connective tissue capsule containing pieces of cartilage.

Ammonium excretion by a symbiotic sponge supplies the nitrogen requirements of its rhodophyte partner

Symbioses between sponges and algae are abundant in the nutrient-poor waters of tropical reefs, yet very little is known of the nutritional interactions that may promote this abundance. We measured nitrogen flux between the sponge Haliclona cymiformis and its symbiotic partner,the rhodophyte Ceratodictyon spongiosum, and assessed the potential importance of this flux to the symbiosis. While the association can take up dissolved inorganic nitrogen (DIN) as ammonium and nitrate from the surrounding sea water, enrichment of the water with nitrate did not affect its rates of photosynthesis and respiration. Much of the DIN normally assimilated by the alga is waste ammonium excreted by the sponge. A nitrogen budget for the symbiosis shows that the nitrogen required for algal growth can potentially be provided by sponge catabolism alone, but that only a small amount of nitrogen is available for translocation back to the sponge in organic compounds. The stable isotope composition (δ15N) was consistent with our interpretation of the sponge supplying excretory DIN to its algal partner, while the results also suggested that this DIN limits nitrogen deficiency in the alga. If our observations are typical of sponge—alga symbioses, then the supply of excretory nitrogen could be a major reason why so many algae form symbioses with sponges on coral reefs.

On-line determination of biomass in a microalga bioreactor using a novel computerized flow injection analysis system

A flow injection analysis (FIA) device has been developed, which is able to assay successfully for biomass in a microalga bioreactor. The device is fully computerized and is operated via diluting small aliquots of the culture followed by measuring optical density (OD); this figure is then accurately correlated with biomass, in terms of both cell number and ash-free dry weight, during the entire culture time. Furthermore, the device is not expensive, is highly versatile, and is easy to operate owing to specifically developed, user-friendly software. The growth rate and biomass productivity of Pavlova lutheri, cultivated under batch and semicontinuous modes, were monitored as experimental testing model.

[Preliminary study on the growth stimulation of marine microalgae stimulated by low level of toxicant]

Cell growth of Nitzschia closterium and Platymonas subcordiformis was stimulated under 4 and 8 micrograms.L-1 anthrancene stress, respectively. The cell growth of two species was also stimulated under 30 mg.L-1 streptomycin stress. The hormesis of marine microalgae cells under low level of anthrancene and streptomycin resulted in low level of free radical and decrease of microorganisms. Furthermore, the hormesis of marine microalgae was also discussed in this paper.

Density and diversity of protozoa in some arid Australian soils

This is the first extensive study of soil protozoa of arid lands. Twenty-six samples from litters, soils, termitaria, and a cyanobacterial crust, collected from central and south Australian arid lands, were analyzed for numbers and species of gymnamoebae, ciliates, and testacea. Amoebae ranged from 1,000-5,000/g of material, and were two orders of magnitude more abundant than ciliates. Both groups increased in abundance and species richness from bare soils through spinifex to mulga to chenopod vegetations. Testacea ranged 900-5,000/g with similar species richness throughout vegetations, but reached 11,900/g with a doubling of species in a refugium in Kings Canyon. The most prevalent species of amoebae, ciliates, and testacea were taxa associated with ephemeral and disturbed habitats (r-selection). The cyanobacterial crust might be considered a micro-refugium because it contained a number of non-encysting protozoa, including Thecamoeba sp. and Nassula picta, feeding on cyanobacterial filaments. The numbers and species richness of protozoa under shrubs were greater than in bare soils, supporting the resource island hypothesis that desert plants create soil heterogeneity by localizing soil fertility under their canopies.

Immature stages and re-description of Henneguya suprabranchiae (Myxosporea: Myxobolidae), an intestinal parasite of the catfish Clarias gariepinus in the River Nile, Egypt

A new morphological description, supported by light microscopy photographs, is presented for various immature stages and for mature Henneguya suprabranchiae Landsberg, 1987 spores infecting the intestine of the Nile catfish Clarias gariepinus, Burchell, 1822 (Syn.: C. lazera). Large cysts of 2 to 4.5 mm diameter, containing immature and mature stages, were present in the outer layer of the intestine. They caused severe damage to the smooth muscle and atrophy due to the increased size and resultant pressure of the plasmodial mass. From September 2000 to April 2001, 21 infected fishes were detected, with a parasite prevalence of 21.2%. Nine immature stages were distinguished, and these have been measured, sketched and described. In addition, caudal process development was recorded. The mature spores are re-described and compared with previous descriptions of H. suprabranchiae spores. The main new morphological characteristics described are the number of polar filament coils, triangular thickening of the sporoplasm base, and a suture line visible only in lateral view.

Comparison of in vitro-cultured and wild-type Perkinsus marinus. III. Fecal elimination and its role in transmission

Perkinsus marinus, a pathogen of the eastern oyster Crassostrea virginica, is transmitted directly among oysters. Previous studies found viable P. marinus parasites in the feces and pseudofeces of oysters within hours of injection with parasites, suggesting that the parasite may be voided from live oysters and subsequently dispersed in the water column. The experiments described here were designed to quantify P. marinus shed in the feces and pseudofeces of experimentally infected oysters. The results indicated that parasites were shed in 2 phases. A 'decreasing' phase occurred within 2 wk of challenge and before net parasite proliferation began in the host. An 'increasing' phase occurred after P. marinus had begun replicating. The quantity of P. marinus recovered in the feces and pseudofeces of exposed oysters was only about 5 % of the dose administered. In vitro-cultured P. marinus were eliminated at a greater rate than wild-type P. marinus and the fraction discharged was not associated with culture phase. Oysters that were continuously dosed with P. marinus in their food gradually lost the ability to discard the parasite in pseudofeces. The quantity of P. marinus shed in feces of infected oysters was correlated with both the P. marinus body burden and subsequent survival time, suggesting that noninvasive fecal counts could predict infection intensity and survival. The results indicate that in an epizootic, shedding of P. marinus via feces is relatively small compared to the potential number released by cadavers of heavily infected oysters, but that fecal discharge may be important in transmission before infections become lethal.

Comparison of in vitro-cultured and wild-type Perkinsus marinus. II. Dosing methods and host response

Endoparasites must breach host barriers to establish infection and then must survive host internal defenses to cause disease. Such barriers may frustrate attempts to experimentally transmit parasites by 'natural' methods. In addition, the host's condition may affect a study's outcome. The experiments reported here examined the effect of dosing method and host metabolic condition on measures of virulence for the oyster parasite Perkinsus marinus. Oysters, Crassostrea virginica, were challenged with wild-type and cultured forms of P. marinus via feeding, shell-cavity injection, gut intubation and adductor-muscle injection. For both parasite types, adductor-muscle injections produced the heaviest infections followed by shell-cavity injection, gut intubation, and feeding. There was no difference in parasite burdens between oysters fed cultured cells by acute vs chronic dosing, and parasite loads stabilized over time, suggesting a dynamic equilibrium between invasion and elimination. P. marinus distribution among tissues of challenged oysters indicated that parasites invaded the mantle and gill, as well as the gut, which has been considered the primary portal of entry. Frequency distributions of P. marinus in oysters challenged with 3 different culture phases indicated an aggregated distribution among hosts and suggested that stationary-phase parasites were easiest for the oyster to control or eliminate and log-phase parasites were the most difficult. Host metabolic condition also affected experimental outcomes, as indicated by increased infection levels in oysters undergoing spawning and/or exposed to low oxygen stress.

Confounding factors in bioassays with freshwater and marine organisms

The use of bioassays in ecological risk assessments often raises questions about the causative factors, and insight into the possibility that confounding factors, such as pH or increased ammonia concentrations, might be responsible for the observed toxicity is needed. It was decided to develop a practical approach for the Dutch situation, in which a first screening is carried out based on provisional criteria. In collecting the required data, dozens of experiments were performed, while the scientific literature was searched for additional information. It is concluded that the provisional criteria specified are at present useful tools in interpreting results of bioassays. Depending on the outcome and the aim of the research, it might be necessary to further reduce uncertainties in the interpretation. This might require some additional experiments, using alternative controls or test procedures or altering the composition of the original sample.

Microscale evaluation of the effects of grazing by invertebrates with contrasting feeding modes on river biofilm architecture and composition

River biofilms are a valuable food resource for many invertebrates. In the present study biofilms were cultivated in a rotating annular bioreactor with river water as sole source of inoculum. The resulting biofilms were then presented to starved snails, ostracods, and mayflies as sole food source. The biofilms were then removed and microscopically examined to determine areas that had been grazed. The grazed and ungrazed areas were marked and analyzed for the effects of grazing using confocal laser scanning microscopy and image analyses. Samples were treated with fluorescent probes for nucleic acids to quantify bacterial biomass and fluor-conjugated lectins to quantify exopolymer, and far red autofluorescence was imaged to quantify algal or photosynthetic biomass. Grazing by snails significantly reduced algal biomass (1.1 +/- 0.6 micro m 3 micro m 2 to 0.02 +/- 0.04 micro m 3 micro m 2), exopolymer (5.3 +/- 3.4 micro m 3 micro m 2 to 0.18 +/- 0.18 micro m 3 micro m 2), and biofilm thickness (154 micro m +/- 50 to 11 micro m +/- 5.2; ANOVA, p < or= 0.05). Although bacterial biomass was influenced by grazing snails the impact was not statistically significant (p <or= 0.05). Ostracods had a significant (p <or= 0.05) impact on the algal biomass and exopolymer but not on bacteria. Mayfly grazing resulted in reduction of biofilm thickness to approximately 40 mm and reductions in all biofilm components with little evidence of selectivity. Thus grazing consistently resulted in a significant reduction in autotrophic biomass and exopolymer with a resultant increased importance of bacterial biomass within the grazed regions. Examination of grazed biofilms after a recovery period in the absence of grazing indicated that grazed regions remained predominantly bacterial after 28 days. A comparison of grazing in diclofop methyl and atrazine contaminated (1 ppb and 10 ppb) versus control biofilms indicated no significant influence of the contaminants on grazing patterns.

Phytotoxicity of coloured substances: is Lemna duckweed an alternative to the algal growth inhibition test?

Coloured substances cause problems when interpreting algal tests, because effects due to light absorption can interact with potential toxicity. The Lemna Duckweed growth inhibition test can complement the algal test, on condition that the test is performed on a black, not reflecting surface. On white surfaces, test solution colour can strongly impact Lemna growth. For example, average control sample growth rate of is much higher on white surfaces (0.362 d(-1)) than on black surfaces (0.284 d(-1)). We found that 10 mg l(-1) of the dyestuff "Brilliant Blue R spezial" inhibited average Lemna growth rate about 22% on white surfaces but did not inhibit growth on black surfaces. The reason for this difference stems from the difference in amount of light reflected from below the test beakers. With Brilliant Blue on white surfaces, the test solution colour reduces utilizable light and causes a deterioration of light conditions, whereas on a black surfaces, reflected light is absent a priori, and thus no inhibiting effect was measured. Of particular importance is the choice of test parameter. With Brilliant Blue, a LOEC for average growth rate, based on frond numbers, of 320 mg l(-1) was determined. However, when average growth rate was calculated using dry weights of the plants, the LOEC decreased clearly to 1.0 mg l(-1). In this study, the Lemna test was much more sensitive than the algal test. We recommend Lemna tests be used in addition to algal tests, because doing so may significantly improve the assessment of phytotoxicity of chemicals and sewage.

Sensitivity of different growth inhibition tests--just a question of mathematical calculation? Theory and practice for algae and duckweed

Hazard assessment often needs to compare inhibition values of different test species and different test durations. But the three different methods to calculate inhibition in growth inhibition tests (final biomass, growth rate, area under the growth curve) may lead to very different and sometimes contradicting numerical sensitivities of the test species. This paper will depict why there are these different results and what consequences this has for the evaluation of results. Comprehensive discussion of different aspects will show that using growth rate may eliminate most of the problems occurring for comparisons between test species, different test times and different laboratories. The use of growth rate and the adaptation of toxicity levels maximises reproducibility, comparability and biological sensitivity of biotests.

Dissolved primary production and the strength of phytoplankton- bacterioplankton coupling in contrasting marine regions

We analyzed the strength of phytoplankton-bacterioplankton coupling by comparing the rate of particulate (PPP) and dissolved primary production (DPP) with bacterial carbon demand (BCD) in four contrasting marine regions: offshore and coastal waters of the Southern Ocean, a coastal area of the NE Atlantic, and a coastal-offshore transect in the NW Mediterranean. We measured bacterial heterotrophic production (BHP) and estimated BCD from a literature model. Average phytoplanktonic percent extracellular release [PER = DPP/(DPP + PPP)] was 18-20% in the Antarctic (offshore and coastal, respectively), 16% in the NW Mediterranean, and 7% in the NE Atlantic. A significant inverse relationship was found between PER and total system productivity with pooled data. On average BHP amounted to <5% of total primary production in all regions. However, the strength of phytoplankton-bacterioplankton coupling, estimated as the potential importance of DPP in meeting BCD, differed greatly in the four regions. DPP was highly correlated to BCD in offshore Antarctic waters and was sufficient to meet BCD. In contrast, BCD exceeded DPP and bore no significant relationship in the remaining regions. The data suggest that a strong dependence of bacteria on algal extracellular production is only expected in open-ocean environments isolated from coastal inputs of DOC.

Indicators of ocean and human health

The interactions between humans and the ocean are significant, and necessitate more comprehensive study on an international scale. The world's oceans provide great health benefits to humans ranging from food and nutritional resources, to recreational opportunities and new treatments for human disease. However, recently, human health effects from exposure to substances present in the marine ecosystem such as synthetic organic chemicals (e.g., chlorobiphenyls, chlorinated dioxins and some industrial solvents), polycyclic aromatic hydrocarbons (PAHs), metals (both introduced and anthropogenic), marine toxins, and pathogens have been recorded and are of great concern. This paper reviews our state of knowledge of the interactions between oceans and human health and proposes indicators and a research strategy to investigate and monitor these relationships more closely. Four approaches to gathering information on indicators included here are: biomarkers; cellular pathology; physiological and behavioural responses; and changes in populations. All hold the potential to enhance our understanding of marine environmental quality and far-reaching effects on human health. Monitoring systems that include the rapid assessment of contaminants in the ecosystem and subsequent risk to human populations, with appropriate internationally distributed data bases, need to be developed and validated. Such tools would provide early detection of potential environmental threats, and enhance the ability to prevent human illness.

Causes of ambient toxicity in the Calleguas Creek watershed of southern California

A combination of toxicity tests, chemical analyses, and Toxicity Identification Evaluations (TIEs) were used to investigate receiving water toxicity in the Calleguas Creek watershed of southern California. Studies were conducted from 1995 through 1999 at various sites to investigate causes of temporal variability of toxicity throughout this system. Causes of receiving water toxicity varied by site and species tested. Investigations in the lower watershed (Revolon Slough, Santa Clara Drain, Beardsley Wash) indicated that toxicity of samples to the cladoceran Ceriodaphnia dubia was due to elevated concentrations of the organophosphate pesticide chlorpyrifos, while causes of intermittent toxicity to fathead minnows (Pimephales promelas) and the alga Selanastrum capricornutum were less clear. Investigations at sites in the middle and upper reaches of the watershed (Arroyo Simi and Conejo Creek) indicated that the pesticide diazinon was the probable cause of receiving water toxicity to Ceriodaphnia. Elevated ammonia was the cause of toxicity to fathead minnows in the upper watershed sites. Results of these and previous studies suggest that biota are impacted by degraded stream quality from a variety of point and non-point pollution sources in the Calleguas Creek watershed. Water quality resource manager's efforts to identify contaminant inputs and implement source control will be improved with the findings of this study.

Long chain polyunsaturated fatty acid production and partitioning to triacylglycerols in four microalgae

Gas chromatographic profiling of fatty acids was performed during the growth cycle of four marine microalgae in order to establish which, if any, of these could act as a reliable source of genes for the metabolic engineering of long chain polyunsaturated fatty acid (LC-PUFA) synthesis in alternative production systems. A high-throughput column based method for extraction of triacylglycerols (TAGs) was used to establish how much and at what stage in the growth phase LC-PUFAs partition to storage lipid in the different species. Differences in the time course of production and incorporation of docosahexaenoic acid (22:6n-3, DHA) and eicosapentaenoic acid (20:5n-3, EPA) into TAGs were found in the marine microalgae Nannochloropsis oculata (Eustigmatophyceae), Phaeodactylum tricornutum and Thalassiosira pseudonana (Bacillariophyceae), and the Haptophyte Pavlova lutheri. Differences were not only observed between species but also during the different phases of growth within a species. A much higher percentage of the total cellular EPA was partitioned to TAGs in stationary phase cells of N. oculata compared to P. tricornutum. Although P. tricornutum produces DHA it does not partition it to TAGs. Both T. pseudonana and P. lutheri produce EPA and DHA and partition these to TAGs during the stationary phase of growth. These two species are therefore good candidates for further biochemical and molecular analysis, in order to understand and manipulate the processes that are responsible for the incorporation of LC-PUFAs into storage oils.

Proterozoic ocean chemistry and evolution: a bioinorganic bridge?

Recent data imply that for much of the Proterozoic Eon (2500 to 543 million years ago), Earth's oceans were moderately oxic at the surface and sulfidic at depth. Under these conditions, biologically important trace metals would have been scarce in most marine environments, potentially restricting the nitrogen cycle, affecting primary productivity, and limiting the ecological distribution of eukaryotic algae. Oceanic redox conditions and their bioinorganic consequences may thus help to explain observed patterns of Proterozoic evolution.