Flagellate Species Research Articles

The influence of climate on phytoplankton community biomass in San Francisco Bay Estuary

The distribution of biomass within the phytoplankton community in northern San Francisco Bay Estuary was influenced by environmental conditions resulting from an interdecadal climate regime shift between 1975 and 1993. A decrease in percentage of diatom biovolume characterized the period 1975–1989 and was caused by both a decrease in diatom and an increase in green and bluegreen algae and flagellate species biovolume. Among the diatoms, there was a greater loss of pennate than centric diatoms. The direct role of climate variation on phytoplankton community biovolume was determined using climatically‐related environmental variation that was isolated from the total environmental variation using the covariance between a California climate index and a suite of physical and chemical variables and summarized by principal component analysis. Significant correlation between climatically‐related environmental variation and phytoplankton species and species group biovolume suggested a link between climate and the distribution of biovolume in the phytoplankton community. Further analysis of the possible mechanisms controlling the association between climatically‐related environmental variation and phytoplankton community biovolume confirmed the importance of water temperature, specific conductance, and water transparency to pennate diatom biovolume. Comparison of natural and anthropogenic processes indicated that diatom biovolume at each station was influenced by environmental conditions even though total diatom biovolume in the estuary was strongly influenced by water diversion.

The toxicity of the fungicide propiconazole to soil flagellates

We investigated the effects of the ergosterol-inhibiting fungicide, propiconazole {1-[[2-(2,4-dichlorphenyl) - 4 - propyl - 1,3 - dioxolan - 2 - yl]methyl] - 1H - 1,2,4 triazole; Tilt}, on mixed natural populations of bacterivorous and fungivorous flagellates in soil and on single species of bacterivorous flagellates in liquid culture. The fungicide affected a mixed natural population of fungivorous flagellates less than the population of bacterivorous flagellates. Our results indicated that the effects of propiconazole on flagellates are direct toxic effects and not effects mediated via their food. All tested types of flagellates were significantly harmed when exposed to the concentration of propiconazole normally applied to agricultural fields (625 mg l–1). However, when exposed to the concentration of propiconazole which we expect in the soil water phase after application (ca. 0.6 mg l–1) the effect on most of the tested flagellates was slight. Still, one tested flagellate species, Dimastigella trypaniformis, was extremely sensitive to the compound, and it is possible that field application of propiconazole has negative effects on certain sensitive species, and therefore alters the composition of the soil flagellate community in the direction of a higher r/K ratio.

Embryonic Development in Invertebrates Is Arrested by Inhibitory Compounds in Diatoms.

Phytoplankton blooms are known to induce diarrheic, neurotic, and paralytic shellfish poisoning in humans through the production of potent toxins by several dinoflagellate and flagellate species. Diatoms, another major component of the phytoplankton, have rarely been reported as toxic to marine organisms. But diatoms may be more insidious than is generally believed. High concentrations of domoic acid have been identified in Nitzschia pungens f. multiseries (Douglas and Bates, 1991), and recent studies indicate that several diatom species also contain antimitotic compounds inducing egg mortality in several invertebrates including crustaceans (several copepod species belonging to the genera Calanus, Centropages, Acartia, Eucyclops, Paracyclops,

Regulation of enzymatic activity: one possible role of dietary boron in higher animals and humans.

It is well established that vascular plants, diatoms, and some species of marine algal flagellates have acquired an absolute requirement for boron (B), although the primary role remains unknown. Discovery of naturally occurring organoboron compounds, all ionophoric macrodiolide antibiotics with a single B atom critical for activity, established at least one biochemical role of B. The unusual nature of B chemistry suggests the possibility of a variety of biological roles for B. At physiological concentrations and pH, B may react with one N group or one to four hydroxyl groups on specific biological ligands with suitable configuration and charge to form dissociable organoboron compounds or complexes. Suitable ligands include pyridine (e.g., NAD+ or NADP) or flavin (e.g., FAD) nucleotides and serine proteases (SP). B reacts with the cis adjacent hydroxyls on the ribosyl moiety of the nucleotides or, in the serine proteases, the N on the imidazole group of histidine or the hydroxyl group on the serine moiety. Reversible inhibition by B of activity of SP or oxidoreductases that require pyridine or flavin nucleotides is well known. Therefore, a proposed essential role for B is as a regulator of relevant pathways, including respiratory burst, that utilize these enzymes.

Diversity and Geographic Distribution of Free-Living Heterotrophic Flagellates – Analysis by PRIMER

Data on the distribution of approximately 350 species of heterotrophic flagellates (protozoa) in 31 communities from sites around the world - inclusive of marine and freshwater habitats, water column and benthic habitats, and 'extreme' (i.e. anoxic and hypersaline) habitats - are analysed by the Cluster algorithm in the PRIMER package. We have sought to minimise the impact of factors extrinsic to the actual distribution of organisms which may distort our perception of the geographic patchiness of organisms. In our analyses, communities from areas which are geographically close to each other do not cluster together. Communities from similar habitats cluster together (i.e., water column communities group together, as do benthic communities, or freshwater and marine communities), and communities from more unusual habitats segregate from those of less 'extreme' habitats. We argue that our capacity to draw robust conclusions on the distribution of these organisms is hampered by under-reporting. We favour a model in which there are relatively few species of free-living heterotrophic flagellates, and that most of these species have a cosmopolitan distribution.

Exotic flagellates of coastal North Sea waters

Flagellate species have been shown to survive transocean passage by ballast water and the large dinoflagellateGymnodinium catenatum was introduced from Japanese to Tasmanian waters in this way.Gymnodinium mikimotoi—better known asGyrodinium aureolum—andFibrocapsa japonica as well asAlexandrium leeii are good candidates to have been introduced recently. Species which seem to have been introduced recently into the North Sea but apparently are transported from adjacent seas by currents into the region areGymnodinium chlorophorum andAlexandrium minutum. Species reported as introduced due to misidentifications areGymnodinium catenatum andLepidodinium viride. Under other names the speciesProrocentrum minimum, Prorocentrum redfieldii, andHeterosigma akashiwo have been known for a long time in the North Sea. The recent reports of threeChattonella species may be either due to introduction or they have been overlooked. The reasons why the introduction of flagellates into coastal North Sea waters is difficult to prove will be discussed.

A survey of fungi which kill microscopic animals in the dung of the Amami rabbit

Dung of the early-evolved Amami rabbit of Japan was surveyed for the presence of fungi which attack microscopic organisms. Several species of predacious nematophagous fungi and species endoparasitic in nematodes and rotifers were found. In addition, zygomycetous species attacking amoebae and tardigrades, and one flagellate zoosporic species holocarpic in various host organisms, were found.

Protistan communities in aquifers: a review.

Eukaryotic microorganisms (protists) are a very important component of microbial communities inhabiting groundwater aquifers. This is not unexpected when one considers that many protists feed heterotrophically, by means of either phagotrophy (bacterivory) or osmotrophy. Protistan numbers are usually low (< 10(2) per g dw of aquifer material) in pristine, uncontaminated aquifers but may increase by several orders of magnitude in aquifers subject to organic pollution. Small flagellates (typically 2-3(5) microns in size in situ) are by far the dominant protists in aquifers, although amoebae and occasionally ciliates may also be present in much lower numbers. Although a wealth of new taxonomic information is waiting to be brought to light, interest in the identity of aquifer protists is not exclusively academic. If verified, the following hypotheses may prove to be important towards our understanding of the functioning of microbial communities in aquifers: (1) Differences in swimming behavior between species of flagellates lead to feeding heterogeneity and niche differentiation, implying that bacterivorous flagellates graze on different subsets of the bacterial community, and therefore play different roles in controlling bacterial densities. (2) Bacterivorous flagellates grazing on bacteria capable of degrading organic compounds have an indirect effect on the overall rates of biodegradation.

Protistan communities in aquifers: a review

Eukaryotic microorganisms (protists) are a very important component of microbial communities inhabiting groundwater aquifers. This is not unexpected when one considers that many protists feed heterotrophically, by means of either phagotrophy (bacterivory) or osmotrophy. Protistan numbers are usually low (<10 2 per g dw of aquifer material) in pristine, uncontaminated aquifers but may increase by several orders of magnitude in aquifers subject to organic pollution. Small flagellates (typically 2–3(5) μm in size in situ) are by far the dominant protists in aquifers, although amoebae and occasionally ciliates may also be present in much lower numbers. Although a wealth of new taxonomic information is waiting to be brought to light, interest in the identity of aquifer protists is not exclusively academic. If verified, the following hypotheses may prove to be important towards our understanding of the functioning of microbial communities in aquifers: (1) Differences in swimming behavior between species of flagellates lead to feeding heterogeneity and niche differentiation, implying that bacterivorous flagellates graze on different subsets of the bacterial community, and therefore play different roles in controlling bacterial densities. (2) Bacterivorous flagellates grazing on bacteria capable of degrading organic compounds have an indirect effect on the overall rates of biodegradation.

Harmful algal blooms: Their ecophysiology and general relevance to phytoplankton blooms in the sea

From 60 to 80 species of phytoplankton have been reported to be harmful; of these, 90% are flagellates, notably dinoflagellates. The effects of turbulence on harmful algal bloom (HAB) taxa, their photoadaptive strategies, growth rate, and nutrient uptake affinity (Ks) are considered. Flagellates, including HAB taxa, collectively have a lower nutrient uptake affinity than diatoms. Four major adaptations are suggested to have been evolved to offset the ecological disadvantages of their low nutrient affinity: nutrient retrieval migrations; mixotrophic tendencies; alle‐lelochemically enhanced interspecific competition; and allelopathic, antipredation defense mechanisms. Motility‐based behavioral features of flagellates contributing to their blooms include: phototaxis, vertical migration, pattern swimming, and aggregation, which facilitate nutrient retrieval, trace metal detoxification, antipredation, depth‐keeping, and turbulence avoidance. Neither a general physiological syndrome nor distinctive physiological profile distinguishes harmful flagellate species from nonharmful taxa. However, HAB flagellates exhibit significant ecophysiological differences when compared to diatoms, including greater biophysical vulnerability to turbulence, greater bloom dependence on water‐mass stratification, greater nutritional diversity involving mixotrophic tendencies, greater potential use of allelochemical mechanisms in interspecific competition and antipredation defenses, and unique behaviorial consequences of their motility. Flagellates use a “swim” strategy; diatoms a “sink” strategy.

Fluorescent oligonucleotide rDNA probes that specifically bind to a common nanoflagellate, Paraphysomonas vestita.

Nanoflagellates are ecologically important, but morphological identification requires techniques which are not practicable for use in quantitative studies of populations; alternative methods of accurate recognition of nanoflagellate species in mixed populations are therefore desirable. Fluorescent oligonucleotide probes which hybridize with unique sequences of the small subunit (SSU) rRNA have been exploited as 'phylogenetic stains' in the identification of bacteria. In this paper we describe the preparation and application of probes which specifically hybridize with a common nanoflagellate species, Paraphysomonas vestita. The sequence of nucleotides in the SSU rRNA gene of this flagellate was determined and compared with those of related species to select unique P. vestita sequences 18-21 nucleotides in length. Five sequences in different parts of the SSU rRNA gene were used to design 5'-fluorescently labelled oligonucleotide probes. Published sequences were used to make probes that hybridized with all eukaryotes (EUK) or any cellular organism (UNI), and probes were designed not to hybridize with rRNA (CON). Optimum conditions for hybridization were determined. In all cases, UNI probes hybridized with the cells, but CON probes were only bound to a limited extent. All five probes targeted to P. vestita proved to be species-specific; they hybridized well with this species, but not with three other species of the same genus, nor with three more distantly related flagellate species, nor with a ciliate, nor with bacteria. These probes provide a means of quantitatively measuring the proportion of P. vestita cells in samples of mixed protists.

Preingestive selection of different microalgal mixtures in Crassostrea gigas and Mytilus edulis, analysed by flow cytometry

The potential impact of selective grazing by filter-feeding bivalves was studied on the relative composition of both planktonic and benthic algae that are commonly suspended in coastal areas. Different feeding behaviour was observed in the oyster Crassostrea gigas and the mussel Mytilus edulis. C. gigas preferentially filtered and rejected (as pseudofaeces prior to ingestion) diatom species relative to flagellates. These differences appear to depend upon differences in algal shape and flexibility. Findings also suggest that ratios of rejection to filtration for flagellate species were influenced by the planktonic or benthic origin of the other available algal species. Future studies of trophic flux and resource utilisation should therefore consider the extent to which different filter-feeding species may preferentially filter and/or ingest separate algal species that are simultaneously available in the surrounding seston.

The microbial plankton of Lake Fryxell, southern Victoria Land, Antarctica during the summers of 1992 and 1994

Samples collected from Lake Fryxell, southern Victoria Land, Antarctica in January 1992 and 1994 were analysed for the abundance of bacterioplankton and the diversity and abundance of protistan plankton. At the times of sampling, 14 ciliate species and 10 species of autotrophic flagellate were recorded. The samples contained two species of rotifer (Philodina spp.), which formed the first record of planktonic metazoans in the Dry Valley lakes of this region of Antarctica. Bacterial concentrations ranged between 1.0 and 3.8×108 l-1 in the upper oxic waters increasing to 20×108 l-1 in the anoxic waters. Heterotrophic flagellates decreased in abundance down the oxygenated water column, disappearing completely at 9 m, and ranged between 0.28 and 7.39×105 l-1 in abundance. Autotrophic flagellates were much more abundant exhibiting a number of distinct peaks down the water column (1.89–25.3×108 l-1). The ciliated protozoa were very abundant (up to 7720 l-1) in relation to flagellate and bacterial numbers, typical of oligotrophic lakes world-wide. The distribution of the protistan plankton showed marked zonation, probably in response to the differing salinity and temperature gradients in the water column. Possible trophic interactions are discussed and comparisons with other continental Antarctic lakes made.

New Species of Pigmented Flagellates from Southeastern Brazil

Summary: Three pigmented flagellates: Gloeomonas mamillosa, Lobomonas tubulata (Chlamydomonadales, Chlorophyceae) and Strombomonas quadrangularis (Euglenales, Euglenophyceae) are described as new taxa from material collected in two freshwater bodies located in the Municipality of Rio de Janeiro, Rio de Janeiro State, southeastern Brazil.

Heterotrophic Flagellates from Coral Reef Sediments (Great Barrier Reef, Australia)

Summary Heterotrophic flagellates were identified from the littoral sediments of One Tree Island (Great Barrier Reef, Australia) by light microscopy. A total of 37 species are described of which 3 are new to science. The new species are: Peranema macrostoma, Ploeotia plumosa , and Anehmia exotica , the latter also representing a new genus. One species previously described as Percolomonas membranifera was assigned to a new genus Carpediemonas . The similarities of the species composition from One Tree Island and other locations world-wide were compared using the program PRIMER. The community from One Tree Island shows considerable overlap from other marine benthic sites world-wide. Communities from littoral benthic sites form a cluster separate from pelagic communities — although there is considerable overlap in the species of smaller heterotrophic and/or bacterivorous flagellates. Most species from the benthic community of heterotrophic flagellates appear to have a world-wide distribution, and there is little evidence of endemism.

Biochemical effects of physiological amounts of dietary boron

Research on human and animal boron nutrition has progressed sufficiently over the past decade to develop working hypotheses for biochemical roles of the element. It is well established that vascular plants, diatoms, and some species of marine algal flagellates have acquired an absolute requirement for boron although the primary role remains unknown. Discovery of naturally-occurring boron oxy compounds, all ionophoric macrodiolide antibiotics with a single boron atom critical for activity, established at least one biochemical role of boron. Recent findings suggest that physiological amounts of supplemental dietary boron (PSB) affect a wide range of metabolic parameters in chick and rat model systems as well as humans. Cholecalciferol (vitamin D3) regulates energy substrate utilization; current findings indicate that boron modifies that regulatory function. For example, in chicks, PSB substantially corrected vitamin D3-deficiency-induced elevations in plasma glucose concentrations. Boron also alleviates perturbations in mineral metabolism characteristic of vitamin D3 deficiency. In rachitic chicks, PSB alleviated distortion of the marrow sprouts in the proximal tibial epiphysial plate. Boron may help prevent inflammatory disease as several key regulatory enzymes in the inflammatory response are inhibited by PSB. The findings to date support the hypothesis that boron is essential for animals and humans. Also, boron and vitamin D3 have the same overall effect on the utilization of energy substrates found in plasma. Further advances in boron nutrition research will probably include characterization of the mechanisms through which boron modulates immune function, insulin release, and vitamin D metabolism. © 1997 Wiley-Liss, Inc.

Regeneration of phosphorus and nitrogen by four species of heterotrophic nanoflagellates feeding on three nutritional States of a single bacterial strain

Three physiological states of a single bacterial strain, namely, balanced, phosphorus-rich, and nitrogen-rich bacteria, were obtained by culturing a bacterial strain in chemostats under three different nutrient regimens. Each was shown to be distinctly different in elemental composition with respect to C/N/P ratio. These bacteria were fed to four species of heterotrophic nanoflagellates in batch culture grazing experiments, and the percent regeneration efficiencies of bacterium-bound nitrogen and phosphorus by the flagellates were compared. All flagellate species regenerated comparable amounts of nitrogen, which was thought to be due to their similar internal C/N ratios. There was, however, interspecies variation with regard to phosphorus regeneration: the two faster-growing species (Paraphysomonas imperforata and Bodo designis) released significantly more phosphorus than the two slower-growing species (Stephanoeca diplocostata and Jakoba libera). The observed differences were thought to have been influenced by a combination of life cycle strategies and internal C/P ratios.

Competition for ammonium between plant roots and nitrifying and heterotrophic bacteria and the effects of protozoan grazing

The competition for limiting amounts of ammonium between the chemolithotrophic ammonium-oxidizing species Nitrosomonas europaea, the heterotrophic species Arthrobacter globiformis and roots of Plantago lanceolata (Ribwort plantain) was studied in a series of model systems of increasing complexity, i.e. energy-limited continuous cultures, non-water-saturated continuously percolated soil columns and pots with γ-sterilized soil planted with axetic P. lanceolata seedlings. The effects of bacterial grazing by the flagellate species Adriamonas peritocrescens on the competition for ammonium were also investigated in the three model systems. It was found that N. europaea was a weaker competitor for ammonium than either A. globiformis or plant roots of P. lanceolata. It is assumed that the heterotrophic bacteria have a higher affinity for ammonium than the nitrifying bacteria, whereas growing plant roots have a greater capacity to exploit the soil for ammonium than the immobile nitrifying bacteria. It is not very likely that allelochemicals were involved in suppressing the nitrification process. Four reasons are given for this assumption. Presence of the flagellates strongly stimulated the potential nitrification rate in all model systems. It is assumed that there is a more even distribution over the soil of either nitrifying bacteria or their substrate ammonium in the presence of flagellates. In addition to the distribution effect, there is a stimulation of the potential ammonium oxidation rate. The results are discussed in the light of the function of nitrate as nitrogen sink in the biogeochemical nitrogen cycle.

The biochemical effects of physiologic amounts of dietary boron in animal nutrition models.

This review summarizes evidence that supports working hypotheses for the roles of boron in animal model systems. It is well established that vascular plants, diatoms, and some species of marine algal flagellates have acquired an absolute requirement for boron, although the primary role of boron in plants remains unknown. Recent research findings suggest that physiologic amounts of supplemental dietary boron (PSB) affect a wide range of metabolic parameters in the chick and rat model systems. Much of the current interest in boron animal nutrition began with the initial finding that PSB stimulates growth in cholecalciferol (vitamin D3)-deficient chicks, but does not markedly affect growth in chicks receiving adequate vitamin D3 nutriture. The finding suggests that boron affects some aspect of vitamin D3 metabolism or is synergistic with vitamin D3 in influencing growth. Vitamin D3 regulates energy substrate utilization, and current research findings indicate that dietary boron modifies that regulatory function. The concentration of circulating glucose, the most thoroughly investigated metabolite to date, responds to PSB, especially during concomitant vitamin D3 deficiency. In chicks, PSB substantially alleviated or corrected vitamin D3 deficiency-induced elevations in plasma glucose concentrations. The influence of vitamin D3 on cartilage and bone mineralization is mediated in part through its role as a regulator of energy substrate utilization; calcification is an energy-intensive process. There is considerable evidence that dietary boron alleviates perturbations in mineral metabolism that are characteristic of vitamin D3 deficiency. In rachitic chicks, PSB alleviated distortion of the marrow sprouts of the proximal tibial epiphysial plate, a distortion characteristic of vitamin D3 deficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Ecological Study of Spring-Early Summer Phytoplankton Blooms in A Semi-Enclosed Estuary

Abstract A sampling station in the Eastern Harbour of Alexandria was operated for 51 days between 2 March and 12 June, 1991. the harbour had different wide physical and chemical variations. Six distinct phytoplankton blooms occurred during this period. It is concluded that the physicochemical conditions affected the phytoplankton community structure and species composition. A dense diatom bloom could be maintained in a very weak and/or stabilized water column. A diatom bloom does not necessarily accompany an enhanced nutrient period. the depletion of nutrients and establishment of thermal stratification probably created favourable conditions for dinoflagellate and flagellate species to achieve blooms. the species composition could be shifted over the short term and a dense phytoplankton bloom could possibly dissipate in a few days.