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Very large swarms of the red jellyfish Crambione mastigophora in north-western Australia disrupt swimming on tourist beaches causing economic impacts. In October 2012, jellyfish stranding on Cable Beach (density 2.20 ± 0.43 ind. m⁻²) was estimated at 52.8 million individuals or 14,172 t wet weight along 15 km of beach. Reports of strandings after this period and up to 250 km south of this location indicate even larger swarm biomass. Strandings of jellyfish were significantly associated with a 2-day lag in conditions of small tidal ranges (<5 m). More than 90% of strandings occurred 2 days after winds were blowing onshore, but with the small number of days when satellite wind data were available during the study period, this result was not statistically significant. Dedicated instrument measurements of meteorological parameters, rather than the indirect measures used in this study (satellite winds and modelled currents) may improve the predictability of such events and help authorities to plan for and manage swimming activity on beaches. We also show a high incidence of predation by C. mastigophora on bivalve larvae which may have a significant impact on the reproductive output of pearl oyster broodstock in the region.

Sphingolipids (SLs) are an integral part of all eukaryotic cellular membranes. In addition, they have indispensable functions as signalling molecules controlling a myriad of cellular events. Disruption of either the de novo synthesis or the degradation pathways has been shown to have detrimental effects. The earlier identification of selective inhibitors of fungal SL biosynthesis promised potent broad-spectrum anti-fungal agents, which later encouraged testing some of those agents against protozoan parasites. In this review we focus on the key enzymes of the SL de novo biosynthetic pathway in protozoan parasites of the Apicomplexa and Kinetoplastidae, outlining the divergence and interconnection between host and pathogen metabolism. The druggability of the SL biosynthesis is considered, alongside recent technology advances that will enable the dissection and analyses of this pathway in the parasitic protozoa. The future impact of these advances for the development of new therapeutics for both globally threatening and neglected infectious diseases is potentially profound.

Taxonomic studies, which lead to species identifications, provide a basis for the sustainable utilisation of marine living resources. In Sri Lanka, jellyfish resources are poorly investigated. Therefore, a gelatinous zooplankton survey was carried out from 2016 to 2020, and two edible species of scyphomedusae, viz. Crambione mastigophora and Rhopilema hispidum , which have not yet been commercially exploited in Sri Lanka, were identified and a detailed account of the morphological characteristics including detailed photographs of these two species is presented. Comparative morphological features of C. mastigophora , R. hispidum and their congeners from different geographic locations using data from historical studies are also presented, identifying potential fishing grounds in Sri Lankan waters. In this study, C. mastigophora was re-sampled after a century and R. hispidum was reported for the first time from Sri Lankan waters.

Three populations of Mastigophora diclados were collected from Mount Kinabalu, Mount Alab, and Mount Trus Madi. Each population yielded a total of four, four, and five secondary metabolites, respectively. A new compound, dicladoic acid (1) and the enantiomer of the known chlorantene G (8), along with six known compounds (2-7) were isolated from the MeOH extract of Bornean liverwort Mastigophora diclados. The structures of the novel metabolites were established by analyses of the spectroscopic data, including 1D NMR, 2D NMR, HRESIMS and IR. Isolated compounds shed some light into the chemosystematics of secondary metabolites in M. diclados. Herbertane-type sesquiterpenes were identified as the major metabolites in all three populations in Sabah and could be regarded as a suitable chemotaxonomical marker.

Antarctic pack ice is inhabited by a diverse and active microbial community reliant on nutrients for growth. Seeking patterns and overlooked processes, we performed a large-scale compilation of macro-nutrient data (hereafter termed nutrients) in Antarctic pack ice (306 ice-cores collected from 19 research cruises). Dissolved inorganic nitrogen and silicic acid concentrations change with time, as expected from a seasonally productive ecosystem. In winter, salinity-normalized nitrate and silicic acid concentrations (C*) in sea ice are close to seawater concentrations (Cw), indicating little or no biological activity. In spring, nitrate and silicic acid concentrations become partially depleted with respect to seawater (C* < Cw), commensurate with the seasonal build-up of ice microalgae promoted by increased insolation. Stronger and earlier nitrate than silicic acid consumption suggests that a significant fraction of the primary productivity in sea ice is sustained by flagellates. By both consuming and producing ammonium and nitrite, the microbial community maintains these nutrients at relatively low concentrations in spring. With the decrease in insolation beginning in late summer, dissolved inorganic nitrogen and silicic acid concentrations increase, indicating imbalance between their production (increasing or unchanged) and consumption (decreasing) in sea ice. Unlike the depleted concentrations of both nitrate and silicic acid from spring to summer, phosphate accumulates in sea ice (C* > Cw). The phosphate excess could be explained by a greater allocation to phosphorus-rich biomolecules during ice algal blooms coupled with convective loss of excess dissolved nitrogen, preferential remineralization of phosphorus, and/or phosphate adsorption onto metal-organic complexes. Ammonium also appears to be efficiently adsorbed onto organic matter, with likely consequences to nitrogen mobility and availability. This dataset supports the view that the sea ice microbial community is highly efficient at processing nutrients but with a dynamic quite different from that in oceanic surface waters calling for focused future investigations.

Since the first discovery of the very high virus abundance in marine environments, a number of researchers were fascinated with the world of \"marine viruses\", which had previously been mostly overlooked in studies on marine ecosystems. In the present paper, the possible role of viruses infecting marine eukaryotic microalgae is enlightened, especially summarizing the most up-to-the-minute information of marine viruses infecting bloom-forming dinoflagellates and diatoms. To author's knowledge, ~40 viruses infecting marine eukaryotic algae have been isolated and characterized to different extents. Among them, a double-stranded DNA (dsDNA) virus \"HcV\" and a single-stranded RNA (ssRNA) virus \"HeRNAV\" are the only dinoflagellate-infecting (lytic) viruses that were made into culture; their hosts are a bivalve-killing dinoflagellate Heterocapsa circularisquama. In this article, ecological relationship between H. circularisquama and its viruses is focused. On the other hand, several diatom-infecting viruses were recently isolated and partially characterized; among them, one is infectious to a pen-shaped bloom-forming diatom species Rhizosolenia setigera; some viruses are infectious to genus Chaetoceros which is one of the most abundant and diverse diatom group. Although the ecological relationships between diatoms and their viruses have not been sufficiently elucidated, viral infection is considered to be one of the significant factors affecting dynamics of diatoms in nature. Besides, both the dinoflagellate-infecting viruses and diatom-infecting viruses are so unique from the viewpoint of virus taxonomy; they are remarkably different from any other viruses ever reported. Studies on these viruses lead to an idea that ocean may be a treasury of novel viruses equipped with fascinating functions and ecological roles.

The Seto Inland Sea is the largest enclosed coastal sea in Japan and is also a major fishing ground including aquacultures of fish, bivalves and seaweeds. The incidents of red tides dramatically increased in frequency and scale in the Seto Inland Sea along with serious eutrophication in the 1960s and 1970s. The maximum incident of 299 was recorded in 1976, but the incident has since shown a clear decreasing trend reaching about 100 per year in the late 1980s by virtue of regulation by law, and this level has been maintained thereafter with the level of nutrients supporting red tide occurrences. The 'Law Concerning Special Measures for Conservation of the Environment of the Seto Inland Sea' was legislated in 1973 and industrial loading was decreased to half the level of 1972. The important red tide organisms causing huge fishery damages by fish-kill are Chattonella antiqua, C. marina, C. ovata and Heterosigma akashiwo (Raphidophyceae), and Karenia mikimotoi and Cochlodinium polykrikoides (Dinophyceae). The maximum fishery damage (death of 14.2 million yellowtails) was 7.1 billion yen (about US $60 million) caused by C. antiqua in Harima-Nada in 1972. In 1988, a novel red-tide dinoflagellate species Heterocapsa circularisquama appeared for the first time, and has repeatedly killed both natural and aquacultured bivalves, with the highest damage of 3.9 billion yen to cultured oysters in Hiroshima Bay in 1998.

Large rivers are often highly loaded with suspended particles, but the microbial metabolism related to these particles has rarely been studied. Hence, we investigated activities of the extracellular enzymes leucine aminopeptidase (LAP), phosphatase, beta -D-glucosidase and exo-1,4- beta -glucanase as well as microbial communities associated with suspended particles from the 8 super(th) order River Elbe, and their potential controls. Three fractions were investigated separately - rapidly sinking particles (largest particles), intermediately sinking particles (mediumsized particles), and bulk water including slowly sinking particles (smallest particles). Overall, bulk water had the highest abundances of bacteria, heterotrophic flagellates and ciliates. Extracellular enzyme activities per dry mass were also highest in bulk water, as 83-95 % of total bacteria occurred in this fraction. Medium-sized and large particles had lower enzyme activity per dry mass because of their smaller relative surface area and lower proportions of particulate organic carbon (POC) and particulate nitrogen (PN). Bulk water, the medium-sized and the largest particle fractions contributed 40-85 %, 5-20 % and 10-40 % to total enzyme activity per volume of river water, respectively. Leucine aminopeptidase exhibited its highest relative activity in bulk water, which also had the highest chlorophyll-a content. Cell-specific enzyme activities were generally correlated with the availability of particulate organic matter (POM) per bacterial cell and were therefore highest on medium and large-sized particles. These results indicate that the abundance and activity of attached bacteria were bottom-up controlled by the size and biochemical composition of the particles. However, bacterivorous flagellates and ciliates were abundant on the larger particles. Thus, number and feeding types of particle-attached protozoans suggest that top-down control may have occurred during an algal bloom. Our results show that free-living bacteria dominated the overall microbial metabolism of the water column in the River Elbe. However, bacteria attached to medium-sized and large particles were the most active ones, and contributed 15-58 % to total extracellular enzyme activity in the water column, depending an enzyme and season.

An investigation of the fatty acid composition of a natural arctic plankton community was carried out over two fishing banks located between 63 degree N and 65 degree N off the West Greenland coast. Samples for fatty acid analyses, species determination and biomass assessments of the plankton community were taken at the depth of fluorescence maximum. High biomass and diatom dominance during the spring bloom and low biomass and flagellate dominance in the post-bloom period were reflected by the fatty acid profiles. The total amount of fatty acid ranged from 55 to 132 mu g l super(-1) during the spring bloom and from 1 to 5 mu g l super(-1) during the post bloom. Analysis of the fatty acids showed that when the plankton was dominated by diatoms of the genera Thalassiosira and Chaetoceros, the proportions of C16:1(n-7) and C20:5(n-3) were correspondingly high. C18s, and particularly C18:1(n-9), were more abundant when the plankton was dominated by small autotrophic flagellates, primarily haptophytes. We found a good positive correlation between the common diatom marker, C16:1(n-7)/C16:0, and the biomass percentage of diatoms (r=0.742, P<0.001), as well as between the biomass percentage of flagellates and total C18 fatty acids (r=0.739, P<0.001). This supports the use of these specific fatty acids and fatty acid ratios as general biomarkers of the plankton community. However, the fatty acids are not specific enough to sufficiently characterise the composition of the plankton community, and microscopical support is needed to verify observed trends.

Two new genera in the Arthoniales are described from the Pacific Islands. Glyphopsis, with the new species G. aurantiodisca from New Caledonia is characterized by a thallus containing divaricatic acid and zeorin and sessile grouped ascomata with bright orange discs and raised lecanorine margins, and the ascospores hyaline and muriform. Gossypiothallon, with the new species G. appendisporum from the Solomon Islands is characterized by a byssoid thallus containing zeorin and pedicillate, simple ascomata with pale pink discs, without differentiated margins and hyaline, bacillar, 3-septate ascospores with two polar, usually curved gelatinous appendages. Eight further corticolous crustose lichens are described from either New Caledonia or the Solomon Islands. Byssoloma xanthonicum is characterized by a thallus containing norstictic acid and lichexanthone and 3-septate ascospores. Cliostomum ovocarpum has orange yellow, convex apothecia and 1-septate ascospores. Crocynia minutiloba has palmately branched lobes on a thick whitish byssoid hypothallus and flat lecideoid apothecia. Megalotremis dolabarata has superficial cylindrical grey pycnidia and simple ellipsoid conidia. Pyrenula filiformis has a thallus with pseudocyphellae covering most part of the ascomata and 11–17-septate, slender fusiform to slightly clavate ascospores. Pyrenula mastigophora has 5-septate ascospores with an up to 25 µm long tail at the lower end. Pyrenula spissitunicata has a thallus with lichexanthone, fused ascomata with common ostioles covered by thallus and ascospores resembling a Pyrgillus. The lichenicolous fungus Pyrenidium coccineum (parasitic on Siphula decumbens) has red ascomata which stain herbarium boxes blue.