Showing papers in "Botanica Marina in 2017"

Seaweed reproductive biology: environmental and genetic controls

Abstract: Knowledge of life cycle progression and reproduction of seaweeds transcends pure academic interest. Successful and sustainable seaweed exploitation and domestication will indeed require excellent control of the factors controlling growth and reproduction. The relative dominance of the ploidy-phases and their respective morphologies, however, display tremendous diversity. Consequently, the ecological and endogenous factors controlling life cycles are likely to be equally varied. A vast number of research papers addressing theoretical, ecological and physiological aspects of reproduction have been published over the years. Here, we review the current knowledge on reproductive strategies, trade-offs of reproductive effort in natural populations, and the environmental and endogenous factors controlling reproduction. Given that the majority of ecophysiological studies predate the "-omics" era, we examine the extent to which this knowledge of reproduction has been, or can be, applied to further our knowledge of life cycle control in seaweeds.

Arctic marine fungi: from filaments and flagella to operational taxonomic units and beyond

Abstract: Abstract Fungi have evolved mechanisms to function in the harsh conditions of the Arctic Ocean and its adjacent seas. Despite the ecological and industrial potential of these fungi and the unique species discovered in the cold seas, Arctic marine fungi remain poorly characterised, with only 33 publications available to date. In this review, we present a list of 100 morphologically identified species of marine fungi detected in the Arctic. Independent molecular studies, applying Sanger or high-throughput sequencing (HTS), have detected hundreds of fungal operational taxonomic units (OTUs) in single substrates, with no evidence for decreased richness of marine fungi towards northern latitudes. The dominant fungal phyla may be substrate-specific, as sea-ice and seawater seem to host more Chytridiomycota and Basidiomycota than Ascomycota-dominated driftwood and sediments. Molecular studies have revealed the presence of the Chytridiomycota and Leotiomycetes in Arctic waters, with mounting evidence suggesting a significant role in nutrient and carbon cycling. The high detection frequency of Leotiomycetes is partly due to OTUs from marine Cadophora (Helotiales) that are indistinct from terrestrial strains. Knowledge of Arctic marine fungi has rapidly increased in recent years. Nevertheless, some bottlenecks, such as limited OTU identification persist and more researchers are encouraged to join the study of Arctic marine fungi.

Interactions of daylength, temperature and nutrients affect thresholds for life stage transitions in the kelp Laminaria digitata (Phaeophyceae)

Abstract: Kelp beds worldwide are under pressure from ongoing climate and environmental change. Along European coastlines increases in seawater temperature and changes in nutrient conditions occur where upwelling events are disrupted and also along eutrophicated coasts. In addition, seaweed responses to change may interact with seasonal daylength cycles. We performed a factorial experiment to examine the combined effects of seawater temperatures, nutrient regimes, and photoperiod (long and short days) in order to better understand how latitudinal or seasonal differences in daylengths affects the sensitivity of transient microscopic kelp stages of Laminaria digitata from the North Sea, to warming and eutrophication. While the optimal temperature range for vegetative gametophyte growth was 10-18oC under long summer photoperiod conditions, gametogenesis was induced at lower temperatures between 5 and 15oC, with maximum sporophyte development under long photoperiods and enriched nutrient regimes, which represents local late spring conditions. Although gametogenesis was fastest at 10-15oC, sporophyte recruitment was highest at 5oC. As these particular early life cycle processes in L. digitata have different temperature optima, this may drive the seasonal cycle of recruitment in the field. Increasing summer temperatures due to global warming will increase gametophyte size due to enhanced vegetative growth and inhibition of gametogenesis. This will probably lead to delayed but enhanced recruitment of new sporophytes under cooler autumn to spring conditions over a wide geographical scale, preventing the formation of juvenile sporophytes under stressful summer conditions and possibly changing annual recruitment patterns.

Morphogenesis of Ulva mutabilis (Chlorophyta) induced by Maribacter species (Bacteroidetes, Flavobacteriaceae)

Abstract: Growth and morphogenesis of the sea lettuce Ulva (Chlorophyta) depends on the combination of regulative morphogenetic compounds released by specific associated bacteria. Axenic Ulva gametes develop parthenogenetically into callus-like colonies consisting of undifferentiated cells without normal cell walls. In Ulva mutabilis Foyn, two bacterial strains, Maribacter sp. strain MS6 and Roseovarius strain MS2, can restore the complete algal morphogenesis forming a tripartite symbiotic community. Morphogenetic compounds (=morphogens) released by the MS6-strain induce rhizoid formation and cell wall development in U. mutabilis, while several bacteria of the Roseobacter clade, including the MS2-strain, promote blade cell division and thallus elongation. In this study, 12 type strains of the Flavobacteriaceae family, including six Maribacter strains, were examined for their morphogenetic activity in comparison to the original MS6-strain isolated from U. mutabilis. The bioassay is based on the functional complementation of the tested Flavobacteriaceae strain with the Roseovarius MS2-strain. If the test-strain possesses morphogenetic activity complementary to the factor of the MS2-strain, the complete morphogenesis of U. mutabilis can be restored. This bioassay revealed not only the stand-alone activity of certain bacteria, but also their essential capability to take part in the orchestrated bacteria-induced morphogenesis of U. mutabilis. All Maribacter type strains isolated from Ulva could phenocopy the MS6-strain, whereas some distantly related Flavobacteriaceae and a Maribacter strain isolated from a red alga did not possess any activity.

Red algal parasites: a synopsis of described species, their hosts, distinguishing characters and areas for continued research

Abstract: © 2017 Walter de Gruyter GmbH, Berlin/Boston. Red algal parasites are diverse organisms that are unusual due to the fact that many are closely related to their hosts. Parasitism has developed many times within different red algal groups, but the full extent of parasite biodiversity is unknown, as parasites are easily overlooked due to their small size and often low abundance. Additionally, the literature on red algal parasites is dispersed and has not been compiled in over 30 years. Although criteria have been proposed to define what constitutes a red algal parasite, many parasites are poorly described, and the cellular interactions with their host are poorly known. A few studies have demonstrated that parasites transfer organelles to host cells, which can alter the physiology of the host to the benefit of the parasite. Here, we apply a set of defining criteria for parasites to a compiled list of all described red algal parasites. Our results highlight the lack of knowledge of many key parasitic processes including early parasite development, host cell "control", and parasite origin. Until the biology of more parasites is studied, generalisations on the processes of parasitism in red algae may be premature. We hope this synopsis will stimulate research into this fascinating group.

Seasonal variations of Fucus vesiculosus fertility under ocean acidification and warming in the western Baltic Sea

Abstract: Ocean warming and acidification may substantially affect the reproduction of keystone species such as Fucus vesiculosus (Phaeophyceae) In four consecutive benthic mesocosm experiments, we compared the reproductive biology and quantified the temporal development of Baltic Sea Fucus fertility under the single and combined impact of elevated seawater temperature and pCO2 (1100 ppm) In an additional experiment, we investigated the impact of temperature (0–25°C) on the maturation of North Sea F vesiculosus receptacles A marked seasonal reproductive cycle of F vesiculosus became apparent in the course of 1 year The first appearance of receptacles on vegetative apices and the further development of immature receptacles of F vesiculosus in autumn were unaffected by warming or elevated pCO2 During winter, elevated pCO2 in both ambient and warmed temperatures increased the proportion of mature receptacles significantly In spring, warming and, to a lesser extent, elevated pCO2 accelerated the maturation of receptacles and advanced the release of gametes by up to 2 weeks Likewise, in the laboratory, maturation and gamete release were accelerated at 15–25°C relative to colder temperatures In summary, elevated pCO2 and/or warming do not influence receptacle appearance in autumn, but do accelerate the maturation process during spring, resulting in earlier gamete release Temperature and, to a much lesser extent, pCO2 affect the temporal development of Fucus fertility Thus, rising temperatures will mainly shift or disturb the phenology of F vesiculosus in spring and summer, which may alter and/or hamper its ecological functions in shallow coastal ecosystems of the Baltic Sea

New saprobic marine fungi and a new combination

Abstract: Abstract This paper documents five new saprobic marine fungi occurring on various substrata in the marine environment. Bacusphaeria nypae gen. et sp. nov. was discovered on bases of fronds of Nypa fruticans in Malaysia and phylogenetically, it belongs to the Tirisporellaceae (Tirisporellales, Diaporthomycetidae, Sordariomycetes) based on 18S and 28S rDNA. Cryptovalsa avicenniae, Ceriosporopsis minuta and Jattaea mucronata also belong to the Sordariomycetes; Cr. avicenniae was saprobic on Avicennia marina collected in Saudi Arabia, J. mucronata on intertidal decaying bark of Rhizophora mucronata while Ce. minuta was found on driftwood collected on a sandy beach in Japan. Phylogeny based on 18S and 28S rDNA placed Cr. avicenniae with other Cryptovalsa species in the Diatrypaceae. Jattaea mucronata groups well in the Calosphaeriales and is closely related to J. algeriensis based on a phylogeny using ITS and 28S rRNA and RPB2 genes. Aegeanispora elanii gen. et sp. nov. is an asexual fungus which produces pycnidia on decaying driftwood collected in the Aegean Sea. Combined 18S and 28S rDNA phylogenetic analyses suggest that it is a member of the Pleosporales, Dothideomycetes. Ceriosporopsis minuta resembles C. capillacea with its tubular, long polar appendages of ascospores but dimensions of ascomata and ascospores for the former species are considerably smaller. Ceriosporopsis is considered the best genus to accommodate C. minuta without support from sequence data. Sammeyersia is established as a new genus to accommodate Lulworthia grandispora, a species unrelated to Lulworthia fucicola, the type species. The diagnostic characteristic for the genus is a melanized region at the base of the neck of the ascomata.

Phytohormones in red seaweeds: a technical review of methods for analysis and a consideration of genomic data

Abstract: Abstract Emerging studies suggest that seaweeds contain phytohormones; however, their chemical entities, biosynthetic pathways, signal transduction mechanisms, and physiological roles are poorly understood. Until recently, it was difficult to conduct comprehensive analysis of phytohormones in seaweeds because of the interfering effects of cellular constituents on fine quantification. In this review, we discuss the details of the latest method allowing simultaneous profiling of multiple phytohormones in red seaweeds, while avoiding the effects of cellular factors. Recent studies have confirmed the presence of indole-3-acetic acid (IAA), N6-(Δ2-isopentenyl)adenine (iP), (+)-abscisic acid (ABA), and salicylic acid, but not of gibberellins and jasmonate, in Pyropia yezoensis and Bangia fuscopurpurea. In addition, an in silico genome-wide homology search indicated that red seaweeds synthesize iP and ABA via pathways similar to those in terrestrial plants, although genes homologous to those involved in IAA biosynthesis in terrestrial plants were not found, suggesting the epiphytic origin of IAA. It is noteworthy that these seaweeds also lack homologues of known factors involved in the perception and signal transduction of IAA, iP, and ABA. Thus, the modes of action of these phytohormones in red seaweeds are unexpectedly dissimilar to those in terrestrial plants.

Isolation, fatty acid profiles and cryopreservation of marine thraustochytrids from mangrove habitats in Thailand

Abstract: Abstract Thraustochytrids, marine protists, have attracted attention as a proven alternative source of polyunsaturated fatty acids (PUFAs). We isolated a high diversity of thraustochytrids from Thailand and tested their potential use in the production of high-value fatty acids. The isolated thraustochytrids can be categorized into seven major groups based on unique morphological features, molecular phylogeny and fatty acid profiles. Two of the seven isolated thraustochytrid groups could potentially be new lineages in the Labyrinthulomycetes. The production of total fatty acid (TFA) from these thraustochytrids ranged from 2.4 to 35.6% (w/w), with biomass varying from 0.3 to 8.9 g l−1. The production of arachidonic acid (C20:4) ranged from 0.3 to 8.2% of TFA, eicosapentaenoic acid (C20:5) from 1.5 to 12.4%, docosapentaenoic acid (C22:5) from 9.7 to 27.3%, and docosahexaenoic acid (C22:6) from 14.4 to 51.7%. In addition, the cryopreservation of selected thraustochytrids at −80°C with 10% glycerol, the combination of 5% trehalose and 10% glycerol, and freezing in vapor-phase liquid nitrogen were found to maintain significant cell viability. The information provided in this study could be applied to cryopreservation and biotechnological applications of the economically valuable marine Labyrinthulomycetes from Thailand.

Phylogenetic community structure of fungal endophytes in seagrass species

Abstract: Abstract A total of 81 fungal endophytes were isolated from four seagrass species: Cymodocea serrulata, Enhalus acoroides, Halophila ovalis and Thalassia hemprichii obtained from southern Thailand. Isolates were identified through phylogenetic analyses of the nuclear ribosomal (r) DNA sequences. The majority of isolates belonged to three fungal classes in the Pezizomycotina: Sordariomycetes (55.6%), Dothideomycetes (38.3%) and Eurotiomycetes (4.9%). One isolate (1.2%) was identified in the Saccharomycetes. All Pezizomycotina isolates were placed among clades of terrestrial fungi known to be fungal endophytes in terrestrial ecosystems, and no isolates were classified among known marine lineages. Phylogenetic community structure analyses revealed differences among the four-co-occurring species of seagrasses. Cymodocea serrulata displayed the lowest phylogenetic diversity (PD) as compared to the other three host species. Endophytic communities of E. acoroides mainly clustered within the Sordariomycetes, while Sordariomycetes and Dothideomycetes were equally dominant as endophytes of T. hemprichii and H. ovalis.

Two new epizoic Achnanthes species (Bacillariophyta) living on marine turtles from Costa Rica

Abstract: Abstract It has been known for a long time that marine mammals, such as whales and dolphins, host a very specific epizoic community on their skin. Whether or not a similar community exists on the carapaces of sea turtles is less studied. The present paper describes two new epizoic diatoms from the genus Achnanthes sensu stricto, Achnanthes elongata and Achnanthes squaliformis, found on the carapaces of nesting olive ridley sea turtles (Lepidochelys olivacea) in Ostional Beach on the Pacific coast of Costa Rica, based upon detailed scanning electron microscopy and comparison with the type material of Achnanthes groenlandica var. phinneyi and Achnanthes pseudogroenlandica. The two taxa appear to be closely related on the basis of their morphological features including long, slender valves, absence of terminal orbiculi, large cribrate areolae and absence of typical costae on the internal virgae of both valves. They can, however, be differentiated from each other by the number of areolae per stria, the position of the rapheless sternum and differences in their length/width ratio.

Recent advances in marine mycology

Abstract: The previous special issue of Botanica Marina on Marine Mycology was published in 2010 (Jones and Pang 2010), when the number of known marine fungi was 530 species (Jones et al. 2009). Jones et al. (2015) updated this figure to 1112 species (in 472 genera), which included newly described taxa, with the inclusion of the Chytridiomycota, marine yeasts and a broader definition of what constitutes a marine fungus (Pang et al. 2016). The documentation of new marine fungi and new records brings the current total to 1206 (www.marinefungi.org, 2017). Jones (2011) regarded these figures as an underestimate and suggested there may be as many as 10,000 marine fungi, indicating where these missing fungi might be found. However, controversy surrounds the diversity of marine fungi with Richards et al. (2012) concluding that fungi are low in both diversity and abundance in marine environments. They questioned “Are we overlooking a large diversity of fungi?” Furthermore, Tisthammer et al. (2016) stated that very little is known about the global distribution of marine fungi and that marine fungi are understudied when compared to other microorganisms. Marine fungi are heterotrophic organisms, relying on degrading organic substrates for growth and reproduction, including plant-based substrata, macroalgae, animal remains (Vrijmoed 2000). These substrates are abundant in coastal environments and, therefore, research on marine fungi has been mainly focussed on fungi fruiting on substrata in these environments, where they play a significant role in nutrient cycling (Pang et al. 2016). Recent culture-independent analyses of fungal sequencing obtained from seawater and sediment samples have revealed a high abundance/richness of sequences related to the Ascomycota and the Basidiomycota and possible new lineages of fungi early in the evolution of Fungi using different regions of the ribosomal RNA genes (Richards et al. 2015, Picard 2016, Hasset et al. 2017). Interpretation of the results from molecular studies has to be cautious. Seawater is a dispersal medium, not a growth substrate, while sediment represents a niche for accumulation of fungal propagules. Fungi in these substrates may not represent the active marine populations as many fungal propagules may be of freshwater/terrestrial origin. Using RNA-tag sequencing and fluorescent staining of samples, Richards et al. (2015) found low fungal abundance in upper seawater column samples. This is not surprising as low organic matter in seawater does not support a stable population of fungi; the exceptions are those that occur on phytoplankton. Also, recent molecular studies have repeatedly discovered the dominance of the Ascomycota and the Basidiomycota in seawater/sediments, without acknowledging the individual species, thus making comparisons between different studies difficult (Jones et al. 2015, Richards et al. 2015, Picard 2016, Hasset et al. 2017). There is therefore a gulf in appreciation about what is known about marine fungi using three approaches in their documentation: (a) substrate based studies, (b) isolation from seawater and (c) DNA sampling of water, sediments, often at great depths in the ocean. Although marine fungi are worldwide in their distribution, there are great differences in their diversity in tropical, temperate and cold water habitats. Culture-independent studies have been used only recently to study the diversity of marine fungi and much greater sampling is required to obtain a full picture of their occurrence and distribution. Another area that requires greater study is the much-neglected documentation of parasitic fungi and fungal-like organisms parasitizing plankton and marine invertebrates. This may be attributed to the lack of fresh material of epizootics and the techniques available for their study. This special issue has gathered up active marine mycologists to give updates on marine mycology in the areas related to ecology, phylogeny, pathology and applied aspects. They have also highlighted the gaps of knowledge in marine mycology, suggesting further work in ecologically and industrially important but understudied groups of fungi. The recent research effort in Taiwan, the Middle East, Thailand and Arctic areas has increased our understanding of the diversity of marine fungi in these regions. In this special issue, Suetrong et al. report the diversity of marine fungi in eastern and southern Thai mangroves, while Räma et al. have prepared a list of marine fungi in the Arctic region. Supaphon et al. have investigated the phylogenetic diversity of fungi associated with a few seagrass species collected in Thailand. Exploration of wider geographical locations always results in new marine fungi. Abdel-Wahab et al. report five new marine fungi collected

Implications of rising temperatures for gametophyte performance of two kelp species from Arctic waters

Abstract: The aim of this study was to determine the temperature effects on photosynthesis, growth and reproduction in gametophytes of Alaria esculenta (Linnaeus) Greville and Saccharina latissima (Linnaeus) C. E. Lane, C. Mayes, Druehl et G. W. Saunders from the Artic waters. After 24 days of culture, no gametophytes of either species survived at 20 degrees C. Most growth parameters were greater at 10-15 degrees C than at 5 degrees C. Length and width were similar for both species, but area was greater for A. esculenta and cell number was greater for S. latissima. Female gametophytes were larger than male gametophytes in width and area, but the opposite was observed in cell number. In A. esculenta, but not for S. latissima, the percentage of female gametophytes decreased with increasing temperature. Alaria esculenta female gametophytes produced more sporophytes at 5 degrees C than at 10 degrees C, with no sporophytes at 15 degrees C. In S. latissima, all female gametophytes produced sporophytes at both 5 degrees C and 10 degrees C, with a small percentage of sporophytes at 15 degrees C. Saccharina latissima still had a measurable F v/F m at 20 degrees C, while the F v/F m of A. esculenta was zero at this temperature. Maximum relative electron transport rate (rETR(max)) and non-photochemical quenching (NPQ) were constant in the male and female gametophytes of A. esculenta and the male gametophytes of S. latissima at temperatures between 5 degrees C and 15 degrees C. Photosynthesis was saturated at a higher irradiance in A. esculenta than in S. latissima.

Seasonal variation and yield of sulfated polysaccharides in seaweeds from the Venice Lagoon

Abstract: Abstract Three red seaweeds from the Venice Lagoon: Gracilaria gracilis, Gracilaria vermiculophylla, Gracilariopsis longissima and the green seaweed Ulva rigida were investigated to determine the yields and the annual fluctuation of sulfated polysaccharides (SP) for biotechnological applications. The Gracilariaceae and U. rigida were investigated and evaluated taking into account various environmental parameters of the water column and surface sediments. The annual production of SP was the highest for G. longissima (13.2 tons dw ha−1 year−1), followed by G. vermiculophylla (11.4 tons dw ha−1 year−1) and G. gracilis (7.4 tons dw ha−1 year−1), whereas U. rigida showed the lowest production (2.7 tons dw ha−1 year−1). High nutrient availability, turbidity and phytoplankton blooms inhibited the production of SP in the red seaweeds especially in summer. The SP produced by Gracilariaceae in March and April, at water temperatures ranging between 13°C and 17°C, accounted for more than half of the total annual production. In contrast, U. rigida produced the highest quantity of SP (ulvan) in June with temperatures >25°C.

Carbohydrate-based phenotyping of the green macroalga Ulva fasciata using near-infrared spectrometry: potential implications for marine biorefinery

Abstract: Abstract Marine macroalgal biomass is a promising sustainable feedstock for biorefineries. However, the development of macroalgal biomass for industrial cultivation and processing has been slow. In terrestrial plants, high-throughput phenotyping provides rapid imaging methods to select specimens with required properties, rapidly transforming traditional breeding techniques. To foster the development of macroalgal biomass for biorefinery applications, we developed a near-infrared spectrometry-based method for rapid phenotyping of the macroalga Ulva fasciata based on its glucose, rhamnose, xylose and glucuronic acid contents. Spectral slopes were calculated as indicative of major carbohydrate content change. In addition, different spectral indices were generated to distinguish between low and high contents of glucose, rhamnose, xylose and glucuronic acid in wet and dry biomass. Since glucose is a major monosaccharide in Ulva that is fermentable to bioethanol, as an example of future application, we developed a multivariate data analysis based on partial least squares regression to predict its content in dry and wet biomass samples solely from reflectance data. These methods could provide a useful, high-throughput tool to rapidly select thalli with high carbohydrate content for further propagation and to be used for feedstock development for marine biorefineries.

Supply and survival: glacial melt imposes limitations at the kelp microscopic life stage

Abstract: High-latitude kelp beds may be at risk from increasing sedimentation rates due to glacial melt. Nereocystis luetkeana (hereafter Nereocystis) sporophytes (canopy-forming) occur infrequently downstream of glacial melt where thick layers of sediment accumulate, while Saccharina latissima (hereafter Saccharina) sporophytes (understorey) are common in these areas. We examined whether glacial melt conditions affect adult summer fecundity, how sedimentation affects early gametophyte survival and growth and whether competitive interactions among gametophytes are altered by the presence of sediment. Summer fecundity did not differ in relation to glacial discharge for either species. In single species treatments, there was an effect of sediment on gametophyte survival for Saccharina but not Nereocystis. In mixed species treatments when no sediment was added, Nereocystis had higher survival than Saccharina when Nereocystis was settled first. When sediment was added, Saccharina had higher survival than Nereocystis when Saccharina was settled first. There was no difference in gametophyte growth between the two species for any treatment. Settlement timing may explain the ability of Nereocystis to coexist with Saccharina and to occur in some locations downstream of glacial discharge. Climate change could result in the loss of Nereocystis by favoring Saccharina gametophytes in competitive interactions.

In situ biomass production of Gracilariaceae and Ulva rigida: the Venice Lagoon as a study case

Abstract: Abstract The growth and biomass production of the most abundant Gracilariaceae: Gracilariopsis longissima (S.G. Gmelin) M. Steentoft, L.M. Irvine et W.F. Farnham, Gracilaria gracilis (Stackhouse) M. Steentoft, L.M. Irvine et W.F.Farnham and Gracilaria vermiculophylla (Ohmi) Papenfuss, and of Ulva rigida C. Agardh were studied during 1 year in two areas of the Venice Lagoon, namely Tresse and San Giuliano, that were characterized by different trophic levels and water turbidity. Both growth and macroalgal production were monitored every 7–11 days in cubical cages placed on the bottom within the natural biomass. Environmental parameters, nutrient concentrations in the water column and surface sediments, and sedimentation rates were also determined. The biomass production of the two stations was very different and strongly influenced by the water turbidity and sedimentation rates. In both areas the availability of nutrients were high, but Tresse, where waters were more transparent, was more productive. In that area, the annual production of Gracilariaceae ranged between 21.9 and 28.2 kg fresh weight (fw) m−2 and G. longissima was the most productive species. Ulva production was within the same range (25.8 kg fw m−2). The mean relative growth rates on an annual basis were between 1.87 and 2.41% day−1. In contrast, in the turbid area (San Giuliano), the annual production of Gracilariaceae was much lower, ranging from 9.0 to 12.8 kg fw m−2 and that of Ulva was 15.2 kg fw m−2.

Biotechnological applications of the red alga Furcellaria lumbricalis and its cultivation potential in the Baltic Sea

Abstract: Abstract There is a growing need for diversification of seaweed aquaculture practices in Europe. In the Baltic Sea, very few seaweed species are utilised commercially, and only the kelp Saccharina latissima is presently cultivated, although a common red alga – Furcellaria lumbricalis – has the longest harvesting history in the region. Nevertheless, in recent years, there has been an increasing interest in cultivating F. lumbricalis in Estonian coastal waters. Several pilot studies have been initiated to develop techniques for the vegetative propagation of sporophytes and gametophytes. Based on a literature survey, ongoing investigations and expert opinion, a comprehensive overview of the ecophysiological requirements and chemical composition of different forms of F. lumbricalis is given in this review, together with its potential for biotechnological applications. Recommendations for cultivating the species in open water are given. Overall, biotechnological applications of F. lumbricalis rely on high-value biochemicals like furcellaran, R-phycoerythrin, lutein (carotenoids) and phenolic content (antioxidants). Further bioprospecting is needed to estimate the possible content of oxylipins in the alga.

Effects of environmental parameters on chytrid infection prevalence of four marine diatoms: a laboratory case study

Abstract: The influence of environmental factors on the infection susceptibility of four different marine diatom host species to chytrid infection was tested under laboratory conditions, using host and parasite isolates obtained from diverse coastal areas in north-west Iceland in 2015. Specifically, a total of 120 monoclonal marine diatom host cultures of Navicula, Nitzschia, Rhizosolenia and Chaetoceros were exposed to their chytrid parasites Chytridium type I and Rhizophydium type I and II in Hellendahl glass staining jars which were subdivided in two compartments by nylon filters (mesh size 5 mu m). Infection densities were assessed at different temperatures (5, 15, 20 degrees C), salinities (0, 5, 10, 20, 40), photon fluence rates (PFR; 10, 50, 100, 200 mu mol photons m(-2) s(-1)) and photoperiods (24 h dark, 8: 16 h, 16: 8 h light: dark and 24 h light) after 168 h exposure, using the one-factor-at-a-time method. In addition, growth rates and proline concentrations of the noninfected monoclonal host cultures were determined. In most cases, decreasing growth rates during the acclimatisation process to abiotic stressors were directly related to increases of proline in the host cells. Significant positive associations of infection densities to cell based proline concentrations were predominantly observed in the high-PFR assays and 24-h daylight treatments. At least for half of the tested host-parasite pairs, positive correlations of proline and parasite prevalence were found. In addition, chytrid abundance was also positively correlated with host densities of Navicula sp., Rhizosolenia sp. and Chaetoceros sp. Only in Nitzschia sp., was parasite density negatively associated with proline and showed no significant relationship to host densities, suggesting that other physiological/biochemical factors related to stress might have an impact on the susceptibility of this peculiar host diatom species.

Primary Utricle Structure of Six Halimeda Species and Potential Relevance for Ocean Acidification Tolerance

Abstract: Abstract Variations in utricle morphology may be responsible for different tolerances to ocean acidification (OA) within the macroalgal genus Halimeda, an important sediment producer on reefs. However, differences in species’ utricle morphology and their relationship to calcification and crystal formation have not been well articulated. In the present study, we characterized the utricle morphologies of six Halimeda species. Primary utricle ultrastructure was quantitatively and qualitatively compared to tissue inorganic content and crystal microstructure. Morphologies differed across species and several morphometric relationships were revealed. Primary utricle size (r2=0.70) and diffusion pathway length (r2=0.87) had inverse relationships with inorganic content based on regression analyses, and corresponded to crystal microstructure form. Species with large utricles and long diffusion pathways contained more narrow (~0.15 μm) aragonite needles and minimal micro-anhedral crystal formations. In contrast, species with small utricles and short diffusion pathways elucidated aggregates of micro-anhedral crystals and wider aragonite needles (~0.30 μm). Species’ utricle characteristics generally corresponded to specific evolutionary lineages. Thus, characteristics of Halimeda utricle morphology may control long-term adaptive responses to OA, an idea articulated in the broader literature.

Cell structure and microtubule organisation during gametogenesis of Ulva mutabilis Føyn (Chlorophyta)

Abstract: Abstract Cell structure and microtubule organisation during gametogenesis of the green alga Ulva mutabilis was studied using light microscopy, transmission electron microscopy (TEM) and tubulin immunofluorescence. Microtubules in vegetative cells are organised in parallel bundles traversing the cortical cytoplasm. During gametogenesis, induced blade cells are transformed to gametangia, depending on the maturity of the algae and the removal of regulatory sporulation inhibitors. This differentiation is accompanied by formation of a conical cell projection (papilla) towards the exterior of the thallus. Microtubules form a clear, basket-like configuration converging towards the conical tip, but not reaching it. The conical microtubule structure stops below the tip, leaving a circular “opening”. Parallel to the above, the cell wall of the tip is differentiated, forming a “cap”. Nuclear divisions start at this stage, finally forming the nuclei of future gametes. Cytokinesis takes place by membrane furrowing and vesicle fusion, giving rise to 16 oval-shaped gametes. The conical microtubule organisation is gradually depolymerised, and a cortical, intensely fluorescing microtubule bundle is formed in each gamete. At this stage, the cap at the conical cell wall projection is removed and the exit pore opens. The biflagellate gametes remain initially motionless, connected by thin cytoplasmic bridges. Finally, they are released to the environment upon additional removal of a swarming inhibitor accumulated in the growth medium during gametogenesis.

Recruitment in Ulva blooms in relation to temperature, salinity and nutrients in a subtropical bay of the Gulf of California

Abstract: Abstract Ulva blooms are highly productive ephemeral communities that occur in coastal systems, associated with nutrient enrichment. The objective was to estimate variations in succession, cover, recruitment and length of Ulva species in four blooms and assess their relationship with environmental parameters in Bahía de La Paz, Baja California Sur. At each locality, monthly samplings were performed to register the presence, recruitment, length and cover of species, and temperature, salinity, turbidity and nutrient concentration in surface seawater from February 2013 to October 2015. The species found were Ulva acanthophora, Ulva clathratha, Ulva intestinalis, Ulva flexuosa, Ulva lactuca, Ulva lobata, Ulva nematoidea and Ulva rigida. The Ulva blooms in Casa del Marino, San Juan de la Costa and El Tecolote were multi-species, with U. rigida displaying the highest presence, cover and recruitment, followed by U. acanthophora. Significant differences were found between localities, years and months for biological and environmental factors. A principal component analysis (PCA) revealed significant relationships between higher cover, recruitment and length with higher nutrients concentrations at San Juan de La Costa, Casa del Marino and El Tecolote, indicating favourable conditions that allowed rapid growth. The cover, recruitment and length of U. flexuosa at El Portugués were inversely correlated with temperature.

Impaired growth and reproductive capacity in marine rockweeds following prolonged environmental contaminant exposure

Abstract: Abstract Intertidal macroalgae are resilient organisms, withstanding daily fluctuations in temperature, salinity and air exposure. These sessile seaweeds are exposed to anthropogenic pollution as an additional stressor in their natural habitat alongside coastal waterways, which are often adjacent to industrial centers. One such habitat in the New Bedford Harbor in Massachusetts has been recognized by government agencies as a site of National Priority after several decades of polychlorinated biphenyl and metal discharge. Research has focused on the effects of these contaminants among large-scale trophic cascades, with less emphasis on sessile primary productivity. Macroalgal members of the community were the focus of this study and were used to evaluate the presence and effect of environmental contaminants. Contaminants prominent in highly polluted regions of the harbor were elevated in tissue samples. Field surveys evaluating density and biomass were conducted in five areas of varying contamination and indicated a drastic inhibition of colonization with increasing contaminant load. No differences were detected between sites in terms of oocyte production in a single receptacle, but only individuals from less contaminated regions released those oocytes. Potential causes of decreased population size may therefore be reduction in individual biomass and a decreased ability to release eggs.

The Halosphaeriaceae revisited

Abstract: Abstract The Halosphaeriaceae is a monophyletic group that shares a common ancestor with Microascaceae and, along with the families Graphiaceae, Ceratocystidiaceae, Chadefaudiellaceae and Gondwanamycetacea, is referred to the order Microascales. It constitutes the largest family in Microascales with 63 genera (166 species) and differs from other families in that most species are aquatic (predominantly marine) and characterised by perithecial ascomata, centrum tissue comprising catenophyses, clavate to fusiform asci that generally deliquesce early, hyaline, unicellular to many times septate ascospores usually with appendages. Although approximately 75% of halosphaeriaceous species have been sequenced, their phylogenetic grouping based on morphological features is not supported. This indicates that certain characters have evolved and been lost several times. New sequences have been generated in this study; a phylogenetic analysis based on the 18S and 28S rDNA was run to determine phylogenetic relationships between genera, and pairwise distance of the partial 28S rDNA was calculated. Arenariomyces is a monophyletic genus, which suggests that its ascospore appendage is a good delineating character for the genus. The genus Aniptodera is shown to be polyphyletic; Aniptodera lignatilis is referred to Aniptosporopsis gen. nov. and Aniptodera longispora is referred to Paraaniptodera gen. nov.

Cloning and application of the complete nuclear ribosomal DNA (nrDNA) cistron sequence of Pyropia haitanensis (Bangiales, Rhodophyta)

Abstract: Abstract Pyropia haitanensis (Bangiales, Rhodophyta)((T.J. Chang et B.F. Zheng) N. Kikuchi et M. Miyata) is a unique cultivar in China and the main problem with its cultivation lies in a lack of effective technology to distinguish intraspecific strains. In this study, we firstly obtained the complete sequence of rDNA of Pyropia haitanensis in China, which can help identify intraspecific variation within this species. The whole unit is composed of a small-subunit (SSU) rRNA gene with a full length of 2953 base pairs (bp) with two classes of introns and an exon sequence of 1837 bp; moreover, the complete sequence of the large-subunit (LSU) rRNA gene (length 4444 bp) also contains two introns; the length of the 5.8S rRNA gene is 158 bp; the length of internal transcribed spacers 1 (ITS1) is 334 bp and that of ITS2 is 678 bp; and the complete sequence of intergenic spacer (IGS) is 6969 bp. Some portions of the IGS sequences were used to analyze the similarities among five strains of Pyropia haitanensis; the sequence ranged from 4264 bp to 4273 bp and the G+C content was 53%. We also found 118 variable sites in the IGS which account for approximately 2.8% of the whole length. In conclusion, the nuclear ribosomal DNA sequence turned out to be an effective molecular marker for the taxonomic identification of Pyropia haitanensis.

Proteomic analysis of the marine-derived fungus Paecilomyces sp. strain SF-8 in response to polycyclic aromatic hydrocarbons

Abstract: Abstract An efficient and unique proteomic response is important for fungi to survive in marine environments polluted with polycyclic aromatic hydrocarbons (PAHs). The marine-derived fungus Paecilomyces sp. strain SF-8 was isolated from the soil of salt production sites and was found to remove different PAHs. The PAH-treated strain SF-8 was characterized using elemental analysis and Fourier transform infrared spectroscopy. Paecilomyces sp. strain SF-8 successfully removed 88% of anthracene, 75% of phenanthrene, 67.5% of benzo[a]anthracene, and 99.3% of benzo[b]fluoranthene. In order to gain insight into the molecular response to PAHs in strain SF-8, proteomics analysis of different cells treated with different PAHs was performed. Comprehensive proteomic analysis revealed that the molecular response of the fungus towards PAH was compound specific. Functional classifications showed heightened regulation of major enzymes involved in cellular function and metabolism, and PAH degradation. The key control protein (salicylaldehyde dehydrogenase) of PAH degradation was specifically over-expressed. Our results collectively demonstrated the influence of PAHs in fungal cellular functioning, development and metabolism.

First record of Ruppia maritima in West Africa supported by morphological description and phylogenetic classification

Abstract: Ruppiamaritima (widgeon grass) has been identified phylogenetically for the first time from West Africa (Santiago Island, Cape Verde). Genetic markers distinguished this species from the tetraploid Ruppia cf. maritima previously known from West Africa. Taxonomic description, photographs and molecular phylogenetic classification are provided here. The results show that, in Cape Verde, the species is phylogenetically closer to European and northeast American than to Indo-Pacific populations. This study extends the known distribution of R. maritima, an ecosystem structuring species that provides essential habitat for threatened animals.

Distribution and occurrence of manglicolous marine fungi from eastern and southern Thailand

Abstract: Abstract The species diversity of marine fungi was investigated in eastern and southern Thailand. Senescent and decaying woody substrata were collected from intertidal mangrove forests located in Trat, Prachuap Khiri Khan and Phetchaburi Provinces. A total of 99 fungal species was recorded. These included 84 Ascomycota (85%), two Basidiomycota (2%) and 13 asexual fungi (13%). The average percentage occurrence of the fungi recorded from each site ranged from 0.1% to 13.7%. Based on the percentage of samples in which a particular taxon was found, the most frequent fungi were Quintaria lignatilis (8%), Rimora mangrovei (8%) and Salsuginea ramicola (7%). The results showed that 25 species were common to all three provinces. The Shannon-Wiener diversity index, equitability species evenness index and Margalef’s species richness index were the highest in Trat Province, followed by Prachuap Khiri Khan and Phetchaburi Provinces. Moreover, eight fungal species were new records for Thailand: Aniptodera salsuginosa, Etheirophora bijubata, Etheirophora blepharospora, Neptunella longirostris, Oceanitis cincinnatula, Savoryella melanospora, Sedecimiella taiwanensis and Trichocladium lignicola, and there are three new species. The results from this study provide an insight into the diversity of marine fungi present in Thai mangroves bringing the current total number to 184 species.

Resilience of Cystoseira beds: lack of canopy effects on recruitment

Abstract: Abstract The aim of the study was to evaluate the role of the presence of an adult canopy on the recruitment of the habitat-forming seaweed Cystoseira brachycarpa var. balearica, in the northwestern Mediterranean Sea. To achieve this objective, a field experiment was performed and recruitment was estimated both in the middle and at the edge of cleared patches, as well as within the bed, on ceramic tiles anchored to the rocky substrate. At the end of the study, neither the number nor the heights of Cystoseira thalli were significantly different among the positions, suggesting that there were no facilitating or inhibiting effects on recruitment.