Unialgal Cultures Research Articles

Life history ofChaetomorpha valida(Cladophoraceae, Chlorophyta) in culture

AbstractThe marine green algaChaetomorpha valida(Cladophoraceae, Cladophorales) has been found for several years fouling aquaculture ponds along coasts of the cities Dalian and Rongcheng, P.R. China. Using unialgal culture and microscopic observation, we completed the life history ofC. validaand discovered fragment regeneration for the first time. The life history comprised an isomorphic alternation between gametophytes and sporophytes typical of most other members of the Cladophorales. Male and female gametes fused into zygotes then developed into sporophytes. Quadriflagellate zoospores produced by mature sprophytes gave rise to new gametophytes that yielded biflagellate gametes. Germination of zygotes and zoospores was of the bipolar erect type, as observed in some other species ofChaetomorpha. Fragment regeneration occurred in both gametophytes and sporophytes via production of polar algal fragments, which directly developed into entire filaments to give a self-replicating gene­ration. The results improved understanding of the seasonal abundances ofC. validain spring and summer.

Microplate-based high throughput screening procedure for the isolation of lipid-rich marine microalgae

We describe a new selection method based on BODIPY (4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene) staining, fluorescence activated cell sorting (FACS) and microplate-based isolation of lipid-rich microalgae from an environmental sample. Our results show that direct sorting onto solid medium upon FACS can save about 3 weeks during the scale-up process as compared with the growth of the same cultures in liquid medium. This approach enabled us to isolate a biodiverse collection of several axenic and unialgal cultures of different phyla.

Non-enzymatic antioxidant photoprotection against potential UVBR-induced damage in an Antarctic diatom (Thalassiosira sp.)

In January 1999, unialgal cultures of the diatom Thalassiosira sp., solate from natural phyto- plankton assemblages from Potter Cove, Antarctica, were exposed to solar ultraviolet radiation (UVR, 280- 400 nm) in order to study the long-term acclimation of this species. Ultraviolet radiation B (UVBR, 280-315 nm) inhibited the growth rate during the first and second days of exposure. No UVBR inhibition was observed on the third day. The initial content of α-tocopherol (13 pmol (10 4 cell) -1 ) showed a marked decrease during the exponential growth phase (4 pmol (10 4 cell -1 ) by day 3). The initial content of β-carotene (3 pmol (10 4 cell) -1 ) did not show significant differences over time in cells exposed to UVBR. Two mycosporine-like amino acids (MAAs) were identified: porphyra-334 and shinorine. Cellular concentrations of MAAs increased significantly on days 2 and 3, and exposure of the algae to UVBR significantly enhanced this value. The relative importance of MAAs concentration was significant (P < 0.05) in relation to the α-tocopherol content. A positive correlation was shown between cellular MAAs concentration and growth rate. Our results suggest that photoprotection against UV-induced damage is characterized by short-term consumption of α-tocopherol and longer-term synthesis of MAAs. The UVBR damage/repair ratio during long-term exposure involves the combined action of several endogenous factors within the cell, with MAAs synthesis being the most effective factor related to photoprotection.

Effect of temperature and irradiance on the growth and reproduction of the green macroalga, Chaetomorpha valida (Cladophoraceae, Chlorophyta)

“Green tides” are vast accumulations of unattached green macroalgae associated with eutrophicated marine environments. It had major ecological and economic impacts globally, thus understanding of their detailed conditions was required to inform management decisions. Chaetomorpha valida (Cladophoraceae, Chlorophyta), as a fouling green alga, was found in aquaculture ponds along the coast of Dalian and Rongcheng cities, People’s Republic of China in the past few years. Seasonal abundances of this macroalga in China have presented a significant nuisance and caused great loss to the local aquaculture. Using unialgal cultures, the effect of temperature and irradiance on growth and reproduction were investigated. Healthy growth and reproduction occurred in the range of 17–29°C while the upper lethal limit was at 33°C. A suitable temperature range over 21–29°C and a relatively high irradiance of 108 μmol photons m−2 s−1 were more favorable for growth and reproduction. According to our observations, the diversity of reproductive approaches and wide adaption to temperature can be considered to be key factors that facilitate its excessive growth and colonization in spring and summer. Our results provide a basis for establishing a forecast system and taking remediation measures against seasonal green tides of this macroalga.

Molecular identification and culture observation on Acrochaete leptochaete (Chaetophoraceae, Chlorophyta) from China

Acrochaete leptochaete (Huber) Nielsen (Chaetophoraceae, Chlorophyta) was isolated from the macroalgae Chaetomorpha collected from intertidal pools in Rongcheng, Shandong, China. 18S rDNA combined with ITS regions were used to ascertain the morphological identification of the isolated material. Based on the unialgal culture, asexual reproduction and growth characteristics of A. leptochaete were investigated over wide ranges of temperature and irradiance. Results revealed that asexual reproduction of A. leptochaete could be realized by biflagellate zoospores. The zoospores germinated directly to give self-replicating generations. Zoospore germination was bipolar. A temperature range from 13-21A degrees C and a lower irradiance of 36 mu mol/(m(2)center dot s) were most favorable for the growth of A. leptochaete. Thallus organization, an important taxonomic criterion for the genus Acrochaete, was affected markedly by temperature and irradiance. Our results extend the knowledge about the species' general biology and its morphological plasticity. For classification and identification of a simple microphytic algae like A. leptochaete, which are traditionally placed in the class Chaetophoraceae, we propose that molecular tools associated with culture observations are applied.

A New Insight into Allelopathic Effects of Alexandrium minutum on Photosynthesis and Respiration of the Diatom Chaetoceros neogracile Revealed by Photosynthetic-performance Analysis and Flow Cytometry

The allelopathic effects of Alexandrium minutum, a toxic dinoflagellate, on the diatom Chaetoceros neogracile were evaluated using unialgal cultures evaluated by flow cytometry (FCM) and photosynthetic-performance analysis. Using FCM, we demonstrated that red chlorophyll fluorescence, relative cell size (Forward scatter of blue laser light, FSC) and cell complexity (Side scatter, 90°-angle scatter of blue laser light, SSC) significantly and rapidly decreased in C. neogracile cells exposed to A. minutum. Cells of C. neogracile exposed to A. minutum had fewer active photosynthetic reaction centers and sharply decreased photosynthetic efficiency. These effects were intensified with advancing A. minutum batch culture age and cell density. The supernatant of A. minutum contained the majority of the putative allelopathic compounds, and the biological activity of these compounds remained active less than 9h after release. This paper describes for the first time specific effects of allelochemicals produced by A. minutum on the photosynthetic apparatus of microalgal target cells. The biochemical composition of A. minutum allelopathic agents, however, remains unknown and still needs to be investigated.

Cyanobacterial biofilms on sedimentation basins in a water treatment plant in South Korea

We studied periphytic algal biofilms that formed in the sedimentation basins (SBs) of a water treatment plant (WTP) in South Korea. The submerged cement wall of the basin was heavily coated by mats of algal filaments, which resembled a small sheet of carpet. These biofilms were more common in the dry season (spring and autumn), than the rainy season (summer) and winter. Oscillatoria and Phormidium (Cyanobacteria) were predominant in the biofilm of the SB walls, where the water was stagnant. Lyngbya (Cyanobacteria) and Oedogonium (Chlorophyta) were dominant on the walls of overflow weirs and troughs of the SB, where there was a substantial current. As the biofilm matured, the assemblages were detached from the walls and floated as “scum” on the water, causing contamination. Many factors control the development of cyanobacterial biofilms on the walls of WTPs, including the nutrient levels of the raw water, and interstitial or pore water of biofilm assemblages, temperature, and irradiance. We isolated and grew unialgal cultures of the five most important cyanobacteria of the WTP biofilm. Oscillatoria splendida strongly produced the musty odor from the cultures. We suggest implementation of antifouling strategies to reduce the formation of biofilm on the wall and contamination of water supplies.

MOLECULAR PHYLOGENY OF THE UPRIGHT ERYTHROPELTIDALES (COMPSOPOGONOPHYCEAE, RHODOPHYTA): MULTIPLE CRYPTIC LINEAGES OF ERYTHROTRICHIA CARNEA1.

The phylogeny of morphologically simple algae is problematic due to insufficient morphological characters to aid in distinguishing species and relationships. The problem is further compounded because multiple evolutionary lineages of morphologically similar species occur in most well-sampled biogeographic locations; therefore, location cannot be used as a proxy for species. The phylogeny of the upright members of the Erythropeltidales is partially clarified by combining molecular data, unialgal culture observations, and worldwide sampling. Our results show that there are several well-supported lineages within the Erythropeltidales with only two morphologically recognizable taxa at present. The first is the genus Porphyrostromium, with a well-developed basal crust, which includes two Erythrotrichia species (Porphyrostromium ligulatum comb. nov. and Porphyrostromium pulvinatum comb. nov.). The second is the branched species Erythrotrichia welwitschii (Rupr.) Batters. There are also six strongly supported Erythrotrichia carnea-like lineages. While not completely satisfactory, we propose that one lineage (lineage 2) with samples close to the type locality be designated as E. carnea with a specific isolate as an epitype. The lack of morphology to differentiate the other lineages leads to a taxonomy based solely on gene sequencing and molecular phylogeny, with rbcL sequences differentiating the lineages proposed. We hold off on proposing more species and genera until more data and samples can be gathered.

Protocol for seaweed decontamination to isolate unialgal cultures

Decontamination protocols in seaweeds are essential tools for ecophysiological studies in laboratory cultures. These protocols consist of a set of procedures and physical and chemical treatments that must be adjusted for each species. Thus, the effects of explant size and of combinations of physical treatments (brushing and cutting) and chemical treatments (sodium hypochlorite, detergent, seawater, distilled water, germanium dioxide) on the process of obtaining unialgal culture of two pigmentar morphos of Hypnea musciformis were investigated. It was found that thallus segments 50 mm in length, when transported from the field to the laboratory, remained healthier and were less susceptible to epiphytes than those 7 mm in length. The collected material had surfaces contaminated by diatoms, which were weakly attached, as well as surface contamination caused by strongly attached Sahlingia subintegra. The most efficient combination of physical and chemical treatments was explant brushing, cutting and washing with detergent. This combination eliminated the contamination by S. subintegra, but not all of the diatom contamination. The population of the latter was reduced by using physical treatment and by washing with detergent and distilled water and then exterminated by using germanium dioxide (0.003 mg/L). Employing this protocol, unialgal cultures of H. musciformis could be established in approximately eight to ten weeks.

Importance of intracellular Fe pools on growth of marine diatoms by using unialgal cultures and on the Oyashio region phytoplankton community during spring

We report on the ability for luxury Fe uptake and the potential for growth utilizing intracellular Fe pools for 4 coastal centric diatom isolates and in situ phytoplankton assemblages, mainly composed of diatoms. Iron uptake of the diatom isolates and natural phytoplankton assemblages in the Oyashio region during spring blooms were prevented by adding hydroxamate siderophore desferrioxamine B (DFB). After the addition of DFB, intracellular Fe in the diatom isolates supported 2.4–4.2 cell divisions with 1.2–2.6 Chl a doublings. The intracellular Fe was primarily used for cell generation rather than Chl a production, leading to a reduction in the Chl a cell quota in the Fe-starved cells with time. The metabolic properties of the Fe-starved cells with their cell morphologies were different among species or genera. An on-deck incubation experiment also exhibited 1.9 cell divisions and 0.81 Chl a doublings of phytoplankton after the addition of DFB, also indicating the preference of cell generation over Chl a production. A decrease in the level of cellular Chl a, a main light-harvesting pigment in Fe-starved diatoms, may become a superior survival strategy to protect the cells from high irradiance that can cause photo-oxidative damages through photosynthesis. Such relatively low-Fe with high-light conditions could often occur in surface waters of the Oyashio region from spring to summer.

Utilizing the Effective Xanthophyll Cycle for Blooming of Ochromonas smithii and O. itoi (Chrysophyceae) on the Snow Surface

Snow algae inhabit unique environments such as alpine and high latitudes, and can grow and bloom with visualizing on snow or glacier during spring-summer. The chrysophytes Ochromonas smithii and Ochromonas itoi are dominant in yellow-colored snow patches in mountainous heavy snow areas from late May to early June. It is considered to be effective utilizing the xanthophyll cycle and holding sunscreen pigments as protective system for snow algae blooming in the vulnerable environment such as low temperature and nutrients, and strong light, however the study on the photoprotection of chrysophytes snow algae has not been shown. To dissolve how the chrysophytes snow algae can grow and bloom under such an extreme environment, we studied with the object of light which is one point of significance to this problem. We collected the yellow snows and measured photosynthetically active radiation at Mt. Gassan in May 2008 when the bloom occurred, then tried to establish unialgal cultures of O. smithii and O. itoi, and examined their photosynthetic properties by a PAM chlorophyll fluorometer and analyzed the pigment compositions before and after illumination with high-light intensities to investigate the working xanthophyll cycle. This experimental study using unialgal cultures revealed that both O. smithii and O. itoi utilize only the efficient violaxanthin cycle for photoprotection as a dissipation system of surplus energy under prolonged high-light stress, although they possess chlorophyll c with diadinoxanthin.

Host Selection of Symbiotic Cyanobacteria in 31 Species of the Australian Cycad Genus: Macrozamia (Zamiaceae)

The nitrogen-fixing cyanobacterium Nostoc is a commonly occurring terrestrial and aquatic cyanobacterium often found in symbiosis with a wide range of plant, algal, and fungal species. We investigated the diversity of cyanobacterial species occurring within the coralloid roots of different Macrozamia cycad species at diverse locations throughout Australia. In all, 74 coralloid root samples were processed and 56 endosymbiotic cyanobacteria were cultured. DNA was isolated from unialgal cultures and a segment of the 16S rRNA gene was amplified and sequenced. Microscopic analysis was performed on representative isolates. Twenty-two cyanobacterial species were identified, comprising mostly Nostoc spp. and a Calothrix sp. No correlation was observed between a cycad species and its resident cyanobiont species. The predominant cyanobacterium isolated from 18 root samples occurred over a diverse range of environmental conditions and within 14 different Macrozamia spp. Phylogenetic analysis indicated that endosymbionts were not restricted to previously described terrestrial species. An isolate clustering with Nostoc PCC7120, an aquatic strain, was identified. This is the first comprehensive study to identify the endosymbionts within a cycad genus using samples obtained from their natural habitats. These results indicate that there is negligible host specialization of cyanobacterial endosymbionts within the cycad genus Macrozamia in the wild.

The genus Pseudo-nitzschia (Bacillariophyceae) in Greek coastal waters

Abstract We conducted a first study of Pseudo-nitzschia species and their morphological variability in the main shellfish farming and harvesting areas of Greece between 2004 and 2008. Water samples were collected and preserved, and unialgal cultures of Pseudo-nitzschia species were established. Both preserved and culture material of 12 taxa were examined by transmission electron microscopy and included P. delicatissima, P. fraudulenta, P. galaxiae, P. mannii, P. multistriata, P. pseudodelicatissima, P. pungens, P. subfraudulenta, one morphospecies similar to P. dolorosa and one strain corresponding to a P. delicatissima-like morphotype (all new records for Greek coastal waters); in addition, we found two previously recorded species, viz., P. calliantha and P. multiseries. We present ultrastructural descriptions and morphometric data for the local populations studied.

MOLECULAR PHYLOGENY OF THE CRUSTOSE ERYTHROPELTIDALES (COMPSOPOGONOPHYCEAE, RHODOPHYTA): NEW GENERAPSEUDOERYTHROCLADIAANDMADAGASCARIAAND THE EVOLUTION OF THE UPRIGHT HABIT

The Erythropeltidales are a common group of small, mostly epiphytic, marine red algae. Morphologically, they can be divided into two main groups: species that are crustose and species that are upright. Being morphologically simple, generic boundaries and evolutionary trends are controversial or unknown. We focus our molecular phylogenetic analysis on members that are crustose using samples collected from around the world and placed in unialgal culture. Our data indicate that one upright genus, Porphyropsis, is closely related to crustose genera and that the upright habit evolved at least twice in the order. In addition, the genus Sahlingia is supported as distinct from Erythrocladia. Within samples identified as Erythrocladia, three groups are distinguished: Erythrocladia, composed of crustose aggregating filaments with pyrenoids; Pseudoerythrocladia gen. nov., crustose aggregating filaments without pyrenoids, a sister genus to Porphyropsis also without pyrenoids; and Madagascaria gen. nov., a sister genus to all other Erythropeltidales samples that is only subtly different from Erythrocladia. Within these genera, no clear morphological groups are evident, nor is the level of molecular diversity suggestive of multiple species. We suggest that described species, especially in the genus Erythrocladia, are just morphological variants, due to substrate or environmental variation, and further descriptions of these morphologically simple algae must incorporate molecular data and standardized culture conditions. Key index words: Compsopogonophyceae; crusts; Erythrocladia ;E rythropeltidales;Madagascaria; molecular evolution; Porphyropsis; Pseudoerythrocladia ;R hodophyta; taxonomy Abbreviations: CTAB, cetyl trimethylammonium bromide; MPM, modified Provasoli media; mya, million years ago

Increase in Si:N drawdown ratio due to resting spore formation by spring bloom-forming diatoms under Fe- and N-limited conditions in the Oyashio region

Resting spore formation and Si:N drawdown ratios were investigated under iron (Fe)- and nitrogen (N)-limited conditions using a unialgal culture of Thalassiosira nordenskioeldii and natural phytoplankton assemblages during the spring bloom in the Oyashio region. In the unialgal culture of T. nordenskioeldii, 20% and 100% of the cells formed resting spores under Fe- and N-limited conditions, respectively. The Si:N drawdown ratios were 2- and 14-fold higher in Fe- and N-limited conditions, respectively, compared to Fe- and N-sufficient conditions. At the start of the natural phytoplankton incubation, 18 among 47 identified diatom species were known resting spore-forming species. Approximately 15 common diatom species formed resting spores under Fe- and N-limited conditions. During the natural phytoplankton incubation, the percentage of the resting spores increased with time under both Fe- and N-limited conditions, reaching 25% and 40% of total diatom abundance, respectively. The Si:N drawdown ratios significantly increased with an increase in the contribution of resting spores in both the unialgal culture and natural phytoplankton incubations. These results suggest that if the bloom dominated by neritic, resting spore-forming diatom species decline by either Fe- or N-depletion, Si may be utilized preferentially to N in the upper mixed layer due to the formation of heavily silicified resting spores.

Iridaea cordata (Gigartinales, Rhodophyta): responses to artificial UVB radiation

The effects of UVB radiation on the different developmental stages of the carrageenan-producing red alga Iridaea cordata were evaluated considering: (1) carpospore and discoid germling mortality; (2) growth rates and morphology of young tetrasporophytes; and (3) growth rates and pigment content of field-collected plant fragments. Unialgal cultures were submitted to 0.17, 0.5, or 0.83 W m−2 of UVB radiation for 3 h per day. The general culture conditions were as follows: 12 h light/12 h dark cycles; irradiance of 55 µmol photon.per square meter per second; temperature of 9 ± 1°C; and seawater enriched with Provasoli solution. All UVB irradiation treatments were harmful to carpospores ( $$ 0.17\;{\text{W}}\,{{\text{m}}^{ - 2}} = 40.9 \pm 6.9\% $$ , $$ 0.5\;{\text{W}}\,{{\text{m}}^{ - 2}} = 59.8 \pm 13.4\% $$ , $$ 0.83\;{\text{W}}\,{{\text{m}}^{ - 2}} = 49 \pm 17.4\% $$ mortality in 3 days). Even though the mortality of all discoid germlings exposed to UVB radiation was unchanged when compared to the control, those germlings exposed to 0.5 and 0.83 W m−2 treatments became paler and had smaller diameters than those cultivated under control treatment. Decreases in growth rates were observed in young tetrasporophytes, mainly in 0.5 and 0.83 W m−2 treatments. Similar effects were only observed in fragments of adult plants cultivated at 0.83 W m−2. Additionally, UVB radiation caused morphological changes in fragments of adult plants in the first week, while the young individuals only displayed this pattern during the third week. The verified morphological alterations in I. cordata could be interpreted as a defense against UVB by reducing the area exposed to radiation. However, a high level of radiation appears to produce irreparable damage, especially under long-term exposure. Our results suggest that the sensitivity to ultraviolet radiation decreases with increased algal age and that the various developmental stages have different responses when exposed to the same doses of UVB radiation.

Efeitos do ágar no crescimento de explantes e na formação de calos em morfos pigmentares de Gracilaria domingensis (Kützing) Sonder ex Dickie (Gracilariales, Rhodophyta)

Os efeitos da concentração de ágar no crescimento de explantes e na formação de calos foram avaliados em culturas axênicas de gametófitos femininos de morfos de coloração verde e vermelha de Gracilaria domingensis (Kützing) Sonder ex Dickie. Culturas unialgáceas foram mantidas em água do mar esterilizada (30-32 ups) enriquecida com 25% da solução de von Stosch (VSES 25%), 22 ± 2 °C, fotoperíodo de 14 h, irradiância de 50-80 µmol de fótons m-2 s-1. Para a obtenção de explantes axênicos, segmentos apicais e intercalares dos dois morfos foram cultivados por 48 h em meio VSES 25% com adição de uma solução antibiótica e antifúngica, e submetidos a uma lavagem com uma solução de água do mar esterilizada com 0,5% de hipoclorito de sódio e 200 µL L-1 de detergente por 20 segundos. Para avaliar os efeitos da concentração de ágar, os segmentos axênicos foram inoculados em meio ASP 12-NTA com concentrações distintas de ágar que variaram de zero a 1%. A adição de ágar no meio inibiu o crescimento dos segmentos apicais de ambos os morfos, bem como o crescimento de segmentos intercalares do morfo verde. Observou-se uma tendência geral no crescimento dos explantes, onde a taxa de crescimento foi inversamente proporcional à concentração de ágar. A adição de ágar no meio induziu a formação de três tipos de calo, denominados conforme a região do explante onde se originaram: calo apical, calo basal e calo intermediário. As concentrações de 0,5% e 0,7% de ágar foram as concentrações ótimas para indução de calos basais e calos intermediários no morfo verde, respectivamente. A presença de ágar foi essencial para a formação de calos intermediários e apicais. Os resultados indicam que o ágar apresenta um papel na regulação dos processos morfogenéticos em morfos pigmentares de G. domingensis.

PROTOCOLS FOR THE REMOVAL OF BACTERIA FROM FRESHWATER BENTHIC DIATOM CULTURES(1).

In this study, we describe different combinations of physical separation and antibiotic treatment to remove associated bacteria from freshwater diatoms. Diatoms were purified either from natural epilithic biofilms or from unialgal cultures. We determined that for most strains, different purification procedures have to be combined individually. In a new approach, we show that for some diatom strains, the substitution of associated aquatic bacteria by an antibiotic-sensitive Escherichia coli strain and subsequent treatment with antibiotics may be a successful strategy to obtain axenic diatom cultures. Axenic diatom cultures are essential to study the physiology and biochemistry of individual strains as well as their responses to environmental changes without interference of accompanying bacteria.

In vivo growth fluorometry: accuracy and limits of microalgal growth rate measurements in ecophysiological investigations

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 55:95-104 (2009) - DOI: https://doi.org/10.3354/ame01291 In vivo growth fluorometry: accuracy and limits of microalgal growth rate measurements in ecophysiological investigations Lydia Gustavs*, Rhena Schumann, Anja Eggert, Ulf Karsten University of Rostock, Department of Biological Sciences–Applied Ecology, Albert-Einstein-Straße 3, 18051 Rostock, Germany *Email: lydia.gustavs@uni-rostock.de ABSTRACT: In vivo growth fluorometry (Karsten et al. 1996) is based on the sensitive detection of in vivo chlorophyll a (chl a) fluorescence and monitors its increase over time as an indicator for growth. The method offers a simple, rapid, non-invasive, reproducible and calibration-free measurement of growth rates in unialgal cultures and facilitates multifactorial ecophysiological studies on algal cultures. The technical setup is well suited for use on benthic, adhering, filamentous and colony-forming microalgae. Low detection limits avoid self-shading and nutrient limitation during growth rate determination. Acclimated growth rates should be measured after a pre-incubation phase of 1 to 3 d. A broad data set correlating in vivo chl a fluorescence with cell number, organic carbon and chl a concentration in representative members of the Cyanobacteria, Rhodophyta, Chlorophyta and Bacillariophyceae is presented. A calibration of chl a fluorescence is not required for acclimated growth rate measurements of Bacillariophyceae and Chlorophyta but is recommended for high abundances of Cyanobacteria and Rhodophyta. KEY WORDS: Growth rate · Chlorophyll a fluorescence · Adhering algae · Multifactorial ecophysiological studies Full text in pdf format PreviousCite this article as: Gustavs L, Schumann R, Eggert A, Karsten U (2009) In vivo growth fluorometry: accuracy and limits of microalgal growth rate measurements in ecophysiological investigations. Aquat Microb Ecol 55:95-104. https://doi.org/10.3354/ame01291Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 55, No. 1. Online publication date: April 17, 2009 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2009 Inter-Research.

Haptophytes of the Nervión River estuary, northern Spain

Abstract The meso-macrotidal Nervión River estuary in northern Spain was sampled monthly from March to September 2002 and 2003 to study species composition and abundance of haptophytes in the phytoplankton. From natural samples and uni-algal cultures, 17 haptophyte species were identified using light and electron microscopy. The species were found across a wide range of temperatures and salinities. The most frequently occurring haptophytes in the estuary were species of the genus Chrysochromulina; however, Isochrysis galbana reached highest abundances. Chrysochromulina lanceolata and Phaeocystis globosa were occasionally present at high abundances. Another bloom-forming species, Prymnesium parvum, was recorded only once. Of the genera identified, eight species belonged to Chrysochromulina, two to Prymnesium and the rest of the genera were represented by one species only. The majority of the species were recorded for the first time in the Cantabrian Sea and one of them for the first time in the Atlantic Ocean.