Cryptophyte Rhodomonas Research Articles

Effect of heterotrophic versus autotrophic food on feeding and reproduction of the calanoid copepod Acartia tonsa: relationship with prey fatty acid composition

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 31:267-278 (2003) - doi:10.3354/ame031267 Effect of heterotrophic versus autotrophic food on feeding and reproduction of the calanoid copepod Acartia tonsa: relationship with prey fatty acid composition Elisabetta Broglio1,*, Sigrún H. Jónasdóttir2, Albert Calbet1, Hans H. Jakobsen2,3, Enric Saiz1 1Departament de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CSIC, Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Catalunya, Spain 2Department of Marine Ecology and Aquaculture, Danish Institute for Fisheries Research, Kavalergaarden 6, 2920 Charlottenlund, Denmark 3Present address: Western Washington University Shannon Point Marine Center, 1900 Shannon Point, Anacortes Road, Washington 98221, USA *Email: broglio@icm.csic.es ABSTRACT: We determined the egg production efficiency (EPE: egg production/ingestion) and egg viability of the copepod Acartia tonsa Dana under different heterotrophic and autotrophic diets. EPE was estimated in adult females either as the slope of the linear relationship between specific egg production (EPR) and ingestion rates, or as the quotient: EPR/ingestion rate. The diets, offered in monoculture, were the heterotrophic ciliates Strombidium sulcatum or Mesodinium pulex, the heterotrophic dinoflagellate Gymnodinium dominans, the autotrophic cryptophyte Rhodomonas salina and the autotrophic dinoflagellate Gymnodinium sanguineum. The diets were also analyzed for fatty acid contents and composition, relationships with EPE and reproductive success were determined. Clear differences were found in the fatty acid contents and the composition of the different diets offered, but these differences did not correspond with variability in EPE. However, egg viability was correlated with ingestion of certain prey essential fatty acids; interestingly, our data do not show that ciliates and heterotrophic dinoflagellates are nutritionally superior prey for marine copepods, contrary to general expectations. KEY WORDS: Copepod · Acartia tonsa · Ciliate · Dinoflagellate · Egg production · Food quality · Fatty acids · Egg production efficiency · Hatching success Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 31, No. 3. Online publication date: April 03, 2003 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2003 Inter-Research.

Effects of nutrient limitation on food uptake in the toxic haptophyte Prymnesium parvum

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 31:259-265 (2003) - doi:10.3354/ame031259 Effects of nutrient limitation on food uptake in the toxic haptophyte Prymnesium parvum Alf Skovgaard1,3,*, Catherine Legrand2, Per J. Hansen1, Edna Granéli2 1Marine Biological Laboratory, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark 2Department of Marine Sciences, University of Kalmar, Barlastgatan 1, 391 82 Kalmar, Sweden 3Present address: Departament de Biologia Marina i Oceanografia, Institute de Ciències del Mar, CMIMA-CSIC, Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain *Email: skovgaard@icm.csic.es ABSTRACT: The haptophyte Prymnesium parvum Carter is toxic and frequently responsible for harmful algal blooms in coastal waters. It is a mixotrophic species having the capability to feed on various planktonic microorganisms. It is frequently suggested that mixotrophic algae may obtain inorganic nutrients through phagotrophy and that nutrient depletion should then lead to increased food uptake. To study this, we investigated the feeding activity of P. parvum in semi-continuous, nutrient-limited cultures, using the cryptophyte Rhodomonas baltica as prey. P. parvum showed to be an active predator under all conditions investigated. After 2 h of incubation with prey, 40% of P. parvum cells were either feeding or contained recently formed food vacuoles. However, under the conditions used, no difference in feeding activity was found between treatments. On the contrary, the feeding activity was similar in P. parvum cultures that had been grown under N-limiting, P-limiting, N- and P-limiting, as well as under nutrient-replete conditions. It cannot be excluded that P. parvum under limiting nutrient conditions may acquire nutrients to be used in photosynthetic growth through phagotrophy. It is evident, however, that the species also feeds when inorganic nutrients are present in concentrations sufficient to support maximum phototrophic growth. KEY WORDS: Food uptake · Phagotrophy · Mixotrophy · Toxic algae · Prymnesiophyceae · Nutrient limitation · Semi-continuous cultures · Harmful algal blooms Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 31, No. 3. Online publication date: April 03, 2003 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2003 Inter-Research.

Effect of irradiance on growth, photosynthesis, pigment content and nutrient consumption in dense cultures of Rhodomonas salina (Wislouch) (Cryptophyceae)

The effects of different incident irradiances on growth, photosynthesis, pigment content and nutrient uptake were studied in dense cultures of the cryptophyte Rhodomonas salina (Wislouch) Hill y Wetherbee. Cells were grown for ten days at different incident irradiances: 11, 33, 75, 260 and 320 µmol photon m-2s-1. The average pigment content (phycoerythrin and chlorophyll a) was lower when cells were grown at high irradiances (260 and 320 µmol photon m-2s-1) compared with cells grown under low irradiances (11, 33 and 75 µmol photon m-2s-1).The maximum photosynthetic rate (Pmax) was maximal at 75 µmol photon m-2s-1 , decreasing considerably at the highest irradiance in which apparent photosynthetic efficiency per cell and per chlorophyll a unit (αcell and αchla) also decreased. Results showed that dense cultures of R. salina grew optimally in a range between 75 and 260 µmol photon m-2s-1 with optimal photosynthetic performance at 75 µmol photon m-2s-1. Nitrogen and phosphorus depletion occurred as a consequence of the exponential growth, except under the lowest and the highest irradiances (11 and 320 µmol photon m-2s-1, respectively). Associated to N-limitation, phycoerythrin (PE) and chlorophyll a decreased considerably. It is suggested that R.salina responds to nitrogen-depleted conditions by mobilizing nitrogen from PE, this behaviour being modelled by a relationship between external nitrogen availability and PE mobilization.

The missing links: larval and post-larval development of the ascoglossan opisthobranch Elysia viridis

The stenophagous ascoglossan (=sacoglossan) opisthobranch Elysia viridis has long been a model organism for the study of endosymbiosis or kleptoplasty as well as one of the few herbivores to consume the introduced green macroalga Codium fragile on European shores. Larval and post-larval dynamics of the ascoglossan were investigated. Planktotrophic larvae of E. viridis grew at 5–10 μm d−1 (shell length) at 15°C on a unicellular algal diet (the cryptophyte Rhodomonas baltica); larvae became competent one month post-hatching. Effective feeding and chloroplast acquisition typically started within 2–3 d of metamorphosis. Slugs grew about 8 mm in the first month of post-larval life. During this period, juveniles held in the light did not grow faster or survive better than conspecifics held in the dark; thus, functional kleptoplasty did not occur during first three weeks of benthic life. While larval growth rates and the nature of metamorphic cues are consistent with those of many other opisthobranch species with planktotrophic larvae, measures of post-larval growth—particularly as it pertains to kleptoplasty—is a new contribution to opisthobranch biology.

Biochemical and Immunochemical Investigations on the Light‐Harvesting System of the Cryptophyte Rhodomonas sp.: Evidence for a Photosystem I Specific Antenna

Abstract: Thylakoid membranes of the cryptophyte Rhodomonas sp. were solubilized with the mild detergent dodecyl‐β‐maltoside and subjected to sucrose density gradient centrifugation. The resulting gradients showed six pigment‐bearing bands which were characterized further by means of absorption and fluorescence emission (77K) spectroscopy, polyacrylamide gel electrophoresis and Western immunoblotting. Two of the bands showed characteristics of light‐harvesting complexes, other bands could be attributed to photosystem II and photosystem I. Up to 10 different light‐harvesting proteins could be identified, some of which are specific for photosystem I, others for photosystem II. The polypeptides of the light‐harvesting complex of photosystem II show a higher chlorophyll c/a ratio than the antenna proteins of photosystem I. As in vascular plants, they represent the bulk of the membrane‐intrinsic light‐harvesting proteins.

The fate of lipids during development and cold-storage of eggs in the laboratory-reared calanoid copepod, Acartia tonsa Dana, and in response to different algal diets

The calanoid copepod Acartia tonsa was sampled throughout one generation to examine the fate of lipids during development in culture. Effects of dietary input were examined by feeding A. tonsa for at least one generation with specific monoalgal cultures. Four different algae were tested: the cryptophyte Rhodomonas baltica, the haptophyte Isochrysis galbana clone T-iso, the diatom Thalassiosira weissflogii and the dinoflagellate Heterocapsa triquetra. Further, the effect of cold storage of eggs on the lipid composition of the newly hatched nauplii was examined. During development, the fatty acid composition changes from a tendency towards high levels of long-chain polyunsaturated fatty acids in the early developmental stages towards a tendency to accumulate more saturated and monounsaturated fatty acids in the later developmental stages. However, the content and composition of polyunsaturated fatty acids can be influenced by the dietary input. The highest ratio of 22:6 n−3/20:5 n−3 was achieved using H. triquetra or I. galbana. Higher levels of 20:5 n−3 were achieved by feeding with R. baltica or T. weissflogii. I. galbana and T. weissflogii were particularly suitable for increasing levels of arachidonic acid (20:4 n−6; AA) in A. tonsa.

Utilisation of small-sized food algae byCalanus finmarchicus(Copepoda, Calanoida) and the significance of feeding history

Abstract Temporal trends and effects of changes in the food environment on egg and faecal-pellet production of Calanus finmarchicus were studied over five weeks using four different food regimes, including monocultures of the cryptophyte Rhodomonas baltica (ca. 8 μm diameter), the haptophyte Emiliania huxleyi (ca. 4 μm diameter), and natural E. huxleyi dominated water from a mesocosm enclosure. The functional responses of egg and faecal-pellet production and clearance/ingestion on algal concentration showed that the copepod could utilise R. baltica and E. huxleyi. High concentrations (> 800 μg C 1-1) of both species were needed to reach maximum rates, but significant egg production occurred at low food concentrations ( 4–7 eggs female-1 day-1 at 50–100 μg C 1-1). The life-time egg production was 1000–1800 eggs female-1 in a constant surplus food environment (900 μg C 1-1 of R. baltica), whereas variable food environments generated lower feeding and egg production. Switching to a reduced food environment g...

Role of chloroplast retention in a marine dinoflagellate

The dinoflagellate Gymnodjnium 'gracjlenturn' feeds on the cryptophyte Rhodomonas salina and retains the chloroplasts of the prey as functional kleptochloroplasts. Using kleptochloroplasts. G. 'gracilentum' becomes a mutotroph, acquiring a proportion of its organic carbon demand through photosynthesis, but the kleptochloroplasts and their photosynthetic activity are lost within a few days. Photosynthesis seems, primarily, to be an important means of nutrition for G. 'gracilenturn' during food depletion, thereby enhancing the survival of the species during food limitation and starvation. However, light has a positive effect on growth kinetics of G. 'gracilentum' in food replete cultures: growth and ingestion rates are higher at a high light intensity than at a low light intensity. This effect may be due to other factors than photosynthetic activity of kleptochloroplasts, since a control experiment with a supposed strictly heterotrophic dinoflagellate, Gymnodinium sp., also showed a dependence of growth kinetics on light intensity.

Molecular phylogeny of the stress-70 protein family with reference to algal relationships

The stress-70 protein family has previously been shown to be a useful tool for molecular phylogeny at the kingdom to family levels. Although sequences of many members of the stress-70 family are available, few genes from the Protoctista have been sequenced to date. Phylogenetic analyses of algae based on various molecules have not, as yet, provided clear results concerning relationships between major divisions. We cloned and sequenced several algal stress-70 genes in order to provide additional data and to further analyse phylogenetic relationships among algal divisions. New nuclear sequences were obtained from Guillardia theta (Cryptophyta), Ascophyllum nodosum (Heterokontophyta) and Cyanophora paradoxa (Glaucocystophyta). Phylogenetic trees of the stress-70 protein family calculated using different methods are presented. In our trees, the heterokont alga Ascophyllum nodosum is closely related to the slime mould Dictyostelium discoideum, while the nucleomorph (eukaryotic endosymbiont) of the cryptophyte Rhodomonas salina seems to be related to the chlorobiont lineage. The glaucocystophyte Cyanophora paradoxa and the nuclear sequence (host) of the cryptomonad alga Guillardia theta also seem to be closely related. The Cryptophyta and the heterokont algae have evolved from different secondary endosymbiotic events involving different hosts and probably different endosymbionts. However, until more stress-70 sequences of algal divisions become available no definitive conclusions can be drawn concerning branching of the major divisions.

Molecular phylogeny of the stress-70 protein family with reference to algal relationships

The stress-70 protein family has previously been shown to be a useful tool for molecular phylogeny at the kingdom to family levels. Although sequences of many members of the stress-70 family are available, few genes from the Protoctista have been sequenced to date. Phylogenetic analyses of algae based on various molecules have not, as yet, provided clear results concerning relationships between major divisions. We cloned and sequenced several algal stress-70 genes in order to provide additional data and to further analyse phylogenetic relationships among algal divisions. New nuclear sequences were obtained from Guillardia theta (Cryptophyta), Ascophyllum nodosum (Heterokontophyta) and Cyanophora paradoxa (Glaucocystophyta). Phylogenetic trees of the stress-70 protein family calculated using different methods are presented. In our trees, the heterokont alga Ascophyllum nodosum is closely related to the slime mould Dictyostelium discoideum, while the nucleomorph (eukaryotic endosymbiont) of the cryptophyte Rhodomonas salina seems to be related to the chlorobiont lineage. The glaucocystophyte Cyanophora paradoxa and the nuclear sequence (host) of the cryptomonad alga Guillardia theta also seem to be closely related. The Cryptophyta and the heterokont algae have evolved from different secondary endosymbiotic events involving different hosts and probably different endosymbionts. However, until more stress-70 sequences of algal divisions become available no definitive conclusions can be drawn concerning branching of the major divisions.

Feeding of the heterotrophic freshwater dinoflagellate Peridiniopsis berolinense on cryptophytes: analysis by flow cytometry and electronic particle counting

We measured feeding rates and food select~vlty of the heterotrophic freshwater dinoflagellate Peridiniopsis berolinense by analytic flow cytometry (AFC), electronic particle counting and sizing (EPCS), and conventional microscopy. Several differently sized strains of the common cryptophytes Rhodomonas minuta and Cryptomonas sp. were offered in short-term (1 to 4 h) laboratory experiments as food in concentrations ranging from 3.0 X 104 to 1.0 X 105 cells ml-'. P. berolinense is a raptorial species that attacks its prey by peduncle-feeding. Since P. berolinense sucks out its prey but does not take up whole cells, grazing rates cannot be quantified by established techniques such as fluorescently labeled algae. We measured dinoflagellate ingestion rates as loss rates of algal prey cells. by the increase of autofluorescence within food vacuoles of P. berolinense, and by the direct formation of food vacuoles. Biovolumes of prey and predator were measured by EPCS. The grazing response was variable and depended on the nutritional status of P. berolinense. Heavily starved cells were small, started feeding immediately and were less selective than moderately starved specimens. We show how nutritional status can be assessed by AFC and EPCS prior to the beginning of an experiment. K E Y WORDS: Heterotrophic dinoflagellates Feeding rates . Flow cytometry Peridiniops~s berolinense

Evaluation of Different Phytoplankton for Supporting Development of Zebra Mussel Larvae ( Dreissena polymorpha): The Importance of Size and Polyunsaturated Fatty Acid Content

A marine alga and variety of freshwater algae of known polyunsaturated fatty acid (PUFA) composition were evaluated in the laboratory for their ability to promote development of Dreissena polymorpha from egg through settling and metamorphosis. The three species of algae which promoted development—the marine and the freshwater strain of Chlorella minutissima and the cryptophyte Rhodomonas minuta—were all rich in long-chain (≥ 18 C) n-3 PUFAs, including some 20:5 or 22:6 PUFAs. Dreissena's need for long-chain n-3 PUFAs is consistent with the needs of marine bivalves and freshwater zooplankton. Larval growth rate on the freshwater strain of C. minutissima was about the same as that for R. minuta, but much faster than that for the marine strain of C. minutissima. Mean ages at settling for larvae fed the freshwater C. minutissima were 15 d at 26°C, 17 d at 24°C, and 22 d at 22° C Low survival rates reported for the larvae in nature may be related to low concentrations of long-chain n-3 PUFAs in blue-green and some green algae that dominate eutrophic lakes in summer.

Are marine diatoms favoured by high Si:N ratios?

Competition experiments were performed first with 4 , then with 11 species of marine phytoplankton at various ratios of si1icate:nitrate and various light intensities. Diatoms became dominant at Si:N ratios >25:1 while flagellates were the superior competitors at lower ratios. The light supply did not influence the competitive position of diatoms and non-siliceous flagellates in general, while it was important in determining the outcome of competition at the species level. In the 11 species expenments, Stephanopyxis palmenana was the dominant diatom at high light intensities. It shared dominance with Lauderia annulata at medium and low light intensities and high Si.N ratios. Pseudonitzschia pungens was the dominant diatom at low light intensities and relatively low Si:N ratios. The green alga Dunaliella tertiolecta was the dominant flagellate at high light intensities, while at low light intensities the prymnesiophycean Chrysochromulina polylepis and the cryptophyte Rhodomonas sp. were also important.

Effects of diet on life-history parameters of the marine bryozoan, Celleporella hyalina (L.)

In order to maintain constant environmental conditions during experimental work on the marine bryozoan Celleporella hyalina (L.), it was necessary to develop a simple and inexpensive culture method. C. hyalina survived and grew on a range of algal diets. Amongst these, chlorophyte algae proved least suitable, but the cryptophyte Rhodomonas baltica was found to be outstanding as a foodstuff. Astogeny of Rhodomonas-fed colonies was similar to that reported for naturally occurring colonies, and resulted in the production of viable larvae. Female zooids were occasionally produced in the basal layer. Using R. baltica as food, C. hyalina can be maintained under controlled environmental conditions indefinitely. This, together with the possibility of propagating clonal replicates of colonies, facilitates the experimental investigation of life-history variation in C. hyalina.

UNIQUE LOCATION OF THE PHYCOBILIPROTEIN LIGHT‐HARVESTING PIGMENT IN THE CRYPTOPHYCEAE1

ABSTRACTThe cryptophyte algae, or cryptomonads, comprise a small algal group with a unique photosynthetic apparatus. Both a chlorophyll a/c2 light‐harvesting complex and a phycobiliprotein antenna (which can be either phycoerythrin or phycocyanin) are present, with the phycobiliprotein playing the major role in harvesting light for photosynthesis. Longstanding circumstantial evidence suggested that, in cryptophytes, the phycobiliprotein is located in the intrathylakoid space (thylakoid lumen) rather than on the outer surface of the thylakoid as part of a phycobilisome as in other algae. We used immunogold labeling to show conclusively that 1) the phycoerythrin (PE) of the cryptophyte Rhodomonas lens Pascher and Ruttner is located within the intrathylakoid space, 2) the PE is not exclusively bound to the thylakoid membrane but instead is distributed across the thylakoid lumen and 3) a fraction of this PE is tightly associated with the thylakoid membrane. The thylakoids are not everted to compensate for this unusual arrangement. The location of the major light‐harvesting pigment on the “wrong” side of the otherwise very normal photo‐synthetic membrane is unexpected, unique to the cryptophytes, and, remarkably, does not impair the photosynthetic abilities of this organism. A model is presented which incorporates these results ‐with previous information to give a complete structural picture of the cryptophyte light‐harvesting apparatus.

The cultivation of Acartia tonsa Dana for use as a live food source for marine fish larvae

The marine calanoid copepod Acartia tonsa has been continuously cultivated in the laboratory at the Danish Institute for Fisheries and Marine Research for over 70 generations. A description of the cultivation procedures is presented in this paper. Adult copepods are maintained in 200–450-l tanks and are fed the cryptophyte Rhodomonas baltica. The concentration of adult copepods is held between 50 and 100/l. Eggs are harvested daily and, on average, ca. 25 eggs are collected per female per day.

Effects of Prudhoe bay crude oil on primary production and zooplankton in arctic tundra thaw ponds

The effects of Prudhoe Bay, Alaska, crude oil on the indigenous phytoplankton and zooplankton of tundra thaw ponds were studied under controlled conditions in situ during the summer of 1976. These effects were compared with uncontrolled oil spills on Pond Omega (a year previously) and Pond E (six years previously). In the uncontrolled spills, the phytoplankton species composition of both ponds remained appreciably different compared with control Pond C, although phytoplankton biomass did not differ greatly. Primary production remained low in Pond Omega but had recovered to control levels in Pond E. In controlled subpond experiments, oil caused a decrease of about 90–100% in primary production in five days but recovered to 40–50% of the control level within fifteen days. During that time, phytoplankton biomass decreased initially but recovered within fifteen days. Oil caused a shift in phytoplankton species composition from a predominance of cryptophytes to chrysophytes. Subponds containing two Daphnia middendorffiana and one Brachinecta paludosa per litre of pondwater were also affected by oil, causing zooplankton death within three or four days. After that time, changes in the phytoplankton species composition were similar to control subponds without zooplankton. Oil toxicity to zooplankton or experimental removal resulted in a loss of grazing pressure which caused the elimination of the cryptophyte Rhodomonas sp. This species was still absent from Pond Omega, but was seen in Pond E for the first time, when zooplankton also reappeared after six years. Oil perturbation of tundra thaw ponds causes a loss of zooplankton and a reduction in primary production. Phytoplankton primary production recovers somewhat but algal species composition remains changed because of the loss of zooplankton grazing pressure and the selective effects of oil.

Amino acids and some other nitrogenous compounds in Calanus finmarchicus: Cowey C. B. and E. D. S. Corner, 1963. J. Mar. Biol. Ass., U.K., 43 (2): 485–493

Diatoms dominate productive regions in the oceans and have traditionally been regarded as sustaining the marine food chain to top consumers and fisheries. However, many of these unicellular algae produce cytotoxic oxylipins that impair reproductive and developmental processes in their main grazers, crustacean copepods. The molecular mode of action of diatoms and diatom oxylipins on copepods is still unclear. In the present study we generated two Expressed Sequence Tags (ESTs) libraries of the copepod Calanus helgolandicus feeding on the oxylipin-producing diatom Skeletonema marinoi and the cryptophyte Rhodomonas baltica as a control, using suppression subtractive hybridization (SSH). Our aim was to investigate differences in the transcriptome between females fed toxic and non-toxic food and identify differentially expressed genes and biological processes targeted by this diatom. We produced 947 high quality ESTs from both libraries, 475 of which were functionally annotated and deposited in GenBank. Clustering and assembling of ESTs resulted in 376 unique transcripts, 200 of which were functionally annotated. Functional enirchment analysis between the two SSH libraries showed that ESTs belonging to biological processes such as response to stimuli, signal transduction, and protein folding were significantly over-expressed in the S. marinoi-fed C. helgolandicus compared to R. baltica-fed C. helgolandicus library. These findings were confirmed by RT-qPCR analysis. In summary, 2 days of feeding on S. marinoi activated a generalized Cellular Stress Response (CSR) in C. helgolandicus, by over-expressing genes of molecular chaperones and signal transduction pathways that protect the copepod from the immediate effects of the diatom diet. Our results provide insights into the response of copepods to a harmful diatom diet at the transcriptome level, supporting the hypothesis that diatom oxylipins elicit a stress response in the receiving organism. They also increase the genomic resources for this copepod species, whose importance could become ever more relevant for pelagic ecosystem functioning in European waters due to global warming.