Archives: Bibliographies

Title

Unveiling the transcriptional features associated with coccolithovirus infection of natural Emiliania huxleyi blooms

Publication Type

Journal Article

Year of Publication

2011

Authors

Pagarete A, Corguille LG, Tiwari B, Ogata H, Vargas C, Wilson WH, Allen MJ

Journal

FEMS Microbiology Ecology

Volume

78

Pagination

555-564

ISBN Number

Keywords

host–virus interactions, functional genomics, Phycodnaviridae, marine microbial ecology, marine transcriptomics, mesocosm, Emiliania huxleyi, Espegrend, Bergen, Norway, 11 m3

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Title

Marine heterotrophic bacteria, protozoan and metazoan zooplankton may experience protein N or mineral P limitation in coastal waters

Publication Type

Journal Article

Year of Publication

2011

Authors

Olsen Y, Andersen T, Gismervik I, Vadstein O

Journal

Marine Ecology Progress Series

Volume

81

Pagination

81-100

ISBN Number

Keywords

Planktonic N and P nutrition, Essential nutrients limitation, Conceptual model, Inverse modelling, CNP flow networks, Nutrient release, Growth efficiency, Elemental CNP, stoichiometry, mesocosm, 38 m3, Hopavagen, Norway

Abstract

The objective of the present study was to examine how N and P availability interactwith C metabolism in marine heterotrophic plankton and whether or not heterotrophic groups arelikely to be subjected to essential nutrient limitations in natural coastal waters. The nutrients studiedwere mineral P and N; the latter is a proxy for essential amino acids. We present a general theoreticalframework and criteria for evaluating essential nutrient limitations in heterotrophs. Datawere derived from a comprehensive mesocosm experiment, where food-web flows were estimatedusing inverse modelling. Bacteria of the mesocosm communities were severely P-deficientthroughout. The heterotrophic nanoplankton was most likely limited by another essential nutrientor by food C availability. Ciliates were most likely P-limited, whereas copepods might experienceP limitation, but were more likely limited by another essential nutrient or food C in the presentexperiments. The N contents of the food were close to the theoretical requirements for copepodsand ciliates. All planktonic groups released dissolved inorganic nitrogen (DIN), and all exceptbacteria released dissolved inorganic phosphorus (DIP). Our results suggested that P limitationmight be readily experienced by bacteria, ciliates and perhaps also by copepods, but not by heterotrophicnanoplankton in natural North East Atlantic coastal waters. A predator must balance itsenergy metabolism and growth under the variable availabilities of essential nutrients, and we proposethat C growth efficiency is a dynamic variable mainly dependent on the availability of themost limiting nutrient. We support the view that C availability alone cannot be used as a proxy forthe food limitation of bacterial and zooplankton growth. Specific essential nutrients should beregarded as potential limiting factors, as for phytoplankton. The variable nutritional requirementsof heterotrophic predators will then represent a major driver of heterotrophic species diversity,allowing a broad diversity of heterotrophic species in plankton communities.

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Title

Rapid shifts in picoeukaryote community structure in response to ocean acidification

Publication Type

Journal Article

Year of Publication

2011

Authors

Meakin NG, Wyman M

Journal

ISME Journal

Volume

5

Pagination

1397-1405

ISBN Number

Keywords

picoeukaryotes, Micromonas, Bathycoccus, RubisCO, 11 m3, mesocosm, Bergen, Espegrend, Norway, acidification

Abstract

Rapid shifts in picoeukaryote community structure were observed during a CO2 perturbationexperiment in which we followed the development of phytoplankton blooms in nutrient-amendedmesocosms under the present day or predicted future atmospheric pCO2 (750 latm, seawater pH7.8). Analysis of rbcL clone libraries (encoding the large subunit of RubisCO) and specificquantitative PCR assays showed that two prasinophytes closely related to Micromonas pusilla andBathycoccus prasinos were present, but responded very differently to high CO2/acidification. Wefound that the abundance of Micromonas-like phylotypes was significantly higher (420-fold) underelevated CO2/low pH, whereas the Bathycoccus-like phylotypes were more evenly distributedbetween treatments and dominated the prasinophyte community under ambient conditions.The ISME Journal (2011) 5, 1397–1405; doi:10.1038/ismej.2011.18; published online 17 March 2011Subject Category: microbial population and community ecology

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Title

The role of ciliates, heterotrophic dinoflagellates and copepods in structuring spring plankton communities at Helgoland Roads, North Sea

Publication Type

Journal Article

Year of Publication

2011

Authors

Loder MGJ, Meunier C, Wiltshire KH, Boersma M, Aberle N

Journal

Marine Biology

Volume

158

Pagination

1551-1580

ISBN Number

Keywords

mesocosm, ciliates, helgoland roads, Germany, microzooplankton, 1 m3

Abstract

Mesocosm experiments coupled with dilutiongrazing experiments were carried out during the phytoplanktonspring bloom 2009. The interactions betweenphytoplankton, microzooplankton and copepods wereinvestigated using natural plankton communities obtainedfrom Helgoland Roads (54 11.30N; 7 54.00E), North Sea.In the absence of mesozooplankton grazers, the microzooplanktonrapidly responded to different prey availabilities;this was most pronounced for ciliates such asstrombidiids and strobilids. The occurrence of ciliates wasstrongly dependent on specific prey and abrupt losses intheir relative importance with the disappearance of theirprey were observed. Thecate and athecate dinoflagellateshad a broader food spectrum and slower reaction timescompared with ciliates. In general, high microzooplanktonpotential grazing impacts with an average consumption of120% of the phytoplankton production (Pp) were measured.Thus, the decline in phytoplankton biomass could bemainly attributed to an intense grazing by microzooplankton.Copepods were less important phytoplanktongrazers consuming on average only 47% of Pp. Microzooplanktonin turn contributed a substantial part to thecopepods’ diets especially with decreasing quality ofphytoplankton food due to nutrient limitation over thecourse of the bloom. Copepod grazing rates exceeded microzooplanktongrowth, suggesting their strong top-downcontrol potential on microzooplankton in the field.Selective grazing by microzooplankton was an importantfactor for stabilising a bloom of less-preferred diatom speciesin our mesocosms with specific species (Thalassiosira spp.,Rhizosolenia spp. and Chaetoceros spp.) dominating thebloom. This study demonstrates the importance of microzooplanktongrazers for structuring and controlling phytoplanktonspring blooms in temperatewaters and the importantrole of copepods as top-downregulators of microzooplankton.

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Title

Effects of warming and nutrients on sediment community respiration in shallow lakes: an outdoor mesocosm experiment

Publication Type

Journal Article

Year of Publication

2011

Authors

Liboriussen L, Lauridsen TL, Sondergaard M, Landkildehus F, Sondergaard M, Larsen SE, Jeppesen E

Journal

Freshwater Biology

Volume

56

Pagination

437-447

ISBN Number

0046-5070

Keywords

climate change, global warming, lake, respiration, sediment, Biomanipulation, boreal, waters, Oxygen, state, 2.5m3, freshwater, Jutland, Denmark

Abstract

P>1. Climate warming is expected to change respiration in shallow lakes but to an extent that depends on nutrient state. 2. We measured sediment respiration (SR) over the season in the dark on intact sediment cores taken from a series of flow-through, heated and unheated, nutrient-enriched and unenriched mesocosms. The natural seasonal temperature cycle ranged from 2 to 20 degrees C in the unheated mesocosms. In the heated mesocosms, the temperature was raised 4-6 degrees C above ambient temperatures, depending on season, following the A2 climate change scenario downscaled to the local position of the mesocosms, but enlarged by 50%. We further measured ecosystem respiration (ER) in the mesocosms based on semi-continuous oxygen measurements. 3. SR changed over the season and was approximately ten times higher in summer than in winter. SR showed no clear response to warming in the nutrient-enriched treatment, while it increased with warming in the unenriched mesocosms which also had lower fish densities. 4. ER was not affected by artificial warming or nutrient enrichment, but it was ten times higher in summer than in winter. 5. SR contributed 24-32% to ER. The SR:ER ratio was generally stimulated by warming and was higher in winter than in summer, especially in the nutrient-enriched mesocosms. 6. Our results indicate that climate warming may lead to higher SR, especially in clear, macrophyte-dominated systems. Moreover, the contribution of SR to ER will increase with higher temperatures, but decrease as the winters get shorter.

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Date of Published

Mar

Accession Number

WOS:000287092900003

Type of Article

Article

Alternate Journal

Freshw. Biol.

Title

Effects of Saharan dust on the microbial community during a large in situ mesocosm experiment in the NW Mediterranean Sea

Publication Type

Journal Article

Year of Publication

2011

Authors

Laghdass M, Blain S, Besseling M, Catala P, Guieu C, Obernosterer I

Journal

Aquatic Microbial Ecology

Volume

62

Pagination

201-213

ISBN Number

Keywords

Saharan dust deposition, mesocosms, CE-SSCP, CARD-FISH, clone libraries, Alteromonas macleodii, NW Mediterranean Sea, Corsica, 52 m3

Abstract

The response of the microbial community to Saharan dust deposition was investigatedin 6 large mesocosms (52 m3) deployed at an oligotrophic coastal site in the NW Mediterranean Seain June 2008 (DUNE project). The mesocosms represented well the environmental conditionsobserved at the study site during the 8 d experimental period, and the triplicate mesocosms exhibitedhigh reproducibility for each treatment. Dust deposition resulted in an increase in chlorophyll a concentration(0.22 ± 0.03 ?g l–1), as compared to that in the control treatments (0.12 ± 0.01 ?g l–1), but notreatment effect was observed for bacterial heterotrophic abundance at 5 m depth. Results from thefingerprinting technique CE-SSCP indicate a temporal evolution of the structure of the total (16SrRNA gene) and active (16S rRNA transcripts) bacterial community, and Saharan dust deposition hada noticeable structuring effect on the active bacterial community. Combining results from 16S rRNAgene clone libraries and CE-SSCP indicates that the relative contribution of Alteromonas macleodiito the active bacterial community was enhanced 2-fold following dust addition. The 2 operational taxonomicunits (OTUs) Thiothrix and Alteromonas, belonging to Gammaproteobacteria, and the BacteroidetesOTU NS5-1 were specific to the clone libraries from the dust-amended mesocosms or moreabundant in these than in the control ones. CARD-FISH analyses, however, indicate that these OTUshad overall low abundances (1 to 5% of total DAPI-counts). Despite the pronounced temporal trendobserved during the experimental period, dust deposition had a small, but noticeable structuringeffect on the heterotrophic bacterial community that was detectable only at the OTU level at 99%similarity of the 16S rRNA gene.

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Title

Shifts in biogenic carbon flow from particulate to dissolved forms under high carbon dioxide and warm ocean conditions

Publication Type

Journal Article

Year of Publication

2011

Authors

Kim JM, Lee K, Shin K, Yang EJ, Engel A, Karl DM, Kim HC

Journal

Geophysical Research Letters

Volume

38

Pagination

ISBN Number

Keywords

inorganic carbon, biogenic carbon, acidification, warming, CO2 enrichment, mesocosm, 3 m3, Korea

Abstract

Photosynthesis by phytoplankton in sunlit surfacewaters transforms inorganic carbon and nutrients intoorganic matter, a portion of which is subsequentlytransported vertically through the water column by theprocess known as the biological carbon pump (BCP). TheBCP sustains the steep vertical gradient in total dissolvedcarbon, thereby contributing to net carbon sequestration.Any changes in the vertical transportation of the organicmatter as a result of future climate variations will directlyaffect surface ocean carbon dioxide (CO2) concentrations,and subsequently influence oceanic uptake of atmosphericCO2 and climate. Here we present results of experimentsdesigned to investigate the potential effects of oceanacidification and warming on the BCP. These perturbationexperiments were carried out in enclosures (3,000 Lvolume) in a controlled mesocosm facility that mimickedfuture pCO2 (?900 ppmv) and temperature (3°C higherthan ambient) conditions. The elevated CO2 andtemperature treatments disproportionately enhanced theratio of dissolved organic carbon (DOC) production toparticulate organic carbon (POC) production, whereas thetotal organic carbon (TOC) production remained relativelyconstant under all conditions tested. A greater partitioningof organic carbon into the DOC pool indicated a shift in theorganic carbon flow from the particulate to dissolvedforms, which may affect the major pathways involved inorganic carbon export and sequestration under future oceanconditions. Citation: Kim, J.?M., K. Lee, K. Shin, E. J. Yang,A. Engel, D. M. Karl, and H.?C. Kim (2011), Shifts in biogenic carbonflow from particulate to dissolved forms under high carbondioxide and warm ocean conditions

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Title

Extensive cross-disciplinary analysis of biological and chemical control of Calanus finmarchicus reproduction during an aldehyde forming diatom bloom in mesocosms

Publication Type

Journal Article

Year of Publication

2011

Authors

Jonasdottir SH, Dutz J, Koski M, Yebra L, Jakobsen HH, Vidoudez C, Pohnert G, Nejstgaard JC

Journal

Marine Biology

Volume

158

Pagination

1943-1963

ISBN Number

Keywords

mesocosm, Calanus, Espegrend, 11 m3, Bergen, Norway, PUA, Skeletonema

Abstract

Egg and faecal pellet production and egghatching success of the calanoid copepod Calanus finmarchicuswere monitored over a period of 14 days (14–28April, 2008) while fed water from 4 differently treatedmesocosms and ambient water. Two of the mesocosmsused were inoculated with the polyunsaturated aldehyde(PUA)-producing diatom Skeletonema marinoi, while 2received only nutrient additions with or without silica. Themesocosms developed blooms of S. marinoi, mixed diatomsor the haptophyte Phaeocystis pouchetii, respectively.Faecal pellet production of C. finmarchicus increased withincreasing food availability. Egg production increased withtime in all mesocosms to a maximum single femaleproduction of 232 eggs female-1 day-1 (average of 90eggs female-1 day-1) and followed the development ofciliates and P. pouchetii, but was not affected by theobserved high (up to 15 nmol L-1) PUA productionpotential of the phytoplankton. The hatching success of theeggs produced on the mesocosm diets was high (78–96%)and was not affected by either aldehydes in the maternaldiet or exposure to the dissolved aldehydes in the water

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Title

Carbon and nitrogen flows during a bloom of the coccolithophore Emiliania huxleyi: Modelling a mesocosm experiment

Publication Type

Journal Article

Year of Publication

2011

Authors

Joassin P, Delille B, Soetaert K, Harlay J, Borges AV, Chou L, Riebesell U, Suykens K, Grégoire M

Journal

Journal of Marine Systems

Volume

85

Pagination

71-85

ISBN Number

Keywords

Coccolithophore, Emiliania huxleyi, Mathematical model, Biogeochemical cycling, calcification, mesocosm experiment, Espegrend, Bergen, Norway, 11 m3

Abstract

A dynamic model has been developed to represent biogeochemical variables and processes observed during experimental blooms of the coccolithophore Emiliania huxleyi induced in mesocosms over a period of 23 days. The model describes carbon (C), nitrogen (N), and phosphorus (P) cycling through E. huxleyi and the microbial loop, and computes pH and the partial pressure of carbon dioxide (pCO2) from dissolved inorganic carbon (DIC) and total alkalinity (TA). The main innovations are: 1) the representation of E. huxleyi dynamics using an unbalanced growth model in carbon and nitrogen, 2) the gathering of formulations describing typical processes involved in the export of carbon such as primary production, calcification, cellular dissolved organic carbon (DOC) excretion, transparent exopolymer (TEP) formation and viral lyses, and 3) an original and validated representation of the calcification process as a function of the net primary production with a modulation by the intra-cellular N:C ratio mimicking the effect of nutrients limitation on the onset of calcification. It is shown that this new mathematical formulation of calcification provides a better representation of the dynamics of TA, DIC and calcification rates derived from experimental data compared to classicaly used formulations (e.g. function of biomass or of net primary production without any modulation term). In a first step, the model has been applied to the simulations of present pCO2 conditions. It adequately reproduces the observations for chemical and biological variables and provides an overall view of carbon and nitrogen dynamics. Carbon and nitrogen budgets are derived from the model for the different phases of the bloom, highlighting three distinct phases, reflecting the evolution of the cellular C:N ratio and the interaction between hosts and viruses. During the first phase, inorganic nutrients are massively consumed by E. huxleyi increasing its biomass. Uptakes of carbon and nitrogen are maintained at a constant ratio. The second phase is triggered by the exhaustion of phosphate (PO4 3?). Uptake of carbon and nitrogen being uncoupled, the cellular C:N ratio of E. huxleyi increases. This stimulates the active release of DOC, acting as precursors for TEP. The third phase is characterised by an enhancement of the phytoplankton mortality due to viral lysis. A huge amount of DOC has been accumulated in the mesocosm

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Title

Bottom – up carbon subsidies and top – down predation pressure interact to affect aquatic food web structure

Publication Type

Journal Article

Year of Publication

2011

Authors

Faithfull CL, Huss M, Vrede T, Bergström AK

Journal

Oikos

Volume

120

Pagination

311-320

ISBN Number

Keywords

bottom up, top down, Carbon assimilation, freshwater, glucose, mesocosm, 18 m3, Sweden

Abstract

Human impacts such as eutrophication, overexploitation and climate change currently threaten future global food and drinking water supplies. Consequently, it is important that we understand how anthropogenic resource (bottom – up) and consumer (top – down) manipulations aff ect aquatic food web structure and production. Future climate changes arepredicted to increase the inputs of terrestrial dissolved organic carbon to lakes. Th ese carbon subsidies can either increase or decrease total basal production in aquatic food webs, depending on bacterial competition with phytoplankton for nutrients. This study examines the eff ects of carbon subsidies (bottom – up) on a pelagic community exposed to different levels of top – down predation. We conducted a large scale mesocosm experiment in an oligotrophic clear water lake in northern Sweden, using a natural plankton community exposed to three levels of glucose addition (0, 420 and 2100 ? g C l –1 total added glucose) and three levels of young-of-the-year perch Perca fl uviatilis density (0, 0.56 and 2 individuals m –3 ). Bacterioplankton production doubled with glucose addition, but phytoplankton production was unaff ected, in contrast to previous studies that have manipulated carbon, nutrients or light simultaneously. This suggests that carbon addition alone is not sufficient to reduce autotrophic production, at least in an oligotrophic lake dominated by mixotrophic phytoplankton. Larval perch grazing did not produce a classical trophic cascade, but substantially altered the species composition of crustacean zooplankton and ciliate trophic levels. Glucose addition increased the biomass of rotifers, thus potentially increasing energy transfer through the heterotrophic pathway, but only when fi sh were absent. Th is study illustrates that changes in community structure due to selective feeding by top-predators can determine the infl uence of bottom – up carbon subsidies

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