External Projects BIO

ANTPHIRCO

 Antarctic phytoplankton in a changing world and its consequences for the lower pelagic food web

PhD:Tristan Bigg

P.I.: C.P.D. Brussaard;

Program: NWO Polar Program

Despite phytoplankton, viruses and zooplankton grazers being key players in aquatic ecosystems, only sparse knowledge exists of their seasonal and interactive role in the Antarctic waters. Given the global interest in the Antarctic Peninsula for its ecological importance to the food web, and for the climate change-induced environmental changes occurring there, it is timely to study the following barely explored objectives: (1) the temporal dynamics of phytoplankton, viruses and zooplankton in the coastal waters of the western Antarctic Peninsula, (2) determine viral lysis rates of phytoplankton and compare to micro- and mesozooplankton grazing, (3) examine to what extent viral infection affects the lipid composition of phytoplankton in field and laboratory and (4) establish how changing phytoplankton community structure and biochemical composition controls the lipid composition and overwintering strategies of dominant calanoid copepods. This project will be the first synergistic study on important interactive processes in the waters of the Antarctic Peninsula that are experiencing rapid environmental change. The temporal, comparative and integrative character of this study that spans trophic levels is unique, and will significantly advance our comprehension of aquatic food webs in a changing world.

CARBOCHANGE

Changes in carbon uptake and emissions by oceans in a changing climate

Project period:2011-03-01 to 2015-02-28

PostDoc: dr. Elizabeth Jones

P.I: prof. Hein de Baar

CARBOCHANGE will provide the best possible process-based quantification of net ocean carbon uptake under changing climate conditions using past and present ocean carbon cycle changes for a better prediction of future ocean carbon uptake. We will improve the quantitative understanding of key biogeochemical and physical processes through a combination of observations and models. We will upscale new process understanding to large-scale integrative feedbacks of the ocean carbon cycle to climate change and rising carbon dioxide concentrations. We will quantify the vulnerability of the ocean carbon sources and sinks in a probabilistic sense using cutting edge coupled Earth system models under a spectrum of emission scenarios including climate stabilisation scenarios as required for the 5th IPCC assessment report. The drivers for the vulnerabilities will be identified. The most actual observations of the changing ocean carbon sink will be systematically integrated with the newest ocean carbon models, a coupled land-ocean model, an Earth system model of intermediate complexity, and fully fledged Earth system models through a spectrum of data assimilation methods as well as advanced performance assessment tools.

The NIOZ team contributes the following sets of deep ocean observations of the CO2 system and derived anthropogenic CO2 component:

a) 2011, article in December issue Deep-Sea Research II (Van Heuven et al., 2011)

b) 2010/2011 Dr. Elizabeth Jones; Expedition ANTXXVII/2 Polarstern, from 28 November 2010 (Cape Town) to 5 February 2011 (Punta Arenas)

c) 2012 Dr. Elizabeth Jones, Lesley Salt, Sharyn Crayford; Expedition ANTXXVIII/3 Polarstern, from 7 January (Cape Town) to 14 March 2012 (Punta Arenas)

d) 2010/2011 Dr. Elizabeth Jones, Lesley Salt, Steven van Heuven; three NIOZ expeditions in West Atlantic Ocean; RV Pelagia and RV James Cook

CHARLET

 Primary Production in the North Sea: Changes in Resource Limitation and Energy Transfer (NWO-ZKO-Northsea).

Phd:P. O’Connor

PI:  C. Brussaard,

other project partners: NIOO-KNAW and UvA-IBED.

Primary production by phytoplankton provides the basis of marine food webs and is strongly determined by nutrient and light availability. Measures against eutrophication have mainly led to a reduction in phosphorus inputs into coastal seas like the North Sea, whereas nitrogen and silica loadings were much less reduced. This has resulted in major changes in the relative availability of different nutrients, and there is currently substantial disagreement whether phytoplankton growth in coastal waters is limited by nitrogen, phosphorus, or light. Furthermore, resource-mediated changes in the cellular composition of phytoplankton will have major implications for their nutritional quality for zooplankton, with effects that may cascade throughout the entire aquatic food web. What are the shifts in primary production and species composition of the phytoplankton that we may expect in future years? And how will this affect the efficiency by which the solar energy captured by these primary producers is transferred to higher trophic levels in the marine food web? In this project, we will determine the limiting factors for phytoplankton growth in the North Sea, and how these limiting factors affect the food quality and species composition of the phytoplankton. We will develop novel approaches to assess in-situ resource limitation using stable isotope labeling, and implement the results of these studies in competition models describing phytoplankton growth in the North Sea. Furthermore, we will investigate how the transfer of primary production to the classical zooplankton-based food web versus the viral loop is affected by shifts in the phytoplankton community and their food quality. The project combines mathematical models, laboratory studies and field work during cruises with the R/V Pelagia in two contrasting areas of the North Sea: the productive coastal area with relatively high nutrient inputs from rivers and the central North Sea with much reduced nutrient levels especially during summer. The proposed work will offer key insights into the impact of changes in resource limitation on the carrying capacity of the North Sea.

CORALCHANGE

P.I.'s:  Marina Carreiro-Silva (Lab Horta, Azores, Portugal), Fleur C. van Duyl

Funding: Marie Curie, FCT

The aim of this research project is to determine the factors controlling carbonate production (bioaccretion) and destruction (bio-erosion) of cold-water coral reefs, and how environmental changes will affect the balance between these two processes. The study  focuses on the following key objectives: (1) geographic patterns of bio-erosion and coral calcification of the two major cold-water reef–building species in the NE Atlantic, Lophelia pertusa and Madrepora oculata, and determine its relationship to environmental factors; (2) Use estimates of bioerosion and calcification as an index of the “health” status of deep-sea coral reefs; (3) Characterize the diversity, phylogeny and geographic distribution of bioeroder species; (4) Determine the effects of predicted increases in carbon dioxide partial pressure (pCO₂) and temperature, and their interactions, on the calcification of the scleractinian coral species Lophelia pertusa and Madrepora oculata; (5) Experiments described in (4) will also be used to determine how increased acidification and temperature will affect the relationship between the coral host and endolithic fungi living in their skeletons.

CO2BUF

CO2 buffering capacity in the North Sea

Funding:NWO/ALW project

Period:2008-2012

PhD:Lesley Salt

P.I.: prof. Hein de Baar

Recent observations from the North Sea, a NW European shelf sea, show that between 2001 and 2005 the CO2 partial pressure (pCO2) in surface waters rose by 23 ppm. This is faster than the increase of atmospheric pCO2, which rose in the same period approximately 10ppm. These results indicate that there might be a decline in the buffering capacity of the inorganic carbonate system of the North Sea (increasing Revelle Factor). However, the observed decreased air-sea pCO2 difference in the North Sea could arise from variety of biological, chemical and physical factors and may reflect a combination of natural variability and the longer-term secular trend due to the uptake of anthropogenic CO2.

 Here, we use a follow up of our studies in 2001 and 2005 and thus to extend our North Sea-wide field data set into a time series that will deepen our understanding of the response of the North Sea to rising CO2 conditions. The 2001-2008 data set will be used to budget carbon and nutrient cycles by using a combined ecosystem/transport model. The coupling of those two models enables the simulation of the ecosystem processes with real-time forcing by the physical background conditions such as circulation, water and air temperature, wind fields, light intensity and river loads. This combined model will be used to study the residence time of North Sea water in relation to its buffering capacity of atmospheric CO2. The study will give insight into the question whether the decline in pCO2 is a response to the uptake of anthropogenic CO2 rather than natural interannual variability. Ultimately the proposed work will answer the question whether the buffering capacity of the inorganic carbon system of the North Sea is declining.

Double Trouble

Consequences of Ocean Acidification – Past, Present and Future

Project: Darwin Center for Biogeosciences.

PosDoc: K. Crawfurd,

P.I.: C.P.D. Brussaard,

in cooperation with:  Univ. Utrecht and AWI

Along with climate warming, anthropogenic CO2 is currently causing a significant increase in ocean acidity: Double Trouble (Richard Feely, Barcelona 2007)!

The effects of ocean acidification on marine calcifiers and plankton, as well as the marine carbon cycle are, however, poorly understood.

Here we propose an integrated multidisciplinary research project by combining:

1.  essential laboratory experiments using organisms grown under pCO2 controlled conditions.
2.  state-of-the-art reconstructions of ocean acidification in the geological past.
3. studies of the impact of ocean acidification on the marine carbon cycle.

Together this will quantify the impact of ocean acidification on calcification and feedbacks ona tmospheric pCO2. The impact of past ocean acidification on evolution and extinction will provide important constraints on the adaptation potential of marine calcifiers and non-calcifying plankton. This approach allows for determining the  consequences of differential responses for the marine carbon cycle. Together, these estimates of past and future rates of change and ecosystem turnover with will yield critical assessment of the tipping points in modern environments, crucial for policy makers.

DynAciNoS

Dynamics of acidification in the North Sea: documentation and attribution

Funding: NWO/ZKO Program

Period: 2011-2014

PhD: ms. Nicola Clargo

P.I.: prof. Hein de Baar

Fossil fuel use, land use change and cement production have perturbed the global carbon cycle and have led to the accumulation of carbon dioxide in the atmosphere. This has two major consequences, namely global warming and ocean acidification (“the other CO2 problem”). Sea surface water pH has decreased already by 0.1 unit since pre-industrial time, and based on atmospheric CO2 scenarios, it is projected to further decline by 0.0015-0.002 unit per year over the coming century. However, observations on the Washington coast and in the North Sea (Rijkswaterstaat monitoring) show stronger decreases of 0.045 and 0.02 unit per year, respectively. The North Sea is apparently acidifying 10 times faster than global ocean model predictions. During a cruise in September 2011 a detailed investigation of the spatial and temporal patterns of pH in the North Sea at a basin-wide scale was made by using the high quality methodology in use by the international CO2 research community. This will generate the needed data to see whether the acidification of the North Sea is indeed occurring at such high pace. In addition, we will also elucidate the biogeochemical mechanisms governing the pH in North Sea waters, in particular the balance between production and respiration and the generation of alkalinity. As part of this investigation, we will apply a recently developed modelling technique to attribute pH changes to changing environmental parameters.

FORCE

Future Of  coral Reefs in a Changing Environment.

PI: F.C. van Duyl,

PostDoc:B. Mueller

Project: (EU-ENV)

With a general shift from coral-dominated to macroalgal-dominated systems occurring on many

Caribbean reefs, any process that enhances bioerosion may contribute significantly to the decline of reef habitat quality and ecosystem services. The FORCE proposal will investigate a novel but potentially important mechanism by which sponges accelerate the rate of bioerosion as algal cover increases. Bioeroding sponges can kill live corals and are notorious reef excavators eroding up to 20 kg m^-2 y^-1. Bioerosion by sponges often increases after disturbance and is positively correlated with eutrophication. However, it has recently been shown that cavity sponges on coral reefs mainly consume dissolved organic matter (DOM>90% of their diet). This may imply that the key users of DOM on coral reefs are sponges. Benthic algae exude large amounts of DOM and therefore an increase in macroalgal cover on degrading reefs may stimulate the growth of bioeroding sponges, leading to an increase in bioerosion. The FORCE project will test the hypotheses that 1. Benthic macroalgae release on average more DOM per unit surface than corals, that 2. bioeroding sponges predominantly feed on DOM and that 3. bioerosion of reefs by sponges increases with DOM production by the reef. 

GEOTRACES I,

Global Change and Microbial Oceanography in the West Atlantic Ocean

Funding: NWO/ZKO Program

Period: 2010-2013

dr. Micha Rijkenberg, ing. Patrick Laan, ing. Jeroen de Jong,

P.I.:  prof. Hein de Baar

Re-visiting in 2009-2010 of West Atlantic GEOSECS-1972 produces complete ocean sections of (A) novel trace elements and several isotopes, (B) transient tracers of global change, (C) microbial biodiversity and metabolism, and (D) interpretation by ocean modeling where the sea' will be first-ever ocean sections (sub-projects A, (B), C), while others (sub-project B) will allow unraveling of transient global changes over the past ~35 years CLIVAR).

A) The first-ever high resolution (24 depths at every degree) Atlantic deep section of trace metals Fe, Al, Zn, Mn, Cd, Cu, Co, Ni, Ag will be done, in conjunction with lower resolution sampling for Ba, Rare Earths, natural isotopes 234Th, 230Th, 231Pa, 223Ra, 224Ra, 226Ra, 228Ra,  227Ac and anthropogenic isotopes 129I, 99Tc, 137Cs,  239,240Pu, 238Pu.  

B) Water masses, circulation and mixing are defined by classical S,T,p combined with datasets of dissolved nutrients and O2, as well as transient tracers DIC, CFCs, novel SF6,  3H/3He and 13CO2, 14CO2 also to derive 'ages' of a water mass. The invasion of transients is mostly in the North Atlantic Ocean and partly overlaps with warming of upper ocean waters, and with the increase of CO2 inventory, hence ocean acidification.

C) Biodiversity, abundance and metabolic rates of microbes (eukaryotes, prokaryotes and viruses) will be determined in the meso- and bathypelagic ocean. Particularly, the role of chemoautotrophy in the deep ocean will be investigated as it might represent a thus far unrecognized source of dark ocean ‘primary productivity’.

D) The above datasets A,B,C are in mutual support and moreover combine to serve for Ocean Biogeochemical Climate Modeling towards more rigorous, integrated understanding of processes including the role of the Atlantic Ocean in global change.

GEOTRACES III

GEOTRACES Netherlands-USA Joint Effort on Trace Metals in the Atlantic Ocean

Funding: NWO/ALW project

Period:2010-2013

PostDoc: dr. Rob Middag,

P.I: prof. Ken Bruland (UCSC),prof. Hein de Baar

The GEOTRACES program will for the first time chart the ultralow concentrations of dissolved trace metals in the oceans. In the Atlantic Ocean samples have been collected in years 2010 and 2011 by ships of both The Netherlands and the USA, using ultraclean sampling methods The samples are analyzed by mass spectrometry at the University of Santa Cruz, California. This unique Netherlands-USA collaboration realizes the measurements of dissolved iron, manganese, copper, cobalt and nickel that all are bio-essential for the plankton ecosystem. Aluminium, cadmium and silver are involved in the biological cycle and we try to unravle why and how this involvement is. Lead has been borught into the oceans by mankind due to combustion  of leaded gasoline.

MACUMBA

 Marine Microorganisms: Cultivation Methods for Improving their Biotechnological Applications.

Funding:EU FP 7

MaCuMBA addresses the call KBBE.2012.3.2-02: Improved cultivation efficiency of marine microorganisms’ and proposes a plethora of novel approaches and methodologies, including high-throughput procedures for the isolation of new marine microorganisms, using a wide variety of samples from different marine environments, including those with extreme conditions. MaCuMBA will cultivate marine microorganisms under conditions that approach their natural environment and as such improve the strain isolation and cultivation efficiency. The MaCuMBA consortium will investigate cell-to-cell communication and will use this new knowledge for enhancing isolation, cultivation and expression of silent genes coding for bioactives. MaCuMBA will combine the various approaches and methods and whenever possible develop automated procedures. All of marine samples available to MaCuMBA come from environments that are not or only poorly investigated with regard to the microorganisms that inhabit them and these samples hold promise of novel strains with exciting new biotechnological potential

MoVE:

Microphytobenthos Viral Ecology

PhD:Catia Carreira

P.I.: Dr C Brussaard, NIOZ

        Prof M Middelboe, Section for Marine Biology, University of

       Copenhagen, Helsingør, Denmark

This project links two existing scientific areas to create an innovative research branch in marine viral ecology. Benthic phototrophic organisms, mainly cyanobacteria and diatoms, provide the majority of the primary production in intertidal ecosystems, but the effect of virus infections on these organisms has not been investigated. We have isolated two virus-host systems (one diatom and a cyanobacterium), that we are currently characterising. Several laboratory experiments with these virus-hosts systems suggest that viruses enhance the heterogeneity of photoautotrophic benthic microorganisms. Parallel to this we are improving and adopting an existing fluorescence method to observe virus infection of benthic phototrophs.

NSBWO

The North Sea Ballast Water Opportunity Project

in cooperation with BSH (Germany), GoConsult (Germany), WMU (Sweden) and CaTO (The Netherlands),

Period: 2009-2013

PI: Louis Peperzak

Project manager: Jan Boon

Promovendi: Peter Paul Stehouwer, Cees van Slooten

The NSBWO project strives to provide regional cohesion, encourage innovation, and develop future strategies in ballast water policies and management in the North Sea region, where many of the manufacturers of ballast water treatment systems are based. The North Sea region often acts as a unified region with respect to maritime matters which is also the case in ballast water policies. The NSBWO project offers an excellent platform for such a cooperation.

The project’s objectives are:

1. to strengthen regional cohesion in the implementation, monitoring and enforcement of ballast water management policies,
2. to provide an open research and innovation programme for the North Sea region based on scientific knowledge for implementation  and enforcement of ballast water certification and port state control,
3. to provide future strategies for the North Sea region to reduce ship-borne bio invasions,
4. to involve all stakeholders in the North Sea region, while stimulating open exchange of knowledge, ideas and expertise.

While the overall coordination of this 5-year project is the responsibility of the NIOZ, the project group further consists of The Federal Maritime and Hydrographic Agency of Germany (BSH, Germany), GoConsult (Germany), World Maritime University (Sweden) and CaTO Marine Ecosystems (The Netherlands). The project is co-funded by the INTERREG IVB North Sea Region Programme of the European Regional Development Fund (ERDF) and runs till December 2013.

Further information

For more information about the North Sea Ballast Water Opportunity project, please visit our website www.northseaballast.eu  or contact us at info@northseaballast.eu

NUSS

Nutrition of Sponges on the Saba bank, Dutch Caribbean

PIs: Fleur C. van Duyl, Erik H. Meesters (IMARES).

Funding: WWF, NIOZ

This project studies the nutrition, cover and abundance of sponges on the SABA bank. Due to environmental change on coral reefs characterized by a reduction in life coral cover (due to space competition with benthic macroalgae and coral bleaching events) it is hypothesized that sponges will increase in cover. One of the assumption is that the food supply to sponges increases due to eutrophication and due to increase of benthic macroalgae. By now many sponges are known for their capacity to feed on dissolved organic matter. Benthic macroalgae tend to produce more dissolved organic matter per unit reef projected surface than corals.  The stable carbon and nitrogen isotope composition of several dominant sponge species and that of dominant macrobenthic algae and plankton are studied on different locations. Aim is to determine whether a shift in cover from coral to algal dominated reefs will increase the macroalgal-derived DOM in the diet of sponges.

PHYTURE

Biochemical and ecological effects of resource co-limitation on key phytoplankton species.

PhD student:Douwe Maat

P.I.: Corina Brussaard

Project: Heip-OIO

Phytoplankton fix large amounts of CO2 and account for almost half of the total primary production on Earth. These photosynthetic microorganisms make up the base of the marine food web, providing more than 99% of the organic matter available to higher trophic levels. Quantification of rates, patterns and mechanisms that control phytoplankton production and fate of the resultant organic carbon is an important central theme in marine research. The nature and activity of the phytoplankton community are strongly influenced by physical and chemical factors. Phytoplankton losses by viral lysis, grazing and sinking, however, restrain primary production and are thus equally important for ocean ecosystem productivity and the efficiency of the biological pump. Whether phytoplankton are grazed upon, sink out, or die due to viral lysis, has major implications for energy fluxes and biogeochemical cycles in marine pelagic food webs. Despite these general facts, very little is known of the eco-physiological effects of P-limitation in relation to other phytoplankton growth-regulating resources influenced by anthropogenic activities (e.g. increased levels of pCO2 and warming of surface water and subsequent stratification). Dedicated experiments grant a mechanistic understanding of the consequences of resource co-limitation of phytoplankton for the dynamics transfer of organic matter between the primary producers and primary consumers. Moreover, virtually no data is available pertaining to the impact of viral infection of phytoplankton grown under these resource co-limiting conditions. To our knowledge, no study exists on the qualitative and quantitative changes in intact membrane lipid composition in phytoplankton grown under such conditions (non-infected and virally infected). This project will be the first to address these questions in a concerted and comprehensive manner. Excellently fitting in the NIOZ research themes and enforcing recent collaborative research interests between the applicants, this project’s objectives are to clarify the ecological importance of P-limitation in combination with increasing pCO2 and different levels of irradiance, on (1) the growth and health of three key phytoplankton species, (2) the algal cellular lipid composition and content of non-infected and viral infected phytoplankton, (3) algal host-virus interactions, and (4) on the nutritional value of algal prey and grazing rates by microzooplankton and planktonic bivalve larvae. The results of this timely proposed project will largely advance our comprehension of the effects of expected future climate-driven and anthropogenic changes in resource limitation on phytoplankton production and losses. Furthermore, it will provide a solid base for future studies, supply essential data for a more accurate evaluation of global carbon cycle models, and stimulate the development of urgently needed proxies for past climate change analysis.

SANBA

 Sponge Associated Nitrifying Bacteria and Archaea

PIs: Fleur C. van Duyl, Judith van Bleijswijk.

Funding: NIOZ

Many sponges harbor nitrifying bacteria. Nitrification is a key process in the formation of nitrite, which is a key precursor for denitrification and anaerobic ammonia oxidation (anammox), processes which remove N from the system. We study the diversity of nitrifying bacteria and archaea in cold en warm water coral reef sponges with molecular tools and  microscopy (fluorescent in situ hybridization). Interestingly, nitrifying archaea appear to be  more abundant in sponges than nitrifying bacteria. Many of the nitrifying bacteria and archaea might well be sponge specific. Nitrifying bacteria may be more habitat related (in terms of temperature) than the nitrifying archaea. In incubation experiments we study the nitrification rates of several sponge species and assess active nitrification in cold as well as warm water sponges on coral reefs. Aim is to assess the functional  role of sponge nitrifying microbes  for the sponge and the function of the sponge holobiont for N-cycling on coral reefs.

SeasonTrace

Support of seasonal sea-ice ecosystems by essential trace nutrient elements iron and manganese

Funding: NWO/ALW project

Period: 2010-2012

Co workers: dr. Veronique Schoemann, ing. Patrick Laan, ing. Jeroen de Jong

P.I:prof. Hein de Baar

Seasonal sea ice in the Antarctic and Arctic Oceans constitutes one of the largest biomes on Earth. In the Antarctic with each annual cycle some 16 million km2 sea ice is newly formed and dissappearing again. Similarly Arctic sea ice covers about 15.6 million km2 in northern winter, and used to cover about half i.e. 7 million km2 in late summer (September). However in recent years the late summer Arctic Ocean ice cover has decreased dramatically, likely due to global warming resulting from the greenhouse effect of anthropogenic CO2 emissions into the atmosphere. As a result the Arctic sea-ice habitat is changing rapidly due to replacement of very thick multi-year sea-ice to seasonal about one metre thick sea-ice. Thus overall the seasonal sea-ice gains in worldwide significance. For long time major biological productivity in polar oceans was deemed to take place in spring time at the melting ice edge. This is now complemented by the notion that the high stocks of top predators and under ice krill deeper into the ice fields, and also in wintertime, must have an adequate food supply. The project aims for assessing the abundance and productivity of sea-ice algae as a function of availability of essential trace nutrient elements iron and manganese within the sea-ice environment.

SPOCO₂

The trophic transfer of SPOnge associated microorganisms to their host in COld water coral communities in dark mesopelagic waters

PI: Fleur C. van Duyl.

Funding: EU FP7 infrastructure project ASSEMBLE and NIOZ

This project  studies  the trophic transfer of SPOnge associated microorganisms to their host in COld water coral communities in dark mesopelagic waters along the west coast of Sweden (Tjärnö). High microbial abundance (HMA) sponges in oligotrophic coral reef habitats are capable of assimilating dissolved organic matter (DOM) and can fix CO₂ in the dark. Sponge associated microorganisms are purported to mediate in these pathways. CO₂ fixation is unlike DOM uptake, restricted to chemoautotrophic microorganisms in the sponge. Therefore we use CO₂ fixation and labeling with ¹³C enriched CO₂ of HMA sponges to study the trophic transfer of C fixed by sponge associated chemotrophic microorganisms to sponge cell constituents. The CO₂ fixation rate and the subsequently labeled bacterial, archaeal and sponge specific biomarkers are followed in the sponge holobiont. Incubation experiments with ¹³C enriched CO₂ are conducted with the cold water coral reef sponge Hymedesmia coriacea. Tracing the labeling of biomarkers such as specific fatty acids (FAs) and ether lipids (GDGTs) in time give insight in the occurrence, rate and nature of trophic transfer between the sponge and its associated microorganisms. Increase of δ¹³C in sponge specific fatty acids such as demospongic acids is an evidence of transfer of ¹³C from associated microbes to the sponge. Detailed analysis of the composition and % of labeling of FA and ether lipids in the sponge will reveal contribution of bacterial and archaeal derived products to specific sponge compounds. By using molecular analyses, we will estimate the abundance and activity of chemo-autotrophs and their contribution to the sponge metabolism. This study will increase our understanding of trophic transfer between chemoautotrophic microbiota and marine sponges and the role of associated microbes in the success of sponges in dark oligotrophic environments.

SSS-I E

Seasonality of iron and other trace metals in relation to the rapidly changing ice/water cycle and plankton dynamics of the West Antarctic Peninsula

Period:2012 to 2016

NWO Polar Program

dr. Veronique Schoemann, ing. Patrick Laan, ing. Jeroen de Jong,

P.I.:prof. Hein de Baar

The West Antarctic Peninsula is the most rapidly warming region in the Southern hemisphere, with glacial retreat and ice shelf collapse causing major changes in the marine environment. We will make a systematic investigation of iron, aluminium, manganese and related bio-essential trace metals Co, Ni, Cu, Zn in the water column and the sea-ice of Marguerite Bay throughout two complete annual cycles. This study will serve as a first assessment of the distribution and cycling of iron and the other trace metals in relation to the ice/water cycle and the biological cycle. We will test the working hypothesis that the annual collapse of the bloom of large diatoms at the end of the summer is due to depletion of dissolved iron by the bloom itself. This first study will serve as the baseline for future assessment of changes in relation to the major climate changes at the West Antarctic Peninsula.

STRATIPHYT

Changes in vertical stratification and their impact on phytoplankton communities

Project:(NWO Coastal and Marine Research ZKO).

PostDoc: K. Mojica

PI: C.P.D. Brussaard

 in collaboration with NIOZ, UvA, RUG, UU-IMAU, VU-IVM.

Global warming will change physical, chemical and biological processes in the oceans. Ocean-climate models predict that warming of the surface layer may strengthen vertical stratification, starting earlier in spring and lasting longer in autumn. This results in suppressed upward mixing of nutrients from the deep ocean.  Changes in stratification will have major effects on the growth and species composition of phytoplankton.  This will subsequently impact grazing, viral lysis and sedimentation rates, with cascading effects on ecosystem functioning and biogeochemical fluxes. Little is known, however on the exact implications of global warming for these fundamental processes. We propose to investigate how changes in vertical stratification affect phytoplankton communities (growth, losses and composition) along a North-South gradient in the Atlantic Ocean. Our study will be based on oceanographic cruises from Iceland to the Canary Islands and detailed laboratory experiments with representative phytoplankton species, both integrated in advanced models of hydrodynamics and plankton dynamics and productivity. We have chosen for the Northeast Atlantic Ocean, because it is a key area in global ocean circulation and a large sink for atmospheric CO2, and a major determinant of the climate in Western Europe. Furthermore, the Atlantic Ocean offers a gradient from weak seasonal stratification in the North to strong permanent stratification in the (sub)tropics. This gradient offers ideal opportunities for the comparative study of different stratification regimes. Our integrated approach of physical, chemical, and biological processes, by a new multidisciplinary research team, will enable a better understanding of the implications of global warming for plankton growth in the Northeast Atlantic Ocean.

VIRANT

 Viral impact on microbes in coastal waters of the Antarctic Peninsula and its ecological implications

PostDoC(s):A. Hoogstraten, L. Peperzak, C. Evans,

P.I:C.P.D. Brussaard,

In cooperation with: the British Antarctic Survey (UK)

Viruses exert an impact on the ecology and biogeochemical cycling of all areas of the oceans examined thus far making them an important functional group in marine ecosystems. Ecosystem functioning relies on the microbial food web and specifically on primary productivity. Viruses are mortality agents that directly affect productivity, diversity and the system’s regenerative capacity. Despite these general facts, very little is known of the role of viruses in the Southern Ocean in relation to the key players of the microbial community, bacteria and phytoplankton. Moreover, virtually no data is available pertaining to the relative abundance, distribution, activity and significance of marine viruses at one location over the seasonal cycles of the Antarctic. We propose to alleviate this paucity in our knowledge by a mechanistic and comprehensive study during the production period of Austral spring to early autumn in the waters of the western Antarctic Peninsula. These coastal waters are characterized by high productivity and markedly seasonal phytoplankton blooms which drive the ecology of the habitat. They serve as a nursery ground for krill, a key species in the Antarctic food chain. The area is of special interest as it is one of the three areas of the globe experiencing rapid climate change, with already noticable alterations in phytoplankton community structure.Viral dynamics in relation to their microbial hosts will be studied in line with the relative importance of viruses as a mortality source compared to grazing, which was traditionally considered as the regulator of Southern Ocean food webs. In addition, we will examine the influence of viral infection on host fatty acid composition, a key determinate of food quality and therefore of ecosystem productivity. In order to determine the potential influence of global anthropogenic perturbations in this rapidly changing environment we will conduct laboratory experiments to asses the impact of predicted changes in light availability, salinity and pCO2 on the ecology of phytoplankton and their viruses. This timely research will establish crucially needed baseline measurements of key ecological processes in an early warning site of global change (and therefore highly scientifically, societally and politically relevant), and thus provide valuable data for modeling and prediction of future consequences of anthropogenic perturbations of climate composition.

VRNAAP

Viral regulation on nutrient assimilation by algae and prokaryotes

 PhD-student Abdul Sheik

P.I.: Dr. Marcel Kuypers, Biogeochemistry/Nutrient Group, MPI, Bremen,      Germany

      Dr. Corina Brussaard, Royal Netherlands Institute for Sea Research,       The Netherlands.

The high abundance of marine viruses results in about 1029 viral infections per day, causing the release of ~108–109 tonnes of carbon per day from the oceanic biological pool. However, their influence on the biogeochemical cycles is still poorly understood. This project aims are: (1) to determine the Carbon and Nitrogen assimilation of ecologically relevant algal species during viral infection using bulk measurements and nanoSIMS, (2) to investigate the response of the bacterial community to algal host cell lysis using Atomic force microscope, CARD-FISH and single cell nanoSIMS analysis, and (3) quantify the microbial mediated carbon remineralisation.