Newsletter 12 | 9 March 2016

We gladly present you with another Centre for Wetland Ecology (CWE) newsletter full of information concerning Wetland Ecology.

This newsletter will come to you twice per year to inform you about CWE symposia, STOWA activities and to announce other events and news.

Bart Grutters (coordinator CWE)
Liesbeth Bakker (chair CWE)

www.wetland-ecology.nl
cwe@nioo.knaw.nl
@cwe_wetlands

Please e-mail us so we can spread news about any upcoming events, job offers, symposia, PhD defences or publications, either on our website, twitter or the next newsletter (released September 2016).

Newsletter contents

 

Upcoming events in the Netherlands

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  • Minisymposium Safe Operating Space
    De kennis over het ecologisch functioneren van grote en kleine wateren is de laatste decennia flink toegenomen. Hierbij horen concepten als alternatieve evenwichten, actief biologisch beheer, kantelpunten en plotselinge omslagen. Meer recent zijn daar de concepten natuurgebruiksruimte, planetary boundaries en Safe operating Space bijgekomen. Met deze concepten wordt de speelruimte beschreven waarbinnen een ecosysteem zich kan bewegen zonder over kritische grenzen te gaan. Wetenschappelijk onderzoek heeft hierin de laatste jaren grote stappen voorwaarts gezet. De uitdaging is nu om deze wetenschappelijke inzichten te vertalen naar toepassing in het waterbeheer. Meer informatie.
     
  • Kennisdag slootbeheer en biodiversiteit
    1 april bij NIOO Wageningen (organisatie: NIOO en Watersnip Advies). Slootsystemen zijn in Nederland, met een lengte van meer dan 300.000 km, een belangrijk leefgebied voor aquatische planten en dieren. Voor goed beheer hiervan is begrip nodig van biodiversiteit en het ruimtelijke aspect van de ecologie van sloten. Op de kennisdag wordt een koppeling gemaakt tussen het beheer van slootsystemen en wetenschappelijke kennis. Hierbij gaat bijzondere aandacht uit naar het ruimtelijke aspect van biodiversiteit, en naar de vraag hoe kennis van sturende processen kan worden verworven en aangewend bij slootbeheer. Voor meer informatie en registratie (uiterlijk 11 maart) kijk op de website.
     
  • Nationaal congres veenbodemdaling
    31 maart in Madurodam (organisatie: Platform Slappe Bodem). De bodem in delen van West- en Noord-Nederland daalt voortdurend door de slappe veen- en kleilagen. Verzakkingen en waterproblemen zijn het gevolg. Overheden, waterschappen, aannemers, ingenieursbureaus en kennisinstituten gaan gezamenlijk aan de slag met een grondige aanpak. Die aanpak staat centraal op 31 maart 2016 tijdens het nationale congres over veenbodemdaling: Heel Holland Zakt. Meer informatie en aanmelding op de website.

 

  • Driedaags STOWA congres: Goede monitoring, effectief waterkwaliteitsbeheer!
    19 - 21 april in Burgers' Zoo Arnhem (organisatie: STOWA). Gezond water. Schoon water. Water met diverse planten- en diersoorten. Zwemwater. Water voor de natuur. Water voor de landbouw. Waterbeheerders in Nederland stellen uiteenlopende doelen vast voor hun oppervlaktewateren. De grote vraag is: zijn die doelen haalbaar? Worden ze daadwerkelijk gehaald en wat is het effect van genomen maatregelen? Dat kun je alleen bepalen op basis van kennis over watersysteem en inzicht in de effecten van genomen maatregelen. Monitoring levert meer op dan dat het kost! Meer informatie en registratie op www.stowacongres.nl.

Upcoming CWE Symposium

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CWE Symposium on exotic species in aquatic ecosystems. 24 June 2016 in Wageningen. Please mark the date in your agenda.

 

International conferences

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News

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  • The Amsterdam Water Science symposium was a success! The organizing committee would like to thank all participants and speakers for their outstanding contribution to a successful meeting. The first day of the symposium focused on scientific presentations with great contributions from both international and Dutch guest speakers. During the second day researchers from Amsterdam Water Science presented this new research collaboration and their research in the field of climate change, water quality, water quantity, connectivity and management, with a focus on water in the Netherlands. There was room for talks and discussions during the afternoon breakout sessions where scientists and water managers shared their knowledge. As an outcome of the symposium breakout sessions, Amsterdam Water Science recently funded a number of 7 pilot projects in which students, researchers and stakeholders are actively involved and work together.More information on: http://www.amsterdam-water-science.nl/research/aws-pilot-projects/pilot-projects.html
     
  • Utrecht University has initiated Future Deltas: a worldwide interdisciplinary research on sustainable delta management. Deltas are attractive areas to live in and therefore densely populated. However they are threatened by human impact and climate change. Dealing with these threats requires a solid understanding of how natural and societal systems interact. Future Deltas develops integrated knowledge for future delta life. The team includes biologist George Kowalchuk of the Faculty of Science to incorporate biological processes that contribute to subsidence and the associated changes in ecosystems into our research. More information is available on the website.
     
  • Het digitaal bij elkaar brengen en ontsluiten van alle beschikbare biodiversiteitsdata door middel van het internet, via bijvoorbeeld het ‘Map of Life’ project en de ‘Global Biodiversity Information Facility’ (GBIF), kan worden gezien als een van de belangrijkste ontwikkelingen binnen het biodiversiteitsonderzoek sinds Linnaeus in de achttiende eeuw begon met z’n Hercules-klus om alle plant en diersoorten op aarde te identificeren en een naam te geven. Zo verschaft GBIF inmiddels vrije toegang tot ruim een half miljard data ‘records’ die horen bij meer dan anderhalf miljoen verschillende soorten organismen. Maar sluiten de mogelijkheden die deze online initiatieven bieden wel voldoende aan bij de vragen en methoden van onderzoekers? En benutten onderzoekers wel de kansen die hen geboden worden? In opdracht van NLBIF, de Nederlandse tak van GBIF, zal Jan Kuiper (NIOO-KNAW) het komende jaar onderzoek doen naar het gebruik van GBIF data in de wetenschap, en inventariseren waar mogelijkheden liggen voor GBIF om z’n ‘fit for purpose’ te verbeteren. 
     
  • UNESCO-IHE has vacancy for:
     Lecturer/researcher in wetlands and aquatic biogeochemistry (m/f) 1.0 Fte.
    "We seek a full time position with teaching and research experience in water chemistry, chemical transformations in aquatic systems, and ecologically based pollution abatement techniques applicable to developing countries and countries in transition." More information and application at their website.
     
  • The Platform on the Ecological Restoration of Lakes organises an excursion to Berlin (8 - 12 juni 2016) intended for aquatic ecologists. More information is available here.
     
  • Prof. dr. Fons Smolders will give his inaugural lecture on Friday May 20 at 3.45 PM, Radboud University Nijmegen

Guest column: Jan Roelofs (RU Nijmegen)
Aquatic carbon limitation overlooked

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Until recently it was thought that nitrogen and/or phosphorus were the only elements determining the productivity of submerged aquatic plants in wetlands. In very productive waters only one or a few species become dominant, so biodiversity is strongly influenced by the trophic state of lakes and wetlands.

In the eighties of the last century it became clear that also inorganic carbon can be an important production limiting factor. In many soft-water lakes only plant species occur with many adaptations, in order to deal with carbon limitation. The most abundant plant species in carbon limited soft-water lakes are those with an isoetid growth form, like Isoetes sp, Lobelia dortmanna, Littorella uniflora and many others. Until very recently it was thought, that only these plants were able to cope with carbon limitation, but it becomes more and more clear that some plants with other growth forms also have adaptations to survive in water with very low carbon dioxide levels in the water table, like Sparganium angustifolium, which fully depends on carbon uptake by its roots before the leaves reach the surface. And now there are signs that even in more alkaline waters the amount of carbon in the water table is insufficient to produce enough biomass for survival. Stratiotes aloides, for instance, produces hardly any biomass in alkaline waters at CO2 levels below 200 µmol/l. In a recent study by Sarah Faye Harpenslager the plants appeared to be inefficient in taking up bicarbonate for photosynthesis, but they started  to grow very fast after the thick roots, rich in air channels, entered the sediment, which contained CO2 levels 10 times higher than the overlying water.

Even in very alkaline waters with a high pH it appears that a species like Potamogeton pectinatus did not reach maximum photosynthesis at bicarbonate levels up to 5 mmol/l. In alkaline waters with a pH >8.5 most submerged plant species fully depend on bicarbonate uptake for photosynthesis and bicarbonate uptake is generally ten times less efficient than CO2 uptake. Plants with very thin leaves can reach high photosynthesis easily in very alkaline water, but species with thicker leaves can be limited by carbon, and at high phosphorus levels in the water table they are easily outcompeted by floating species like Azolla sp or Lemna sp.

Consequences of climate change
There are signs that the increase in CO2 from 280 ppm during the last few thousands of years, up to 400 ppm in the last few decades, already influences plant composition in boreal soft-water lakes. Those lakes, still dominated by many isoetid plant species, are more and more invaded with small patches of elodeid species like Callitriche hamulata and Myriophyllum alterniflorum, plants with very fine leaves and therefore efficient in taking up CO2 from the water table. From a paleo study by Peter Spierenburg in an almost pristine lake in Norway, it appeared that Callitriche hamulata entered the lake in the seventies, but became a co-dominant species in the last 15 years. From the diatom assemblages in the cores it appeared that there were no changes in nutrient availability and pH during the last 60 years. Culture experiments revealed that species like  Callitriche hamulata and Myriophyllum alterniflorum will outcompete all isoetids by the expected doubling of the  CO2, even on oligotrophic and mesotrophic sediments.

Climate change will not always lead to higher carbon dioxide availability in the water. Increasing temperatures will lead to lower oxygen levels in the water  and will stimulate decomposition in the sediments. The balance between aerobic and anaerobic decomposition will shift towards anaerobic decomposition. Anaerobic decomposition is an acid consuming process where bicarbonate is produced, thus leading to alkalinisation of the sediment and water layer. A study of the distribution of the soft-water macrophyte Luronium natans showed, that between 1950 and 1980 acidification was the main cause of disappearance of this species in the Netherlands, while in the period between 1980 and 2010, in all locations  where the species had disappeared, the water was not soft anymore.

Anaerobic decomposition can lead to very high alkalinities, where, under nutrient rich conditions, carbon can be limited for submerged vegetation, and floating species like for instance Lemna species or Azolla species become dominant.
In the tropics it is normal that in eutrophic waters floating species, like Eichornia crassipes, are the dominant and extremely productive species, probably because they can take up phosphorus and nitrogen with their extended root systems and CO2 from the air, where the diffusion rate of carbon dioxide is 10000 times higher than in water.

Investigations by Sarian Kosten and Ernandes Sobreiro showed, that those expanding vegetations of water hyacinth sequester high amounts of carbon. Whether this will lower the emission of greenhouse gasses to the atmosphere has to be investigated further.

PhD graduations

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  • Gerard ter Heerdt (University of Groningen), 19 February 2016, "Establishment of different riparian plant communities from the same soil seed bank". More information.
  • Karlijn Brouns (Utrecht University), 24 February 2016, "The effects of climate change on decomposition in Dutch peatlands". More information.
  • Rob Fraaije (Utrecht University), 31 August 2016, "Optimizing stream restoration to improve riparian plant diversity". More information.

Recent key publications

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  • Bennetsen et al. 2016. Species distribution models grounded in ecological theory for decision support in river management. Ecological modelling doi:10.1016/j.ecolmodel.2015.12.016
  • Burson et al 2016. Unbalanced reduction of nutrient loads has created an offshore gradient from phosphorus to nitrogen limitation in the North Sea. Limnology and Oceanography doi: 10.1002/lno.10257.
  • Eekhout et al. 2015. Morphological assessment of reconstructed lowland streams in the Netherlands. Advances in Water Resources doi:10.1016/j.advwatres.2014.10.008
  • Frenken et al 2016. Warming accelerates termination of a phytoplankton spring bloom by fungal parasites. Global Change Biology doi:10.1111/gcb.13095
  • Harpenslager et al 2016. Harnessing facilitation: Why successful re-introduction of Stratiotes aloides requires high densities under high nitrogen loading. Biological Conservation doi:10.1016/j.biocon.2015.12.031
  • Howison et al 2015. Large herbivores change the direction of interactions within plant communities along a salt marsh stress gradient. Journal of Vegetation Science doi:10.1111/jvs.12317
  • Kefi et al 2016. When can positive interactions cause alternative stable states in ecosystems? Functional Ecology doi:10.1111/1365-2435.12601
  • Mojica et al. 2016. Latitudinal variation in virus-induced mortality of phytoplankton across the North Atlantic Ocean. The ISME Journal doi:10.1038/ismej.2015.130
  • de Paoli et al 2015. Processes limiting mussel bed restoration in the Wadden-Sea. Journal of Sea Research doi:10.1016/j.seares.2015.05.008
  • Salguero-Gómez et al 2016. Fast–slow continuum and reproductive strategies structure plant life-history variation worldwide. PNAS doi: 10.1073/pnas.1506215112
  • Soons et al 2016. Seed dispersal by dabbling ducks: an overlooked dispersal pathway for a broad spectrum of plant species. Journal of Ecology doi:10.1111/1365-2745.12531
  • Van Donk et al 2016. Pharmaceuticals may disrupt natural chemical information flows and species interactions in aquatic systems: ideas and perspectives on a hidden global change. Reviews of Environmental Contamination and Toxicology doi:10.1007/398_2015_5002
  • Van Dijk et al 2016. Salinization of coastal freshwater wetlands; effects of constant versus fluctuating salinity on sediment biogeochemistry. Biogeochemistry doi:10.1007/s10533-015-0140-1
  • Vermaat et al 2016. Annual sulfate budgets for Dutch lowland peat polders: The soil is a major sulfate source through peat and pyrite oxidation. Journal of Hydrology doi:10.1016/j.jhydrol.2015.12.038