Profiles

Jakob Walve

Jakob Walve

Forskare

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Arbetar vid Institutionen för ekologi miljö och botanik
Telefon 08-16 17 30
E-post jakob.walve@su.se
Besöksadress Svante Arrhenius väg 20 A
Rum N250
Postadress Institutionen för ekologi miljö och botanik 106 91 Stockholm

Om mig

Jag är marinekolog med fokus på hur näringsämnen påverkar och omsätts i Östersjöns ekosystem. Särskilt intresserar blomningarna av kvävefixerande cyanobakterier samt övergödningseffekter i kustzonen, t ex förhöjda mängder växtplankton och syrebrist.

DEEPs Marinekologiska Laboratorium - Pelagial

Jag är föreståndare för det Marinekologiska laboratoriet vid institutionen som utför kemiska och biologiska analyser och undersökningar för forskning och miljöövervakning. Grunden i verksamheten är flera intensiva provtagningsprogram i fria vattenmassan för att övervaka miljön i Östersjön, program som integreras med LTER, långsiktig ekologisk forskning. Tidsserier av näringsämnen och plankton, vissa påbörjade redan på 1970-talet, blir allt värdefullare för att förstå Östersjöns ekologi och vad som styr förändringar. De regelbundna provtagningarna utgör dessutom en viktig plattform för olika kortare forskningsprojekt som samlar in ytterligare data.

 

Cyanobacteria bloom in the Baltic Sea
Ytansamling av kvävefixerande cyanobakterier i Östersjön.

 

Undervisning

Jag föreläser och deltar i fältmoment på kurserna Akvatisk Ekologi, Marine Population and Ecosystem Dynamics, och sommarkursen i Marinbiologi.

Forskning

Miljöanalys Svealandskusten (Svealands kustvattenvårdsförbund, SKVVF). Resultat presenteras bland annat på webplatsen Svealandskusten i den årliga rapporten med samma namn. Miljöanalysfunktionen drivs i samarbete med Östersjöcentrum.

Himmerfjärdsprojektet. Kontrollprogram för Himmerfjärdsverket (SYVAB)integrerat med forskning om hur ekosystemeffekter av näringsämnesutsläpp till Himmerfjärden kan minimeras genom praktiserad adaptiv förvaltning. Se karta och diagram med resultat.

Cyanobakterier i Östersjön. Vi studerar de kvävefixerande cyanobakteriernas ekologi och fysiologi. Jennie Barthel Svedén är nu doktor, hon försvarade sin avhandling (thesis) i oktober 2016.

Samverkan

Nationell Marin Miljöövervakning (Havs och Vattenmyndigheten). We utför hög-frekvent pelagisk övervakning vid Askö (B1) och Landsortsdjupet (BY31). Vi tar också prover månatligen i nordöstra eg. Östersjön (BY29).

Himmerfjärdsprojektet (SYVAB). Se forskning ovan.

Miljöanalys Svealandskusten (SKVVF). Se forskning ovan.

Publikationer

I urval från Stockholms universitets publikationsdatabas
  • 2016. Nils Ekeroth (et al.). Journal of Marine Systems 154, 206-219

    Benthic nutrient dynamics in the coastal basin Kanholmsfjarden, NW Baltic proper, were studied by in situ flux measurements and sediment samplings in 2010-2013. The benthic release of NH4 and DIP from anoxic sediments in Kanholmsfjarden were calculated to renew the standing stock inventories of DIN and DIP in the overlying water in roughly 1 year. Starting in summer 2012, mixing of oxygen-rich water into the deep part of the basin temporarily improved the oxygen conditions in the deep water. During the 1 year oxygenated period, the total phosphorus inventory in the surficial sediment increased by 0.4 g P m(-2) or 65%. This was most likely due to stimulated bacterial P assimilation under oxygenated conditions. By July 2013, the bottom water had again turned anoxic, and DIP and DSi fluxes were even higher than earlier in the study period. These high fluxes are attributed to degradation of sedimentary pools of P and Si that had accumulated during the bottom water oxygenation in 2012. The strong correlation between DIP and DSi fluxes and the similar dynamics of DIP and DSi in the sediment pore water and near bottom water, suggest a similar redox dependency of benthic-pelagic exchange for these nutrients.

  • 2014. Jakob Walve, Johan Gelting, Johan Ingri. Marine Chemistry 158, 27-38

    Even though the availability of trace metals influences nitrogen fixation and growth of cyanobacteria, field data on their cellular metal composition are scarce. In this study, contents of Al, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, and the major elements C, N, P and Si were studied in filamentous, nitrogen-fixing cyanobacteria sampled over the growth season March-October at two locations in the Baltic proper (years 2004 and 2007) and one location in the Bothnian Sea (2006). The Al and Ti contents indicated that lithogenic Fe was an important Fe fraction associated with Nodularia spumigena, but not with Aphanizomenon sp. Treatment with an oxalate-EDTA solution indicated that less than 5% of total Fe was adsorbed as oxides, but relatively high adsorbed fractions were found for Mn and Cu. Despite the large variation in biomass and dissolved Fe concentrations, the Fe:C ratio of Aphanizomenon was highly consistent within years and across sampling stations (76 +/- 13 mu mol mol(-1) C. average +/- 1SD), indicating growth controls other than Fe. Species-mixed samples corrected for lithogenic metals indicate similar Fe content in Nodularia as in Aphanizomenon. Calculations based on the use efficiency of Mo for N-2 fixation indicate that most Mo in Nodularia and at least a third of the Mo in Aphanizomenon are used in nitrogenase, corresponding to 5-24% of the Fe content. The high Ni content suggests excess storage or extensive use in enzymes such as Ni superoxide dismutase or in Fe-dependent Ni-hydrogenases. The trace metal composition of the investigated Baltic cyanobacteria was similar to that reported for the oceanic genus Trichodesmium, suggesting common physiological requirements of these filamentous nitrogen-fixing cyanobacteria.

  • 2011. Daniel J. Conley (et al.). Environmental Science and Technology 45 (16), 6777-6783

    Hypoxia is a well-described phenomenon in the offshore waters of the Baltic Sea with both the spatial extent and intensity of hypoxia known to have increased due to anthropogenic eutrophication, however, an unknown amount of hypoxia is present in the coastal zone. Here we report on the widespread unprecedented occurrence of hypoxia across the coastal zone of the Baltic Sea. We have identified 115 sites that have experienced hypoxia during the period 1955-2009 increasing the global total to ca. 500 sites, with the Baltic Sea coastal zone containing over 20% of all known sites worldwide. Most sites experienced episodic hypoxia, which is a precursor to development of seasonal hypoxia. The Baltic Sea coastal zone displays an alarming trend with hypoxia steadily increasing with time since the 1950s effecting nutrient biogeochemical processes, ecosystem services, and coastal habitat.

  • 2007. Jakob Walve, Ulf Larsson. Aquatic Microbial Ecology 49, 57-69
Visa alla publikationer av Jakob Walve vid Stockholms universitet

Senast uppdaterad: 27 november 2017

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