Dr. Sairah Malkin
Post-doctoral Fellow (visiting guestworker)
Department: Ecosystem Studies
T. +31 (0) 113 577 498 
F. +31 (0) 113 573 616 
Sairah.Malkin(at)nioz.nl
-or- smalkin(at)vub.ac.be

Visiting address:

Korringaweg 7

4401 NT Yerseke

The Netherlands

Postal address:

Postbus 140

4400 AC Yerseke

The Netherlands

• Benthic-pelagic coupling in coastal marine systems
• Microbial ecology in aquatic sediments
• Limnology of large lakes, with a particular interest in benthic energy pathways

• Sediment biogeochemical analyses
• Microsensor profiling
• Reactive-transport analyses

Desulfobulbaceae filaments: The ecology of a newly discovered electrogenic sulphur oxidizing bacterium in marine sediments

Recently, a new microbial lifestyle was discovered from marine sediments, in which long filamentous bacteria appear capable of transporting electrons over centimeter-scale distances. These bacteria (belonging to the family Desulfobulbaceae) harvest electrons from free sulphide at subsurface depths within marine sediments and transport these electrons to oxygen at the sediment surface. In doing so, these bacterial filaments facilitate electron transport across length scales four orders of magnitude greater than any other known microbial electron transfer. The implications of this microbial strategy on biogeochemical cycling may be large, but as yet, are almost entirely unknown.

I am working mainly on three aspects of their ecology:

• the natural distribution of these electrogenic bacteria in the seafloor
• constraints on their metabolic rates and current density (with L. Burdorf)
• biogeochemical consequences of their growth and metabolism (with D. Seitaj, AMF Rao)

The photo above depicts sediment, collected from Rattekaai Salt Marsh, which can host a high density of the electrogenic filamentous bacteria. At the sediment surface I’ve grown a diatom biofilm which you see producing oxygen. (Hydrogen sulphide and pH microsensors are also visible.) I am currently preparing a manuscript identifying the effects of diel oxygen oscillations on the sulphide oxidation rates, behaviour, and growth of these enigmatic bacterial filaments.

My work has been conducted in the lab of FJR Meysman (project Holoflow), with a cast of collaborators, including D. Seitaj, L.Burdorf, and E-M Zetsche (Ecosystem Studies), D. Vasquez-Cardenas and H.T.S. Boschker (Marine Microbiology), and A.M.F. Rao (U. Rimouski, Canada).

Presentations:

Malkin, S.Y., Tramper, A., FJR Meysman (Jul 2013) Sulphide oxidation by electrically conductive bacterial filaments in a dynamic oxygen environment (Gordon Research Conference, Applied and Environmental Microbiology), USA

Malkin, S.Y., Seitaj, D. & F.J.R. Meysman (Sep 2012) Widespread occurrence of electrochemical oxygen consumption in the  seafloor. International Society for Microbial Ecology (ISME) Meeting, Copenhagen, Denmark.

Malkin, S.Y., Seitaj, D. & F.J.R. Meysman (Aug 2012) Electrogenic sulphide oxidation by long distance electron transmission finds a niche in marine hypoxic zones. Association for the Sciences of Limnology and Oceanography (ASLO) Meeting, Otsu, Japan.

Papers:

Malkin, S.Y., Seitaj, D., Vasquez-Cardenas, D., Zetsche, E-M., Boschker, H.T.S., and Meysman, F.J.R. Natural occurrence of microbial long-distance electron transport in the seafloor (In review).

Long-term declines in planktonic primary production in the Oosterschelde: two decades of benthic grazer control?

The Oosterschelde is a productive macrotidal embayment on the Dutch coast of the North Sea. It serves as a marine nature reserve and is home to an economically important blue mussel farming industry. In the late 1980s, the system was subject to a major re-engineering (the Delta Works) which resulted in increased water transparency and decreased nutrient loading. Despite these major and abrupt changes to the ecosystem, surprisingly, the effects at that time on phytoplankton production were not even detectable.

In remarkable contrast, we have now recently documented a 3-4 fold decline in phytoplankton production in the Oosterschelde over the two decades since the Delta Works project. Rather than being driven by changes in resource supply, we infer these changes in plankton primary production have mainly been driven by expanding benthic grazing pressure from proliferating Pacific Oysters (pictured). This investigation represents one of a limited number of studies that has been able to capture progressive multi-decadal phytoplankton productivity changes with direct measurements. The study demonstrates the effect of benthic grazing pressure over long time scales, not only on the biomass of autotrophic community, but also on the system-level productivity. 

This work is the result of many years of primary production measurements coordinated by Jacco Kromkamp (Marine Microbiology) and was conducted in additional collaboration with Peter Herman (Spatial Ecology).  

Papers

Malkin, S.Y., Herman, P.M.J., Peene, J., and J.C. Kromkamp. Two decades of phytoplankton primary production declines in the Oosterschelde coastal ecosystem. Ecosystems (In review).

Deep chlorophyll maxima (DCM) as hotspots of biogeochemical cycling and trophic transfer efficiency

In recent work on the Laurentian Great Lakes, I observed that a deep chlorophyll layer appears to be providing an essential food subsidy to the littoral zone foodweb. This food subsidy may be a particularly important pathway of nutrition to benthic mussels (i.e., invasive quagga mussels), because the biomass and the growth of these animals is intensely food limited.  

As an extension of this work, we are reviewing the distribution and consequences of DCMs, focussing on key regions where the vertical distribution of phytoplankton may have overlooked consequences for trophic transfer efficiency.

Papers

Malkin, S.Y., Silsbe, G.M., Smith, R.E.H., and E.T. Howell. 2012. The deep chlorophyll layer nourishes benthic filter feeders in the coastal zone of a large clear lake. Limnol. Oceanogr. 57(3): 735-748.

Malkin, S.Y., Silsbe, G.M., Smith, R.E.H., and E.T. Howell. 2012. The deep chlorophyll layer nourishes benthic filter feeders in the coastal zone of a large clear lake. Limnol. Oceanogr. 57(3): 735-748.

Leon, L.F., Smith, R.E.H., Malkin, S.Y., Depew, D., Hipsey, M.R., Antenucci, J.P., Higgins, S.N., Hecky, R.E., and R.Y. Rao. 2012. Nested 3D modelling of the spatial dynamics of nutrients and phytoplankton in a Lake Ontario nearshore zone J. Great Lakes Res. (special issue L. Ontario coastal zone) 38(Supp.4): 171-183.

Malkin, S.Y., Bocaniov, S.A., Smith, R.E.H., Guildford, S.J., and R.E. Hecky. 2010. In situ measurements confirm the seasonal dominance of benthic algae over phytoplankton in nearshore primary production of a large lake.  Freshwater Biol. 55(12): 2468-2483.

Malkin, S.Y., Dove, A., Depew, D., Smith, R.E.H., Guildford, S.J., and R.E. Hecky. 2010. Spatio-temporal patterns of water quality in Lake Ontario and their implications for nuisance growth of Cladophora. J. Great Lakes Res. 36(3): 477-489.

Auer, M.T., Tomlinson, L.M., Higgins, S.N., Malkin, S.Y., Howell, E.T., and H.A. Bootsma. 2010. Great Lakes Cladophora in the 21st century: Same algae – different ecosystem. J. Great Lakes Res. 36(1): 248-255.

Ozersky, T., Malkin, S.Y., Barton, D.R., and R.E. Hecky. 2009. Dreissenid phosphorus excretion can sustain nuisance Cladophora glomerata growth along the Halton shore of Lake Ontario. J. Great Lakes Res. 35(3): 321-328.

Malkin, S.Y., Sorichetti, R.J., Wiklund, J.A., and R.E. Hecky. 2009. Seasonal abundance, community composition, and silica content of diatoms epiphytic on Cladophora glomerata. J. Great Lakes Res. 35(2): 199-205.

Hiriart-Baer, V., Arciszewski, T., Malkin, S.Y., Guildford, S.J. and R.E. Hecky. 2008. Use of pulse amplitude modulated (PAM) fluorescence to assess light versus nutrient limitation in Cladophora from Lake Ontario. J. Phycol. 44(6): 1604-1613.

Higgins, S.N., Malkin, S.Y., Howell, E.T., Guildford, S.G., Campbell, L., Hiriart-Baer, V., and R.E. Hecky. 2008.  An ecological review of Cladophora glomerata (Chlorophyta) in the Laurentian Great Lakes. J. Phycol. 44(4): 839-854.

Malkin, S.Y., Guildford, S.J. and R.E. Hecky. 2008. Modeling the growth of Cladophora in a Laurentian Great Lake in response to changes due to the exotic invader Dreissena and to lake warming. Limnol. Oceanogr. 53(3): 1111-1124.

Malkin, S.Y., Johannsson, O.E. and W.D. Taylor. 2006. Small-bodied zooplankton communities yet strong top-down effects on phytoplankton in the absence of fish. Arch. Hydrobiol. 165: 313-338.

Toohey, B.D., Kendrick, G.A., Wernberg, T., Phillips, J.C., Malkin, S., and J. Prince. 2004. The effects of light and thallus scour from Ecklonia radiata canopy on an associated foliose algal assemblage: the importance of photoacclimation. Mar. Biol. 144: 1019-1027.