Group for aquatic biogeochemistry and climate change
Our research group study transport, production and degradation of organic material in the marine environment – we wish to understand the interrelation between these processes and the chemical-physical conditions in the ocean. Over all this has a large implication for the chemistry and life in the ocean and on Earth. A significant part of our work is dedicated to the development of microsensors, imagine-techniques and underwater technology, that are used for detailed studies of microbial processes in the laboratory as well as in situ. In recent years the group has dedicated a larger focus to consequences of climate change for element cycling in the Arctic. Especially we have an interest in the importance of sea-ice cover for CO2 exchange between atmosphere and water as well as water and sediment. The efforts of the research group are closely coordinated with another research group that was founded by Ronnie at Scottish Association for Marine Science (UK).
Professor, Dr Scient. Ronnie N Glud
Post doc Dr. Daniel McGinnis,
Technician Anni Glud
Ph.D – stipend Morten Larsen
Ph.D – stipend Karl Attard
Ph.D – stipend Zeljko Jovanovic
Ph.D – stipend Gunnvor a Nordii
Ph.D – stipend Morten Larsen
Ph.D – stipend Dorte H Søgaard
Ph.D – stipend Kunuk Lennert
Ph.D – stipend Marita Carlsson
Based at Scottish Association for Marine Science (SAMS)
Senior Lecturer Dr. Henrik Stahl
Technician Andy Reynolds
Technician John Montgommery
Ph.D – student Gavin Turner
Three selected research topics
Sea-ice a key component of Polar Ecosystems. Sea-ice is a characteristic feature of the Poles and the sea-ice extent regulate biological cycles and regional element cycling in the region. Sea-ice is a complex matrix consisting of solid crystals and fluid brines. The brine hold extreme conditions of high salinities and low temperatures, but host specially adapted microbial communities that can contribute significantly to the ecosystem based carbon turn-over. During winter the dense brine gradually leaks out and is replenished by sea-water or by melt water. Sea-ice is extremely dynamic and the chemical conditions and physical structure is constantly changing with variations in temperature, water-flow, snow cover and light. These impose severe stress on the microbial communities, but also have implications for the rate of brine leakage and sea-ice permeability. Overall the biological activity and the physical dynamic regulate the exchange of CO2 between the atmosphere and ocean, but more importantly brine leakage may also contribute to a net export of solutes and gasses from the surface of the ocean to the deep sea. Using a range of complementary techniques we investigate i) the microbial sucession and ecology of sea-ice, ii) the microbial process rates in sea ice, iii) the quantitative importance of sea-ice associated carbon turn-over, iv) Sea-ice mediated CO2 down-draw and its importance for the global CO2 house hold.
Abyssal and hadal carbon mineralization
The deep-sea covers almost 50% of the Earth – and even though the specific activity is low – the vast extent means that the diagenetic processes in the abyss are important for global element cycling. We investigate which microbial processes that are responsible for the degradation of organic material that reach the sea-bed, but also how efficient carbon is degraded and what factors that regulate the degradation efficiency. Overall the efficiency by which carbon is degraded versus buried in the seabed is a key factor for regulating the CO2 and O2 levels in the oceans and atmosphere.
Recovery of sediments from the deep-sea is associated with shift in hydrostatic pressure and transient heating which affect chemical and microbial conditions. Thus, to obtain trustworthy results it is essential to perform measurements directly at the sea-bed and we have developed a range of deep sea landers that autonomously can perform measurements and experiments directly at the sea-bed. Most of the open ocean reach a depth of 4-6 km, but deep sea trenches that reach down to almost 9-11km depth remain unstudied. Recently (Dec 2010), we have carried out work in the Mariana Trench – down to the deepest site on Earth (10.980 m) using specially designed instrumentation. Preliminary investigations indicate that the trenches act as hotspots for deep-sea carbon turn-over and are important for the deep-sea carbon budget.
Microscale patchiness and diagenetic hot spots
Traditionally marine sediments have been regarded as a layered structure of various microbial processes and with little horizontal variations. However, most organic material reach the seabed in the form of aggregates and carcasses and these induce localized enrichments of food. These packages induced short-lived microbial hotspots and have cascadal effects on the microbial community structure and microbial grazers. Using state of the art imagine and microsensor techniques we investigate the micro scale dynamics around such hot spots – how they affect microbial and meiofaunal behaviour and ecology – but also how important ”hot spots” are for the overall element cycling in sediments. Other processes can induce microbial microniches in the sea-bed – these include benthic fauna activities, plant roots and advection. Using sophisticated planar sensors and imagine we investigate the microbial processes and dynamics around such structures and quantify how important they are for large scale element cycling.
Recently we have used microsensors to investigate the chemical conditions in the guts of pelagic grazers (i.e. copepods). They are among the most abundant metazoans in the ocean and the gut may represent hotspots for microbial driven production of greenhouse gasses.
Scientific publications 2008-2010
83. BD Eyre, RN Glud, N Patten (2008) Mass coral spawning – a natural large scale nutrient addition experiment. Limnol Oceanogr 53: 997-1013
84. RN Glud, BD Eyre, N Patten (2008) Biogeochemical responses to coral mass spawning at the Great barrier Reef: Effects on respiration and primary production. Limnol Oceanogr 53: 1014-1024
85. NL Patten, Mitchell JG, Middelboe M, Eyre B, Seuront L, Harrison PL, Glud RN (2008) Bacterial and viral dynamics during a mass spawning period on the Great Barrier Reef . Aqua Microb Ecol 50:209-220
86. S Rysgaard, RN Glud, MK Sejr, ME Blicher, HJ Stahl (2008) Denitrification activity and oxygen dynamics in Arctic sea-ice. Polar Biol 31:527-537
87. K Hancke, TB Hancke, LM Olsen, G Johnsen, RN Glud (2008) Temperature effects on microalgae photosynthesis-light responses measured by O2-production, pulse amplitude modulation (PAM) fluorescence and 14C-assimilation. J Phycol 44:501-514
88. RN Glud (2008) Oxygen dynamics of marine sediments. Mar Biol Res 4:243-289
89. MS Jørgensen, RN Glud, M Middelboe (2008) Virus dynamics in a coastal sediment: Seasonal pattern, controlling factors and relations to the pelagic-benthic coupling. Mar Biol Res 3:165-179
90. DM Mikkelsen, S Rysgaard, RN Glud (2008) Microalgal composition and primary production in Arctic sea ice – a seasonal study from Kobberfjord/ Kangerluarsunnguaq, West Greenland. Mar Ecol Prog Ser 368:65-74
91. RN Glud, H Stahl, P Berg, F Wenzhofer, K Oguri, H Kitazato (2009) In situ microscale variation in distribution and consumption of O2: A case study from a deep ocean margin sediment (Sagami Bay, Japan). Limnol Oceanogr 54:1-12
92. RN Glud, B Thamdrup, H Stahl, F Wenzhoefer, A Glud, H Nomaki, K Oguri, NP Revsbech, H Kitazato (2009) Nitrogen cycling in a deep ocean margin sediment (Sagami bay, Japan). Limnol Oceanogr 54:723-734
93. S Rysgaard , J Bendtsen , LT Pedersen, H Ramløv, RN Glud (2009) Increased CO2 uptake due to sea-ice growth and decay in the Nordic Seas. J Geophys Res 114: C09011
94. P Berg, RN Glud, A Hume, H Stahl, K Oguri, V Meyer, H Kitazato (2009) Eddy correlation measurements of oxygen uptake in deep ocean sediments. Limnol Oceanogr Meth 7:576-584
95. NP Revsbech, RN Glud (2009) Biosensor for laboratory and lander-based analysis of benthic nitrate plus nitrite distribution in marine environments. Limnol. Oceanogr Meth 7:761-770
96. RN Glud, J Woelfel, U Karsten, M Kuhl, S Rysgaard (2009) Benthic microalgal production in the Arctic: Applied Methods and status of the current database. Bot Mar 52:559-571
97. MS Carlsson, RN Glud, JK Petersen (2010) Degradation of mussel (Mytilus edulis) fecal pellets released from hanging long-lines upon sinking and after settling at the sediment. Can J Fish Aqua Science 67:1376-1387
98. FJR Meysman ,OS Galaktinonov, RN Glud, JJ Middelburg (2010) Oxygen penetration around burrows and roots in aquatic sediments. J Mar Res 68:309-336
99. Askaer L, B Elberling, RN Glud, M Kuhl, FR Lauritsen, HP Joensen (2010) Soil heterogeneity effects on O2 distribution and CH4 emissions from wetlands: In situ and mesocosmos studies with O2 planar optodes and membrane inlet mass spectrometry. Soil Biol Biogeochem 42:2254-2265
100. RN Glud, P Berg, A Hume, P Batty, ME Blicher, K Lennert, S Rysgaard (2010) Benthic exchange rates across hard-bottom substrates quantified by eddy-correlation in a sub-arctic fjord system. Mar Ecol Prog Ser 417:1-12
101. DH Søgaard, M Kristensen, S Rysgaard, RN Glud, PJ Hansen, KM Hillingsøe (2010) Autotrophic and heterotrophic activity in Arctic first-year sea-ice: Seasonal study from Marlene Bight, SW Greenland. Mar Ecol Prog Ser 419:31-45
102. M Middelboe, RN Glud, M Filippini (in press) Viral abundance and activity in the deep sub-seafloor biosphere. Aquatic Microb Ecol
103. Tang KW, RN Glud, A Glud, S Rysgaard, TG Nielsen (in press) Copepod guts as biogeochemical hotspots in the sea: Evidence from microelectrode profiling of Calanus spp. Limnol Oceanogr
104. Santos IR, RN Glud, D Maher, D Erler, BD Eyre (in press) Diel coral reef acidification driven by porewater advection in permeable sand. J Geophys Res