Research on benthic macroorganisms and their interaction with the biogeochemistry of marine sediments
We study how benthic plants and animals are adapted to life in anoxic and sulfidic marine sediment, and how these organisms affect microbial activity in sediments. The microbial processes are focused on carbon, nitrogen, sulfur and iron cycling. The work is conducted primarily in Danish tidal flat and saltmarsh areas as well as in tropical mangrove forests.
The research has during recent years focused on the impact of invasive species on the composition of native flora and fauna in estuaries. More specifically, we examine how potential flora and fauna regime shifts affect estuarine sediment biogeochemistry and ecosystem functioning.
Research Leader
Erik Kristensen
Research group
Laboratory technician Birthe Christensen
Post doc Cintia O. Quintana
Post doc Thomas Valdemarsen
PhD student Matthieu Delefosse
PhD student Mia Østergaard Pedersen
PhD student Perrine Mangion
M.Sc. student Tessa Buchwald
M.Sc. student Hanh Nguyen
M.Sc. student Marine Therese Suzanne Consigny
Current research activities
The influence of marine invasive species on ecosystem structure and function (MARINVA)
This research project is collaborative among groups from University of Southern Denmark, Copenhagen University and Roskilde University. Overall, we examine the structural and environmental consequences of invasive marine algae and benthic animals in Danish coastal waters. The increasing human mobility (shipping etc.) combined with the expected climate changes will promote invasions of new species to Danish waters. Some of these species will not affect our ecosystems, while other species will cause serious changes in the receiving systems. This study area focuses on three species (one alga, a polychaete species complex, and one oyster) from Asia, North America and Japan, respectively. All three species are now more or less well established in Danish coastal waters. However, our knowledge on their distribution, physiological adaptations and environmental requirements is limited. The research focuses on how (and to which extent) each individual species affects its new community with emphasis on ecosystem element and energy transformations. The work is innovative by combining laboratory experiments and field work at different scales from individual over population to ecosystem level. The contribution from University of Southern Denmark is focused on the invasive polychaete Marenzelleria viridis with respect to: 1. Is this new species capable of outcompeting the native polychaete species Nereis diversicolor? 2. How does this new species affect sediment biogeochemistry?
Key parameters and processes affecting the re-establishment of eelgrass in estuaries and coastal waters (REELGRASS)
The last 10-15 years effort to reduce nutrient loading of Danish waters is now paying off as reduced pelagic nutrient levels. As a consequence, the light climate has improved and light now reaches sediments that were in the dark some years ago. This has not happened and although much effort has been spent to elucidate the lacking reestablishment, our understanding of the main processes and mechanisms of reestablishment is still limited. Our hypothesis is that processes involved in the reestablishment of eelgrass are different from those affecting eelgrass mortality and decline in coverage. This project examines spatially and temporally links between eelgrass reestablishment and physical, chemical and biological factors related to sediment properties. These include current and wave induces stress, cohesive behavior of sediments, history of the sediment organic pools, sediment biogeochemical processes and biomixing and grazing of macrofauna. These studies are conducted in the field at survey stations in areas where eelgrass potentially should have colonized and in areas where they are reestablished. These surveys are combined with a suite of laboratory studies where sediment conditions, physical stress, light intensity, temperature, oxygen and nutrient conditions are varied under strict control. Our intention is that the results of this project improve the currently insufficient dynamic models to simulate areas of potential recolonization. With the implementation of the EU Water Frame Directive, eelgrass will be a key indicator for the evaluation of water quality in coastal waters. Our studies aim to provide the needed information and knowledge for a successful use of eelgrass as a water quality and habitat indicator.
Stress thresholds for deterioration and recovery of shallow freshwater and marine macrophyte communities; the role of sediment processes
Vegetation of rooted plants in shallow freshwater and marine areas stabilizes the ecosystems element cycling and biodiversity. Eutrophication during the last decades has caused considerable decline in the coverage of rooted macrophytes. However, during recent years, action plans for the aquatic environment has reduced the discharge of nitrogen and phosphorus, but not always with the expected reestablishment of macrophytes. The purpose of this project is to investigate the influence of sediment conditions and associated physical, chemical and biological processes for the decline and reestablishment of coherent meadows of rooted macrophytes. In other words, we attempt to define and identify sediment related stress thresholds for rooted aquatic macrophytes. We will focus on a comparison of thresholds in freshwater and marine environments. The work is partitioned into 4 topics: 1. Chemical stress effects caused by microbial transformation and biogeochemistry of C, N, P, S, Fe and Mn in sediments; 2. The functional influence of benthic fauna for transport and biogeochemical processes in sediment with focus on vegetation health; 3. The anchoring capacity and survival of rooted vegetation under various sediment conditions and time scales in areas under reestablishment; 4. Integration of the results from topic 1-3 by the use of model considerations of plant communities response to environmental stress. We hope to identify the biogeochemical stress threshold that separates deterioration and recovery of plant communities.
Scientific publications from 2008 to 2011
Kristensen, E. (2008). Mangrove crabs as ecosystem engineers, with emphasis on sediment processes. J. Sea Res. 59: 30-43
Kristensen, E., Bouillon, S., Dittmar, T. & Marchand, C. (2008). Organic carbon dynamics in mangrove ecosystems. Aquat. Bot. 89: 201-219
Bouillon, S., Borges, A.V., Castañeda-Moya, E., Diele,K.,Dittmar, T., Duke, N.C., Kristensen, E., Lee, S.Y., Marchand, C., Middelburg, J.J., Rivera-Monroy, V.H., Smith III, T.J. & Twilley, R.R. (2008). Mangrove production and carbon sinks: a revision of global budget estimates. Global Biogeochemical Cycles 22: GB2013, doi: 10.1029/2007GB003052
Kristensen, E., Poovachiranon, S., Suraswadi, P., Thongtham, N., Flindt, M., Andersen, F.Ø. & Holmer, M. (2008). Mangrove research at Phuket Marine biological Center, Thailand, with emphasis on biogeochemistry and ecology of the Bangrong mangrove forest. Phuket Mar. Biol. Ctr. Res. Bull., Spec. Publ. 31: 25-40
Thongtham, N., Kristensen, E. & Phungprasan, S.-Y. (2008). Leaf removal by leaf-eating sesarmid crabs in the Bangrong mangrove forest, Phuket, Thailand; with emphasis on the feeding ecology of Neoepisesarma versicolor. Estuar. Coast. Shelf Sci. 80: 583-590.
Kristensen, E., Flindt, M.R., Borges, A.V., Bouillon, S. (2008). Emission of CO2 and CH4 to the atmosphere by sediments and open waters in two Tanzanian mangrove forests. Mar. Ecol. Prog. Ser. 370: 53-67.
Valdemarsen, T., Holmer, M., Kristensen, E. (2009). Metabolic threshold and sulfide-buffering in diffusion controlled marine sediments impacted by continuous organic enrichment. Biogeochemistry 95:335-353
Penha-Lopes, G., Bartolini, F., Limbu, S., Cannicci, S., Kristensen, E., Paula, J. (2009) Are fiddler crabs potentially useful ecosystem engineers in mangrove wastewater wetlands? Marine Pollution Bulletin 58:1694-1703
Penha-Lopes, G., Bartolini, F., Limbu, S., Cannicci, S., Mgaya,Y., Kristensen, E., Paula, J. (2010) Ecosystem engineering potential of the gastropod Terebralia palustris (Linnaeus, 1767) in mangrove wastewater wetlands - a controlled mesocosm experiment. Environmental Pollution 158: 258-266
Valdemarsen, T., Kristensen, E., Holmer, M. (2010). Sulfur, carbon, and nitrogen cycling in faunated marine sediments impacted by repeated organic enrichment. Mar. Ecol. Prog. Ser. 400: 37-53
Valdemarsen, T., Kristensen, E. (2010). Degradation of dissolved organic monomers and short-chain fatty acids in sandy marine sediment by fermentation and sulfate reduction. Geochim. Cosmochim. Acta 74: 1593-1605
Penha-Lopes, G., Kristensen, E., Flindt, M., Mangion, P., Bouillon, S., Paula, J. (2010). The role of biogenic structures on biogeochemical functioning of mangrove constructed wetlands sediments – A mesocosm approach. Marine Pollution Bulletin 60: 560-572
Tang, M., Kristensen, E. (2010). The impact of cordgrass, Spartina anglica, on macrobenthos distribution in the Danish Wadden Sea. Helgoland Mar. Res. 64: 321–329
Kristensen, D.K., Kristensen, E., Mangion, P. (2010). Food partitioning of leaf-eating mangrove crabs (sesarminae): Experimental and stable isotope (13C and 15N) evidence. Estuar. Coast. Shelf Sci. 87: 583-590
Canal-Vergés, P. Vedel, M., Valdemarsen, T., Kristensen, E., Flindt, M.R. (2010). Resuspension created by bedload transport of macroalgae: implications for ecosystem functioning. Hydrobiologia 649: 69-76
Kristensen, E., Mangion, P., Tang, M., Flindt, M.R., Ulomi, S. (2011). Benthic metabolism and partitioning of electron acceptors for microbial carbon oxidation in sediments of two Tanzanian mangrove forests. Biogeochemistry 103:143–158
Papaspyrou, S., Thessalou-Legaki, M., Kristensen, E. (2010). The influence of infaunal (Nereis diversicolor) abundance on degradation of organic matter in sandy sediments. J. Exp. Mar. Biol. Ecol. 393: 148-157
Valdemarsen, T., Canal-Vergés, P., Kristensen, E., Holmer, M., Kristiansen, M.D., Flindt, M.R. (2010) Vulnerability of Zostera marina seedlings to physical stress. Mar. Ecol. Prog. Ser. 418: 119-130
Kristensen, E., Hansen, T., Delefosse, M., Banta, G.T., Quintana, C.O. (2011) Contrasting effects of the polychaetes Marenzelleria viridis and Nereis diversicolor on benthic metabolism and solute transport in sandy coastal sediment. Mar. Ecol. Prog. Ser. (in press)
Quintana, C.O., Hansen, T., Delefosse, M., Banta, G.T., Kristensen, E. (2011) Burrow ventilation and associated porewater irrigation by the polychaete Marenzelleria viridis. J. Exp. Mar. Biol. Ecol.397: 179-187
Jørgensen, B., Demétrio, C.G.B., Kristensen, E., Banta, G.T., Petersen,H.C., Delefosse, M. (2011). Bias-corrected Pearson estimating functions for Taylor’s power law applied to benthic macrofauna data. Statistics and Probability Letters (in press)