SAC # 105

Agriculture, Invaders, and Multiple Stressors in Aquatic Ecosystems



TIME | 24 March 2011, 4pm onwards

LOCATION | CSAFE Seminar Room, , Dunedin

SPEAKER | Christoph Matthaei


Many aquatic ecosystems worldwide are affected by inputs of nutrients, fine sediment and pesticides, raised water temperatures, reduced water exchange rates due to abstraction, and introduced invaders. While these stressors are known to exert individual effects on aquatic communities and ecosystem functioning, their combined impacts are poorly understood. In a series of studies in streams and streamside channels, we have investigated key stressors in pairs and triplets, to determine their individual and combined effects on community composition (invertebrates, fish), algal biomass and leaf decomposition. Each stressor had strong individual effects, but in combination stressors often produced synergistic or antagonistic outcomes. For example, the presence of sediment can prolong the adverse effects of herbicide in streams. Moreover, the reduced flow associated with water abstraction often acts synergistically to increase the negative impact of deposited sediment. In contrast, water abstraction acted antagonistically to decrease the adverse impact of invasive trout on native fish by providing refuges from trout predation. Because ecological consequences of multiple stressors are often unpredictable based on knowledge of single effects, resource managers need to know how stressors interact. 

About the Speaker

Qualifications: Habilitation (Aquatic Ecology) University of Munich 2002 (the highest possible academic degree in Germany, Switzerland, Austria and France); PhD (Environmental Sciences) Swiss Federal Institute for Environmental Science and Technology (EAWAG), Duebendorf, and Swiss Federal Institute of Technology (ETH), Zurich 1996

Present Position: Senior Research Fellow, Department of Zoology, University of Otago

Previous positions: Research Fellow, Department of Zoology, University of Otago (since November 2002); Assistant Professor (Habilitand), Department of Zoology, University of Munich (LMU) – October 1999 to October 2002; Research Fellow, Department of Zoology, University of Munich – June 1998 to October 1999; Research Fellow, Department of Zoology, University of Otago (grantee of the Swiss National Science Foundation) – September 1996 to May 1998


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