Staff

Timothy John Alexander

Dr. Timothy John Alexander

Postdoc

Department Fish Ecology & Evolution

About Me

  • Postdoc in the group Biodiversity Dynamics

Research interests

I am interested in research that guides integrated approaches to conservation and natural resource management at the resolution of ecosystems, or ideally socio-ecological systems. I am currently working as a postdoc with Projet Lac.

The main objectives of the project are to:
- Assess the current ecological status of Swiss lakes with particular emphasis on fish communities.
- Use current and historical environmental data to identify key factors that influence the development and distribution of fish biodiversity.
- Establish a reference collection of fishes at the Natural History Museum of Bern as a basis for future research.

The ecological assessment aligns with efforts by other European countries to fulfill their obligations under the EU Water Framework Directive. Under this mandate, member countries are obligated to assess, and if necessary improve, the ecological status of their lakes (among other freshwater ecosystems). The assessment process is based on identifying distinct types/typologies of each ecosystem and, within the typology, comparing each waterbody to control or reference site via indicators or indices. Lacustrine fish communities form a major component of the assessment. Although Switzerland is not part of the EU, we’re conducting a comparable sampling program to contribute to Europe-wide ecological assessments and to generally better understand the ecology of fish communities in Swiss lakes.

The second objective of the project is to shed further light on the effects of current and historical anthropogenic influence on lake biodiversity and ecosystem functioning. A history of eutrophication in Swiss lakes by anthropogenically derived phosphorus has led to major changes in the ecology of these waterbodies. The problems peaked in the late 1970's and the government responded by introducing a successful nutrient control program that put many lakes on a trajectory back towards their natural state. The repercussions of eutrophication are still evident today though in places such as Lago di Lugano where, although the lake is almost 300m deep, very little lives below 30 metres due to low oxygen caused by decaying organic matter in conjunction with thermal stratification. My colleagues have identified that the lack of oxygen in deeper waters has caused the extinction of some endemic fish species and the erosion of genetic diversity by forcing previously distinct populations and species to interbreed within the most eutrophic lakes (http://www.nature.com/nature/journal/v482/n7385/abs/nature10824.html). This project aims to go deeper into such patterns for fish species across lakes representing a wide range natural and anthropogenic conditions.

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Projects

Almost two-thirds of the native fish species of Switzerland are threatened by extinction. To preserve or specifically enhance aquatic biodiversity and habitats ...
We work to combat what we consider the largest stumbling block on the way to successful biodiversity management and conservation in aquatic ecosystems: the lack of quantitative baseline data
We study causes of variation in diversity of fish assemblages and we wish to understand how variation in diversity affects the lake ecosystems

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Curriculum Vitae

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Selected publications

Alexander, T. J.; Vonlanthen, P.; Périat, G.; Degiorgi, F.; Raymond, J.-C.; Seehausen, O. (2015) Evaluating gillnetting protocols to characterize lacustrine fish communities, Fisheries Research, 161, 320-329, doi:10.1016/j.fishres.2014.08.009, Institutional Repository
Vonlanthen, P.; Périat, G.; Seehausen, O.; Alexander, T.; Guillard, J.; Colon, M. (2014) Untersuchung der Fischpopulation im Lago di Poschiavo und im Silsersee, 51 p, Institutional Repository
Vonlanthen, P.; Périat, G.; Seehausen, O.; Alexander, T. (2014) Artenvielfalt und Zusammensetzung der Fischpopulation im Hallwilersee, 37 p, Institutional Repository
Alexander, T. J.; Johnson, C. R.; Haddon, M.; Barrett, N. S.; Edgar, G. J. (2014) Long-term trends in invertebrate-habitat relationships under protected and fished conditions, Marine Biology, 161(8), 1799-1808, doi:10.1007/s00227-014-2462-2, Institutional Repository
Cohen, P. J.; Alexander, T. J. (2013) Catch Rates, composition and fish size from reefs managed with periodically-harvested closures, PLoS One, 8(9), e73383 (12 pp.), doi:10.1371/journal.pone.0073383, Institutional Repository
Alexander, T. J.; Vonlanthen, P.; Périat, G.; Degiorgi, F.; Raymond, J. C.; Seehausen, O. (2015) Estimating whole-lake fish catch per unit effort, Fisheries Research, 172, 287-303, doi:10.1016/j.fishres.2015.07.024, Institutional Repository

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Address

E-Mail: timothy.alexander@eawag.ch
Phone: ---
Fax: +41 58 765 2168
Address: Eawag
Seestrasse 79
6047 Kastanienbaum
Office: CA B12

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Research Group

Biodiversity dynamics

Projet Lac

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