Groundwater invertebrates are the highest organisms in groundwater ecosystems. They are widely distributed and their appearance is mainly related to water quality. To date, little is known on how these organisms move through aquifers. The common understanding is that they are moving passively through the established pore system of aquifers; mainly within wider pores. However, it has been speculated that some of these organisms can actively dig through sediments. These theoretical ideas were recently confirmed for the first time in some of our own preliminary lab investigations. The fauna actively altered the pore system and established a network of new flow paths. Our hypothesis is that these networks are maintained and result in a change of transport properties of aquifers. Consequently, preferential flow due to fauna activities is hypothesized to increase.

The objective of the thesis is (1) to investigate digging activities and movement of fauna lab column experiments, (2) to evidence transport changes due to the activity of fauna in aquifers, (3) to quantify these changes in transport with the help of tracer applications and mathematical modeling.

The work will include conducting laboratory column experiments in temperature chambers, tracer experiments in the course of the experiments to monitor flow paths changes over time, and mathematical modelling analysing the resulting tracer concentration curves.

Christine Stumpp

The master student’s office is in Munich (Helmholtz Zentrum München, Institute of Groundwater Ecology).

Christine Stumpp christine.stumpp@helmholtz-muenchen.de Tel. +49 89 3187 4165

Lab work, interdisciplinary research question, mathematical modeling

English

Stumpp, C., and Hose, G. C. (2013) The impact of water table drawdown and drying on subterranean aquatic fauna in in-vitro experiments. PLoS ONE, 8, e78502, doi: 10.1371/journal.pone.0078502

Humphreys, W.F. (2009) Hydrogeology and groundwater ecology: Does each inform the other? Hydrogeology Journal, 17(1), 5-21.

Mathers, K.L., Millett, J., Robertson, A.L., Stubbington, R. and Wood, P.J. (2014) Faunal response to benthic and hyporheic sedimentation varies with direction of vertical hydrological exchange. Freshwater Biology 59(11), 2278-2289.