Project A11

Multiple stressor effects on sculpins (Cottus sp.) and related top-down effects on riverine food-webs

Hypothesis 1 Hypothesis 1 ARC 2 ARC 3 ARC 4 Field studies Fish Parasites Food webs

Project leader

PD Dr. Kathrin Lampert

Project Summary

In stream ecosystems, fish are highly mobile top predators that significantly shape food-web interactions. They are also highly affected by multiple stressors and immediately respond to stressors such as salinization and elevated water temperatures. The project will investigate stressor response patterns in two model species (Cottus rhenanus and C. gobio). We are planning a detailed analysis of dispersal and recolonisation patterns (WP1) as well as adaptation to stressors and stressor combinations (WP2). In addition, the influence of Cottus sp. on prey invertebrates and the food web in general will be investigated (WP3). The survival of small populations in isolated locations of the Emscher catchment as well as large populations in the Kinzig and the Rhine makes Cottus sp. an ideal candidate to test local adaptation.

The first part of the project will focus on the distribution and genetic diversity of Cottus sp. in the partly degraded and partly restored Emcher/Boye catchment and in the moderately stressed Kinzig catchment under single and multiple stressor conditions. Since the restoration projects in the Emscher catchment started, C. rhenanus was re-introduced but also dispersed naturally into the rehabilitated tributaries despite high water temperatures in summer.

A higher tolerance for warm temperature and higher salinity might explain the fast recolonisation of habitats, where environmental conditions have improved just enough for tolerant genotypes. We will combine field data with molecular methods. Individuals of Cottus sp. will be caught, marked and monitored in the field. A wide range of environmental variables (including temperature and salinity) will be correlated with fish presence and individual relatedness.

Population genetic diversity will be analysed using neutral genetic markers (WP1). In addition, we will use transcriptome data as well as detailed candidate gene analyses and qPCR to analyse candidate genes of the respiratory chain (oxygen stress response), osmoregulation (salinity stress response) and the immune system (pathogen response) for evidence of adaptation to environmental stressors (WP2).

In addition, the project will characterise the influence of Cottus sp. on food web interactions by comparing small water bodies with and without predatory fish. In cooperation with other projects, we will investigate resource abundance, feeding types and parasite diversity. The synthesis of this integrative approach will provide a deeper understanding of the ecological and evolutionary consequences of stressor impact on vertebrate and invertebrate populations.

PhD topic(s)

Camilo Escobar (University of Cologne)

Multiple stressor effects on sculpins (Cottus sp.) and related top-down effects on riverine food-websultiple stressor effects on Cottus spp.

In stream ecosystems fish are highly mobile top predators that significantly shape food-web interactions. They are also highly affected by water quality and immediately respond to water quality changes. Among the wider Rhine catchment many fish species, the sculpin (genus Cottus) stands out as a good model to evaluate the ecological state of river stretches because they are small, benthic fish that prey on invertebrates. They are widespread and usually common, but have no commercial value which means that they are not anthropogenically relocated and show natural distribution patterns. Actually, since restoration projects of the Emscher started, the species was re-introduced but also dispersed naturally into the rehabilitated side streams of the Emscher even though temperatures can get quite high especially during the summer months. The survival in small isolated locations as well as in the large populations in the main rivers makes Cottus an ideal candidate to test local adaptation. A higher tolerance for warm temperature and higher salinity might explain the fast re-colonization of habitats where environmental conditions have improved just enough for tolerant fish. Taking this into consideration, the current project will use sculpins (Cottus) as a model to investigate the stress response patterns in fish. The main objectives of this project are: To analyse the dispersal and re-colonisation patterns as well as adaptation to stressors and stressor combinations of Cottus in both the Kinzig and Emscher catchments. In addition, the influence of Cottus on prey invertebrates and the food web in general will be investigated.

To achieve this, we plan to combine ecological with molecular methods. Cottus will be caught, marked and monitored in the field. Different water parameters will be correlated with fish presence and individual relatedness as well as population genetic diversity will be analysed using neutral genetic markers. In addition, we will use transcriptome data as well as detailed candidate gene analyses and qPCR to analyse candidate genes of the respiratory chain (oxygen stress response), osmoregulation (salinity stress response) and the immune system (pathogen response) for evidence of adaptation to environmental stressors. And finally, in cooperation with other RESIST projects the species-specific genetic analyses will be linked to more general models targeting dispersal, survival and reproduction probabilities of fish in mosaic landscapes. And to understand the fish’s influence on food web interactions and investigate the resource abundance, feeding types and pathogen diversity. The synthesis of this integrative approach will provide a deeper understanding of the ecological and evolutionary consequences of stress on vertebrate and invertebrate populations.

Contact: cescobar@uni-koeln.de

First Supervisor: PD Dr. Kathrin Lampert (University of Cologne, Zoological Institute)
Second Supervisor: Prof. Dr. Ralph Tollrian (Ruhr University Bochum, Animal Ecology, Evolution and Biodiversity)
Mentor: N.N.

Overview of all doctoral researchers