How does fishing affect the ecosystem? Find out with an experiment in the lab with guppies

Project description

• Fishing targets large- fish because management regulations impose minimum size limits.
• This selection against large individuals drives evolution towards smaller body size and earlier maturation.
• But these effects also propagate down food chains from top predators to primary producers.
• These ecological effects are believed to impede fish population recovery, even when fishing is halted.

Experiment at BIO with guppies
We have several populations of guppies exposed to different fishing regimes. Now we want to evaluate if these fishing regimes lead to changes in:

1) consumption rate, which determines the predatory capacity of fish and thus its effect on lower trophic levels,
2) excretion rate of the nutrients, ammonium and phosphorous, which determines the ability of nutrient recycling in the ecosystem.

Finally, we will create microcosms representing microbial communities, which will be supplied with fish excretory products. This will allow us to test the effect of fish on several microcosm processes, e.g., community metabolism, litter mass loss rate and nutrient concentration.



Together we will take different ecosystem and fish measurements:

  • Observe fish feeding behaviour
  • Perform fish excretion rate measurements
  • Measure community metabolism in large aquaria
  • Measure chlorophyll in large aquaria
  • Set up a microcosm experiment


The project involves: labwork


Starting date/period: Flexible, contact me to arrange this.



You will learn about the effect of fishing and its ecological effects. You will have hands-on experience on working in the lab with fish, from doing behavioural observations, to taking community metabolism measurements, and performing your own microcosm experiment.



Flexible depending on the task/s you choose to do


Interested by this project? Need more info? Contact Beatriz Diaz Pauli (

Project number: 036





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