Fish feeding conditions in lakes with different planktonic food web structure and macrovegetation (MICROFISH) No.

Agreement with State Education Development Agency of the Republic of Latvia No. Programme number

The food webs of water bodies (lakes, rivers etc.) play an important role in the functioning processes of lake ecosystems. Without paying increased attention to the overall exploration of the lake ecosystem, it is not possible to explain how the ecosystem will respond to potential environmental changes and how these changes will affect the overall functioning of the lake ecosystem, especially the development of natural resources (fish stocks, commercial fish species). Scientific data-based plans for the management of lakes cannot be developed if any part of the lake's ecosystem is ignored.


The main objective of the project is to improve knowledge on how lake food webs function, thereby enabling the development of scientific and data-based plans for the management of lakes that combine economic and ecological criteria. An additional objective is to determine how aquatic plants in lakes (as the living environment for fish) and plankton organisms (including microbial food web components as potential food items for larval fish) influence fish eating habits in different lakes. Lakes will be divided into four different groups: 1) aquatic plant (macrophyte) rich lakes with high fish feeding pressure; 2) macrophyte poor lakes with low fish feeding pressure; 3) macrophyte rich lakes with low fish feeding pressure; 4) macrophyte poor lakes with high fish feeding pressure.


The MICROFISH project includes the following activities:

  • Seasonal sample gathering (around 150 samples) from 8 different lakes (4 Latvian and 4 Estonian) by using novel fieldwork equipment and methods for studying food webs in lakes;
  • Studying the impact of aquatic plants (as the fish living environment) and plankton organisms (including micro-biological food web components as potential food items of fish larvae) in different lakes on natural fish resources (fish stock development, fish survival and their eating habbits);
  • Studying how food webs (especially microbial loop) function in different lake ecosystems;
  • Studying the impact on fish stocks by planktonic food web structure and macrophytes – how this influences the development of fish larvae and how fish in turn, particularly their eating habbits (eating of certain species of the food web), structure lake food webs
  • Studying how macrophytes (as living places and shelter) are structuring the relationships between planktonic communities and fish;
  • Eating habbits and factors of larval fish survival will be researched. It is planned that results will provide an overall understanding of how ecosystems function in different types of lakes;
  • Developing and testing novel equipments and methods to collect fish larvae and assess their abundances in lakes;
  • Testing novel methods (gut segmentation analysis by using epifluorescence microscopy) to assess the larval fish diet;
  • Presenting results of the project in 3 international conferences and preparing 3 publications in international scientific journals.

Project duration: January, 2019 – January, 2022

Project manager: post-doctorate researcher Katrit Karus, katrit.karus@videsinstituts.lv

The project is financed by: European Regional Development Fund Activity "Post-doctoral Research Aid" of the Specific Objective 1.1.1 "To increase the research and innovative capacity of scientific institutions of Latvia and the ability to attract external financing, investing in human resources and infrastructure" of the Operational Programme "Growth and Employment", the State budget of the Republic of Latvia and the foundation „Institute for Environmental Solutions“.