Minute algae-eating creatures, just visible to the naked eye, are being researched in the hope of learning more about Cardiff Bay's water quality.
Zooplankton are mostly 1-2mm and can just be seen by the naked eye
The zooplankton study has been launched by Cardiff University, the Centre for Ecology and Hydrology (CEH) and Cardiff Harbour Authority (CHA).
David Lowe, of CHA said: "Zooplankton are vital to sustaining the ecological balance in our freshwaters".
They provide food to birds and fish in the bay's artificial lake.
Cardiff University PhD student Faye Merrix, who is involved in the research, said the work could prove to be significant.
''This three-year project could point the way forward to controlling the algae in Cardiff's freshwater lake," she said.
Previous studies have looked at the environmental implications of changing from salt water to freshwater, following the creation of Cardiff Bay's £197m barrage in 1999.
It includes the impact on birds, flora and insect populations.
The CHA hopes to increase understanding of the relationship between zooplankton, the growth of algae and the impact on oxygen levels.
Experts say we know 'remarkably little' about bay water life
Mr Lowe added: "Monitoring of zooplankton over time will not only assist our understanding in this area of Wales, but may provide useful data for future studies".
Plankton is made up of tiny plants called phytoplankton and tiny animals called zooplankton.
One aspect researchers will look for is an increase in species such as Daphnia - water fleas which eat algal cells and could improve water clarity.
These creatures, which can grow up to 5mm, could also encourage plant growth.
Professor Steve Ormerod, of Cardiff University's school of biosciences said: "Cardiff Bay is a unique water body of a type that we still know remarkably little about - for example how its species assemble and interact.
"This project therefore represents a real opportunity to contribute internationally to new knowledge in aquatic ecology and conservation biology."
Dr Steve Thackeray, from the CEH, added that it was an "exciting project" and was part of an attempt to "generate solutions to today's pressing environmental issues".