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Hi! My name is Kasia Piwosz and I am a professor at the National Marine Fisheries Research Institute in Gdynia.

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In my work, I study ecological relationships between microorganisms living in sea water.

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Microorganisms are wildly diverse.

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The number of protozoan species is estimated at several to several million,

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and bacteria even trillion.

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However, describing new species is very difficult due to their small size.

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You need a really good microscope to observe the beauty and see the details of the structure.

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Therefore, the discovery of the true biodiversity of microorganisms was only possible after the development of molecular methods.

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Today, in evolutionary and ecological research, the entire DNA of organisms is sequenced.

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By comparing the obtained DNA sequences, phylogenome trees are built that have hundreds of branches.

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Most life on our planet is invisible to the naked eye.

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But that doesn't mean it's invisible.

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If all organisms living in the seas and oceans were weighed, 70% of the weight would be microorganisms.

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If all marine microorganisms were combined to form people, there would be over a million times more than there are on earth today.

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Half of the oxygen we breathe is produced by microorganisms that live in the seas.

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Unicellular algae that fix carbon dioxide form the basis of the trophic pyramid in the sea.

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Half of their production is eaten directly by tiny crustaceans (zooplankton),

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which is fish food.

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The other half, on the other hand, is secreted directly into the water column, either as a result of stress or as a result of cell disintegration.

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This released matter is inaccessible to animals.

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However, it can be used by bacteria.

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Bacteria, in turn, are food for protozoa,

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which are food for larger protozoa,

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which are food for even larger protozoa.

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The largest protozoa, which actually reach the size of hundredths of a millimeter,

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can be eaten by crustaceans

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which are food for fish.

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This closes the microbial loop in the sea.

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Microbial food webs are at the center of my scientific interests.

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My research focuses on the role of protozoa in the carbon flux in the ecosystem

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and on the impact of microplastics on organisms.

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The implementation of this research is possible thanks to two projects funded by the National Science Centre.