Virtual Museum of Canada

WATERS OF LIFE

LIFE UNDERWATER

PLANKTON - PHYTOPLANKTON - ENVIRONMENT AND ADAPTATIONS

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Aquatic plants at Lake Saint-Pierre

Lake Saint-Pierre

Cyanobacteria are the only algae capable of fixing atmospheric nitrogen in addition to nitrogen dissolved in the water column. Nitrogen is essential for algal growth.

Lake Saint-Pierre with trees in the background

Lake Saint-Pierre

Cyanobacteria therefore have an advantage over other types of algae when nitrogen concentrations in the water are low.

Trees on an island near the St. Lawrence River

St. Lawrence River

The quantity and diversity of phytoplankton are good indicators of water quality.

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Aquatic plants and algae

Aquatic plants and algae

The greater the variety of species, the healthier the ecosystem. However, excessive growths of phytoplankton caused by an abundance of fertilizers can asphyxiate the lake.

Algae growing on aquatic plants underwater

Algae growing on aquatic plants

Some types of algae grow on plants, instead of floating in the water column. They make the surface they are attached to feel sticky. This category includes many species of green algae, cyanobacteria and diatoms.

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Video filmed under a microscope of a cladoceran seeking to eat a colony of Volvox.

VIDEO - 0 min 12 s
One of the advantages of colony life for the green alga Volvox is that cladocerans, a type of herbivorous zooplankton, are unable to consume them because the sphere formed by the algal colony is too large for these filter-feeders.

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LIFE UNDERWATER

PLANKTON - PHYTOPLANKTON