Friday, March 22, 2024

Algae, Up Close and Personal

The close up pics posted yesterday are actually details of an algal specimen we collected from our lake over the weekend. The sections looked like bits of carpet or cardboard, covered in green algae. Some were floating, and others were lying curled up on the sediment.

Cardboard-like piece of algae on lake floor
 Photo: Dale Schultz

Floating segment, overturned
Submerged segment 

The presence of algae in a lake does not mean it's a 'bloom' or a nuisance - they are an integral part of the lake ecosystem, and together with phytoplankton, are the basis of the aquatic food web. Algae 'green-up' earlier in spring than vascular plants, since they can photosynthesize in much lower light levels. Incomplete ice cover this past winter (climate change) has most likely contributed to algae's early start. Once other organisms that feed on algae hatch, their temporary dominance is whittled away. 

This algae (possibly Planktothrix) has gas vesicles on its surface that affect its buoyancy. As gases are produced and released, the segments can rise and fall in the water column. Look at this amazing texture it exudes - like dinosaur skin.

It was difficult to pick the pieces up and keep them intact, so we scooped them up using a shallow container. They felt slimy and slippery, like a placenta. I also had the notion that it was "there, but not there." 

Planktothrix is a filamentous algae - this close up shows the small green filaments of which it is composed. 

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