Plankton Party at the Lake Merritt Docks

By Constance Taylor

Pop Quiz:

 What process produces half the Earth’s oxygen?

 Tick tick tick… pencils down.

 Answer: Phytoplankton photosynthesis! (Nat Geo. 2006)

 Thank yoooooooou, phytoplankton!

I assume he’s actually zooplankton, but humor me.

Speaking of zooplankton, what’s the difference between it and phytoplankton?

Ah!  Glad I asked.  Phytoplankton is autotrophic, prokaryotic, or eukaryotic algae that live close to the surface of water where there’s enough sunlight for photosynthesis.  Zooplankton includes eggs and larvae of fish, insects, crustaceans, annelids, and small protozoans and metazoans. Essentially, “phyto-” = plants and “zoo-” = animals.

Bacterioplankton is a relatively new group that’s been added to the plankton family- they play an important role in remineralizing organic material down the water column.

“Plankton” is one word used for infinite organisms, seeing that new species are always being discovered.

Anthony discovering the secrets stuck to Lake Merritt urbanite, photo by Dianne Fristrom

Anthony DeCicco from the Golden Gate Audubon Society deftly guided us through all the new words and designations on Wild Oakland’s Plankton Walk.  He introduced us to the microscopic organisms that thrive in the waters of Lake Merritt with his arsenal of pipettes, field microscopes, plankton nets, and collection trays.

Who knew what secrets were in the waters of our beloved slough?

Looking at water samples

The birds do, at least- diving ducks like Ruddys, Goldeneyes, Canvasbacks, and Buffleheads love to eat the plants and algae as well as invertebrates like aquatic insects, mollusks, crustaceans, and shrimp.  So all these invertebrates in their juvenile stages are what now?  Imagine me cupping my hand to my ear while you shout… Zooplankton!  Heyo!  High five.

Tintinninds (zooplankton) photo by Revital Katznelson

There are two main groups of zooplankton- Holoplankton and Meroplankton.  Holoplankton remain microscopic their entire life cycle and are the most abundant protein source in the world, while meroplankton graduate within their life cycle to become larger organisms.

Plankton can generally be divided into two categories- Nektonic and Planktonic.  Nektonic plankton can swim against currents, while planktonic plankton drift where the currents take them.

So you can have nektonic meroplankton, planktonic holoplankton, planktonic phytoplankton, and maybe even nektonic bacterioplankton…I think there’s a joke in there somewhere.  First person to come up with a punchline gets to go on a Wild Oakland walk for free!

Towing plankton nets at the Lake Merritt docks

Other special guests of the day included Katie Noonan and some of her students from the Oakland High Environmental Science Program.  Not only did she bring a digital microscope for us to look at samples, but her students also showed us how to tow the plankton nets along the dock and take samples of the water.  Katie told us that 90-95% of plankton species in the Bay are not native… wow.  They come from all over the world- Japan, Australia, the Mediterranean- in bait containers, ballast water, on the hulls of commercial shipping vessels, etc.

Looking through the digital microscope in the Lake Merritt Boathouse classroom

Katie Noonan has been taking her science students to Lake Merritt to study plankton for the past ten years, so she’s got a very good idea of what kinds of microorganisms are in the water.  To see pictures of the plankton her class has found you can go to:

Thanks to Anthony DeCicco, Katie Noonan, and her students for making this walk a success.  Thanks also go to Stephanie Benavidez and Alexa Fulper from Oakland Parks and Recreation for allowing us to collect samples from the slough- it’s a protected wildlife refuge and collecting is by permit only, so we appreciate their permission for our walk.

And of course, thank you to everyone who came and participated!  Wild Oakland doesn’t happen without you.

See you in February!

Former zooplankton... shrimp at Lake Merritt

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