A Blitzin’ Day at Lake Merritt

By Ellen Hong

February 23. It was a beautiful Sunday morning in Oakland, a day too nice for anyone to stay indoors. And what better way to spend time outside than to explore the wildlife of Lake Merritt by participating in the Bioblitz?

Using underwater robots, nets, microscopes, and the help of experts, everyone was observing and recording all the plants and animals that live at Lake Merritt. It was awesome to see everyone so excited and enthusiastic about nature, and I couldn’t wait to be a part of it all!

After checking in at the Rotary Nature Center, grabbing a schedule and throwing on a goofy green sash labeled “BIOBLITZ”, I went to the dock at the Lake Merritt boathouse where Rebecca Johnson from the California Academy of Sciences was leaned over the side of the dock, pointing out some of the creatures living in the water. She identified a tunicate clinging to the dock and then showed us a picture of one in her sea-animal identification guide.

Tunicate identification, from the California Academy of Sciences. Photo: Ellen Hong

Tunicate identification, from the California Academy of Sciences. Photo: Ellen Hong

“Tunicates are filter-feeders,” she explained. “They have a basket inside of them that allows them to filter plankton (their food) and let water out.” As some little kids came over and curiously pointed to the mussels Johnson had collected in a bucket, she took them both out and passed them around, explaining that mussels have two shells held together by a muscle, hence the name of the animal. They have a really unique way of eating: they pull a sample of water in through a tube and have special sorters that take in the “good-sized” plankton and releases the water. But that’s not all—once the food is filtered, it’s stuck in a special mucus,twirled around like a spool of thread, and slurped up like spaghetti. How’s that for weird eating?

Mediterranean mussel. Photo: Ellen Hong

Mediterranean mussel. Photo: Ellen Hong

“Have you ever seen a mussel that looks like it’s slightly cracked open? That actually means that it’s eating!” Johnson commented. She held up one of the mussels she had collected and explained that the species we would find at Lake Merritt have most likely come from different parts of the world. The one she was holding was probably from the Mediterranean- since Lake Merritt is so close to the port of Oakland where ships come from all over the world, there are many marine hitchhikers that end up in the bay, some eventually making their way to Lake Merritt.

The vast array of species you can find here is actually what inspired accomplished marine biologist Jim Carlton, a world-class expert on marine invertebrates, to start his career! His beginnings consisted of leaning over the side of that dock, observing what lay in the water, and wondering what it all was and where it come from… just like some of us were doing that Sunday morning.

After about an hour of hanging around the docks, learning from Rebecca and also getting to look into microscopes at some of the plankton samples participants had gathered, I decided it was time to explore a new area. I walked over to the pollinator garden, excited to see and learn more about bees, butterflies, and flowers.

I walked in to see Tora Rocha, the parks supervisor for Oakland Parks and Recreation, pointing out the garden’s incredible Bee Hotel to some fascinated visitors. In case you haven’t seen it, it’s a beautiful structure packed with logs that people have drilled holes into to give bees a safe place to live.

Bee Hotel. Photo: Ellen Hong

Bee Hotel. Photo: Ellen Hong

A man with a backpack, a net, and a huge smile on his face joined the group and exclaimed how awesome the bee hotel was. Introduced as Liam O’Brien, a conservationist from San Francisco who loves butterflies and works to save them, he was fascinated by the intricacy of the hotel.

Suddenly the topic of conversation switched from bees to butterflies, and O’Brien radiated passion as he talked about how upsetting it is that butterflies are at the very bottom of the food chain, 80% of them eaten by birds. His desire to save these butterflies has manifested in a campaign to ban the commercial sale of butterflies in San Francisco.

“The butterflies that get released at weddings and all sorts of other events…that needs to stop,” he said. Simply put, “We don’t think of butterflies as wildlife because they’re so pretty.”

That gave me something to ponder as the group started dispersing. Soon everyone began their iNaturalist quests, snapping photos of various bees and butterflies in the garden. Rocha, O’Brien, and Eddie Dunbar, founder of the Insect Sciences Museum of California, were the perfect team of experts to lead us in the wildlife hunt. The beautiful gulf fritillary butterflies and the tiny white swallowtail eggs I saw nesting on the underside of the leaves of milkweed plants… all I can say is, nature is incredible.

Pointing to a patch of plantain, considered a weed by most people, Rocha commented that “This is the host plant for the buckeye butterfly. We stopped removing these last year and saw so many more buckeyes!” The moral of the story: leave a patch of weeds in your garden; you never know what kind of critters they may foster!

When asked by a bioblitzer about the crops in the garden and whether caterpillars may be an issue, Rocha proudly explained that all Oakland parks are pesticide-free. And to answer the question: “Caterpillars share the food.” The fine netting surrounding the plants protect them from birds, which do more harm than caterpillars anyways, but the caterpillars are not an extreme problem. Caterpillars found on the plants are taken to the pollinator garden so that they can thrive. “It’s all about sharing the space,” Rocha commented.

The group then moved on to the Mediterranean garden, where there were many more bees to be found. I personally fell in love with the gray digger bee, which some like to call the “teddy bear” of bees because it’s covered in fur. It was adorable!

Gray digger bee. Photo: Ellen Hong

Gray digger bee. Photo: Ellen Hong

Although I wasn’t able to participate in every event at the bioblitz (there were also underwater robots to see what was living on the bottom of Lake Merritt, bird identification, and plant identification), I’m glad I could be a part of such an awesome event that got so many people engaged with the ecology around them. I hope everyone who came out to the blitz enjoyed observing, learning about, and appreciating the beauty that is nature!

Check out all the observations from the Bioblitz here!:


Ellen Hong is a senior in high school and interns for Wild Oakland.

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