In September 1962, 14-year-old Jim Carlton wandered away from a family picnic in Lakeside Park at Lake Merritt and hopped down the embankment at Adams Point, where he landed squarely on a weird, small reef. Curious, he picked up one of the rock-like things and took it home.
“My mother,” he says, “relegated it — and me — to the basement.”
His interest piqued, a week later Carlton returned to the lake and, in the Rotary Club Nature Center, found a glass display case exhibiting the thing he’d found: a tube worm. The display had the species name, and a placard that said the tube worm hailed originally from the South Seas. Somehow, this weird rock-like thing turned out to be the evidence of an animal that had made its way across thousands of miles of ocean, through the Bay, through Lake Merritt, and up onto the sandy shore of Adams Point.
“I thought that was the coolest thing,” Carlton said.
The teenager went on to pore over natural history books and scientific literature. He started walking the shoreline constantly to see what else he could find. A few years later he headed off to UC Berkeley, then to UC Davis for a PhD, and into a long and successful career in marine biology studying invasive species and extinction.
The wild side of Lake Merritt inspired Carlton’s career. This Sunday, Feb. 23, is a chance for everyone else to join in on the fun. Nerds for Nature, iNaturalist, Wild Oakland, the California Academy of Sciences and The Oakland Museum of California are leading a bioblitz to see how many Lake Merritt species can be tallied in a single day in America’s oldest wildlife refuge; as maybe the world’s foremost expert on Lake Merritt’s marine life, Carlton will be online from the East Coast to provide advice, identifications, corrections, and context.
The critter-counting starts at 9 a.m. at the Rotary Club Nature Center on Bellevue Avenue, but the events go all day and feature a plant walk, bird spotting, mud sampling, and species bingo. The San Francisco Microscopical Society is lending a microscope station for help with the numerous small creatures that live in the lake. OpenROV, a Bay Area-based DIY robotics team, is lending its underwater robot to take video under the lake.
And make no mistake: Lake Merritt may be at the center of a large and busy urban area, but it’s teeming with life.
Carlton returned Monday to preview the bioblitz and demonstrate just how much strangeness there is hiding in plain sight. Lying on his stomach and peering into the water near the bird refuge islands, he scraped barnacles, clams and mussels off the wall. Among the rocks in the shallow water near Adams Point he found handfuls of tiny, hopping invertebrates, as well as several small snails. In a handful swiped from the underside of the sailboat dock he found tunicates, sea squirts, and some shrimp. Each time he peered into the water or mud again, Carlton found something to be excited about. His list at the end of the morning had 29 species from 13 different families.
“Cool!” he said at one point, while examining the eggs of an Atlantic oyster drill. “You guys are going to have a good haul.”
The story of Lake Merritt’s life mirrors in some ways the story of the Bay Area: Most of the creatures living in the lake are non-natives, immigrants from the far-flung reaches of the globe who have found the Bay Area to their liking.
Carlton called it an “accidental zoo,” a showcase of the world’s diversity. (In a 1998 paper in Science he and co-author Andrew Cohen of the Center for Research on Aquatic Bioinvasions labeled the San Francisco Bay possibly the most invaded estuary in the world; Carlton says Pearl Harbor now competes for the title.) Lake Merritt, as a lake connected to the estuary, shares that fate.
“One of the big stories of the lake,” Carlton said, “is that it’s so invaded.”
Species arrived packed in with oysters in the late 1800s, on the fouled hulls of wooden sailing ships, and in cargo ship ballast water. Some, like shipworms, arrived in the wood of wooden sailing ships. Many of them are still hanging out today. Peering over the edge of the lake wall, Carlton called out places of origin: the mid-Atlantic, the Indo-Pacific, the Mediterranean. “And that’s just the stuff we see here,” he said.
Exotic species are frustrating. We’ll never quite know Lake Merritt or its ecology the way it was. But adding up the life that’s present, naming the thing in front of you, still makes an inspiring day outdoors. There’s change to be documented, particular species rising and falling, each individual observation the first step in creating a bigger picture of the lake itself. Carlton returns to the edge of Lake Merritt every few years, and always takes a walk to see what’s different, because there’s always something to see.
Monday, as he greeted his old friend the lake again, Carlton wandered off on his own, scrambling down banks and across the riprap shoreline, leaving the group behind just as he’s done since he was 14 years old, saying out loud to no one in particular, “Cool!”
The free Lake Merritt Bioblitz takes place this Sunday from 9 a.m. to 5 p.m. All events start at the Rotary Club Nature Center at 600 Bellevue Avenue; for further directions, information and details, or to RSVP, see iNaturalist’s project page.