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Sand Scholars

Pomona students pursue serious science in the surf, studying whether people playing at the beach harm the eggs of grunion.

Grunion are part of California beach lore, carrying on their famously floppy spawning ritual on summer nights when the tide is right. But trouble may arrive with daylight, as countless humans play and sunbathe on the same shores where these mysterious fish leave their eggs.

This summer, Pomona College students guided by Assistant Professor of Biology Nina Karnovsky are studying just how much impact all that human activity has on the grunion eggs that hatch under the sand. The student researchers trek to Laguna Beach several times a week, and if that sounds cushy – maybe even a little fishy – rest assured that they’re hard at work gathering data, followed by long hours in the lab. This is the first research of its kind involving grunion, and the results may shed light on the future of these unique fish found only along the coasts of California and Mexico. The project was recently featured in the Los Angeles Times.

“People say ‘hey, you’re hanging around the beach all day, that’s pretty nice.’ But we do a bit of work there,” says Max Kowal ’08, a biology major from Massachusetts. “It’s a lot of work.”

Using GPS, students have mapped out five sizeable sections of Laguna Beach that attract differing levels of human activity. Caitlin Guthrie ’08, an environmental analysis major from Washington State, focuses on observing and recording the level of activity in each of those areas.

Casey Williams ’08, a biology major from San Diego, collects eggs from the designated areas and raises them in the lab, searching for a correlation – or lack thereof – between the number of eggs hatched and the level of human activity in the area the eggs came from. He takes samples from the beach immediately after a grunion run, several days later and immediately after they hatch.

As a control, Kowal raises eggs in the lab, and places equal numbers in wide containers of sand. Some he walks on for part of the day. Others remain untouched so he can evaluate the impact of human activity on the survival rate of the eggs.

Grunion season is from March to August, and during that time the “runs” – when the fish spawn on the beach – go on for several nights after each high tide that comes with the full or new moon. Though the fish’s precise arrival times can be unpredictable, the patient grunion watcher is rewarded with the strange silvery scene of thousands of fish covering the beach. Females plant their tails into the sand and deposit their eggs. Males wrap around the females and fertilize the eggs. The fish then flop their way back into the ocean.

The eggs, meanwhile, incubate in the sand until the next high tide, when the waves wash over them. The combination of wetness and agitation leads the eggs to hatch, and the young ride the waves out to sea.

The idea for the Pomona College summer research project hatched last year, when Karnovsky oversaw a biology major Christine Cass ’05 as she looked into what factors lead grunion to choose certain areas to spawn – it turned out there were many. During that research, Karnovsky started to notice the human impact on the grunion. Commercial fishing of grunion is forbidden, but during parts of the grunion season beachgoers are free to catch the fish by hand. On some runs, Karnovsky said, it looked as though not a single fish made it back to the ocean.

Previous research, conducted by Pepperdine University, has focused on how grunion eggs are affected by beach grooming, where debris is removed by machinery. This Pomona project is the first to look at how ordinary human beach activity – walking, playing Frisbee, sand-castle-building – affects the grunion eggs. (Laguna Beach, now known nationwide because of the MTV reality show of the same name, is one of the most popular beaches in coastal Orange County.)

“I’ve always loved grunion,’’ says Karnovsky, who fondly recalls going out on grunion runs while pursuing her doctoral degree at nearby UC Irvine. “I’ve always been fascinated by them. This was a great opportunity to solve some of the unsolved mysteries about these wonderful fish.”

Two more Pomona students are delving into other questions about grunion. Zachary Brown ‘07, a chemistry major from Alaska, is researching just where the grunion go after a run – nobody seems to know. “All we have about where they go is really anecdotal,” says Karnovsky, noting that those anecdotes have the fish staying close to shore.

Brown’s research entails removing tiny earbones, known as otoliths, from grunion. When that chore is done, he will return to his home state this summer to work in an advanced instrumentation lab at the University of Alaska, Fairbanks. There he’ll be conducting elemental analysis of the rings of growth (sort of like those on the tree) in the ear bone. Fish incorporate the chemistry of the body of water they’re in into their otolith, and chemical analysis can determine the fish’s movements from one body of water to another, say, from an estuary to the sea.

Sonia Fang ’08, a biology major from the nearby city of San Marino, also is studying otoliths to determine which grunion show up on the peak nights of spawning: the older, more experienced ones or the younger ones? She’ll be bringing the ear bones to the Alaskan Fishery Science Center in Seattle to learn how to do this.

Students wrote funding proposals for their research, with help from Karnosky, and they will write papers presenting their results. She also plans to have the students present their research at a scientific conference and hopes to get their results published in a scientific journal. The idea, Karnovsky says, is to expose the students to all aspects of scientific research, from fieldwork to lab work to publication. That’s not unusual at Pomona. As a small liberal arts college, Pomona is able to offer undergraduate students the sort of research opportunities and close interactions with faculty that are often reserved for graduate students at larger institutions.

And if the work of science can sometimes be tedious -- even when conducted at the beach – the students were rewarded several times with the awe-inspiring sight of grunion spawning. “Oh, man, when it really starts and the run gets going, it’s amazing to see,” says Brown. “The whole beach can be covered with silver (fish) just flopping around.”