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July/August 2006
Sand Scholars
Pomona students pursue serious science in the surf, studying whether
people playing at the beach harm the eggs of grunion.
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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.
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Grunion wriggle on Laguna Beach as part of their
famous spawning ritual. |
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“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.
Biology Professor Nina Karnovsky's summer
research students at work in the lab. |
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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.
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Back at Pomona, students raise grunion eggs in these
containers as part of a control for the research. |
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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.”
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