 |
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.
|
|
Grunion wriggle on Laguna Beach as part of their
famous spawning ritual. |
|
|
|
|
“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.
Biology Professor Nina Karnovsky's summer
research students at work in the lab. |
|
|
|
|
|
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.”
|
|
Back at Pomona, students raise grunion eggs in these
containers as part of a control for the research. |
|
|
|
|
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.”
|
