Nicole Kirchhoff
Indoor Urchins
It's morning in
Franklin, Maine, and the young ones are already out for a swim. The
temperature is perfect; the water is clear, and just down the hall,
refreshments are already percolating away. This is the life — especially
if you're a green sea urchin.
Tucked away in a
quiet, temperature-controlled room at the University of Maine's Center
for Cooperative Aquaculture Research (CCAR) in Franklin, dozens of
bristly, thumbnail-size urchins vie for position on the walls of
specialized tanks, waiting to be released among the rocky crags and
crevasses of the Atlantic. Unlike their wild counterparts, the verdant
invertebrates lead a life of leisure, their every need addressed by
UMaine graduate student Nicole Kirchhoff.
Coddling baby urchins
is part of Kirchhoff's multifaceted investigation into green urchin
aquaculture. Working with CCAR Manager Nick Brown, she hopes to develop
efficient and reliable techniques for raising juvenile urchins.
Hatchery-raised urchins could one day be used to reseed the Maine coast,
where overharvesting in the late '80s and early '90s led to the collapse
of the urchin fishery.
"No one had ever done
this type of research before," says Kirchhoff as she harvested eggs from
one of the large urchins serving as brood stock for the program. "We
have looked at everything: brood stock management, how to grow juveniles
economically. There is still a lot we don't know."
The first stage of
Kirchhoff's work focused on urchins' reproductive biology. By
manipulating the length of day and the temperature in the lab, she was
able to change urchins' seasonal spawning cycle, causing them to produce
viable eggs and sperm year-round. Lab tests are under way to determine
if the eggs and sperm produced out of season are fully developed.
Since each female
urchin is capable of releasing as many as 3 million eggs per spawning,
the few hundred or so hefty adults that make up the program's parent
stock provide more than enough offspring to keep the trash can-size
rearing tanks full of planktonic urchin larvae. By precisely controlling
environmental factors and diet, Kirchhoff has been able to raise young
urchins no larger than the period at the end of this sentence to a
respectable 10 millimeters or larger — a critical size in the life of a
young urchin.
"Once they get past 15
millimeters or so, they become much less susceptible to predators," says
Kirchhoff. "At that size, they could be used to restock areas where the
urchin population is low."
Another part of
Kirchhoff's master's work looked at urchins' rate of growth under varied
environmental conditions. Captured and caged in mesh tubes beneath the
waves of Penobscot Bay, a population of more than 5,000 fingernail-size
urchins was carefully measured and monitored for six months. Data
collected on the juveniles will help to determine optimal bottom type,
currents, temperatures and other factors that could influence the
success of green urchin aquaculture and reseeding programs.
Kirchhoff is now
applying what she learned from her initial research to develop a better
understanding of urchins' breeding biology and to determine the optimal
conditions for successful rearing of juveniles. With every discovery,
new questions arise that offer new opportunities for research.
"The interest in green
sea urchin aquaculture is definitely growing," says Brown. "Nicole's
research has been very successful. We basically started with nothing and
now we're at the forefront of research in the U.S."
Back to Student Focus
