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FISH AND WILDLIFE RESEARCH INSTITUTE
genomes in marine sediments or bottom
waters as round, featureless cells, which
lie dormant until favorable conditions
trigger the transition back to a plank-
tonic and highly reproductive stage of
the lifecycle. The regular seasonality of
Florida red tide blooms supports the
existence of this type of strategy for K.
brevis, with dormant “seeds” riding out
the unfavorable conditions of the spring
and early summer months, reawakening
closer to fall, and transforming into so-
called vegetative cells that multiply rap-
idly to cause the sometimes-catastrophic
blooms. “Whether the cysts are in the
sediments or in the water column, I do
think it’s reasonable to suspect that there
is a resting stage of some kind,” says Cary
Lopez, a phytoplankton ecologist at
FWRI. It’s also possible, however, that
the species goes directly from reproduc-
ing more slowly during a period of sexual
reproduction to more rapidly reproduc-
ing during asexual stages, without first
transitioning into a cyst.
Determining whether the species
has a resting stage could be a boon to
managers seeking to predict and con-
trol red tide events as blooms in the
Gulf begin to form, just as knowledge
of resting cysts in other harmful algal
species helps scientists manage blooms
elsewhere. For example, researchers
studying Alexandrium fundyense, a
dinoflagellate whose blooms cause reg-
ular, toxic red tides that compromise
ecological and human health along the
northeastern coast of the US into Can-
ada, have mapped out two distinct cyst
beds—accumulations of resting-stage
cells deposited by prior blooms. The
research team that described these hide-
outs also noted that the size and distri-
bution of those cyst repositories cor-
related with the extent of blooms thatfollowed.^3 Finding similar cyst depos-
its in K. brevis would confirm that this
part of the lifecycle exists, and would
allow researchers to monitor dormant
populations for signs of an impending
bloom in the Gulf.
The opportunity to collect and
study K. brevis cysts in the lab, or to
generate them from an earlier life
stage, could also help determine what
precipitates the change from one life
stage to another. “If we could identify
this resting stage and then understand
what drives the transition from a rest-
ing cyst to a vegetative cell, that would
be very important,” says Lopez. She
adds, however, that funding is oftenfunneled to more-pressing mitigation
and monitoring research, so research-
ers aren’t scouring the Gulf for K. bre-
vis cyst beds. Hubbard adds that while
she and her team do keep an eye out
for cysts when sifting through sediment
samples, they are predominately rely-
ing on oceanographic measures, such
as water temperature and the speed
and direction of relevant currents,
along with cell counts of K. brevis, to
generate red tide forecasts.
“Right now, we’re using physical
data to be able to predict what’s going
to happen with blooms,” Hubbard says.
“Not knowing whether there is some
similar accumulation of Karenia cells
and where that might be makes it really
challenging to be able to predict exactly
when and where blooms might start.”READY TO BLOOM: K. brevis cells in the veg-
etative stage of their lifecycle are primed to
undergo mitosis, increasing population numbers
quickly and potentially leading to a red tide.Blooms are patchy. Conditions can change
day to day and beach to beach.
—Barbara Kirkpatrick,
Gulf of Mexico Coastal Ocean Observing System