The open ocean - A Fascination for Fish: Adventures of an Underwater Pioneer - page 264

dotted Mastigias papua, from the islands of Palau, added a touch of
humor with its clownish activity. Several varieties of these jellies can
be found in Palau, some of which have become trapped in small, land-
locked saltwater lakes known as the “Jellyfish Lakes.”
All in all we had twelve di¤erent species of jellies, ranging in size
from the large and beautiful, golden-colored sea nettle to a little fresh-
water jelly that we collected from a vineyard irrigation pond in Napa
Valley. All did quite well, though we had problems at first with the
Palau jellies, which didn't seem to be growing as they should. We were
fortunate to be visited early on by Kazuko Shimura, the jelly expert
from Enoshima Aquarium. She had worked with more species of jel-
lies than anyone in the world, and, despite the language barrier, she
managed to point out that we needed more light for the Palau jellies
to photosynthesize. Taking her advice we doubled their light, and their
growth took o¤.
Partway through the show an aquarium member brought us a jar
containing a small medusa that, she said, had appeared that summer
in large numbers in the Petaluma River above San Francisco. My daugh-
ters and I used to water-ski in that river when we lived in Marin County,
so, being a believer in having fun at work, I hitched up my ski boat
(and the skis!), and Freya, her friend Peter Ferrante, and I took o¤ for
Petaluma to find the mystery jellies, and maybe get a little skiing in as
long as we were there.
We found the little walnut-sized jellies in the boat-turning basin right
in downtown Petaluma. It turned out that they are a brackish-water
species from the Sea of Azov in Russia, probably transported here in the
ballast tanks of a ship. Their introduction to the region, unfortunately,
may have serious impacts on local marine life—especially the tiny fry
of the striped bass population of the brackish San Francisco Bay and
Sacramento Delta—because of their e¤ective feeding strategy. Rhyth-
mically pulsing their bell, these jellies swim to the surface, stop, and
then spread their tentacles out like a net and drift slowly down to the
bottom. Any little creature in the way of this stinging net is captured.
Of course, there's no way to get rid of the jellies now, even if they
do start decimating fish. Once introduced into California waters, they're
here to stay, like several other alien creatures that have shown up in