NUTRIENTS - Marine Pollution: What Everyone Needs to Know - page 34

using chloroplasts that they retain from algae that they ate
previously.
Pfiesteria was a major problem in water with high nutrient
levels from sewage and agricultural runoff. It made headlines
and caused considerable concern and controversy in the scien-
tific community for many years. Part of the controversy was
due to an inability to isolate a toxin from the cells. The toxin
was finally identified chemically, and was found to be a very
unstable chemical that disappears from the water quickly,
which accounts for the difficulty in finding it. Pfiesteria toxicity
varies from nontoxic to highly toxic. Toxic strains are capable
of killing fish by both toxins and physical attack from feeding
upon the skin. Some strains do not produce enough toxin to
kill fish, but can kill fish larvae by physical attack. From 1991
to 1998 Pfiesteria was linked to major kills of juvenile Atlantic
menhaden ( Brevoortia tyrannus ) in the two largest estuaries on
the US mainland, but for some reason, it hasn't been heard
from lately.
In the 1980s a brown tide of tiny organisms, Aureococcus
anophagefferens , in eastern Long Island had severe impacts on
eel grass populations and the once-thriving Peconic Estuary
bay scallop industry, estimated at one time to be worth $2 mil-
lion. This population has not recovered after many years dur-
ing which there have been only occasional reoccurrences of
moderate brown tides.
How widespread is their occurrence?
HABs have been known throughout history and their inci-
dence appears to be increasing, but there is also greater aware-
ness and research into the problem. The varieties of toxic algae
include many species, and HABs have been appearing more
frequently around the world. This increase includes more fre-
quent blooms of familiar species as well as blooms of new spe-
cies not previously known to be harmful or not known at all.
Over the past two decades many more toxic species have been