a rmisancp and 'rivasivp frpshwatpr alga

DESCRIPTION: DicJymo is a freshwater
diatom (type of alga) that uses stalks to
attach to streambed material. It forms
a thick mat which smothers rocks,
submerged plants and other materials.
As the stalks lengthen, the beige/brown
mats shred into the stream and are
sometimes washed white at the ends,
looking similar to tissue paper. Although
they appear slimy, didymo mats feel like
wet wool.

RISK OF SPREAD: Recreational
equipment, including boats, kayaks,
lifejackets and fishing gear (particularly
waders) is the most likely way for didymo
to spread. Didymo can remain viable
for several days if kept moist, and can
be transferred in microscopic form on
equipment to new waterways. Infection
may only need a single cell. This means
fishermen travelling internationally
contribute to the risk of spread.lt is not possible
to eliminate didymo from a waterway once it. has
become affected. Decontaminating equipment
between use in different freshwater systems
is the key to preventing further spread
and leaving an environment for all to enjoy.

DON'T SPREAD DIDYMO: Where possible,
equipment should be restricted to use in
a single waterway. If this is not feasible, we
suggest the decontamination methods of CHECK,
CLEAN, DRY.

CHECK:

Before leaving a river's edge, look
for clumps of algae and sediment,
and remove them. Leave them at
the site.

CLEAN:

Soak all gear for at least one
minute in a 2% (by volume)
solution of household bleach,
or a 5% (by volume) solution of
dishwashing detergent or salt.
All surfaces must be in contact
with the cleaning solution for
a full minute. Water-absorbent
equipment (lifejackets, waders)
should be soaked thoroughly to
ensure complete contact.

DRY:

If cleaning is not practical, after
the item is dry to the touch, leave
it to dry for at least another 48
hours before using in another
freshwater system.

Fish and Game New Zealand

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PRO^

MORE INFORMATION:
www.epa.gov/region8/water/monitoring/didymosphenia.html
www.fedflyfishers.org/conDidymo.php

THE THREAT: Didymo is an invasive freshwater alga
that can form massive blooms. Didymo can smother
streambeds and adversely affect freshwater fish,
plant andinvertebrate species by depriving them of
habitat, and also impact recreational opportunities.
It is not considered a significant human health risk,
but. in recent years has been spreading to previously
unaffected areas in North America, Europe and
Asia, and has been detected in New Zealand. This
species historically formed blooms in fast-fiowing,
cold, clean waters but now didymo is increasing its
ecological range. Recent research shows that many
countries across the globe provide suitable habitat
for didymo to thrive.

Map of the world showing regions where suitable stream habitats
for didymo are located. Results for Australia are preliminary
(McNyset, US Environmental Protection Agency)


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