PESTICIDES IN SHRIMP HATCHERY WATER SUPPLY
From: Todd Blacher <todd_blacher@yahoo.com>
To: shrimp@yahoogroups.com
Date: 25 Oct 2002
Our hatchery is located in an area that also has
heavy agricultural
production, and of course heavy pesticide use. Where can I find information
regarding toxicity levels of commonly used pesticides in agriculture for
shrimp larvae production?
Todd Blacher
e-mail:
todd_blacher@yahoo.com
***************
COMMENTS 1:
If you are suspicious of your water quality, you
should have the
algae analyzed for the problem material. Or vice versa you could analyse the
water before and after algae culture. You may wish to bioassay your system
with good quality artificial seawater against the water you are using.
Algae is a very good bioaccumulator of all types of pollutants from heavy
metals to hydrocarbons. Algae is particularly useful for detecting
levels of pollutants which may escape limits of detection of certain
analytical methods or not be present all the time in the culture water.
I once had to deal with an aquaculture site which had
pesticide problems and we were unable to control the problem economically
with activated carbon or absorption resins. We resorted to large raceways
with Nanochloropsis sp. and Dunaliella sp. to filter the incoming water. We
then diatom filtered prior to UV treatment this water for use in the
hatchery and the problem ended.
Phil Boeing
e-mail:
pboeing@dc.rr.com
***************
COMMENTS
2 :
I can tell you from experience that several
insecticides (cypermethrin,
methylparathion and endosulfan being three I have tested) are acutely toxic
to postlarvae at levels that can't be detected using normal detection
methods. If you figure that sub-lethal effects may be felt at levels around
100x below that, it is possible that pesticides may be having some impact on
the larvae culture.
There is a lot of information on pesticides in the EcoTox database
(http://www.epa.gov/ecotox/) for
various species of fish, molluscs and crustaceans.
Dan Fegan
e-mail:
fegan@loxinfo.co.th
***************
COMMENTS
3 :
Don't know about larvae, but you may contact Dr.
Miguel Bettancourt (mbl@victoria.ciad.mx)
from CIAD, Mexico. He did his PhD on pesticide toxicity on juvenile vannamei
and found interesting results, especially on sub-lethal effects of low
pesticide concentrations. Basically, the shrimp start to show moult delay
and a sharp increase in integument malformations. Maybe he knows of
published reports or will be able to inform you of potential effects on
larvae. Do you know which pesticides farmers use around your hatchery?
e-mail:
nunosimoes@prodigy.net.mx