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The Australian and New Zealand Guidelines for Fresh and Marine
Water Quality emphasise the importance of using regionally-relevant
species in ecotoxicity test programmes. For marine waters in tropical
regions, however, there is currently a lack of ecotoxicity tests
available to meet the guideline requirements of at least five species
from four taxonomic groups.
With this in mind, ESA has initiated a test development programme aimed
at developing ecotoxicity tests specifically for tropical marine waters of
Australia. As part of this program, ESA has developed a sub-lethal toxicity
test using the milky oyster, Saccostrea echinata.
Milky oysters, also commonly called black-lip oysters, inhabit sheltered
oceanic tropical waters across northern Australia, the Philippines and the
western Pacific islands. They have an oval shell and grow up to 12
centimetres in length. While edible, they are not as in demand as other
oyster species and commercial production has so far been minimal for this
species.
The test, developed by Dr Rick Krassoi, examines the effect of a test
material on the larval development of S. echinata from zygote to D-veliger
stage, reached 48 hours after fertilisation. The test follows the standard
ASTM protocol developed for North American bivalve species.
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Milky Oyster - D-veliger larvae at 48-hours
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Milky Oyster, common on tropical rocky shores
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ESA has achieved NATA accreditation for the milky oyster larval development
test. This adds to our existing accredited tropical marine tests, the microalgal
(Nitzschia closterium and Isochrysis galbana) growth inhibition test, the tiger
prawn (Penaeus monodon) acute toxicity test, and the barramundi (Lates calcarifer)
acute imbalance test.
We are also investigating a number of other tropical marine species for inclusion
into our toxicity testing programme. These include species of echinoderm, crustacean
and fish. If these species prove successful, we envisage being able to offer a full
suite of tropical marine ecotoxicity tests to satisfy the ANZECC/ARMCANZ guideline
requirements in the very near future.
In addition to tropical marine tests, ESA also offers a number of tropical
freshwater tests, including a duckweed (Lemna aequinoctialis) growth inhibition
test and a green hydra (Hydra viridissima) population growth test. These tests
were originally developed by the Environmental Research Institute of the
Supervising Scientist (ERISS). We also offer acute fish imbalance tests with
rainbowfish (Melanotaenia splendida splendida) and barramundi.
Please contact Dr Rick Krassoi, info@ecotox.com.au or telephone +61 2 94209481,
for further information on the milky oyster larval development test or any of
our other tropical ecotoxicity tests.
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ESA
10 Years |
This Year Ecotox Services Australasia (ESA) celebrated its 10th Anniversary. The company was founded in 2001 in a small lab in Alexandria. During the past decade ESA has grown and in 2004 moved into larger premises in Lane Cove to accommodate the increased culturing and testing facilities now offered by the lab.
In recent years ESA has achieved GLP Recognition in addition to its NATA accreditation and has developed many new test protocols for Ecotoxicity Testing.
The company hopes to continue to grow, with a sustained focus on research and development, to be able to offer clients
testing options for all the ecosystem types found in the Australasian
region and meet any regulatory / licensing requirements.
The Management and staff of ESA would like to wish you a Merry Christmas &
a Happy New Year and look forward to a promising and prosperous 2012. Our Laboratory will be operating on a reduced roster between 23rd December and 3rd January, but look forward to assisting you with any enquiries or scheduling of tests after that period. |
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SPOTLIGHT ON.... |
Duckweed (Lemna spp.)
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 Duckweed is a
small aquatic macrophyte occurring in quiescent freshwaters in both
tropical and temperate regions. Duckweed typically consists in 2 to 5
leaves, named fronds, and 1 to 2 roots. The fronds, where maximal water
and nutrient adsorption takes place, have developed air pockets, named
aerenchyma, that provide the plant with buoyancy. The root mainly
provides the plant with stability and facilitates its dispersion due to
its sticky characteristic.
Duckweeds reproduce asexually, by the
budding of daughter fronds that detach from the mother frond when they
have reached maturity. Duckweeds are also capable of reproducing
asexually: they are actually the smallest flowering plant, eventually
producing the smallest fruit of about 1mm!
Duckweeds are widely used for
ecotoxicity testing. In addition to being an ecologically important
group, duckweeds are a sensitive and useful test organisms for testing
turbid and coloured water. This gives the duckweed an advantage over
algal toxicity tests which may require filtering, compromising sample
integrity.
ESA currently offers testing with several species of
duckweed: Lemna disperma commonly found in the temperate regions of
Australia and Lemna aequinoctialis from tropical Australia. Lemna minor
is also used by ESA: This species is not endemic to Australia and has to
be kept in our Quarantine Approved Premises (QAP) with a Class 5
facility with Quarantine Containment (QC) Level 2.
The chronic toxicity test offered by ESA consists of exposing duckweeds to
effluents, receiving waters or chemicals for 4 to 7 days. The test uses a
decrease in frond numbers relative to the control as an indication of
toxicity. A decrease in duckweed mass can also be used as a secondary
endpoint.
The duckweeds are cultured In House, testing can therefore be conducted
year-round and is one of the many NATA-endorsed tests that ESA offers.
The test is commonly used in a suite of 5 or more tests as generally
required by the ANZECC water quality guidelines.
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