Initial Response to the George River Water Quality Panel

Initial Response to the George River Water Quality Panel
Dr Marcus Scammell & Dr Alison Bleaney, 1 July, 2010
The Panel has come to the conclusion that the toxin or toxins present in the
George River are within acceptable limits, and therefore pose no threat to the
ecosystem or the community.
This is despite recognition that there have been oyster mortality events and
apparent other anomalies within the catchment. It was these mortality events
and anomalous ill-thrift that led to our investigations.
Our study consisted of four parts:
1) Is there a toxin of concern in the George River that can enter the oyster
growing areas?
This was addressed in the study by grab samples that found the river
water and natural occurring foam returned toxic results in ordinary
The Panel appears to have disregarded this data on the basis that, in their
opinion, inappropriate test organisms were used (ie. oyster larvae, sea
urchins and daphnia). The choice of organisms will be discussed in detail
later, but, oysters were specifically chosen because we were investigating
oyster deaths following rainfall.
2) What is the cause of the toxicity observed following part 1?
No toxic man-made chemicals were chemically identified in part 1 of the
study so a concentrating technique was employed: the skimmer box.
Despite the concentrating technique, no man-made chemicals were
detected over the following year of investigation. Ultimately a chemical
signature from E.nitens leaf was finally matched with a chemical signature
from the toxic water.
The Panel accepts this finding but disputes its relevance to undiluted water
samples. The Panel says that the skimmer box concentrates toxicity by
1400 times (although they have no measurements to prove this) and says
that there are multiple stressors in the bay with no new supporting
3) The National Institute of Water and Atmospheric Research (NIWA) in
New Zealand was asked to repeat the study to determine if our
conclusions were correct.
The Panel has been sent NIWA’s public presentations by the author but
does not appear to have take them into account.
4) NIWA was asked to determine the environmental relevance of the
toxin, ie. calibrate the toxin and determine if it is likely to cause the
oyster deaths that have been repeatedly observed.
NIWA concluded that if the particulate matter in the water column
increases by a factor of 3-5 times above the river’s particulate
concentration during dry weather flow then exposed oysters would be at
risk of toxicity. Turbidity data for the river demonstrates that particulate
matter is well above a factor of 5 following rainfall. Oyster deaths are
observed following rainfall. NIWA concludes that this is a very likely
scenario resulting in the observed oyster deaths.
The Panel has rejected NIWA’s conclusions but has not clearly indicated why,
in discussions to date.
The Panel also rejects Dr. Fiona Young’s tests of undiluted river water on
human cell lines.
A detailed examination of the Panel’s conclusions, and the discrepancies with
our results, will take some time but will be forthcoming.