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ConTRIBuTIonS To AgRICulTuRAl SECToRS
NOvEMBER 2013 PARTNERS
bArrAmundi with A side
serve of lotus flower
by dr GIo brAIdottI
native water plants such as the lotus,
Nelumbo nucifera, are proving proficient at
remediating waste aquaculture water for
recycling back into ponds, including Queensland’s
inland barramundi ponds, which constitute the
state’s largest inland aquaculture industry.
The bioremediation potential of plants
native to Australia and Papua New Guinea
(PNG) was described in an ACIAR project and
addressed an issue identified by the Australian
Barramundi Farmers Association as a major
priority area in need of innovation.
The beauty of the ACIAR solution is that the
plants themselves possess commercial value.
The lotus, for instance, has nutritional, medicinal
and ornamental value. Thus new horticulture
industries can be developed as a by-product of
sustainably recycling aquaculture pond water.
This work was a continuation of the
ACIAR-funded scoping study ‘Development
of capacity for aquaculture of indigenous fish
species in Papua New Guinea’, which sought
to assist inland aquaculture development in
PNG and Australia in an environmentally and
culturally sensitive way. This included targeting
herbivorous native fish species for aquaculture
to avoid the need for expensive feeds.
However, water availability and the quality
of the discharge water proved a limiting factor
to aquaculture development. Barramundi
were then used as the culture species in
trials of bioremediation using aquatic plants
undertaken by the Queensland Department of
Agriculture, Fisheries and Forestry (QDAFF), led
by Dr Evizel Seymour.
The aquatic plants tested are common to
both PNG and Australia—duckweed (Spirodela
punctata and Wolffia angusta) and lotus (N.
nucifera). Water savings were achieved with both.
While duckweed produced water savings
of 22%, lotus proved much more effective,
producing astonishing savings of 62%. The
plants were also proficient at removing waste
nutrients, including 45% of ammonia nitrogen,
35% of total nitrogen, 19% of total phosphate
and 32% of all suspended solids.
Importantly, fish growth rates were not
affected by water re-use.
“Reducing environmental impacts
and increasing ecological sustainability
are important elements of aquaculture in
Queensland,” Dr Seymour says.
“ Water re-use and water discharge quality to
the natural environment are factors currently
concerning the aquaculture industry, especially
inland barramundi farming.”
The Great Barrier Reef Marine Park Authority
is increasingly scrutinising farming practices
as part of efforts to protect the quality of
river water that flows onto the reef from land-
Environmental requirements in Queensland
are becoming more stringent and farmers are
required to move towards zero discharge to
the environment under both state and federal
policy and legislation.
For the trials, native lotus seed was sourced
from Ross River in Townsville, Queensland, and
duckweed from a barramundi farmer’s ponds.
Both have potential for commercialisation. For
example, uses for duckweed as an animal feed
are well documented.
Bio-Tech Waste Management Pty Ltd (1998)
trialled duckweed as a feed for chickens, ducks,
sheep, fish and abalone. Additionally, numerous
studies promote duckweed as a low-cost feed for
tilapia, but none have actually compared the costs
of duckweed production to other feed sources.
In developing countries where feed
ingredients may be unobtainable and labour
is the only commodity, duckweed may be a
viable feed source to provide protein. This may
be relevant to highland Papua New Guinea,
where protein supplies are short.
The lotus has been consumed in its various
processed forms throughout Asia and quality
product from Australia was expected to capture
the interest of Asian markets. All parts of the
lotus are used in Asian medicine; the leaves and
flowers contain various aromatic substances
and the rhizomes and seeds are high in calcium
and kalium (potassium).
“ The leaves, flowers, seeds and the parts of
the root system known as rhizomes can be used
in food and medicine and, of course, lotus is a
popular ornamental plant,” Dr Seymour says. n
ACIAR project: FIS/2004/065
ACIAR contributions cut across all sectors,
from fisheries on the high seas to aquaculture,
cropping, livestock and forestry.
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