Wamberal Lagoon Catchment Aquatic Survey Final Report (PDF ...

5.6. Vegetation
Generally the catchment of Wamberal Lagoon was in a relatively healthy state without
any large aquatic weed outbreaks. The roadside drains and tributary creeks are dominated
by native Bulrush/Cumbungi (Typha spp.) with some small soft reeds, grasses and
Nasturtium (Tropaeolum majus).
The main stream Forresters Creek, south of the entrance road is within the Wamberal
Lagoon Nature Reserve and the foreshores are dominated by Swamp Oak (Casuarina
glauca) and Paperbarks (Melaleuca linariifolia and M. styphelioides).
The catchment south of the Entrance road is further divided by Crystal Street with
Residential land to the south and parkland (Archibold Park) and undeveloped land to the
north. This undeveloped land is a swampy area comprising thick Paperbark forests with
an understorey of saw grass and sedges Gahnia spp. This area represents a significant
environmental area with Gramastacus burrows indicated in a 1.5 ha area adjacent to
Archibold Park.
The northern section of Wamberal catchment north of the entrance road consist of a
low lying flat wetland area, dominated by sections of paperbark forest, reeds, tall saw
sedges and long grasses. This area has numerous small drainage lines, ponds and
depressions that pond and pool water, creating numerous ephemeral habitats. This
section also has a small area approximately 1 ha in size comprising mostly common rush
(Juncus sp) and surrounded by a mixture of various melaleucas that contains a population
of Gramastacus crayfish.
Feeding into this northern catchment area are a number of small creeks and drains
mostly in residential areas that feed into the central wetland zone. Most of these
smaller creeks and drains have Cumbungi growing in the shallow stream beds. This
native species is beneficial in that it will slow flow rates, filter the water, trap nutrients,
create habitat and its root system will hold the stream bed together limiting erosion if
flash flood flows.
At the end of Carbeen Road, was an outbreak of duckweed with scattered azolla thrown
in, this was the only sign of duckweed in this catchment. Beside Carbeen Road on the
northern side is a concrete drain that basically runs the full length of the road discharging
water at the end of the road where the duckweed outbreak occurred. We commonly see
this type of weed outbreak under these conditions; concrete drains tend to channel
nutrients directly to the end of the drain without any filtering or nutrient absorption
occurring along the way generating nutrient rich water at the end of the drain conducive
to duckweed and azolla proliferation.
No noxious or nasty aquatic weeds were identified from this catchment. Milfoil, Canadian
pondweed, Salvinia, Alligator Weed & Water Hyacinth, etc., were all absent which was
another exceptionally good news story.
Wamberal Lagoon Catchment Report Australian Aquatic Biological P/L 28