-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
273
MA18 – Gawler River
Intertidal seagrass habitat at St Kilda during low tide. Photo:
S. Bryars, 28 October 2012.
Cell detail
Cell MA18 is 164 km2 in area and extends about 15 km alongshore
from the southern side of the St
Kilda boat channel to Port Gawler Beach and about 12 km
offshore.
Benthic habitats
Cell MA18 is dominated by a mosaic of seagrass types from the
intertidal to offshore, with
substantial areas of bare sand inshore and midshore (Figure
MA18.1, Table MA18.1).
Seagrass
The spatially dominant seagrasses are Posidonia angustifolia, P.
australis, P. sinuosa, Amphibolis
antarctica, Zostera and Heterozostera (Cheshire et al. 2002,
Bryars et al. 2006, DEH 2008, Bryars and
Rowling 2009). The current spatial pattern of subtidal seagrass
species distribution (Posidonia and
Amphibolis) reflects the historical spatial pattern of nutrient
discharges, with selective loss of
Amphibolis (Bryars and Rowling 2009). Large amounts of seagrass
have disappeared from the
inshore zone and fragmentation of other meadows has also
occurred.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
274
Figure MA18.1. Benthic habitats of Cell MA18. Note that mangrove
and saltmarsh habitats are not
shown on the map.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
275
Reef
None mapped.
Sand
Bare sand occurs mainly at Section Bank, as well as inshore
adjacent to the Bolivar WWTP outfall and
midshore north of the Outer Harbor shipping channel where
seagrass losses have occurred (Cheshire
et al. 2002, Shepherd et al. 1989). Dittmann (2008) described
the sediments at Section Bank as fine
to medium sand.
The amount of bare sand has increased substantially in many
parts of the cell due to the historical
loss of seagrass, especially adjacent to the Bolivar WWTP
outfall (Shepherd et al. 1989).
Estuaries
Gawler River is a recognised estuary (DEH 2007).
Table MA18.1. Summary of benthic habitats mapped within Cell
MA18.
(Data were extracted from a benthic habitat GIS layer supplied
by the Department of Environment,
Water and Natural Resources)
Habitat group Habitat type Area (km2) % total cell area
Sand
Sand, Bare, Continuous 17.7 10.8
(Sand Total) (17.7) (10.8)
Seagrass
Seagrass, Continuous, Dense 31.7 19.3
Seagrass, Continuous, Medium 38.5 23.4
Seagrass, Continuous, Sparse 1.9 1.2
Seagrass, Patchy, Dense 8.8 5.4
Seagrass, Patchy, Medium 17.6 10.7
Seagrass, Patchy, Sparse 47.9 29.2
(Seagrass Total) (146.5) (89.2)
Total 164.2 100
Cell values
The cell is utilised for recreational/commercial fishing and
boating. The intertidal seagrass/sand flats
(and in particular the Section Bank) are an important habitat
and fishing area for species such as blue
swimmer crab, baitworms and mud cockle. The subtidal sands and
seagrasses are important habitats
and fishing areas for species such as King George whiting, blue
swimmer crab and southern garfish.
St Kilda is a regionally significant location for recreational
fishers to wade and ‘rake’ for blue
swimmer crab.
The cell has been utilised for numerous scientific studies (see
next section).
Habitat values
The cell is regionally significant due to the extensive subtidal
seagrass meadows and intertidal flats
with seagrass and/or sand.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
276
Intertidal and shallow subtidal seagrass and sand habitats at
Section Bank support a high diversity of
fishes and invertebrates (Connolly 1994, Jones et al. 1996,
Jackson and Jones 1999, Dittmann 2008).
Dittmann (2008) considered the Section Bank to be a hotspot of
invertebrate infauna diversity within
intertidal and estuarine mudflats of the AMLRNRM region. The
subtidal seagrass and sand habitats
around Outer Harbor have a high diversity of fishes, epifauna
and infauna (Loo and Drabsch 2008).
The cell lies within a region of low macroalgal species
diversity (see Baker and Gurgel 2010); which is
probably mainly due to a lack of reefs. Gillanders et al. (2008)
listed 27 fish species for the Gawler
River estuary.
Bryars (2003) listed 10 fish and five macroinvertebrate
fisheries taxa for the seagrass habitat
between the Firing Range and Outer Harbor, 14 fish and seven
macroinvertebrate fisheries taxa for
the unvegetated soft bottom habitat between the Firing Range and
Outer Harbor, eight fish and five
macroinvertebrate fisheries taxa for the tidal flat habitat
between the Firing Range and St Kilda, 10
fish and two macroinvertebrate fisheries taxa for the tidal
creek habitat between Port Parham and St
Kilda, and seven fish and four macroinvertebrate fisheries taxa
for the mangrove habitat between
Light Beach and St Kilda.
While the deeper subtidal seagrass habitats are likely to
support a range of species (e.g. see Bryars
2003), apart from mapping studies that have characterised the
benthos (Shepherd and Sprigg 1976,
Tanner 2002, DEH 2008, Bryars and Rowling 2009), few biological
surveys appear to have been
undertaken on these habitat types within Cell MA18.
Threats
While the immediate coastline is unpopulated, there are a number
of catchment water, stormwater
and wastewater inputs from within or adjacent to the cell,
including the Bolivar WWTP outfall and
Gawler River. Annual discharge volume (35.3 GL), total nitrogen
load (487.3 T) and total suspended
solid load (1272 T) from the Bolivar WTTP outfall have all been
substantial (Wilkinson et al. 2005). A
more recent figure of 600 T for total nitrogen indicates that
the annual discharge load from the
Bolivar WWTP has increased (National Pollutant Inventory
2011/12). Wilkinson et al. (2005)
estimated that mean annual stormwater flow for the Gawler River
is substantial at 15.1 GL and that
annual total discharge loads for nitrogen (31.3 T) were
relatively low but that suspended solids (2327
T) were relatively high in comparison to the Adelaide
metropolitan coastal waters. The cell is also
influenced by wastewater discharge from the Penrice soda factory
which lies outside of the cell in
the Port River (Fernandes et al. 2009). Stormwater inputs to the
Port River-Barker Inlet estuary could
also potentially influence Cell MA18 (see Cell MA14/15/16/17).
Thus the threat to nearshore
habitats from nutrient and sediment discharges is
significant.
Periodic dredging of the Outer Harbor shipping channel is also a
threat to seagrass within the vicinity
of the channel (the most recent major dredging event was in
2006, Tanner and Rowling 2008).
Seagrass habitats within Cell MA18 have been dramatically
impacted by historical and ongoing
anthropogenic activities; these threats have been
well-documented (see Shepherd et al. 1989,
Westphalen et al. 2004) and efforts are underway to mitigate
some of them (e.g. reuse of
wastewater from Bolivar WWTP). While poor water quality is
probably limiting the ability of
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
277
seagrasses to recolonise the inshore zone adjacent to Bolivar
WWTP outfall, the remaining
seagrasses in the offshore area appear to be in good condition
(e.g. Bryars et al. 2006).
The introduced macroalgal species Caulerpa taxifolia and C.
racemosa var. cylindracea are
established within the cell (Wiltshire et al. 2010) and pose an
ongoing threat to subtidal soft bottom
communities.
A potential threat to ecosystems within the cell (but which is
not assessed by the present report) is
the discharge and accumulation of persistent organic pollutants
in sediments adjacent to the Bolivar
WWTP outfall (see Fernandes et al. 2008, 2010).
Bryars (2003) identified that a potential threat to intertidal
sand/seagrass habitats was human
trampling (see photo below) and bait digging (although crab
raking should also be added to this).
Drift macroalgae that is fuelled by nutrient-rich wastewater is
also an issue for the tidal flats within
the cell (Connolly 1986, e.g. see photo below).
Intertidal sand and seagrass habitat at St Kilda showing
evidence of human trampling in the foreground and
nutrient-driven green macroalgal growth in the distance. Photo:
S. Bryars, 28 October 2012.
The sand habitat at Section Bank has been assessed previously
for its potential as a source of sand
for Adelaide’s beach replenishment program (Cheshire et al.
2002), but has not been used to date. If
this activity proceeded, then the direct (and possibly indirect)
impacts from dredging of the sand
would be significant (Cheshire et al. 2002).
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
278
The EPA established some monitoring sites within the cell during
2009 where habitat condition
(using remote video) and water quality are assessed
periodically. The results from the EPA program
are yet to be published.
The main ongoing threats would appear to be nutrient inputs from
Bolivar WWTP outfall and the
Penrice soda factory within the Port River. The Penrice soda
factory is apparently closing down in
2013. While the catchment is highly modified for
agricultural/urban use and there are intermittent
but significant flows down the Gawler River (Wilkinson et al.
2005), the potential impact of any
nutrients/sediments or other pollutants from this particular
source on adjacent benthic habitats is
unknown.
Threat analysis
Risk ratings for identified threats to seagrass and sand ranged
from low to high (Table MA18.2). Reef
was not assessed as it does not occur within the cell.
Table MA18.2. Results of threat analysis for Cell MA18.
Threat
Habitat
Seagrass Reef Sand
C L RV RR C L RV RR C L RV RR
Wastewater (Bolivar WWTP outfall)
3 6 18 H 3 6 18 H
Wastewater (Penrice soda outfall)
1 4 4 L
Stormwater (Port River-Barker Inlet system)
1 4 4 L
Catchment water (Gawler River)
2 4 8 M
Physical disturbance (bait digging, crab raking, trampling)
1 4 4 L 1 4 4 L
Physical disturbance (smothering by introduced Caulerpa)
2 5 10 M 2 5 10 M
The effects of wastewater from Bolivar WWTP on inshore seagrass
loss in the area are well
documented and accepted (see Shepherd et al. 1989, Westphalen et
al. 2004). The high risk rating
for seagrass from Bolivar wastewater reflects that while inshore
seagrass loss has occurred and the
threat is likely to continue (L=6), seagrasses further offshore
still appear healthy and the overall
proportion of loss is probably severe (C=3). Thus the risk
rating for seagrass was high (RV=18). The
high risk rating for sand from wastewater reflects the
relatively small amount of sand habitat in the
cell (which is mainly intertidal) and the high coverage of drift
macroalgae in the region which is
fuelled by nutrient-rich wastewater. However, it was more
difficult to assign a risk rating to sand
habitat in this region because some of the coverage is actually
due to historical seagrass loss and a
transformation from seagrass to sand. Nonetheless, it was
considered likely (L=6) that a severe
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
279
consequence (C=3) of Bolivar WWTP on sand habitat is occurring.
Thus the risk rating for sand was
high (RV=18).
As the area of seagrass is relatively large and the Port
River-Barker Inlet stormwater system lies
outside the cell, it was considered possible (L=4) that a minor
consequence (C=1) could occur. Thus
the risk rating was low (RV=4).
As the area of seagrass is relatively large but there is
potential for an impact on seagrass from the
Gawler River catchment, it was considered possible (L=4) that a
moderate consequence (C=2) could
occur. Thus the risk rating was moderate (RV=8).
It was considered possible (L=4) that physical disturbance of
intertidal seagrass and sand from bait
digging, crab raking and trampling could have a minor
consequence (C=1). Thus the risk rating was
low (RV=4).
While the introduced macroalgal species Caulerpa taxifolia and
C. racemosa var. cylindracea are
established within the cell it is possible that due to
environmental limitations, the threat of further
spread may be minimal (see Rowling 2007, Westphalen 2008,
Wiltshire et al. 2010). Given that there
is a large area of seagrass and sand habitat within the cell, a
risk rating of moderate (RV=10) was
assigned based upon an occasional likelihood (L=5) of a moderate
consequence (C=2) occurring.
Actions and Priority
Table MA18.3. Recommended actions and priority for Cell
MA18.
Component Issue Proposed action Priority of action
Key players
Seagrass, Sand
Nutrients from the Bolivar WWTP outfall
Support initiatives for reuse of wastewater and reduction of
nutrient loads (e.g. Bolivar Environment Improvement Program)
High City of Salisbury / City of Playford / AMLRNRM Board / SA
Water
Seagrass, Sand
Nutrients from the Penrice soda factory
Support initiatives to reduce
inputs to the Port River (NB the Penrice soda factory is
apparently closing down in 2013)
High EPA / Penrice Soda Holdings Ltd
Seagrass Sediments and nutrients from catchment and
stormwater
Support initiatives for catchment revegetation and improved land
management practices (e.g. Playford Greening and Landcare Group)
Support initiatives to collect and reuse stormwater (e.g. Water
Proofing Northern Adelaide initiative)
Medium Medium
City of Salisbury / City of Playford / District Council of
Mallala / Other Local Government Areas within the catchment /
AMLRNRM Board City of Salisbury / City of Playford / AMLRNRM Board
/ SA Water
Further investigations
Ongoing monitoring of seagrass coverage and health is required
to assess the effectiveness of future
changes in wastewater discharges.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
280
(This page is intentionally blank)
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
281
MA19 – Middle Beach
Mangrove and intertidal seagrass/sand habitats adjacent to Port
Gawler Beach. Photo: S. Bryars, 2001.
Cell detail
Cell MA19 is 127 km2 in area and extends about 9 km alongshore
from Port Gawler Beach to the
Light River Delta and about 15 km offshore.
Benthic habitats
Cell MA19 is dominated by a mosaic of seagrass types from the
intertidal to offshore (Figure
MA19.1, Table MA19.1). There are also significant areas of
intertidal sand at Port Gawler Beach and
Middle Beach that were not mapped by DEH (2008).
Seagrass
The spatially dominant seagrass in the northern part of the cell
is Posidonia, with some Amphibolis
and Heterozostera/Zostera (Tanner 2002, Tanner et al. 2012).
Some loss of seagrass has occurred in
the southern inshore part of the cell (shown as patchy seagrass)
due to effluent from the Bolivar
WWTP outfall which lies outside the cell to the south.
Reef
None mapped.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
282
Figure MA19.1. Benthic habitats of Cell MA19. Note that
mangrove, saltmarsh and sandy beach
habitats are not shown on the map.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
283
Sand
Relatively little bare sand occurs in this cell. Narrow strips
of bare sand (not mapped by DEH 2008)
do occur at Port Gawler Beach and Middle Beach and are
categorised as low-energy reflective
beaches (Short 2001). Dittmann (2008) described the sediments at
Port Gawler Beach as medium to
coarse sand.
Estuaries
No recognised estuaries occur in this cell.
Table MA19.1. Summary of benthic habitats mapped within Cell
MA19.
(Data were extracted from a benthic habitat GIS layer supplied
by the Department of Environment,
Water and Natural Resources)
Habitat group Habitat type Area (km2) % total cell area
Sand
Sand, Bare, Continuous 0.3 0.2
(Sand Total) (0.3) (0.2)
Seagrass
Seagrass, Continuous, Dense 18.5 14.6
Seagrass, Continuous, Medium 39.1 30.9
Seagrass, Continuous, Sparse 11.2 8.8
Seagrass, Patchy, Dense 1.4 1.1
Seagrass, Patchy, Medium 7.4 5.8
Seagrass, Patchy, Sparse 48.8 38.6
(Seagrass Total) (126.3) (99.8)
Total 126.6 100
Cell values
The cell is utilised for recreational/commercial fishing and
boating. The intertidal seagrass/sand flats
are an important habitat and fishing area for blue swimmer crab.
The subtidal seagrasses are
important habitats and fishing areas for species such as King
George whiting, blue swimmer crab and
southern garfish. Middle Beach is a regionally significant
location for recreational fishers to wade
and ‘rake’ for blue swimmer crab.
Habitat values
The cell is regionally significant due to the extensive subtidal
seagrass meadows and intertidal
seagrass/sand flats.
The intertidal sand habitat at Port Gawler Beach is an important
nursery area for western king prawn
(Kangas and Jackson 1998) and is occupied by numerous other
invertebrates (Dittmann 2008). The
intertidal seagrass habitat at Port Gawler Beach supports
substantial fish production (Jones et al.
2008).
The cell lies within a region of very low macroalgal species
diversity (see Baker and Gurgel 2010);
which is probably mainly due to a lack of reefs.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
284
Bryars (2003) listed 10 fish and five macroinvertebrate
fisheries taxa for the seagrass habitat
between the Firing Range and Outer Harbor, 14 fish and seven
macroinvertebrate fisheries taxa for
the unvegetated soft bottom habitat between the Firing Range and
Outer Harbor, eight fish and five
macroinvertebrate fisheries taxa for the tidal flat habitat
between the Firing Range and St Kilda, 10
fish and two macroinvertebrate fisheries taxa for the tidal
creek habitat between Port Parham and St
Kilda, and seven fish and four macroinvertebrate fisheries taxa
for the mangrove habitat between
Light Beach and St Kilda.
While the subtidal seagrass habitats are likely to support a
range of species (e.g. see Bryars 2003),
apart from mapping studies that have characterised the benthos
(Shepherd and Sprigg 1976, Tanner
2002, DEH 2008, Bryars and Rowling 2009), few biological surveys
appear to have been undertaken
on these habitat types within Cell MA19.
Threats
The immediate coastline is sparsely populated (Middle Beach
settlement) and possibly receives
intermittent freshwater inputs from the Gawler River (which lies
just outside the cell to the south)
and the Light River (which lies outside the cell to the north).
Nonetheless, the catchments adjacent
to the coast are highly modified (rural use, urban settlements)
and nutrient/sediment inputs are
possible during heavy rainfall events. Seagrasses within the
northern part of the cell are in good
condition with low epiphyte cover and no indication that the
Light River is impacting on nearshore
seagrasses (Tanner et al. 2012). However, Wilkinson et al.
(2005) estimated that mean annual
stormwater flow for the Gawler River is substantial at 15.1 GL
and that annual total discharge loads
for nitrogen (31.3 T) were relatively low but that suspended
solids (2327 T) were relatively high in
comparison to the Adelaide coastal waters. Thus,
nutrients/sediments from the Gawler River do
present a potential threat to nearshore habitats within the
cell.
Seagrass habitats in the southern part of the cell have been
negatively impacted by nutrient
discharge from the Bolivar WWTP which lies outside the cell to
the south (Shepherd et al. 1989).
Annual discharge volume (35.3 GL), total nitrogen load (487.3 T)
and total suspended solid load
(1272 T) from the Bolivar WTTP outfall have all been substantial
(Wilkinson et al. 2005). A more
recent figure of 600 T for total nitrogen indicates that the
annual discharge load from the Bolivar
WWTP has increased (National Pollutant Inventory 2011/12).
Bryars (2003) also identified that a
potential (albeit minor) threat to nearshore habitats was
increased nutrients from septic tank
overflows at Middle Beach.
Off-road vehicle use presents a potential threat to the
intertidal sand/seagrass habitats in the area
(Bryars 2003, Purnell et al. 2010). Bryars (2003) also
identified that a potential threat to intertidal
habitats was human trampling and bait digging (although crab
raking should also be added to this).
The intertidal flats at Port Gawler Beach are threatened by
smothering from mangroves that are
rapidly expanding in aerial coverage.
The EPA established some monitoring sites within the cell during
2009 where habitat condition
(using remote video) and water quality are assessed
periodically. The results from the EPA program
are yet to be published.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
285
Threat analysis
Risk ratings for identified threats to seagrass and sand ranged
from low to moderate (Table MA19.2).
Reef was not assessed as it does not occur within the cell.
Table MA19.2. Results of threat analysis for Cell MA19.
Threat
Habitat
Seagrass Reef Sand
C L RV RR C L RV RR C L RV RR
Wastewater (Bolivar WWTP outfall)
2 6 12 M
Catchment water (Gawler River)
1 4 4 L
Physical disturbance (bait digging, crab raking, trampling)
1 4 4 L 1 4 4 L
Physical disturbance (off-road vehicle use)
1 4 4 L 1 4 4 L
Physical disturbance (smothering by mangroves)
2 6 12 M
As the area of seagrass is relatively large but historical
seagrass loss has occurred in some areas, it
was considered that a moderate consequence (C=2) would likely
(L=6) continue from the Bolivar
WWTP outfall. Thus the risk rating was moderate (RV=12).
As the area of seagrass is relatively large and the Gawler River
lies outside the cell, it was considered
possible (L=4) that a minor consequence (C=1) could occur. Thus
the risk rating was low (RV=4).
It was considered possible (L=4) that physical disturbance of
intertidal seagrass and sand from bait
digging, crab raking and trampling could have a minor
consequence (C=1). Thus the risk rating was
low (RV=4).
It was considered possible (L=4) that physical disturbance of
intertidal seagrass and sand from off-
road vehicles could have a minor consequence (C=1). Thus the
risk rating was low (RV=4).
As mangroves are known to be rapidly colonising bare sand off
Middle Beach and there is relatively
little bare sand within the cell, it was considered likely (L=6)
that this transformation will continue
with a moderate consequence (C=2) for the sand habitat across
the cell. Thus the risk rating was
moderate (RV=12).
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
286
Actions and Priority
Table MA19.3. Recommended actions and priority for Cell
MA19.
Component Issue Proposed action Priority of action
Key players
Seagrass Nutrients from the Bolivar WWTP outfall
Support initiatives for reuse of wastewater and reduction of
nutrient loads (e.g. Bolivar Environment Improvement Program)
Medium (but High in adjacent Cell MA18)
City of Salisbury / City of Playford / AMLRNRM Board / SA
Water
Seagrass Sediments and nutrients from catchment water
Support initiatives for catchment revegetation and improved land
management practices (e.g. Playford Greening and Landcare Group)
Support initiatives to collect and reuse stormwater (e.g. Water
Proofing Northern Adelaide initiative)
Low Low
City of Playford / District Council of Mallala / Other Local
Government Areas within the catchment / AMLRNRM Board City of
Playford / District Council of Mallala / AMLRNRM Board / SA
Water
Sand, Seagrass
Off-road vehicles in intertidal
Support initiatives to reduce off-road vehicle use
Low District Council of Mallala / AMLRNRM Board
Further investigations
Biological surveys of subtidal seagrass habitats would be useful
to better understand habitat values
and to compile meaningful species lists for the cell.
Ongoing monitoring of seagrass coverage and health is required
to assess the effectiveness of future
changes in wastewater discharges.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
287
MA20 – Light River Delta
Posidonia seagrass habitat that would be typical of the cell.
Photo: S. Bryars, 18 December 2006 (taken off
Adelaide)
Cell detail
Cell MA20 is 60 km2 in area and extends about 4 km alongshore
adjacent to the Light River Delta and
about 13 km offshore.
Benthic habitats
Cell MA20 is dominated by a mosaic of seagrass types from the
intertidal to offshore (Figure
MA20.1, Table MA20.1).
Seagrass
The spatially dominant seagrass is Posidonia, with some
Amphibolis and Heterozostera/Zostera
(Tanner 2002, DEH 2008, Tanner et al. 2012).
Reef
None mapped.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
288
Figure MA20.1. Benthic habitats of Cell MA20. Note that the
mangrove and saltmarsh habitats of
the Light River Delta are not shown on the map.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
289
Sand
A negligible area of sand has been mapped.
Estuaries
Light River Delta is a recognised estuary (DEH 2007).
Table MA20.1. Summary of benthic habitats mapped within Cell
MA20.
(Data were extracted from a benthic habitat GIS layer supplied
by the Department of Environment,
Water and Natural Resources)
Habitat group Habitat type Area (km2) % total cell area
Sand
Sand, Bare, Continuous 0.03 0.04
(Sand Total) (0) (0)
Seagrass
Seagrass, Continuous, Dense 5.4 9.0
Seagrass, Continuous, Medium 20.9 35.0
Seagrass, Continuous, Sparse 18.3 30.6
Seagrass, Patchy, Dense 0.3 0.5
Seagrass, Patchy, Medium 0.9 1.6
Seagrass, Patchy, Sparse 14.0 23.3
(Seagrass Total) (59.9) (100)
Total 59.9 100
Cell values
The cell is utilised for recreational/commercial fishing and
boating. The seagrasses are important
habitats and fishing areas for species such as King George
whiting, blue swimmer crab and southern
garfish.
Habitat values
The cell is regionally significant due to the extensive subtidal
seagrass meadows, intertidal flats with
seagrass, and existence of the Light River estuary.
The cell lies within a region of very low macroalgal species
diversity (see Baker and Gurgel 2010);
which is probably mainly due to a lack of reefs.
At least 26 native and three exotic fishes occur in the Light
River estuary, with another 25 species
that could possibly also occur there (EBS Ecology 2012).
Bryars (2003) listed 10 fish and five macroinvertebrate
fisheries taxa for the seagrass habitat
between the Firing Range and Outer Harbor, eight fish and five
macroinvertebrate fisheries taxa for
the tidal flat habitat between the Firing Range and St Kilda, 10
fish and two macroinvertebrate
fisheries taxa for the tidal creek habitat between Port Parham
and St Kilda, and seven fish and four
macroinvertebrate fisheries taxa for the mangrove habitat
between Light Beach and St Kilda.
While the seagrass habitats are likely to support a range of
species (e.g. see Bryars 2003), apart from
mapping studies that have characterised the benthos (e.g.,
Shepherd and Sprigg 1976, Tanner 2002,
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
290
DEH 2008, Tanner et al. 2012), very few biological surveys
appear to have been undertaken on these
habitat types within the cell.
Threats
The immediate coastline is unpopulated, and while the catchment
is highly modified for agricultural
use and there are intermittent (but unquantified) flows down the
Light River, it appears that the
supply of any nutrients or other pollutants to the subtidal
seagrasses offshore is diffused by the
mangrove delta and tidal flats (Tanner et al. 2012). Seagrasses
within the cell are in good condition
with low epiphyte cover and there is no indication that the
Light River is impacting on inshore
seagrasses (Tanner et al. 2012).
EBS Ecology (2010a) identified a number of minor threats to
tidal creeks, mangroves and
saltmarshes in the Light Beach region, including physical
disturbance from off-road vehicle use.
The EPA established some monitoring sites within the cell during
2009 where habitat condition
(using remote video) and water quality are assessed
periodically. The results from the EPA program
are yet to be published.
Threat analysis
Risk ratings for identified threats to seagrass were low (Table
MA20.2). Reef was not assessed as it
does not occur within the cell. No measurable threats to sand
were identified.
Table MA20.2. Results of threat analysis for Cell MA20.
Threat
Habitat
Seagrass Reef Sand
C L RV RR C L RV RR C L RV RR
Catchment water (Light River)
1 4 4 L
As the area of seagrass is relatively large and there is
currently no evidence of an impact from
catchment water, it was considered that a minor consequence
(C=1) could be possible (L=4). Thus
the risk rating for seagrass was low (RV=4).
Actions and Priority
Table MA20.3. Recommended actions and priority for Cell
MA20.
Component Issue Proposed action Priority of action
Key players
Seagrass Nutrients / sediments
Support initiatives for catchment revegetation and improved land
management practices
Low District Council of Mallala / Light Regional Council /
AMLRNRM Board
Further investigations
Biological surveys of seagrass habitats would be useful to
better understand habitat values.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
291
MA21 – Port Prime
Amphibolis antarctica seagrass habitat that would be typical of
the cell. Photo: S. Bryars, 19 December 2012
(taken off Adelaide)
Cell detail
Cell MA21 is 97 km2 in area and extends about 5.5 km alongshore
from the Light River Delta to Port
Prime and about 18 km offshore.
Benthic habitats
Cell MA21 is dominated by a mosaic of seagrass types from the
intertidal to offshore (Figure
MA21.1, Table MA21.1). Some areas of bare sand also occur in the
cell.
Seagrass
The spatially dominant seagrass offshore and midshore is
Amphibolis and Posidonia (Tanner 2002).
Reef
None mapped.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
292
Figure MA21.1. Benthic habitats of Cell MA21.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
293
Sand
Bare sand occurs mainly inshore. The landward sections of bare
sand are categorised as low-energy
reflective beaches and include Light Beach and Prime Beach
(Short 2001).
Estuaries
No recognised estuaries occur in this cell.
Table MA21.1. Summary of benthic habitats mapped within Cell
MA21.
(Data were extracted from a benthic habitat GIS layer supplied
by the Department of Environment,
Water and Natural Resources)
Habitat group Habitat type Area (km2) % total cell area
Sand
Sand, Bare, Continuous 0.7 0.7
(Sand Total) (0.7) (0.7)
Seagrass
Seagrass, Continuous, Dense 18.4 19.1
Seagrass, Continuous, Medium 38.2 39.6
Seagrass, Continuous, Sparse 27.2 28.2
Seagrass, Patchy, Medium 1.0 1.1
Seagrass, Patchy, Sparse 11.0 11.4
(Seagrass Total) (95.8) (99.3)
Total 96.5 100
Cell values
The cell is utilised for recreational/commercial fishing and
boating. The intertidal seagrass/sand flats
are an important habitat and fishing area for blue swimmer crab
and yellowfin whiting. The subtidal
sands and seagrasses are important habitats and fishing areas
for species such as King George
whiting, blue swimmer crab and southern garfish.
Habitat values
The cell is regionally significant due to the extensive subtidal
and intertidal seagrass meadows.
The cell lies within a region of very low macroalgal species
diversity (see Baker and Gurgel 2010);
which is probably mainly due to a lack of reefs.
Bryars (2003) listed 10 fish and five macroinvertebrate
fisheries taxa for the seagrass habitat
between the Firing Range and Outer Harbor, 14 fish and seven
macroinvertebrate fisheries taxa for
the unvegetated soft bottom habitat between the Firing Range and
Outer Harbor, eight fish and five
macroinvertebrate fisheries taxa for the tidal flat habitat
between the Firing Range and St Kilda, 10
fish and two macroinvertebrate fisheries taxa for the tidal
creek habitat between Port Parham and St
Kilda.
While the seagrass and sand habitats are likely to support a
range of species (e.g. see Bryars 2003),
apart from mapping studies that have characterised the benthos
(e.g., Shepherd and Sprigg 1976,
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
294
Tanner 2002, DEH 2008), very few biological surveys appear to
have been undertaken on these
habitat types within the cell.
Threats
The immediate coastline is unpopulated and there are no direct
freshwater inputs to the coast. Thus,
there is unlikely to be any land-based threat from
nutrients/sediments.
EBS Ecology (2010a) identified a number of minor threats to
tidal creeks, mangroves and
saltmarshes in the Light Beach region, including physical
disturbance from off-road vehicle use.
Off-road vehicle use presents a potential threat to the
intertidal sand/seagrass habitats in the area
(Bryars 2003, Purnell et al. 2010).
Threat analysis
Risk ratings for identified threats to seagrass and sand were
low (Table MA21.2). Reef was not
assessed as it does not occur within the cell.
Table MA21.2. Results of threat analysis for Cell MA21.
Threat
Habitat
Seagrass Reef Sand
C L RV RR C L RV RR C L RV RR
Physical disturbance (off-road vehicle use)
1 4 4 L 1 4 4 L
It was considered possible (L=4) that physical disturbance of
intertidal seagrass and sand from off-
road vehicles could have a minor consequence (C=1). Thus the
risk rating was low (RV=4).
Actions and Priority
Table MA21.3. Recommended actions and priority for Cell
MA21.
Component Issue Proposed action Priority of action
Key players
Sand, Seagrass
Off-road vehicles in intertidal
Support initiatives to reduce off-road vehicle use
Low District Council of Mallala / AMLRNRM Board
Further investigations
Biological surveys of seagrass and sand habitats would be useful
to better understand habitat values
and to compile meaningful species lists for the cell.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
295
MA22 – Thompson Beach
Thompson Beach at low tide. Photo: S. Bryars, 21 October
2012.
Cell detail
Cell MA22 is 88 km2 in area and extends about 6.5 km alongshore
from Port Prime to Great Sandy
Point and about 15 km offshore.
Benthic habitats
Cell MA22 is dominated by a mosaic of seagrass types from the
intertidal to offshore (Figure
MA22.1, Table MA22.1). Significant areas of bare sand also occur
in the intertidal.
Seagrass
The spatially dominant seagrass offshore and midshore is
Amphibolis and Posidonia (Tanner 2002).
Reef
None mapped.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
296
Figure MA22.1. Benthic habitats of Cell MA22.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
297
Sand
Bare sand is characterised by sandy/muddy sediments in the
intertidal. The landward sections of
bare sand are categorised as low-energy reflective beaches and
include Prime Beach and Thompson
Beach (Short 2001).
Estuaries
No recognised estuaries occur in this cell.
Table MA22.1. Summary of benthic habitats mapped within Cell
MA22.
(Data were extracted from a benthic habitat GIS layer supplied
by the Department of Environment,
Water and Natural Resources)
Habitat group Habitat type Area (km2) % total cell area
Sand
Sand, Bare, Continuous 2.7 3.1
(Sand Total) (2.7) (3.1)
Seagrass
Seagrass, Continuous, Dense 21.0 23.9
Seagrass, Continuous, Medium 44.7 51.1
Seagrass, Continuous, Sparse 15.0 17.2
Seagrass, Patchy, Dense 0.2 0.2
Seagrass, Patchy, Medium 2.2 2.5
Seagrass, Patchy, Sparse 1.7 2.0
(Seagrass Total) (84.8) (96.8)
Total 87.6 100
Cell values
The cell is utilised for recreational/commercial fishing and
boating. The intertidal sand flats at
Thompson Beach are utilised for boat launching. The intertidal
seagrass/sand flats are an important
habitat and fishing area for blue swimmer crab and yellowfin
whiting. The subtidal seagrasses are
important habitats and fishing areas for species such as King
George whiting, blue swimmer crab and
southern garfish.
Habitat values
The cell is regionally significant due to the extensive subtidal
seagrass meadows and intertidal flats
with seagrass and/or sand.
The cell lies within a region of very low macroalgal species
diversity (see Baker and Gurgel 2010);
which is probably mainly due to a lack of reefs.
Bryars (2003) listed 10 fish and five macroinvertebrate
fisheries taxa for the seagrass habitat
between the Firing Range and Outer Harbor, 14 fish and seven
macroinvertebrate fisheries taxa for
the unvegetated soft bottom habitat between the Firing Range and
Outer Harbor, eight fish and five
macroinvertebrate fisheries taxa for the tidal flat habitat
between the Firing Range and St Kilda, 10
fish and two macroinvertebrate fisheries taxa for the tidal
creek habitat between Port Parham and St
Kilda.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
298
While the seagrass and sand habitats are likely to support a
range of species (e.g. see Bryars 2003),
apart from mapping studies that have characterised the benthos
(e.g., Shepherd and Sprigg 1976,
Tanner 2002), very few biological surveys appear to have been
undertaken on these habitat types
within the cell.
Threats
The immediate coastline is sparsely populated (small settlement
at Thompson Beach) and there are
no direct freshwater inputs to the coast. Bryars (2003) did
identify that a potential threat to
nearshore habitats was increased nutrients from septic tank
overflows at Thompson Beach.
However, there is unlikely to be any major land-based threat
from nutrients/sediments.
Off-road vehicle use presents a potential threat to the
intertidal sand/seagrass habitats in the area
(Bryars 2003, Purnell et al. 2010).
The EPA established a monitoring site within the cell during
2009 where habitat condition (using
remote video) and water quality are assessed periodically. The
results from the EPA program are yet
to be published.
Threat analysis
Risk ratings for identified threats to seagrass and sand were
low (Table MA22.2). Reef was not
assessed as it does not occur within the cell.
Table MA22.2. Results of threat analysis for Cell MA22.
Threat
Habitat
Seagrass Reef Sand
C L RV RR C L RV RR C L RV RR
Physical disturbance (off-road vehicle use)
1 4 4 L 1 4 4 L
It was considered possible (L=4) that physical disturbance of
intertidal seagrass and sand from off-
road vehicles could have a minor consequence (C=1). Thus the
risk rating was low (RV=4).
Actions and Priority
Table MA22.3. Recommended actions and priority for Cell
MA22.
Component Issue Proposed action Priority of action
Key players
Sand, Seagrass
Off-road vehicles in intertidal
Support initiatives to reduce off-road vehicle use
Low District Council of Mallala / AMLRNRM Board
Further investigations
Biological surveys of seagrass and sand habitats would be useful
to better understand habitat values
and to compile meaningful species lists for the cell.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
299
MA23 – Parham
A tidal creek draining across intertidal sand flats at Webb
Beach with Parham settlement in the distance.
Photo: S. Bryars, 21 October 2012.
Cell detail
Cell MA23 is 98 km2 in area and extends about 7 km alongshore
from Great Sandy Point to just north
of Parham and about 12 km offshore.
Benthic habitats
Cell MA23 is dominated by a mosaic of seagrass types from the
intertidal to offshore (Figure
MA23.1, Table MA23.1). Significant areas of bare sand also occur
in the intertidal.
Seagrass
The spatially dominant seagrass offshore is Posidonia (Tanner
2002).
Reef
No reef has been mapped, but a small section of limestone reef
is known to occur within the cell
(‘Parham Reef’, see Northern Reef in Collings et al. 2008).
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
300
Figure MA23.1. Benthic habitats of Cell MA23.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
301
Sand
Bare sand is characterised by sandy/muddy sediments in the
intertidal. The landward sections of
bare sand are categorised as low-energy reflective beaches and
include Webb Beach and Parham
Beach (Short 2001).
Estuaries
No recognised estuaries occur in this cell.
Table MA23.1. Summary of benthic habitats mapped within Cell
MA23.
(Data were extracted from a benthic habitat GIS layer supplied
by the Department of Environment,
Water and Natural Resources)
Habitat group Habitat type Area (km2) % total cell area
Sand
Sand, Bare, Continuous 3.0 3.1
(Sand Total) (3.0) (3.1)
Seagrass
Seagrass, Continuous, Dense 27.8 28.3
Seagrass, Continuous, Medium 45.5 46.4
Seagrass, Continuous, Sparse 19.1 19.5
Seagrass, Patchy, Dense 0.1 0.1
Seagrass, Patchy, Medium 2.3 2.4
Seagrass, Patchy, Sparse 0.0 0.0
(Seagrass Total) (94.8) (96.8)
Total 98.0 100
Cell values
The cell is utilised for recreational/commercial fishing and
boating. The intertidal sand flats at Webb
Beach and Port Parham are utilised for boat launching. The
intertidal seagrass/sand flats are an
important habitat and fishing area for blue swimmer crab and
yellowfin whiting. The subtidal
seagrasses are important habitats and fishing areas for species
such as King George whiting, blue
swimmer crab and southern garfish.
Habitat values
The cell is regionally significant due to the extensive subtidal
seagrass meadows and tidal flats with
seagrass and/or sand. Parham Reef is also of significance as it
is one of very few reefs in the NE of
Gulf St Vincent. A subtidal survey of Parham Reef found a
variety of fishes, macroalgae and
invertebrates (Collings et al. 2008).
Bryars (2003) listed 10 fish and five macroinvertebrate
fisheries taxa for the seagrass habitat
between the Firing Range and Outer Harbor, 14 fish and seven
macroinvertebrate fisheries taxa for
the unvegetated soft bottom habitat between the Firing Range and
Outer Harbor, and eight fish and
five macroinvertebrate fisheries taxa for the tidal flat habitat
between the Firing Range and St Kilda.
The cell lies outside of the area assessed for macroalgal
species diversity by Baker and Gurgel (2010).
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
302
While the seagrass and sand habitats are likely to support a
range of species (e.g. see Bryars 2003),
apart from mapping studies that have characterised the benthos
(e.g., Shepherd and Sprigg 1976,
Tanner 2002), very few biological surveys appear to have been
undertaken on these habitat types
within the cell.
Threats
The immediate coastline is sparsely populated (small settlements
at Webb Beach and Parham) and
there is very little freshwater input to the coast. Bryars
(2003) did identify that a potential threat to
nearshore habitats was increased nutrients from septic tank
overflows at Parham and Webb Beach.
However, there is unlikely to be any major land-based threat
from nutrients/sediments.
EBS Ecology (2010b) identified a number of minor threats to
tidal creeks, mangroves and
saltmarshes in the Parham region, including physical disturbance
from off-road vehicle use and
illegal creation of boat ramps within Baker Creek (which is a
tidal creek to the south of Webb Beach).
Off-road vehicle use presents a potential threat to the
intertidal sand/seagrass habitats in the area
(Bryars 2003, Purnell et al. 2010).
Examination of the habitat map (Figure MA23.1) and aerial photos
shows a distinct straight-line scar
of bare sand about 1.5 km in length through the seagrass
directly opposite the boat ramp at Parham.
It is likely that this boating channel (which has markers) was
caused by (or deliberately created for)
boat use. By comparing the DEH (2008) habitat map with a more
recent aerial photo (2010) it
appears that the bare sand at the seaward or western end of the
scar is increasing in size due to
erosion (SBPO).
Threat analysis
Risk ratings for identified threats to seagrass and sand were
low (Table MA23.2). No measurable
threats to reef were identified (a small amount of unmapped reef
does occur within the cell).
Table MA23.2. Results of threat analysis for Cell MA23.
Threat
Habitat
Seagrass Reef Sand
C L RV RR C L RV RR C L RV RR
Physical disturbance (erosion in boating channel and creation of
illegal channels)
1 4 4 L
Physical disturbance (off-road vehicle use)
1 4 4 L 1 4 4 L
It was considered possible (L=4) that physical disturbance of
seagrass within the boating channel
could have a minor consequence (C=1). Thus the risk rating was
low (RV=4). However, this risk rating
could change in the future if the erosion is found to be
increasing the area of sand.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
303
It was considered possible (L=4) that physical disturbance of
intertidal seagrass and sand from off-
road vehicles could have a minor consequence (C=1). Thus the
risk rating was low (RV=4).
Actions and Priority
Table MA23.3. Recommended actions and priority for Cell
MA23.
Component Issue Proposed action Priority of action
Key players
Sand, Seagrass
Off-road vehicles in intertidal
Support initiatives to reduce off-road vehicle use
Low District Council of Mallala / AMLRNRM Board
Seagrass Erosion in boating channel at Port Parham
Undertake further investigations of potential erosion in the
boating channel
Medium District Council of Mallala / AMLRNRM Board
Further investigations
A survey of the boating channel off Parham Beach and ongoing
monitoring is required to determine
if the channel is increasing in size due to erosion.
A follow-up to the 2007 Reef Health survey of Parham Reef would
be useful to gauge condition
trending and as a control site for reefs off metropolitan
Adelaide which are in poor condition.
Biological surveys of seagrass and sand habitats would be useful
to better understand habitat values
and to compile meaningful species lists for the cell.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
304
(This page is intentionally blank)
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
305
MA24 – Middle Spit
Intertidal sand flats to the north of Parham settlement at the
boundary of the Defence Force Prohibited
Area. Photo: S. Bryars, 21 October 2012.
Cell detail
Cell MA24 is 98 km2 in area and extends about 8 km alongshore
from just north of the Parham
settlement around Middle Spit to Lorne Beach and about 10 km
offshore.
Benthic habitats
The cell is dominated by a mosaic of seagrass types from the
intertidal to offshore (Figure MA24.1,
Table MA24.1). Significant areas of bare sand also occur in the
intertidal.
Seagrass
The spatially dominant seagrass offshore is Posidonia (Tanner
2002).
Reef
None mapped.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
306
Figure MA24.1. Benthic habitats of Cell MA24.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
307
Sand
Bare sand is characterised by sandy/muddy sediments in the
intertidal. The landward sections of
bare sand are categorised as low-energy reflective beaches and
include Parham Beach and Lorne
Beach (Short 2001).
Estuaries
No recognised estuaries occur in this cell.
Table MA24.1. Summary of benthic habitats mapped within Cell
MA24.
(Data were extracted from a benthic habitat GIS layer supplied
by the Department of Environment,
Water and Natural Resources)
Habitat group Habitat type Area (km2) % total cell area
Sand
Sand, Bare, Continuous 7.2 7.4
(Sand Total) (7.2) (7.4)
Seagrass
Seagrass, Continuous, Dense 22.9 23.4
Seagrass, Continuous, Medium 48.3 49.4
Seagrass, Continuous, Sparse 17.3 17.8
Seagrass, Patchy, Dense 0.4 0.4
Seagrass, Patchy, Medium 1.5 1.6
(Seagrass Total) (90.4) (92.6)
Total 97.7 100
Cell values
The cell is utilised for recreational/commercial fishing and
boating. The intertidal seagrass/sand flats
are an important habitat and fishing area for blue swimmer crab
and yellowfin whiting. The subtidal
seagrasses are important habitats and fishing areas for species
such as King George whiting, blue
swimmer crab and southern garfish.
Habitat values
The cell is regionally significant due to the extensive seagrass
meadows and intertidal sand flats.
The cell lies outside of the area assessed for macroalgal
species diversity by Baker and Gurgel (2010).
Bryars (2003) listed 11 fish and five macroinvertebrate
fisheries taxa for the seagrass habitat
between Macs Beach and the Firing Range, 13 fish and six
macroinvertebrate fisheries taxa for the
unvegetated soft bottom habitat between Macs Beach and the
Firing Range, and eight fish and five
macroinvertebrate fisheries taxa for the tidal flat habitat
between Macs Beach and the Firing Range.
While the seagrass and sand habitats are likely to support a
range of species (e.g. see Bryars 2003),
apart from mapping studies that have characterised the benthos
(e.g., Shepherd and Sprigg 1976,
Tanner 2002), very few biological surveys appear to have been
undertaken on these habitat types
within the cell.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
308
Threats
The immediate coastline is unpopulated and there are no direct
freshwater inputs to the coast. Thus,
there is unlikely to be any land-based threat from
nutrients/sediments.
The cell lies within the southern part of the Defence Force
Prohibited Area which is used at times for
bombing exercises. A study showed that seagrasses were being
impacted by the bombing activities
with holes created in the seagrass meadows (URS 2003).
Off-road vehicle use presents a potential threat to the
intertidal sand/seagrass habitats in the area
(Bryars 2003, Purnell et al. 2010).
Threat analysis
Risk ratings for identified threats to seagrass and sand were
low (Table MA24.2). Reef was not
assessed as it does not occur within the cell.
Table MA24.2. Results of threat analysis for Cell MA24.
Threat
Habitat
Seagrass Reef Sand
C L RV RR C L RV RR C L RV RR
Physical disturbance (bombing)
1 4 4 L
Physical disturbance (off-road vehicle use)
1 4 4 L 1 4 4 L
It was considered possible (L=4) that physical disturbance of
seagrass from bombing within the
defence firing range could have a minor consequence (C=1). Thus
the risk rating was low (RV=4).
However, the precise extent and nature of bombing activities is
unknown.
It was considered possible (L=4) that physical disturbance of
intertidal seagrass and sand from off-
road vehicles could have a minor consequence (C=1). Thus the
risk rating was low (RV=4).
Actions and Priority
Table MA24.3. Recommended actions and priority for Cell
MA24.
Component Issue Proposed action Priority of action
Key players
Sand, Seagrass
Off-road vehicles in intertidal
Support initiatives to reduce off-road vehicle use
Low District Council of Mallala / AMLRNRM Board
Sand, Seagrass
Bombing in Defence Force Range
Liaise with Defence Force to better understand nature of bombing
and potential threat
Low District Council of Mallala / AMLRNRM Board / Defence
Force
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
309
Further investigations
Further on ground investigation of the impact of Defence Force
activities on seagrass habitats may
be warranted.
Biological surveys of seagrass and sand habitats would be useful
to better understand habitat values
and to compile meaningful species lists for the cell.
-
Bryars (2013) Nearshore marine habitats of the AMLRNRM region:
values, threats and actions
310
(This page is intentionally blank)