Fremantle Port Inner Harbour and Channel ... - Fremantle Ports

3. Monitoring Sites
3.1. Water Quality Overlying Seagrass and Coral
Sites to monitor water quality overlying seagrass and coral have been located in BPPH
management zones in each of five regions, as well as at reference sites (Figure 3.1). These
regions are:
• The Deep Water Channel;
• The Offshore Disposal Area;
• Rous Head and north of the Harbour Entrance;
• South of the Harbour Entrance; and
• Hall Bank corals.
As described in the DSDMP (Fremantle Ports, 2009), the monitoring site locations are based
on BPPH management zones defined by modelling of seagrass and coral minimum light
requirements. The management zones shown in Figure 3.1 are:
• Zone of Loss (ZoL - < 30% minimum light requirement);
• Zone of Effect (ZoE - 30 to 100% minimum light requirement); and
• Zone of Influence (ZoI – total suspended solids (TSS) – 2 mg/L above background for
any 3 hour duration throughout the dredging period).
The locations of water quality monitoring sites overlying seagrass shown in Figure 3.1 are
based on habitat mapping that was ground-truthed in December 2009 (Oceanica,
unpublished), as per the matrix of regions vs. management zones shown in Table 3.1 (and
rationale described in the DSDMP).
The locations of water quality monitoring sites overlying corals shown in Figure 3.1 are at the
northern and western sections of Hall Bank. The two sites overlie coral communities of similar
benthic cover, species composition and depth distribution. There are no known reference
sites for Hall Bank corals in the Perth metropolitan region.
Table 3.1
Matrix of BPPH management zones vs. seagrass and coral monitoring sites
Region Zone of Loss Zone of Effect
Zone of
Influence
Reference Total
Seagrass Sites
Deep Water
Channel
- 2 sites 2 sites 2 sites 6
Offshore
Disposal Area
- 2 sites 2 sites 2 sites 6
Rous Head and
north of the
Harbour
2 sites 2 sites 2 sites 2 sites* 8
Entrance
South of the
Harbour
- 2 sites 2 sites 2 sites* 6
Entrance
Total 26
Coral Sites
Hall Bank Corals - - 2 sites - 2
Total 2
* Note that these reference sites as shown in Figure 3.1 are within the Zone of Influence; however, it is not
anticipated that these sites will be impacted by the dredge plume. In the unlikely event that one of these
reference sites shows any influence from dredging (e.g. via aerial observations and comparison to other
reference sites), then it shall be relocated.
3.2. Return Water Plume
Water samples will be taken at six monitoring sites along a plume transect at increasing
distance from the return water outlet / weir box, with an example shown in Figure 3.1 and
Figure 3.2. The transect will follow the approximate trajectory of the plume and therefore
Oceanica: Fremantle Ports: Inner Harbour and Channel Deepening - Water Quality Monitoring Program 5