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

3. Results3.1 Benthic habitat mapA satellite image was taken on 25 December 2011 which had adequate coverage of theOffshore Disposal Area and surrounds. Benthic habitats were delineated using this image andground-truthing data to produce a localised post disposal benthic habitat map of the OffshoreDisposal Area (Figure 3.1).The total spatial extent of seagrass documented during the IHD baseline study was estimatedat a total of 71.9 ha of seagrass habitat within the Offshore Disposal Area and surroundingpredicted zone of potential loss, and predicted zone of potential effect (Section 1.1;Figure 1.2). This survey found an estimated total of 52.03 ha of seagrass habitat withinthese same areas (Table 3.1). This represents an estimated loss of 19.9 ha of seagrasshabitat. The majority (76%) of seagrass habitat loss occurred within the Offshore DisposalArea.The information from this benthic habitat map was combined with IHD post disposal benthichabitat map to update the benthic habitats in the Gage Roads area (Figure 3.2). Thechanges in benthic habitat areas are shown in Figure 3.3.Table 3.1Seagrass habitat loss with the Offshore Disposal Area, Zone of Potential loss andPotential EffectZoneOffshore Disposal Area(Direct loss)Pre disposal seagrasshabitat (ha) - Dec 2009Post disposal seagrasshabitat (ha) - Dec 201115.4 0.03 14.9Potential Loss 7.9 6.7 1.2Potential Effect 48.7 45.3 3.4Total Habitat 71.9 52.03 19.9Habitat loss (ha)Oceanica: Fremantle Ports: FP – Gage Roads Offshore Disposal Area Seagrass Recovery Project, Phase I – Initial Survey 19