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

3.2 Seagrass recovery3.2.1 Seagrass density baseline dataDuring the Phase I survey, mean shoot counts for P. angustifolia ranged from 12 shoots perm 2 (at site 37D) to 407 shoots per m 2 (at site SH50) (Figure 3.4). Summarised seagrassshoot density data are included as a table within Appendix E.500450400350Shootcount(m 2 )300250200150100500Disturbed Transition UndisturbedBars indicate mean (n=15) ± 2 seFigure 3.4Baseline mean seagrass shoot countsSeagrass shoot density within each zone ranged from:12-240 shoots per m 2 at disturbed sites;100-293 shoots per m 2 at transition sites; and257-407 shoots per m 2 at undisturbed sites.Seagrass shoot density data from IHD baseline ('undisturbed') sites (SH32, SH50 and SH51)collected in November 2010 were between 591-605 shoots per m 2 , which are about twice thedensity recorded in the same undisturbed sites of this survey (257-407 shoots per m 2 ).Results from this survey are within the overall range in shoot densities (284-630 shoots perm 2 ) recorded throughout the IHD monitoring program at sites SH32, SH50 and SH51 and arecomparable and within the range of 'natural' variability in seagrass density previouslydescribed for this depth (Oceanica 2010c).Statistically significant differences (P values < 0.05) in mean seagrass shoot density occurredbetween all zones (undisturbed, transitional and disturbed) (Table 3.2 and Table 3.3).Oceanica: Fremantle Ports: FP – Gage Roads Offshore Disposal Area Seagrass Recovery Project, Phase I – Initial Survey 23