For this reason, fast growing and quick to recover hydroids (Bradshaw et al., 2003 and Harris, 1975) were excluded from overall assemblage analyses and were analysed separately. To account for geographic variation, 12 areas were identified across the bay, which contained reef and pebbly sand habitat. 5 areas were selected in the MPA, and 7 areas in the OC, with 2 replicate sites in each area. All areas were sampled in 2008 and 2011 giving a total of 24

sites for each MAPK inhibitor year. The position of transects were haphazardly selected within each site by starting the video tow at the site GPS and allowing the wind and tide to dictate the direction of the transect. A towed flying video array with selleck compound mounted High Definition

HD video was used to survey each site, which constituted a 200 m transect over heterogeneous and sensitive benthos (Sheehan et al., 2010). The HD video system included a camera (Surveyor-HD-J12 colour zoom titanium, 720p), LED lights (Bowtech Products limited, LED-1600-13), two green laser pointers (Z-bolt Scuba-1) and a mini CTD profiler (Valeport Ltd.). An umbilical connected the video system topside to a Bowtech System power supply/control unit allowing control of light intensity and camera focus, zoom and aperture. The camera was positioned at a 45° angle to the seabed, with the three lights fixed in front and below the camera to provide improved image definition and colour. The lasers were used to quantify field of

view (Freese et al., 1999) and were positioned parallel to each other. Species counts were determined by viewing each video transect ‘site’ at normal speed, recording every identifiable organism that occurred on pebbly sand habitat if it passed through the ‘gate’ formed by the 2 laser dots. All organisms present were identified to the highest taxonomic level possible and their abundance recorded. Taxonomically similar species, which could not be distinguished with confidence, were grouped, such as branching sponges and hydroids. To calculate the area of pebbly sand per video transect, the occurrence of observable pebbly Sclareol sand was timed regardless of whether species were present or not. The area of each transect was calculated by multiplying the length of the tow by the distance between the laser gate, which was set according to water visibility (good visibility = 45 cms; bad visibility 30 cms). The transect area was then divided by the total time of each transect and multiplied by the amount of pebbly sand time, giving the area of pebbly sand per tow. Species counts could then be calibrated per tow to estimate density (individuals m−2).