Biophysical Survey of Mafia Island Marine Reserves

Occasionally, proofing did not confirm either patch boundaries or patch type.
Consequently, patch types and boundaries were revised. This then directed the selection
of locations for further proofing. This process was repeated until a consensus was
reached; the image was then processed to create a final patch mosaic. Each patch was
assigned a colour to denote the patch type, finally resulting in the delineation of the
habitat present in each marine reserve area. It should be noted that a high resolution
satellite image was only available for the purposes of this report for NIMR. The images
used for the basis of the patch mosaic creation for SIMR and MBIMR were of far lower
resolution.
Ground Proofing Methodology (High Resolution Satellite Image - NIMR)
Ground proofing transects perpendicular to a series of biophysical features were
conducted by snorkel and SCUBA diving. These were designed to provide habitat cross
sections and geo-referenced patch boundaries which could be overlaid onto the high
resolution satellite image. Along these transects, benthic composition data was collected
(Table 2). For SCUBA, benthic composition was recorded every two meters. For snorkel,
percentage composition was recorded for each habitat patch transversed. Habitat patches
were then created and categorised according to the habitat categories described in
Appendix 1. All transects were GPS tracked so they could be overlaid onto the image.
Table 1. A sample of dive transect data including the prescribed habitat categories (Appendix 1) and
benthic cover types (Table 2).
TRANSECT 1
Meters 0 2 4 6 8 10 12 14 16 18 20 22 24
Cover Type SC SC SC HM RK SC SC HM MA MA HCBR HCBR HCBR
Habitat Type REEF SLOPE
ALGAL
RIDGE ACROPORA COMM
Meters 26 28 30 32 34 36 38 40 42 44 46 48 50
Cover Type SG SG SG SA SG SG SG SG SG MA SA RB SA
Habitat Type
SEAGRASS
BEDS LAGOONAL -
Additional data were collected by spot checks using snorkel, SCUBA and
percentage composition data using manta tows. Also, benthic composition data were used
from benthic composition data collected from the species survey section of this report.