Biophysical Survey of Mafia Island Marine Reserves

2. Coral Reef Habitats
Benthic Composition
Benthic composition data were collected in conjunction with reef fish and
invertebrate abundance. Surveyors recorded the benthic or substrate type every 0.5m
starting at 0.5m along a 25m transect set at a constant depth. This resulted in the
collection of 50 points per transect. Transects were laid along the reef at various depths
from 4 to 12 m. Depths depended on the topography of individual reefs. The total number
of surveys carried out depended on the extent of the reef, but at least four transects per
depth were laid in each reef habitat assessed at a minimum of four sites. Two or more
depths were surveyed for each reef habitat. GPS positions were taken for the entry points
for all transect survey dives. Composition data were collected using the categories listed
below in Table 2.
Table 2. Benthic composition categories and associated codes
Category Code Category Code
HARD CORAL: ALGAE
Branching HCBR Turf Algae - Rubble TARK
Columnar HCC Turf algae - Rock TARB
Plate HCP Nutrient Indicator Algae NIA
Encrusting HCE Coralline algae CCA
Foliaceous HCF Macroalgae MA
Massive HCM ABIOTIC
Sub-massive HCSM Sand SA
Solitary HCS Rubble RB
Bleached Coral BL Rock RK
OTHER BIOTIC: Silt ST
Soft coral SC Dead coral DC
Sponge SP
Other Benthic Organisms OBO Other OT
Seagrass SG