Surveys in the Marshall Islands
NRAS surveys include recording fish, coral, invertebrate and seaweed data on a series of 4 transects; 2 divers work on each of the four transects that are located at predetermined depths. The transect method was chosen to represent the characteristics of the whole site, over a range of depths (between 5 to 20 m) to give a wide enough coverage on different zones on the reef . Each diver would swim the transect four times, accomplishing different duties at a time.
A 50 m tape measure is
used as a marker so the same transect would be covered on return swims
from one end of the transect to the other. 20 meters is the maximum
depth for the deep transect, allowing enough time for the pair of scuba
divers to complete the work without going in to decompression time. On
each transect two scuba divers collect the information. Each diver has
two jobs, accomplished by two separate transect swims.
DATA (belt transects). Fish counts are undertaken by one scuba diver,
swimming along the 50 m length measuring tape. The fish surveyor swims
along the designated depth contour recording fish while the buddy lays
the tape measure behind. Fish surveyors record all target fish, within
an estimated box of 5 meters, 2.5 m to either side of the tape, 5 m
above and 5 m forwards. The target fish are recorded at family and
species level. The fish species recorded are estimated into three size
classes: A 6-10cm, B 10-20cm, C >20cm. The meandering swimming
pattern allows to record the smaller species and the sedentary species.
LINE INTERCEPT TRANSECT (LIT). LITs are carried out according to
AIMS-ASEAN methodology with minor adjustments (English, 1997).
Recorders note all features at two levels, AIMS-ASEAM life-forms and
target coral genera or species. The coral data is collected by a diver,
swimming along the length of the 50 m measuring tape and recording the
substrate below the tape at every 50 cm.
SEAWEED DATA COLLECTION. A quadrat of 25 cm x 25 cm dimension is placed next to the transect at the 10 m, 20 m, 30 m, and 40 m marks. Density or percentage coverage is estimated inside the quadrats and averaged for each depth. Target genera and larger groups are identified. Samples of seaweeds are taken for preservation and cataloguing at the library of the College of the Marshall Islands.
English, S. A., C. R.
Wilkinson, and V. J. Baker (eds.) 1997. Survey manual for tropical
marine resources. Australian Institute of Marine Science, Townsville.
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