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International Journal of Marine Science 2014, Vol.4, No.61, 1-13
http://ijms.biopublisher.ca
7
Figure 4 Distribution of grid inhabited by scallop based on the eco-geographical variables in Brebes District: a. sedimen dasar
perairan (seabed sediments, φ); b. bathimetri (bathymetry, m); c. jarak dari muara sungai (distance from estuary, km); d. materi
padatan tersuspensi (TSS, mg/L); e. kecepatan arus dasar perairan (seabed current velocity, m/sec); f. suhu dasar perairan (seabed
temperature, °C); g. salinitas dasar perairan (seabed salinity, ‰); h. pH dasar perairan (seabed pH); and i. kepadatan plankton dasar
perairan (seabed plankton density, ind/L). Persentase grid=Grid percentage (%), Area studi=Study area, Simping=scallop, Pasir
Lumpuran=Muddy Sand, Lanau=Silt, Lumpur=Mud
size of study area (m = 0.312). Marginality coefficient
of the estuary distance variable was relatively smaller.
This showed that scallop habitat just slightly different
from the average of study area for that variable.
Marginality values of the five variables were able to
explain 59.1 % of the overall variability of the data
(Table 3).
Specialization coefficient indicated that the habitat of
scallop had a relatively narrow range in the distance of
estuary (-0.747), depth (0.458) and plankton density
(
-
0.422) (Table 3). This proved that the ecological
niches of scallop were relatively limited to three variables.
Although the data of current velocity, temperature,
salinity and pH of the seabed were available, but due
to the narrow range of possible values, these variables
were not included in the ENFA (Leverette, 2004).
Mean value comparison technique and Kolmogorov-
Smirnov test between the study area and the location
where the scallop on each variable could be used to
assess the trends in habitat preference. As a result, the
mean current velocity at the location inhabited by
scallop was higher than the mean current velocity of
study area. Same case happened with the average
value of salinity. In contrary, the average temperature
at the location of scallop was lower than the average
temperature of the study area. While the average pH
value was relatively similar between the study areas
with the location inhabited by scallop (Table 4).
Kolmogorov-Smirnov test results showed that
between the location inhabited by the scallop and the
entire study area were significantly different for all
environmental variables applied (p <0.05, Table 5).
This was also evidenced by the large value of Total
Specialization (3.822), while the value of its Total
Tolerance was relatively low (0.262) (Table 2),
indicating that the scallop had a narrow ecological
niche and had a relatively low tolerance towards its
environmental conditions.