International Journal of Marine Science, 2016, Vol.6, No.11, 1-10
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2.2 Sampling methodology
The present study was carried out in the month of March and April, 2014. The burrows were selected randomly in
the direction of upper to lower part of sandy shore. The unsaturated resin was poured in the burrows until the
burrows were totally filled during the low tide. Crab if, emerged from that burrow was collected and classified
according to the sex and the carapace length (CL) was measured using digital vernier calipers (± 0.01 mm;
INSIZE Model No. 1137-150). When the burrow cast were solidified (approximately after 1 hour), they were dug
out and brought to the lab for further measurement. The casts were cleaned to remove the sediment from the
surface. Only complete casts were used for analysis. The burrows were classified according to their shape and
various measurements like opening diameter (OD), burrow Inclination angle (IA), total depth (TD), total length
(TL), horizontal length (HL), length, diameter and depth of various branches of the burrows and length and width
of burrow chambers were measured (Figure 2). The burrow volume was measured by weighing the burrow (±
1gm) and dividing the burrow weight with the density of the unsaturated resin (0.96 gm/cm
3
).
Figure 2 Burrow architecture of
Ocypode ceratophthalmus
with various measurements of burrow cast. a. J shape, b. J shape with
branch at the base, c. Bulb shape, d. Single tube burrow, e. U shape burrow, f. Multi branched burrow, g. Y shape with double
opening, h. Y shape burrow. (O. D. - Burrow opening diameter; T. D. – Total depth; T. L. – Total length; I. A.: Burrow inclination
angle; H. L. – Horizontal length; C. L. – Chamber length; C. W. – Chamber width; B
1
L – Branch 1 length; B
2
L – Branch 2 length; B.
A. – Branch inclination angle; DPA– Depth of primary arm; DSA – Depth of secondary arm; DEB- Depth of extra branch)
Variation in sediment temperature was measured along the depth of the burrow in the afternoon low tides.
Burrows with different opening sizes were selected randomly. The diameter of the burrow openings was measured
using vernier calipers (±0.1 mm) and the sand surface temperature at the burrow opening was measured using a
digital thermometer (Eurolab ST9269B, ± 0.1°C). The temperature of sediment was measured at every 5 cm depth
interval up to the depth of 25 cm. Temperature measurements could not be recorded beyond the depth of 25 cm
because of the limited length of probe of the instruments.
