Environmental Engineering Reference
In-Depth Information
The microtopography of the periostracum of mussel shells has been shown to be
capable of exhibiting foul-resistance and foul release properties. In addition the
mussel may be releasing chemicals which may prevent biofouling. The elastic modulus
of the periostracum of
Mytilus galloprovincialis
has been reported to be 100 MPa
whereas that of PMMA is about 3.7 GPa which could also inluence the interfacial
strength [27].
During the growth of the barnacle its base-plate enlarges in a horizontal direction
whereas the parietal plate grows in a downward direction. Because the cement cells
of the barnacle are the modiied epidermal cells, the secretion of cement is linked to
its moulting cycle. The secretion takes place between consecutive moulting cycles
at the periphery of the base-plate. The low viscous cement lows and spreads itself
to ill any gap between the base-plate and the solid substrate. When the base-plate
grows further, new active cement glands are formed at the periphery and the old
ones stop secreting. So, they lay embedded in the hardened cement still carrying the
non-solidiied liquid adhesive inside them. So, the cured cement appears as discrete
concentric rings throughout the base-plate. It has been reported that this underwater
adhesive produced by a barnacle is a multi-protein complex and the underwater
attachment is a multi-functional process [1].
The chemical composition of the cements retrieved from different barnacles is listed in
Table 4.5
. The lipid and protein content between each cement is signiicantly different.
The table also shows the composition of the cement recovered from
Amphibalanus
reticulatus
attached on PMMA and on mussel shell. Considerable differences in the
composition are observed in the cements removed from different surfaces indicating
that this organism produces cement of different composition depending upon the
surface on which it attaches itself to.
Figure 4.3
shows the Fourier-transform infrared
(FTIR) spectra of the cements removed from PMMA and a mussel shell [28].
Table 4.5 Chemical composition (%) of the analysis of three cements from
A. reticulatus and their comparison with the literature reports from different
barnacle species
Type of cement
Carbohydrate
Lipid
C
H
N
Protein
Barnacle
RC
19
0.33
50.63
4.71
4.71
89.4
A. reticulatus
P-C
4
0.10
33.5
3.76
9.29
58.1
A. reticulatus
MSP-C
0.25
0.10
27.46
0.96
1.3
28.2
A. reticulatus
Normal cement
2
8.2
41.05
5.96
11.15
69.7
Lepadidae fascicularis
Normal cement
−
0.69
−
−
−
84.4
Balanus crenatus
Normal cement
−
−
−
−
−
85.9
Balanus nubilus
Normal cement
−
2.74
−
−
−
70
B. nubilus
