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International Journal of Marine Science 2015, Vol.5, No.9, 1-4
http://ijms.biopublisher.ca
3
Table 1 Phytoplankton composition in the gut of mussels preserved in four difference preservatives
Formaldehyde and
glutardialdehyde
Lugol’s solution
Alcohol
Filtered seawater
Average phytoplankton abundance (10
2
cells ml
-1
)
7.3±1.2
6.9±0.3
1.8±0.5
0.35±0.32
Composition (%)
Cascinodiscus
sp.
20.5
22.3
35.3
40.3
Bacteriastrum
sp.
18.2
15.1
1.5
-
Chaetoceros
sp.
16.9
15.2
2.8
-
Thalassionema
sp.
10.3
10.5
14.1
4.2
Pleurosigma
sp.
8.3
9.1
10.2
19.8
Rhizosolenia
sp.
5.9
7.2
15.3
21.3
Neoceratium
sp.
6.2
6.8
7.1
8.1
Nitzschia
sp.
3.2
3.5
0.2
-
Lauderia
sp.
3.0
3.1
2.8
1.3
Leptocylindrus
sp.
2.7
3.0
5.8
1.5
Others
4.8
4.2
5.9
3.5
The result of current study demonstrated partially
degradation of phytoplankton cells in the sample
collected from the gut of mussels preserved with 70%
alcohol. Alcohol is not a suitable preservative in
preserving gut content of bivalve, because moderate
concentration of alcohol (70%) could kills the bivalve
quickly within 1 minute. This results in limited
amount of preservative access to the stomach contents
of mussel (Navarro, 2005). Although the low
temperature slowed down the degradation process, the
long transportation time of 4 hours significantly
reduced the quality of the samples. Since most of the
laboratories are often located far from the study areas.
Therefore, preservative that can offer better
preservation quality for longer time is desirable.
Phytoplankton cells collected from the gut of mussels
in the sample that preserved with Lugol’s solution and
formaldehyde- glutardialdehyde mixture were in good
condition.
Mixture
of
formaldehyde
and
glutardialdehyde was found to be the best preservative
for gut content of bivalves. In fact, formalin is
generally the preferred fluid for fixation and is
widely used. The mixture of formaldehyde and
glutardialdehyde is believed to be the optimal
preservative of animal tissues (formaldehyde) and
feature of phytoplankton cells (glutardialdehyde)
(Navarro, 2005). Mixture of formaldehyde and
glutardialdehyde also can preserve the cell wall
structure of phytoplankton and last for many years in
good condition without attention. However, The
International Agency for Research on Cancer branch
of the World Health Organization classifies
formaldehyde and glutardialdehyde as carcinogenic in
humans and it has been demonstrated to contribute to
respiratory pathologies, allergies and respiratory tract
cancers (Kerns et al., 1983). Enactment of the
Formaldehyde Standard (29 CFR 1910.1048
Formaldehyde) law in the US in 1987 also raised
awareness that formaldehyde is a potential carcinogen
worldwide (Titford and Horenstein, 2005). Exposure
to high levels of formaldehyde can cause
accumulation of fluid in the lungs, severe shortness of
breath, bronchitis and rapid heart rate. Exposure to
low levels can irritate, and burn the eye, nose, throat,
and skin (Nogueira et al., 1997; Infante et al., 1981).
Therefore, analyzing samples preserved with
formaldehyde might put researchers in healthy risk as
they are dealing with highly carcinogenic chemicals.
Interestingly, the result of current study demonstrates
that the phytoplankton abundance and composition
recorded in gut of mussels preserved with Lugol’s
solution were similar to that preserved in the mixture
of formaldehyde and glutardialdehyde. This suggests
Lugol’s solution has high potential as an alternative to
formaldehyde and glutaraldehyde for preserving gut
content of bivalves. Ten minutes exposure of bivalve
to Lugol’s solution allowed the chemical access to the
gut contents. Then, storing the mussels in cold water
kill the mussel by temperature shock and therefore
stop the secretion of new enzyme and minimizing the
enzymatic activities in the gut of mussels (Khessiba et
al., 2005). In addition, the result of current study also