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What do science is all about? Science is everything around us. My first impression on science was that it is an endless fact! To me, science need a lot of studies so that its realibility cannot be argued. The knowledge we today can still be altered. Thus, as none has proven otherwise wrong, and still as that was the very best our scientists' explanation can come up, so guys just accept it, whether you like it or not. But no worry, science is most of the time is fun. Cheers!

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Cockles, a morphology study

Cockle is a bivalve belonging to the family Arcidae. Cockles (scientific name Anadara Granosa) or blood cockles or locally known as ‘kerang’ is one of the bivalve species that is commercially cultured in Malaysia.

Its production accounts for more than 85% of the total aquaculture production, (Department of Fisheries, Kuala Lumpur, Rabihah Mahmood , 1989). Study conducted by Malaysia’s Department of Fisheries in 2004 conclude that a total of 64,564.75 tonnes of cockles was produced nationwide which total up revenue of RM54, 214, 980. This has been made possible by the abundant supply of natural seeds, extensive areas of mudflats on the sheltered west coast of Peninsular Malaysia suitable for cockle cultivation, and the favorable market demand.

Growth rate of culture cockle is affected by environment conditions and population density. Pathansali (1966) found that on culture beds, at a density of 525 – 1050/sq.m a size of 18–32 mm was attained in 10–12 months. Pathansali and Soong (1958) found that on natural beds where the density was less than 10.5/sq.m, A. Granosa grew from 4–10mm to 18–32 mm in nine months. Broom (1985) also confirmed that both density and exposure affect the growth of the culture cockle.

Cockles are found in muddy areas. They can live in 20 m water depth but concentrates in the littoral area (time for ground drying: 6 - 10 hours/day and night). (Tran Hoang Phuc Fisheries Review No-6/1997). Cockles is a typically intertidal species which naturally lives in an area of silty bottom with relatively low salinity and some time of desiccation every day (Kuang et al., 1995). Their feeding habit is related to the bottom feed where they live. Their important nutrient components are organic detritus (98% were found in cockle's intestine), phytoplankton and unicellular algae. (Tran Hoang Phuc Fisheries Review No-6/1997).

Anadara Granosa reproduces from August to February. One female can produce 518,400 - 2,313,200 eggs. (Tran Hoang Phuc Fisheries Review No-6/1997). They can be adaptable to salinity of 14 - 300 and optimum temperature ranging from 20 - 30°C. (Tran Hoang Phuc Fisheries Review No-6/1997).

In Malaysia, cockles industry is bound to Fisheries (Conservation & Culture of Cockles) Regulations 1964. This regulation is for the management, control and licensing of collection of adult cockles and cockle spats from natural spatfall areas and cultured areas. The minimum size for collection of adult cockles and cockle spats is also determined in this regulation, and there is also a fee charged for the license to collect cockles. It is stated in Article 6 - (1) No cockle which is less than ¼ inch, measured in a straight line across the widest part of the shell, shall be taken for the purpose of transplanting to a cultured cockle bed. (2) No cockle which is less than 1 ¼ inches, that is equivalent to 3.175 cm, measured in a straight line across the widest part of the shell shall be taken for consumption.

Bivalves are known to have the ability to accumulate metals (Darracot & Watling, 1975). Since cockles accumulates heavy metals in their soft tissues and constitutes one of the important food chains in the coastal environment, it is therefore useful in predicting any metal contamination in the coastal communities. Heavy metals tend to accumulate in specific tissues through filtering process. Cockles are able to accumulate heavy metals with the bioconcentration factor reaching up to 10⁶ (Nur Fajar Yanta, 2000). Ecotoxicological studies show that metal accumulation depends on the size of the mussel; different tissues show different tendencies to accumulate metals; and metals influence physiological responses including the filteration rates and growth.

In comparison to fish and crustaceans, cockles have a very low level of activity of enzyme systems capable of metabolizing persistent organic pollutants such as aromatic hydrocarbon and polychlorinated biphenyls. Therefore contaminants concentration in the tissues of cockles more accurately reflects the magnitude of environmental contamination (Philips, 1977, 1980, 1990).

Reference

Alias Mohd. Yusof, N. F. Yanta and A.K. H. Wood, (2003), The Use of Bivalves as Bio-Indicators in the Assessment of Marine Pollution Along a Coastal Area, Journal of Radioanalyical and Nuclear Chemistry, (Vol. 259), pg. 119-127.

Anonymous, Fisheries (Cockles Conservation and Culture) Regulations, 1964, pg. 106, Retrieved April 8, 2007 from http://faolex.fao.org/docs/pdf/mal4801.pdf

Anonymous, (2001), Food Regulations 1985 : Fourteenth Schedule, Laws of Malaysia: Food Act and Regulations (Act 281) (9th ed.), MDC Publishers Printers Sdn. Bhd., Ulu Kelang, Kuala Lumpur, pg. 219.

Bay of Bengal News, Better management through better Knowledge: BOBP cockle activities in Malaysia, Issue No. 26, June 1987.

Bay of Bengal News, Cockles Culture in Malaysia, Issue No. 18, June 1985.

Broom M.J. (1985), The biology and culture of marine bivalve of Genus Anadara. ICLARM Studies and Review 12:37pp. Retrieved December 20, 2006 from http://www.fao.org/docrep/field/003/AB887E/AB887E07.htm#ch7.

Extoxnet, (Revised 9/93), Toxicology Information Brief, Bioaccumulation, Retrieved September 15, 2006 from http://extoxnet.orst.edu/tibs/bioaccum.htm

Fisheries Informatics Centre (Vietnam’s Ministry of Fisheries), (1997), Tran Hoang Phuc - Fisheries Review No-6/1997 Biological characters and technique of oyster Anadara granosa culture at Tra Vinh coastal water, Retrieved December 2, 2006 from http://www.fistenet.gov.vn/details_e.asp?Object=2113515&News_ID=5385895

Kuang, S, J. Fang, H. Sun & et. al. (1995), Preliminary Study on Suitable Environ-mental Conditions for Embryonic and Larval Development of Blood Clam Tegillarca granosa. In: Annual Report (1995) of National Climb B Plan 'Fundamental Studies on Improving the Germplasm and Disease Resistance of Mariculture Species'. pp127-134.

Malaysia’s Department of Fisheries, (2004), Estimated Aquaculture Production by State and System, Retrieved April 8, 2007 from http://www.dof.gov.my/v2/fperangkaan/perangkaan2004/14_1.htm

Malaysia’s Department of Fisheries, (2004), Estimated Wholesale Value fo Aquaculture Production by State and Culture System, Retrieved April 8, 2007 from http://www.dof.gov.my/v2/fperangkaan/perangkaan2004/14_2.htm

Pathansali, D. (1966). Notes on the biology of the cockle Anadara Granosa Proc. Indo-Pac. Fish. Counc. 11:84–98. Retrieved December 20, 2006 from http://www.fao.org/docrep/field/003/AB887E/AB887E07.htm#ch7.

Pathansali, D. and M.K. Soong. 1958. Some aspects of cockle (Anadara granosa L) culture in Malaysia. Proc. Indo-Pac. Fish. Counc. 8:26–31. Retrieved December 20, 2006 from http://www.fao.org/docrep/field/003/AB887E/AB887E07.htm#ch7.

Rabihah Mahmood, (1989), Report of the Workshop and Study Tour on Mollusc Sanitation and Marketing, Status and Problems of Mollucs Production, Sanitation and Marketing in Malaysia, Retrieved January 3, 2007 from http://www.fao.org/docrep/field/003/ab710e/AB710E17.htm

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