International Journal of Aquaculture, 2017, Vol.7, No.25, 166-173
166
Research Article Open Access
Some Metal Elements Concentration in
Malletia cumingii
(Hanley, 1860)
(Bivalvia) in Okpon River, Cross River State, Nigeria
Fidelis Bekeh Ada
, Eyom IbiamAsira
Dept. of Fisheries and Aquatic Sciences, Faculty of Agriculture and Forestry, Cross River University of Technology, Obubra Campus, Cross River State, Nigeria
Corresponding author Email
International Journal of Aquaculture, 2017, Vol.7, No.25 doi
Received: 16 Aug., 2017
Accepted: 06 Sep., 2017
Published: 31 Dec., 2017
Copyright © 2017
Ada and Asira, This is an open access article published under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Ada F.B., and Asira E.I., 2017, Some metal elements concentration in
Malletia cumingii
(Hanley, 1860) (Bivalvia) in Okpon River, Cross River State, Nigeria,
International Journal of Aquaculture, 7(25): 166-173 (doi
Abstract
Molluscs are important food item all over the globe. They have been harvested from the wild and some cultured for food;
such that 20% of aquatic animal protein comes from molluscs. They have also been widely used as indicator of pollution. On the
other hand, many are intermediate hosts of parasitic disease of many animals and man.
Malletia cumingii
is usually harvested in
Okpon River, a tributary of Cross River in Cross River State of Nigeria. Because of the value of Molluscs as indicator of pollution,
this species was analyzed to ascertain the metal elements concentration levels for reason that some of these metals are toxic to man.
Samples were collected from three locations along the River. Sampling was done two times to include the two main seasons of the
year (dry and wet seasons). The samples were oven-dried (MAMMART) at 100°C and were pounded in mortar to powder form.
Metal concentrations were measured using flame photometer (RP 7) and atomic absorption spectro-photometer. Metals analyzed
included Copper, Cadmium, Chromium, Iron, Manganese, Nickel, Lead, Zinc, Calcium and Magnesium at different wavelengths.
Results showed that metal concentration was increasing from the upper reaches of the river downward except zinc. It was suggested
that zinc have a point source in the upper reaches while others metals were added to the water body by anthropogenic activities.
However, the concentration of the metals did not reach toxic level in the molluscs for human consumption.
Keywords
Metal elements;
Malletia cumingii
; Okpon River; Concentration; Toxicity; Cross River State
1 Background
The study of molluscs is always an important one as molluscs are used as human, aquatic and many terrestrial
animals’ food (Gupta and Gupta, 2006). Because of their importance in human food, they are used in Aquaculture
to create a net gain in protein to help alleviate the fishing pressure on feral fin fish. Nine million, one hundred
Metric tonnes (22 percent) of Aquaculture products in 2014 A.D. were molluscs (FAO, 2016). Unlike carnivorous
fish, which need a fish-based food, molluscs feed on diet based on plant materials. Molluscs feed both in natural
and artificial environments. They are less expensive because they are of low trophic level (Simpkins and Williams,
1989; Okon and Ibom, 2012). Sequel to this, species like Pacific oyster (
Crassostrea gigas
), Japanese carpet shell
(
Ruditapes philippinarum
), Yesso scallop (
Patinopecten yessoensis
), blue mussel (
Mytilus edulis
) and the blood
cockle (
Anadara granosa
have been cultured). Contribution of molluscs to world food fish Aquaculture in 2013
was 20.10% by weight (15.5 million metric tons) and 13.80 % by money value (20.7 USD) (FAO, 2015).
Many serve as intermediate hosts of parasitic helminthes (David, 1994; Ntonifor and Ajayi, 2007; Abe, 2010;
Kalu et al., 2012). They are also identified as the most appropriate group of organisms to be used as
environmental bio indicators because of the following qualities. They are cosmopolitan in distribution, individuals
have limited mobility, exhibit wide variation in life cycle strategies such that a particular strategy can be
monitored, their sizes are large enough, absence of external and internal skeleton bring them closer to their
environment and have limited ability to excrete pollutants directly via their kidney or other excretory tissues, they
are sensitive to environmental chemicals, simple and well and well known internal organisation an quantities of
the pollutants are measurable in their tissues, organs or whole organism (Oehlman and Schutle-Oehlman, 2003).
Modification or changes in environment is a continuous phenomenon. Altering their habitat affects survival
(Ayotunde and Ada, 2013). Direct destruction of some of these habitats because of agricultural and urban
