Biography:

Abstract:

Fluoride affects large number of processes including photosynthesis, respiration, and protein synthesis and enzyme activities of higher plants, green algae and bacteria. It significantly inhibits the growth of crab, fish, shrimp and bivalve. Also, it inhibits the wide variety of ATPases, including the bacterial ones. It is interesting to note that fluoride forms tetra-coordinated fluoroaluminate complexes with aluminum, AlF4-, that acts as a high affinity structural analogue of r-phosphate of GTP. Fluoride tends to accumulate in the exoskeleton and bone tissues of aquatic animals. Its levels in marine biota are higher in areas of anthropogenic origin. Environmental pollution affects commercially shrimps and mollusk. They spend most of their life in the upper reaches of the estuaries where they become closer to the discharged water containing sewage, industrial, and agricultural wastes. Actually, fluoride is documented as a toxic harmful pollutant to a variety of animals when it exists in high concentrations. The fluoride toxicity was assessed in the short-term (4 days) and long-term (28 days) to the aquatic snail Potamopyrgus antipodarum. Fluoride pollution affects numerical processes such as: reproduction and movement behaviour and may potentially affect natural population of invertebrates. The study pointed to the effect of high fluoridated seawater on edible marine bivalves that are supposed to be major sources for human consumption. Bivalve Paphia textile was selected for this purpose because of its economic importance and nutrition value. The land catch bivalves, Paphia textile were collected from the Abu Qir Bay of Alexandria by using a hand net with mesh size of 0.2 cm during September 2010 and January 2011. 17 individual bivalves were placed in each aquarium. Six glass aquariums of dimensions 40 X 40 X 80 cm were used, containing 10 liter of unfiltered seawater (as control) collected from Abu-Qir Bay. Series of different fluoride concentrations of 2.5, 5, 10, 20 and 40 ppm, as fluoridated natural seawaters, were added to the first five aquariums, respectively. The sixth aquarium was filled with unfluoridated seawater (for the control state). Total length of shell; T.L., (the distance between the two tips, measured in cm) was determined. Similarly, total width length of shell; .T.W., (the distance between the two lateral ends, measured in cm) and the total wet weight of individual bivalve; T.Wt. (in grams), were measured. Also, the fluoride content in the different tissues (foot, liver and shell) of bivalves was determined every three days following the colorimetric procedure of zirconium alizarin red S (Zr-ARS). The seawater quality of Abu-Qir Bay was detected (salinity, pH, dissolved oxygen, carbohydrates, silicon, phosphorus, calcium, magnesium, fluoride and sulphate). The performed statistical analyses (Correlation matrix and multiple regression analyses) clarified the effect of fluoride on the growth rate of bivalve and its accumulation in the different tissues. The growth rate of Paphia textile species was affected by fluoride levels in seawater. Insignificant growth rate was detected in the higher fluoridated levels of 10, 20 and 40 ppm. This may be accompanied with the abnormal calcification in the shells that leads to their structural distortion. Also, fluoride accumulation in foot, liver and shell tissues was studied. Generally, foot and liver tissues showed greater fluoride accumulation in different fluoridated seawaters than those of the control one. Also, bivalves' liver tissues showed higher fluoride uptakes (1.93, 1.91, 168 and 1.10 mg/g, respectively) in fluoridated seawaters of 2.5, 10, 20 and 40 ppm than those determined for control one (0.85 mg/g). This reflects the toxic action of fluoride on the bivalve species. Its toxicity action resides in the fact that fluoride ions acts as enzymatic poisons that inhibiting enzyme activity and, ultimately, interrupting metabolic processes such as glycolysis and synthesis of proteins. Some studies informed its accumulation in soft tissues, specially, the liver tissue. Shell tissues had approximately similar fluoride contents to control tissues in lower different fluoridated sweaters (2.5 and 5 ppm) and gave higher fluoride uptakes in higher fluoridated seawater levels (10, 20 and 40 ppm) than that of control case. Furthermore, bivalve's species in the control medium showed an ideal case of growth and a fluoride release. Accordingly, bivalve, Paphia textile can be used as a bioindicator for monitoring fluoride pollution in the ecosystems. In addition, it is recommended to study the impact of the consumption of this important economical marine organism on human health. Also, it seems advisable to monitor the fluoride concentration in the ecosystem and to detect its adverse effects on different aquatic organisms.