Effects of pollution on marine crustaceans in Qatari waters: a baseline survey and a case study on genotoxicity indicators in an endemic shrimp
Hassan, HM 2018, Effects of pollution on marine crustaceans in Qatari waters: a baseline survey and a case study on genotoxicity indicators in an endemic shrimp , PhD thesis, University of Salford.
In this thesis the baseline and seasonal variations of the trace metals (TM) (Arsenic (As), Cadmium (Cd), Cobalt (Co), Chromium (Cr), Copper (Cu), Iron (Fe), Manganese (Mn), Nickel (Ni), Lead (Pb), Vanadium (V) and Zinc (Zn).
Methylmercury (CH3Hg), organotins (OT) and polychlorinated biphenyls (PCBs) concentrations were investigated within the tissue of three selected marine organisms together with sediment and water. The first round of sampling was carried out in September, November and December 2014. Samples were then collected in May and June 2015, and finally in July 2016. The species used for the research are all indigenous to Qatari waters and included Portunus pelagicus, the blue swimming crab, a commercially important edible species, Balanus Amphitrite, the striped barnacle, an invasive species that arrived in Qatar on the hulls of merchant ships, and now part of the local fauna. This species is often used as bio-indicator of coastal pollutants. The final selected species is the endemic caridean shrimp, Palaemon khori which inhabits the Avicenna marina mangrove forest at Al-Khor, Qatar.
The order of the heavy metal concentrations for the three species was Zn > Cu > As > Fe > Mn > Pb > Cr > Cd > Co > Ni > V for P. pelagicus, Zn > Fe > Cu > As > Cd > Mn > Ni > Cr > V > Pb > Co for B. Amphitrite and Zn ˃ Cu > Fe ˃ Mn > Ni ˃ Pb > As > Cr > Cd > Co > V for P. khori. Methylmercury was measured in all of the three species averaging 1.25μg/kg throughout. The three organotin monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) were detected in all three species. TBT levels were observed at 0.58ngSng-1, 0.78ngSng-1 and 1.91ngSng-1 for P. segnis, B. Amphitrite and P. khori respectively. The results also revealed that concentrations of the contaminants within water samples were negligible, the majority being below detection limits. However, PCB congeners 2,2,3,5-Tetrachlorobiphenyl and 2,2,4,5,5-Pentachlorobiphenyl were detected in the tissue of P. pelagicus averaging 1.70 μg/kg for the former and 4.56 μg/kg for the latter. Results from the tissue of P. khori ranged from 1.5μg/kg - 2μg/kg and 4.28μg/kg – 5.21μg/kg respectively.
Seasonal variation studies showed fluctuating degrees of variability among pollutants depending on the target species and the pollutant. The results showed an increase in some pollutant concentrations from the winter months through to the summer, while subsequently other pollutants revealed a decrease in concentrations.
The direct effect of varying levels and combinations of pollutants (the maximum concentrations of trace metals, OT and MeHg found in the environment according to the literature, and a tenfold increase in those concentrations in an individual setting and in a combined setting) under laboratory controlled conditions on the endemic P. khori was assessed using classical (mortality) and genotoxicological (aneuploidy) endpoints, after 4 and 8 weeks of exposure. Our results showed that with regards to mortality on average the highest mortality was observed in shrimps exposed to TM at x10 of the maximum environmentally observed levels or TM in combination with other pollutants. The pollutant inducing the highest aneuploidy levels were trace metals and CH3Hg in combination with OT (both at x10 concentration).
The data presented in this study represents the first ever estimated baseline for seasonal variations of contaminants, in both the marine environment and associated animal tissues from the coastal waters of Qatar. The data obtained from the genotoxic investigations are a fundamental part in establishing the first ever record for the karyotype of P. khori, while also providing a genotoxicological overview of the effect of these pollutants on the species at a genetic level.
Hassan Mustafa Hassan