Organic Pollutants along the Qatari Coast: A Case Study of the Pearl Oyster (Pinctada radiata)

The Qatari marine environment is endangered due to high industrial expansion and anthropogenic pressure over the last few decades. The presence of common contaminants such as total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons (PAHs) is a threat to the marine environment. The aim of this study is to determine the environmental threats and risks posed by organic contaminants to Qatar’s marine environment using pearl oyster ‘Pinctada Radiata’ as the indicator study organism. The samples (marine sediment, seawater, and oysters) were collected four times within two years in different seasons from the four sites (Simaisma, Al Khor, Umm Bab, and Al Wakra), on March 2017, December 2017, May 2018, and November 2018. A total of 144 samples were analyzed, 48 samples of seawater, 48 samples of sediment and 48 samples of oysters. Levels of organic contaminants (TPHs and PAHs) were quantified in seawater, marine sediment and oyster tissues (P. radiata). In addition, the TOC and particle sizes were measured in abiotic matrices as well as the temperature, salinity, and pH of seawater in the study areas. Overall, the organic contaminants (TPHs and PAHs) were more readily detected in oyster tissue samples than marine sediment and seawater samples collected from the same areas. The surface seawater samples showed negligible levels of PAHs, while TPHs were ranged from 1.164 to 271.77 μg/L. The concentration of TPHs and PAHs in surface marine sediment were ranged between (75.02 -1751.82) and (4.25 - 36.73) μg/kg dry weight respectively. In oyster tissue samples, the level of TPHs was ranged from 633.33 to 6666.67 μg/kg dry weight, with the highest concentrations measured in Simaisma, while PAHs concentration showed an extreme variation from 25.90 to 2244.03μg/kg dry weight. The present study could, however, provide useful background information for further investigations to understand the presence of organic contaminants in Qatar’s marine environment.

Spat efficiency in the pearl oyster Pinctada radiata (Leach, 1814) in the surface and bottom water at Karantina Island

The present study was carried out to determine the spat efficiency in the pearl oyster (Pinctada radiata, Leach, 1814) in surface and bottom water at Karantina Island (Izmir/Turkey). Polyethylene mesh bags were used as collectors. An annual average of 175.16 ± 11.32 spat m−2 was obtained from PSC (placed surface collectors) and 82.65 ±3.89 spat m−2 was obtained from PBC (placed bottom collectors). The largest number of new spat attachments occurred in August, both on PSC and PBC: 44 ± 3.46 and 26 ± 2.88 spats were found respectively in the outer and inner mesh bags of PSC, and 33 ±5.77 and 48 ± 6.92 spats were found respectively in the outer and inner mesh bags of PBC. New spat attachments (≥ 10 mm) continued throughout the study period, except April and May. Adult pearl oysters (≥ 50 mm) were found in May. There was a significant difference between PSC and PBC in the total number of spat attachments, the monthly spat attachments and the first spat attachments (p < 0.05). The total number of new spat attachments was positively correlated with temperature and chlorophyll a for both depths (p<0.05).

New data on Pinctada radiata (Leach, 1814) (Bivalvia: Pteriidae) in the Adriatic Sea

The first recorded population of Pinctada radiata in the Adriatic Sea was observed on the pier in Porto Montenegro marina (Tivat, Montenegro), in August 2016. Numerous individuals inhabited pier walls at a depth of 5 m. The shell height (SH) values for the 15 randomly collected individuals of P. radiata ranged between 32.2 mm and 52.1 mm with an average SH value of 38.3 mm (standard deviation ±6.1). Further surveys in Montenegro will provide information on the establishment of the observed population and what is its impact on local biodiversity.