Effect of copper nanoparticles and organometallic compounds (dibutyltin) on tilapia fish

Abstract Background Mozambique tilapia (Tilapia mossambica) are commonly used in the assessment of aquatic environment quality and also considered as useful bio-indicators during environmental pollution monitoring. Copper-oxide and dibutyltin are used as antifouling underwater hall paints. Copper nanoparticles (Cu-NPs) are serious water pollutants but their impact in fish’s performance remains poorly understood. Results In the present study, we have exposed tilapia, a freshwater edible fish to two different doses (15 mg/L) of Cu-NPs and (2 mg/L) dibutyltin for 6 days. The doses selected were eco-relevant considering the contamination levels of certain water resources. The results indicated that the activity oxidative stress enzymes reduced glutathione (GSH), acetylcholinesterase (AChE), and glutathione-S-transferase (GST) were significantly decreased in the liver, brain, and gills of the treated groups when compared to control. Conclusion Taken together, the results suggest that short-term exposure of tilapia fish to Cu-NPs and dibutyltin causes oxidative stress and impart serious deleterious effects in the tissues which may affect fish growth and development and causes death. In the case of the gills, liver, and brain when exposed to both concentrations of CuO and dibutyltin (NPs), although the activity of these enzymes showed an inhibition in the liver when exposed to both concentrations of NPs. The present study investigated that CuO-NPs are more toxic than dibutyltin

Environmental characteristics of the United Arab Emirates waters along the Arabian Gulf : Hydrographical survey and nutrient salts

225-232<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Surface and bottom seawater samples were collected monthly from October 1993 to September 1994 at twenty-four stations. The levels of different parameters were in the range of : temperature (16.90-34.60°C), salinity (35.2-44.0×10-3 ),transparency (0.5- 13.0 m), pH (7.91-8.60), dissolved oxygen (3.63-9.02 mg/l), biological oxygen demand (0.05-6.11mg/l), ammonia (ND- 15.32μg-at N/l), nitrite (ND-5.18μg-at N/l), nitrate (0.07-14.32μg-at N/l), phosphate (0.01- 10.2 μg-at P/l), and silicate (0.4-26.5μg-at Si/l). The patterns of distribution indicated insignificant differences between surface and bottom layers due to the shallowness of the area, turbulence of the water column, and effects of sewage wastewaters. Water temperatures exhibited their lowest average value in the winter season and the highest in the summer season. The lowest averages of salinity, transparency, pH, and dissolved oxygen were measured in the summer season. Whereas, the highest averages for these parameters were observed in the winter season. Except for nitrate and phosphate, insignificant differences between average values of other nutrient salts in the summer and winter seasons were observed. Nitrate and phosphate showed lower average values in the summer season compared to the winter season due to the increase in the rate of uptake by phytoplankton which was more abundant in the summer season. Horizontal patterns of distributions for hydrographic parameters revealed only an increase for transparency and a decrease for biological oxygen demand in a seaward direction. Except for Sharjah creek, no distinct horizontal patterns of distributions for nutrient salts were observed. At Sharjah, most of the nutrient salts decreased in a seaward direction due to the presence of effective sewage pollution sources inside the creek. The atomic ratio of the elements N: P: Si were similar in Abu-Dhabi, Umm al-Quwain, and Ras al-Khaimah areas, but with lower values in Sharjah. It is concluded that the discharge of sewage and industrial wastes has affected the quality of  seawater inside some semi-enclosed areas, especially Sharjah creek, as indicated by the increase in the levels of biological  oxygen demand and the elevation in the concentrations of the nutrient salts.</span

Biological data from sharks landed within the United Arab Emirates artisanal fishery

Landing site and market surveys of sharks landed along the Arabian Gulf coast of the United Arab Emirates were undertaken between October 2010 and September 2012 to obtain biological data from this artisanal fishery. Data were collected on the size and sex of 12 482 individuals representing 30 species. Maximum sizes of Carcharhinus sorrah, C. amblyrhynchoides and Hemipristis elongata were extended by at least 300 mm total length (TL) compared with published global maxima. The size at 50% maturity was determined for males of five species and this indicated that the males of smaller shark species (&lt;1 000 mm maximum TL) in the fishery were largely mature. For many species, including Loxodon macrorhinus and Mustelus mosis, overall sex ratios were male-biased, indicating that sexual segregation is likely in those species. Furthermore, sex ratios for several species, such as Rhizoprionodon acutus, showed differences across seasons. Overall, the landings contained a high proportion of juveniles, causing concerns about the sustainability of this fishery. Biological parameters of a number of species differed from those recorded earlier for the region, demonstrating a need for additional local data collection to support the development of management measures.Keywords: Arabian/Persian Gulf, conservation, sex ratio, size at maturity, size compositio

Shark Diversity in the Arabian/Persian Gulf Higher Than Previously Thought: Insights Based on Species Composition of Shark Landings in the United Arab Emirates

Although fish fauna in the Arabian/Persian Gulf have been studied for decades, shark diversity has only been recently investigated in the region. Here, we present a first comprehensive account of shark diversity from the United Arab Emirates based on fishery-dependent data collected at market and landing sites over a two-year period of field sampling. Landings across the country were dominated by carcharhinids, and six species were found to be most abundant, including the spot-tail shark, Carcharhinus sorrah, and the milk shark, Rhizoprionodon acutus, contributing 31.8 % and 29.9 %, respectively, of the total number of sharks. While observed landings varied among regions and across seasons, results showed that shark landings were dominated by small-sized species, which may be a reflection of overexploitation. We are now expanding the existing checklist of shark species in the Persian Gulf from 27 to 31, having utilized both morphological identification and genetic barcoding in validating the existence of the grey bamboo shark, Chiloscyllium griseum; the tawny nurse shark,Nebrius ferrugineus; the silky shark, Carcharhinus falciformis; and the sandbar shark, Carcharhinus plumbeus, in these waters. This inventory provides an urgently needed assessment of current regional diversity patterns that can now be used as a baseline for future investigations evaluating the effect of fisheries on shark populations. Results emphasize the need for research on life history traits of the various species in order to determine their regional conservation status, but also reveal that a precautionary approach to conservation will be necessary to mitigate anthropogenic impacts

The Trade in Sharks and Their Products in the United Arab Emirates

The rapid growth in the demand for shark products, particularly fins, has led to the worldwide overexploitation of many elasmobranch species. Although there are growing concerns about this largely unregulated and unmonitored trade, little information still exists about its dynamics, the species involved and the impact of this pressure on stocks in various regions. Our study provides the first attempt at characterizing the trade in shark products from the United Arab Emirates (UAE), the fourth largest exporter in the world of raw dried shark fins to Hong Kong. A review of trade records and informal interviews with local traders confirmed that the UAE is being used as hub in the broader North Indian Ocean region for the trade in shark products with the Emirati fishery minimally contributing to this trade. Results based on morphological identification of sharks (n = 12,069) and DNA barcoding of tissue samples (n = 655) indicated that the trade was made up of at least 37 species. The most abundant families represented at the Dubai study site were the Sphyrnidae (9.3%), Lamnidae (9%) and Alopiidae (5.9%). While information was mostly limited to shark products originating from the UAE and Oman, results indicated that 45.3% of species traded were considered to be at high risk of global extinction based on the IUCN Red List Global Assessments. Since many of the species found during this survey are likely part of stocks shared with other countries, regional cooperation and management will be crucial to ensure their long term survival