Coral spawning in the Gulf of Oman and relationship to latitudinal variation in spawning season in the northwest Indian Ocean

Despite a wealth of information on sexual reproduction in scleractinian corals, there are regional gaps in reproductive records. In the Gulf of the Oman in the Arabian Sea, reproductive timing was assessed in four common species of broadcast spawning corals using field surveys of gamete maturity and aquarium observations of spawning activity. The appearance of mature gametes within the same month for Acropora downingi, A. hemprichii, Cyphastrea microphthalma and Platygyra daedalea (≥ 75% of colonies, n = 848) indicated a synchronous and multi-specific spawning season. Based on gamete disappearance and direct observations, spawning predominantly occurred during April in 2013 (75- 100% of colonies) and May in 2014 (77-94% of colonies). The difference in spawning months between survey years was most likely explained by sea temperature and the timing of lunar cycles during late-stage gametogenesis. These reproductive records are consistent with a latitudinal gradient in peak broadcast spawning activity at reefs in the northwestern Indian Ocean which occurs early in the year at low latitudes (January to March) and progressively later in the year at mid (March to May) and high (June to September) latitudes

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

بعض الخصائص الهيدروكيميائية لمياه دولة الإِمارات العربية المتحدة المطلة على الخليج العربي وخليج عمان

Surface and bottom water samples were collected from the United Arab Emirates waters along the Arabian Gulf and the Gulf of Oman during the period from October 1993 to September 1995. Samples were analyzed for temperature (21.1-33.5oC), salinity (35.86-43.20%), pH (7.94-8.40), transparency (4.5-17.5 m), dissolved oxygen (3.94-8.72 mg/1), ammonia (ND-22.7 ug-at N/l), nitrite (ND-2.16 (ug-at N/l), nitrate (ND-18.12 ug-at N/l), phosphate (0.01-4.22 ug-at P/l), and silicate (0.62-15.38 ug-at Si/1). The levels and distributions of the hydrochemical parameters in the investigated area showed that the Arabian Gulf seawater exhibited higher salinity (1.07 times), and ammonia (1.60 times) compared to the Gulf of Oman waters. Meantime, the Gulf of Oman waters were more transparent (1.30 times), and more oxygenated (1.07 times) . Moreover, seawater at the Gulf of Oman showed a tendency to concentrate nitrite (1.25 times), nitrate (1.72 times), phosphate (1.40 times), and silicate (1.06 times) which reveal relatively oligotrophic conditions in the Arabian Gulf waters. The Calculated atomic ratios of the elements P:N:Si in seawater of the Arabian Gulf and the Gulf of Oman were, particularly in the Gulf of Oman water, different from Redifield ratio and indicated that inorganic phosphorus was the limiting factor.تمت دراسة التغيرات الفصلية والمكانية لبعض الصفات الهيدروكيميائية مثل دوجة الحرارة - الملوحة - النفاذية - الأس الهيدروجيني - الأكسجين المذاب - الأملاح المغذية ( الأمونيا - النيتريت - النيترات - الفوسفات - السيليكات ) في مياه دولة الإِمارات العربية المتحدة المطلة على الخليج العربي وخليج عمان خلال الفترة من أكتوبر1993 وحتى سبتمبر1995 . أوضحت الدراسة وجود تغيرات فصلية ومكانية واضحة في معظم الصفات الهيدروكيميائية وخصوصاً درجات الحرارة - الملوحة وبعض الأملاح المغذية . أوضحت الدراسة أيضاً ارتفاع درجات الملوحة وارتفاع تركيز الأمونيا في مياه الخليج العربي عنها في مياه خليج عمان وبالعكس تميزت مياه خليج عمان بزيادة تركيز الأكسجين المذاب ومعظم الأملاح المغذية مثل النيتريت - النيترات - الفوسفات "السيليكات مما يدل على زيادة إِنتاجية مياه الدولة المطلة على خليج عمان . أوضحت الدراسة أيضاً أن نسب النيتروجين والفسفور والسيلكون في مياه الدولة بوجه عام اختلفت خصوصاً في منطقة خليج عمان عن النسب العادية ، وقد دلت هذه النسب على أن الفسفور هو الامل المحدد في المنطقة