Unveiling the ecological status of the Arabian Gulf's marine ecosystem: Insights from benthic community analysis.

This study assessed the ecological health of waters within the Saudi Arabian Exclusive Economic Zone, by utilizing benthic biotic indices with a marine monitoring dataset covering the years 2013 to 2018. This comprehensive evaluation covered a vast expanse, encompassing 67 distinctive sampling locations characterized by a wide range of depth and salinity gradients. The study examined spatial fluctuations in the benthic community and assessed potential correlations with environmental variables, including salinity, depth, sediment texture, total organic carbon, and other relevant factors. The macrobenthic density varied across the study sites, with an average density of 566 ± 120 ind.m-2. The Shannon diversity index ranged from 3.21 and 5.90, with an average of 4.70 ± 0.52. Based on the average AMBI values, all the locations were categorized as either slightly disturbed or undisturbed. Additionally, the M-AMBI analysis indicated that 95.5 % sites were in good or high ecological status.

Primary production in the Saudi coastal waters of the Arabian Gulf.

The Arabian Gulf is a warm (summer SST > 30 °C) and hypersaline (salinity > 40 psu at any time) marginal sea of the Indian Ocean. This paper reports on a 3-year study of seasonal and spatial changes of primary production and associated physico-chemical and biological parameters in the coastal waters of Saudi Arabia in the western Arabian Gulf. The primary production rates were low and yet showed a seasonality, with a major spring peak and a minor autumn peak, and a possible significant role for heterotrophs. While the strong relationships between the net changes of carbon uptake and nutrients between seasons showed a control of primary production by the availability of nutrients, the decrease in primary production between spring and summer when nutrients continued to increase suggests that the primary production at this time could have been controlled by higher ambient temperatures and intensities of incident light.

Accelerated burial of petroleum hydrocarbons in Arabian Gulf blue carbon repositories.

Massive consumption of petroleum since the past century has led to considerable emissions into marine ecosystems. Marine sediments may accumulate substantial quantities of petroleum and associated contaminants in oil-producing areas. Here, we report accelerated accumulation of total petroleum hydrocarbons (TPH) in 'blue carbon' vegetated ecosystems of the Arabian Gulf - the world's most important region for oil production. In addition to increased accumulation with the onset of oil exploitation, sediment records reflect a large depositional event associated with the 1991 Gulf War, with the magnitude of these maxima varying across habitats, depending on their elevation along the shoreline. Blue carbon ecosystems of the Arabian Gulf currently bury about 2300 megagrams (Mg) of TPHs annually and have accumulated TPH stocks of 59,799 Mg over the past 25 years alone. Massive burial and sequestration of TPH by blue carbon ecosystems is an important, but thus far unrecognized, removal mechanism in the Arabian Gulf. Conserving these ecosystems is important to avoid possible remobilization of sequestered TPH into the surrounding environment.

Assessment of the organotin pollution in the coastal sediments of the Western Arabian Gulf, Saudi Arabia.

Organotin compounds (OTCs) are persistent pollutants and are considered as chemicals of environmental concern. They enter the marine environment from the antifouling paints containing organotin compounds on the hulls of ships and boats. We report the results of a study conducted in 2015 on the level of butyltins (TBT, DBT, and MBT) and phenyltins (TPhT, DPhT, and MPhT) in the sediments collected from three fishing harbors (Jubail, Khobar, and Qatif) and a reference site (Half Moon Bay). The concentrations of OTCs in the sediments vary widely among the different sampling locations. Overall, the phenyltins contribute more than the butyltins and the order of the abundance is: MPhT > DPhT > MBT > DBT > TPhT. In most stations, the concentrations of MBT are higher than DBT. The sediments from Khobar and Qatif are moderately polluted, whereas those from the Jubail are ranked as highly polluted. The concentrations of TBT at all study sites are less than the detection limit, and hence, the environmental and ecotoxicological risks are low.

Occurrence and sources of polar lipid tracers in sediments from the Shatt al-Arab River of Iraq and the northwestern Arabian Gulf.

Shallow surface sediment samples from the southern part of the Shatt al-Arab River estuary of Iraq and the northwestern Arabian Gulf were analyzed for polar lipid compounds including n-alkanoic acids, n-alkanols, steroids and triterpenoids. The results showed that the n-alkanoic acids, methyl n-alkanoates and n-alkanols typically ranged from C12 to C32 with total concentrations of 3.2 to 108.2 µg g(-1)dwt sample, from C12 to C30 with totals of 1.1 to 18.9 µg g(-1)dwt sample, and from C14 to C32 at 1.8 to 112.6 µg g(-1)dwt sample, respectively. Steroids and triterpenoids were detected and included stenols, stanols, stenones, stanones, tetrahymanol, tetrahymanone and extended ßß-hopanes. The total steroid concentrations ranged from 2.8 to 78.4 µg g(-1)dwt sample, whereas the triterpenoids varied from 0.05 to 7.6 µg g(-1)dwt sample. The simple regression analysis of the results and the spatial distribution patterns of the identified organic tracers indicated that the inter-compound relationships were related mainly to their major sources. Cluster analysis and principal component analysis (PCA) of data set showed that the sampling sites are similar. These sources were allochthonous (terrestrial vegetation), autochthonous (plankton residues and bacteria in the sediments) and anthropogenic (sewage and petroleum).