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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.

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The Gulf of Aqaba (hereafter 'the Gulf') is a narrow, semi-enclosed, warm, high saline, and oligotrophic water body. This baseline study provides the first quantitative data on deep-sea (207-1281 m depth) benthos of the Gulf. Fifty-five benthic species (predominantly polychaetes) with a density of 160-670 ind. m-2, species richness of 11-25, and Shannon-Wiener diversity (H') of 3.14-4.17 bits. ind.-1 were recorded from nine stations. The density and H' of benthos of the Gulf are comparable with those of the Red Sea, while both are lower than those reported from the Arabian Sea and the Mediterranean Sea. The good-high ecological status of benthic communities indicates the absence of major stress in the deep-sea habitats of the Gulf. As large-scale urbanization is proposed in the Saudi coastal areas of the Gulf, this study is expected to provide a baseline dataset for future environmental impact assessments.

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This paper reports a deep-water coral framework (a single colonial bush or a larger bioconstruction of coral covering the sea bottom), formed entirely by the scleractinian coral Eguchipsammia fistula (Alcock, 1902) (Dendrophylliidae), in the northern Red Sea waters of Saudi Arabia at a depth of about 640 m. The framework consists of mostly live corals with a total area of about 10 m2 and the length of the individual coral branches range from 12 to 30 cm. Although E. fistula is ubiquitous, this discovery is the second record of a framework formed by this species and the first discovery of a large living reef in the Red Sea. The results of the genetic study indicate the potential existence of a genetic variation of E. fistula in the Red Sea. This discovery implies that the Red Sea has favorable habitats for framework-forming DWC species and highlights the need for conducting more systematic surveys for understanding their distribution, abundance, and ecology.

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Plastics pollution is ubiquitous. Microplastics (<5 mm in diameter) and mesoplastics (5-20 mm in diameter) are emerging as the most common plastic particulates found in the marine environment. In this study, the occurrence of microplastics and mesoplastics in the gastrointestinal tract (GI) of some commercially important fish collected from Chennai and Nagapattinam of Tamil Nadu, Southeast coast of Bay of Bengal was assessed. A new and improved alkaline digestion method, using alcoholic potassium hydroxide (KOH) was carried out to destroy the organic matter. Following this method, twenty plastic particulates were isolated from the GI tract of 17 individual fish. Fourier Transform Infrared Radiation analysis (FTIR) showed that polymers found in GI tracts were of Polyethylene, Polyamide and Polyester types. Given the dry fish is India's biggest market and popular delicacy, the presence of microplastics in the fish gut is a potential serious human health concern, as they are directly consumed.

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A novel and selective electrochemical sensing of nicotine is studied using copper tungstate decorated reduced graphene oxide nanocomposite (CuWO4/rGO) nafion (Nf) immobilized GC electrode (GCE). The CuWO4/rGO nanocomposite is synthesized using sonication method and characterized by HR-TEM (High resolution transmission electron microscopy), SEM (Scanning electron microscopy), FT-IR (Fourier transform infrared spectroscopy), SAED (Selected area of electron diffraction pattern), XRD (X-ray diffraction), Raman spectroscopy, Thermo gravimetric analysis (TGA) and EDX (Energy dispersive X-ray diffraction) techniques. The CuWO4/rGO/Nf immobilized GCE shows better electrocatalytic response for the detection of nicotine as compared to bare GCE. A better selectivity and sensitivity is achieved using CuWO4/rGO/Nf immobilized GCE to detect 0.1 µM nicotine in the presence of 100-fold excess concentrations of different interferents. The present CuWO4/rGO/Nf immobilized GCE electrochemical sensor exhibits an ample range of sensing from 0.1 µM to 0.9 µM and the low detection limit is found to be 0.035 µM (S/N = 3). Comparable results are achieved for the determination of nicotine in various real samples such as cigarettes (Gold flake and Wills) and urine samples with improved recoveries.

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This study reports the levels of total arsenic and arsenic species in marine biota such as clams (Meretrix meretrix; N=21) and pearl oyster (Pinctada radiata; N=5) collected from nine costal sites in Jan 2014, and cuttlefish (Sepia pharaonis; N=8), shrimp (Penaeus semisulcatus; N=1), and seven commercially important finfish species (N=23) collected during Apr-May 2013 from seven offshore sites in the western Arabian Gulf. Total As and As species such as dimethylarsinic acid (DMA), arsenobetaine (AB), trimethylarsine oxide (TMAO), arsenocholine (AC), tetramethylarsonium ion (Tetra), arsenosugar-glycerol (As-Gly) and inorganic As (iAs) were determined by using ICPMS and HPLC/ICPMS. In bivalves, the total As concentrations ranged from 16 to 118mg/kg dry mass; the toxic iAs fraction contributed on average less than 0.8% of the total As, while the nontoxic AB fraction formed around 58%. Total As concentrations for the remaining seafood (cuttlefish, shrimp and finfish) ranged from 11 to 134mg/kg dry mass and the iAs and AB fractions contributed on average 0.03% and 81% respectively of the total As. There was no significant relationship between the tissue concentrations of total As and iAs in the samples. There was also no significant relationship between As levels in seafood and geographical location or salinity of the waters from which samples were collected. Based on our results, we recommend introducing a maximum permissible level of arsenic in seafood from the Gulf based on iAs content rather than based on total As. Our analyses of cancer risks and non-cancer hazards identified non-negligible risks and the potential for hazards; the greatest risks were identified for expatriate consumers of bivalves and high-end consumers of seafood. Despite this, many uncertainties remain that would be best addressed by further analyses.

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The presence of morphologically identical individuals that are genetically divergent, known as cryptic species, is a phenomenon that is likely to be of importance at the theoretical level, for speciation studies, and at the applied level, for management purposes. Cryptic species are probably common in the marine environment, and they have been described in a variety of habitats. Here we present the first case of cryptic speciation in the mesopelagic environment for the Benthosema lanternfishes. Based on mitochondrial and nuclear sequences, we describe the presence of widely divergent Benthosema pterotum cryptic species that diverged at least 5 million years ago. Our results have important theoretical, as well as practical implications, related to developing mesopelagic fisheries.

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