An assessment of microplastics threat to the marine environment: A short review in context of the Arabian/Persian Gulf.

Microplastics are recognised as a (persistent) pollutant and are believed to be ubiquitous in the marine environment. The importance of this issue is evident from the large number of technical publications and research efforts within the past decade. However, the Arabian (Persian) Gulf region has few reported datasets in spite of being an area with excessive plastic use and a hefty generation rate of plastic solid waste. This communication aims at stimulating a discussion on this topic focusing on the available regional and international datasets, along with the environmental conditions that are likely to contribute to the disintegration and transport of the plastic debris rendering it as microplastic. This work also highlights some of the constraints in sampling techniques, identification methods, and the reported units of microplastics. Most studies employ neuston nets of variable dimensions that samples different thicknesses of surface water, which also posses a major constraint in standardising field sample collection. Extrapolation of a trawl to units such as particles.km-2 without considering the fact that neuston nets collect three-dimensional samples, is also another aspect discussed in this communication. This study also intends to initiate a discussion on standardising the practices across the region to enable an intercomparison of the reported data. In addition, it calls for a comprehensive assessment using the standardized methodology for putting a mitigation plan for microplastics as a potential threat detected in environmental sinks.

Isolation of Gram-positive Firmibacteria as major eicosapentaenoic acid producers from subtropical marine sediments.

In this study, a total of 172 putative omega-3 producers were isolated from 28 sediment samples from the Arabian Gulf employing a selective isolation procedure using marine agar containing 0·1% triphenyl tetrazolium chloride (TTC). Out of these 172 isolates, 19 isolates produced eicosapentaenoic acid (EPA) as confirmed by Gas Chromatography-Mass Spectrometry (GC-MS). The EPA content of the isolated bacterial strain varied from 1·76 to 6·52% of total fatty acids. Among the 19 isolates of EPA producers, while 17 isolates harboured both pfaA gene and Δ6 desaturase gene, only five isolates harboured Δ5 desaturase gene. Two of the EPA positive strains harbour none of the three genes tested. The 16s RNA identification of these isolates revealed that except one, all the EPA producers were Gram-positive marine bacteria belonging to the phylum Firmicutes, family Bacillacea, genera Bacillus and Oceanobacillus. Halomonas pacifica was the only Gram-negative Gamma-Proteobacteria detected to produce EPA from this region. SIGNIFICANCE AND IMPACT OF THE STUDY: Recently, marine bacteria are considered as a promising source of polyunsaturated fatty acid (PUFA) over marine fishes and microalgae. PUFA producers reported from polar and deep-sea sources were restricted to five well-known marine genera under two distinct domains of bacteria such as proteobacteria (Shewanella, Colwellia, and Moritella) and cytophaga group (Flexibacter, Psychroflexus). This study revealed that subtropical marine environment could also be the source of PUFA producing bacteria, and they predominantly belonged to the class of Firmibacteria. This finding opens up new avenue for research to study the inherent mechanism and physiology of such organisms from this unique environment.

Eolian dust affects phytoplankton in the waters off kuwait, the arabian gulf

Summer phytoplankton assemblages from surface waters off Kuwait were enriched with levels of eolian dust (10(5), 10(6), and 10(7) mg/m(3)), similar to seasonal dust fallout for this region. Algal growth was positive and dose dependent. Highest biomass was up to 527 &mgr;g chlorophyll a/l on day 5. The maximum doublings of biomass per day were 0.64, 0.77, and 1.42, corresponding to 10(5), 10(6), and 10(7) mg/m(3) enrichment and were significantly higher than the 0.56 for control. Changes in the phytoplankton species composition occurred with changes in biomass, with small algae dominating peak populations. It is suggested that through enrichment of trace elements via eolian dust, a high level of phytoplankton biomass and growth can be sustained in this arid environment.