Search

Ecosystems worldwide are suffering from climate change. Coral reef ecosystems are globally threatened by increasing sea surface temperatures. However, gene expression plasticity provides the potential for organisms to respond rapidly and effectively to environmental changes, and would be favored in variable environments. In this study, we investigated the thermal stress response in Pocillopora coral colonies from two contrasting environments by exposing them to heat stress. We compared the physiological state, bacterial and Symbiodiniaceae communities (using 16S and ITS2 metabarcoding), and gene expression levels (using RNA-Seq) between control conditions and heat stress (the temperature just below the first signs of compromised health). Colonies from both thermal regimes remained apparently normal and presented open and colored polyps during heat stress, with no change in bacterial and Symbiodiniaceae community composition. In contrast, they differed in their transcriptomic responses. The colonies from Oman displayed a more plastic transcriptome, but some genes had a higher basal expression level (frontloading) compared to the less thermotolerant colonies from New Caledonia. In terms of biological functions, we observed an increase in the expression of stress response genes (including induction of tumor necrosis factor receptors, heat shock proteins, and detoxification of reactive oxygen species), together with a decrease in the expression of genes involved in morpho-anatomical functions. Gene regulation (transcription factors, mobile elements, histone modifications and DNA methylation) appeared to be overrepresented in the Oman colonies, indicating possible epigenetic regulation. These results show that transcriptomic plasticity and frontloading can be co-occurring processes in corals confronted with highly variable thermal regimes.

We document the benthic ctenophores Coeloplana sp. and Vallicula multiformis from Oman, extending their geographic range. A new Coeloplana species was found forming aggregations on gorgonians of two octocoral host genera, Melithaea and Euplexaura, representing associations previously unknown to occur in the Indo-West Pacific region. Our findings also illustrate the concurrent presence of the ectocommensal ophiuroid Ophiothela mirabilis, which adversely affects other Coeloplana species in the tropical West Atlantic, where it is considered invasive. This exploration contributes to our understanding of the biogeography, species distribution, and ectosymbiotic associations of these genera, setting the stage for a comprehensive species description and in-depth analysis of host relationships in future studies. [ABSTRACT FROM AUTHOR]

Intraspecific chemical communication between echinoderms has often been limited to prespawning aggregation. However, sea cucumber farmers have long observed year-round adult aggregation as a potential source of disease propagation and the suboptimal use of available sea pen acreage and food resources. In this study, through spatial distribution statistics, we demonstrated the significant aggregation of the aquacultivated sea cucumber Holothuria scabra both as adults in large sea-based pens and as juveniles in laboratory-based aquaria, proving that aggregation in these animals is not only observed during spawning. The role of chemical communication in aggregation was investigated using olfactory experimental assays. Our study established that the sediment that H. scabra feeds on as well as the water preconditioned by conspecifics induced positive chemotaxis in juvenile individuals. More specifically, through comparative mass spectrometry, a distinct triterpenoid saponin profile/mixture was identified to be a pheromone allowing sea cucumber intraspecific recognition and aggregation. This "attractive" profile was characterized as containing disaccharide saponins. This "attractive" aggregation-inducing saponin profile was, however, not conserved in starved individuals that were no longer attractive to other conspecifics. In summary, this study sheds new light on the pheromones in echinoderms. It highlights the complexity of the chemical signals detected by sea cucumbers and suggests a role of saponins well beyond that of a simple toxin. [ABSTRACT FROM AUTHOR]

The different characteristics and atmospheric forces over the Sea of Oman and the Arabian Sea are assumed to influence zooplankton seasonality and community structure. This work aimed to characterize the abundances and seasonality of coastal and surface mesozooplankton communities in the Sea of Oman (Muscat) and the Arabian Sea (Salalah), and the effects of environmental factors on their distribution. Zooplankton samples two contrasting coastal regions; 22 in the Sea of Oman, and 20 in the Arabian Sea, were collected during 2013-2014 from the surface and analyzed. Total zooplankton abundance was divided by the number of samples to obtain the monthly average abundance per meter cube (ind•m-3) of sea water. A total of 91 species were observed from all 42 samples of which 58 were copepods, among which 47 were calanoid copepods. Species composition varied significantly between the two locations. The similarity between the two communities was highest (samples were closest to each other) during the winter, and showed the largest differences in composition in the summer. The seasonal changes in community structures were most significant for copepods and calanoid copepods (p= 0.0002 and p= 0.0003 respectively) and less significant for non-copepods (p= 0.0057). Only few species (17 in the Sea of Oman and 20 in the Arabian Sea) represented more than 90% of the total zooplankton abundance. There was a distinct pattern of seasonal variation in the abundance of zooplankton in the Arabian Sea, especially copepods and meroplankton, but there was no such pattern in the Sea of Oman. Some successful species such as Temora turbinata and Penilia avirostris in the Sea of Oman, and Oithona spp. in the Arabian Sea seem able to exploit a wide range of prey from phytoplankton to small ciliates and thus feed through the microbial loop. [ABSTRACT FROM AUTHOR]

Dense aggregations of serpulid worms were encountered in the Daymaniyat Islands (Gulf of Oman) from 10 to 20 m depth, over the period January–March, 2021. The species responsible for these aggregations belongs to the Filograna/Salmacina-complex (Annelida: Serpulidae). This species has been present in the area and observed along the Oman coastline, but high-density aggregates like this have not been reported before. The most probable cause of the aggregations, supported by field observations and Aqua-MODIS satellite data, was natural eutrophication with a subsequent algal bloom linked to the local winter monsoon. This observation emphasises the importance of documenting biodiversity and dynamics of reef communities along the Oman coastline. [ABSTRACT FROM AUTHOR]

Pasteurized fresh milk requires an accurate estimation of shelf life under various conditions to minimize the risk of spoilage and product losses. Milk samples were stored for 56 h in an oven at 25 °C and for 15 days in a refrigerator at 4 °C. Samples were analyzed using an electronic nose (e-nose), total bacterial count, titratable acidity and pH to determine the quality of milk. Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) were used to analyze e-nose data of milk stored at 25 °C, and 4 °C. A clear shift in quality was identified by the e-nose, which also appeared in the total bacterial count after 24 h and 12 days for storage at 25 and 4 °C, respectively. On the other hand, titratable acidity exceeded the normal limits of 0.14 % - 0.21 % after 24 h for storage at 25 °C (0.247 ± 0.006 %) and after 15 days for storage at 4 °C (0.25 ± 0.01 %). If pH was a good indicator of quality for samples stored at 25 °C, it showed no clear trends for samples stored at 4 °C. Based on the microbial count data and e-nose output, the milk had a shelf life of 0.3 day (i.e. 8 h) when stored at 25 °C. Shelf life was extended to 9 days when stored at 4 °C. [ABSTRACT FROM AUTHOR]

Aims: To assess the consumption, willingness to consume, availability and knowledge of people about the whole grain food products across the Sultanate of Oman. Methods: A self-administered survey was conducted among a convenience sample of adults to assess the consumption, willingness to consume, availability and knowledge about whole grain products across all the nine Governorates of Oman. Results: Almost all respondents (99%, n = 1891) reported that they consume rice and bread at least 4 days per week. Less than 5% of adults indicated that they consume brown rice, whereas 20% to 90% consume whole grain bread. Forty percent of the respondents indicated that they did not know, which type of bread or rice either white or brown, is healthier. Only 20% to 30% of the respondents reported that brown rice or whole wheat bread was available in the market all the time. The various indexes (0 to 1, where 0 as nil and 1 as maximum) developed based on the survey results for the availability, knowledge and willingness to consume whole grain products were 0.36 to 0.87, 0.35 to 0.64 and 0.51 to 0.57 respectively, in different Governorates of Oman. Conclusion: The results indicated that there is an urgent need to educate the Omani people about the nutritional and health benefits of consuming whole grain products and to improve the availability of whole grain food products across Oman. [ABSTRACT FROM AUTHOR]

Mariculture cage farming in Oman is in its infancy stage. This study provides important baseline information about the initial state of mariculture in Oman and for the sustainable management of future local cage farming. Our main objective was to evaluate the spatio-temporal variations of water quality and hydrography around a gilthead seabream (Sparus aurata) cage farm in Quriyat (Sea of Oman). Starting in July 2018, we conducted a monitoring program over one year in which physico-chemical variables and nutrient levels were regularly measured at the farm cages and at reference sites away from the farm. Vertical flow profiles were recorded at the farm and analysed together with remotely sensed data. The results showed no significant differences among physico-chemical variables and nutrient levels between cages and reference sites. However, there were clear seasonal as well as significant short-term variations in the measurements. Winter conditions are usually homogeneous over the water column without reaching extremes. In summer we recorded surface temperatures of up to 32 °C and extended periods of hypoxia below 35 m depth. Periods of pronounced stratification were interrupted by energetic irregular flow pulses that triggered short up or down-welling events which lead to strong variations of temperature and oxygen. We did not measure a significant impact of the cage farm on the local environment. Our results rather point to the particular importance of monitoring temperature and oxygen levels. Both variables can approach threshold levels for fish farming, especially during summer. We determined the relevant characteristics of the local system and defined requirements for adequate monitoring. The findings of this study provide a timely baseline for future research on the interactions between local cage farms and the marine ecosystem and will assist in the planning and management of mariculture in Oman. [ABSTRACT FROM AUTHOR]

This paper provides an overview of the current status and future potentials of nature-based tourism in the Sultanate of Oman with particular focus on sea turtles at Ras Al Hadd. The paper uses objective yardsticks such as inbound tourist arrivals, nationality and spending patterns, seasonality, employment, as well as gross domestic product contribution derived from secondary data from national and international sources to appraise the current situation. Additionally, based on the review of relevant literature, a strengths, weaknesses, opportunities, and threats analysis is used to summarize relevant socioeconomic, political, environmental, and regulatory issues. While there is strong evidence of government commitment to develop nature-based tourism in the country, a number of key issues related to tourist facilities, human activities, environmental conditions, economic research, and capacity development are highlighted for further attention. Most importantly, the analysis suggests a potential to increase the contribution of sustainable sea turtle tourism to Oman's gross domestic product. To realize this potential the sector needs to (1) consider the seasonal variation of tourists, (2) develop its accommodation capabilities especially at sites with ecological uniqueness while ensuring minimum negative impacts on biodiversity, (3) increase the number of Omani nationals employed in the tourism industry and improve their skills through training, (4) develop marketing tools to attract the dominant inbound ecotourism groups to the country, (5) enhance sustainable planning implementation in the Omani tourism sector, and (6) most importantly ensure an effective implementation of legislation protecting sea turtles and their habitats. It is hoped that policymakers can use these findings to set a direction on sustainable sea turtle tourism in Oman, while promoting the effective conservation of these species. [ABSTRACT FROM AUTHOR]

In most organisms, specific structures are responsible for detecting light patterns and vision. Several species of sea urchins appear to have a diffuse photoreceptor system that enables them to detect light and in some cases objects. The presence of extraocular vision was investigated on a sea urchin common in northern Oman,Diadema setosum. Urchins from 8- to 10-m deep coral communities were used in controlled experiments that quantified the orientation response of the urchins to various visual cues: size, contrast and colour of circular targets simulating urchins’ outlines. Urchins responded to black discs down to 11° initial visual angle but not to smaller discs. The minimum grey-scale value triggering a response was between 50 and 37% black. Urchins responded to red targets but not to green or blue ones. An average angular distance between spines of 5.3° suggested a visual acuity of about 10.6°.D. setosumthus showed extraocular vision allowing them to detect objects of different sizes, contrasts and to some extent colour, supporting the hypothesis that the whole sea urchin’s body acts as a single large compound eye. [ABSTRACT FROM AUTHOR]

The dynamics of potentially harmful phytoplankton in relation to environmental parameters was investigated in the semi-enclosed Bay of Bandar Khayran (Sea of Oman) from April 2006 through April 2011. In total, 24 potentially harmful algal species were identified, including 11 species of dinoflagellates and eight species of diatoms. The dinoflagellates Prorocentrum minimum (Pavillard) Schiller, 1933, Scrippsiella trochoidea Balech ex Loeblich III, 1965, and Noctiluca scintillans (Macartney) Kofoid and Swezy, 1921 were most abundant during the Southwest Monsoon (SWM, July-September) and Northeast Monsoon (NEM, January-March) seasons, while other species occurred in low abundance and with no clear seasonal patterns. A dense bloom of Cochlodinium polykrikoides Margalef, 1961 that affected the distribution and abundance of other harmful algal species (HAB) was observed for the first time in the Sea of Oman during 2008-2009. Prorocentrum minimum increased in abundance during and after the decay of the Cochlodinium bloom while S. trochoidea was suppressed during this bloom, increasing thereafter once again. Noctiluca scintillans disappeared in the late SWM and NEM of 2008 and SWM of 2009, when blooms typically occur annually. Prorocentrum minimum and S. trochoidea persisted throughout the annual cycle of all years, enhancing their capability to bloom in the region under favorable conditions of high light intensities and relatively warm waters of low turbulence. [ABSTRACT FROM AUTHOR]

Dispersal is a crucial ecological process, driving population dynamics and defining the structure and persistence of populations. Measuring demographic connectivity between discreet populations remains a long-standing challenge for most marine organisms because it involves tracking the movement of pelagic larvae. Recent studies demonstrate local connectivity of reef fish populations via the dispersal of planktonic larvae, while biogeography indicates some larvae must disperse 100–1000 s kilometres. To date, empirical measures of long-distance dispersal are lacking and the full scale of dispersal is unknown. Here we provide the first measure of long-distance dispersal in a coral reef fish, the Omani clownfish Amphiprion omanensis, throughout its entire species range. Using genetic assignment tests we demonstrate bidirectional exchange of first generation migrants, with subsequent social and reproductive integration, between two populations separated by over 400 km. Immigration was 5.4% and 0.7% in each region, suggesting a biased southward exchange, and matched predictions from a physically-coupled dispersal model. This rare opportunity to measure long-distance dispersal demonstrates connectivity of isolated marine populations over distances of 100 s of kilometres and provides a unique insight into the processes of biogeography, speciation and adaptation. [ABSTRACT FROM AUTHOR]

The Regional Organization for the Protection of the Marine Environment (ROPME) Sea Area (RSA) in the northern Indian Ocean, which comprises the Gulf, the Gulf of Oman and the northern Arabian Sea, already experiences naturally extreme environmental conditions and incorporates one of the world's warmest seas. There is growing evidence that climate change is already affecting the environmental conditions of the RSA, in areas including sea temperature, salinity, dissolved oxygen, pH, and sea level, which are set to continue changing over time. The cumulative impacts of these changes on coastal and marine ecosystems and dependent societies are less well documented, but are likely to be significant, especially in the context of other human stressors. This review represents the first regional synthesis of observed and predicted climate change impacts on marine and coastal ecosystems across the ROPME Sea Area and their implications for dependent societies. Climate-driven ecological changes include loss of coral reefs due to bleaching and the decline of fish populations, while socio-economic impacts include physical impacts from sea-level rise and cyclones, risk to commercial wild capture fisheries, disruption to desalination systems and loss of tourism. The compilation of this review is aimed to support the development of targeted adaptation actions and to direct future research within the RSA. [ABSTRACT FROM AUTHOR]

The question of whether growth in bivalves is predictable in terms of environmental condition is addressed directly by trying to infer juvenile scallop growth from environment data within and between two locations in the Baie des Chaleurs, Québec. Using models based on either self-organizing models – the group method of data handling (GMDH) algorithm - or multilinear regressions, scallop growth was found to be predictable. GMDH models lead consistently to better predictions than multilinear regressions and could thus be a useful alternative tool in managing scallop fisheries aquaculture. Temperature and food availability were the most prominent variables included in the GMDHD models, emphisizing their importance as physical determinants of scallop growth. [ABSTRACT FROM PUBLISHER]

Echinoderms form a remarkable phylum of marine invertebrates that present specific chemical signatures unique in the animal kingdom. It is particularly the case for essential triterpenoids that evolved separately in each of the five echinoderm classes. Indeed, while most animals have Δ5-sterols, sea cucumbers (Holothuroidea) and sea stars (Asteroidea) also possess Δ7 and Δ9(11)-sterols, a characteristic not shared with brittle stars (Ophiuroidea), sea urchins (Echinoidea), and crinoids (Crinoidea). These particular Δ7 and Δ9(11) sterols emerged as a self-protection against membranolytic saponins that only sea cucumbers and sea stars produce as a defense mechanism. The diversity of saponins is large; several hundred molecules have been described in the two classes of these saponins (i.e., triterpenoid or steroid saponins). This review aims to highlight the diversity of triterpenoids in echinoderms by focusing on sterols and triterpenoid glycosides, but more importantly to provide an updated view of the biosynthesis of these molecules in echinoderms. [ABSTRACT FROM AUTHOR]

The Indian Ocean Dipole (IOD) is an interannual mode of climate variability in the Indian Ocean that has intensified with 20th century global-warming. However, instrumental data shows a global-warming hiatus between the late-1990s and 2015. It is presently not clear how the global-warming hiatus affects modes of climate variability such as the IOD, and their basin-wide ocean-atmosphere teleconnections. Here, we present a 26-year long, biweekly record of Sr/Ca and δ18O from a Porites coral drilled in the Gulf of Oman. Sea surface temperature (SSTanom) is calculated from Sr/Ca ratios, and seawater δ18O (δ18Osw-anom) is estimated by subtracting the temperature component from coral δ18O. Our δ18Osw-anom record reveals a significant regime shift in 1999, towards lower mean δ18Osw values, reflecting intensified upwelling in the western Indian Ocean. Prior to the 1999 regime shift, our SSTanom and δ18Osw-anom show a clear IOD signature, with higher values in the summer of positive-IOD years due to weakened upwelling. The IOD signature in SSTanom and δ18Osw-anom disappears with the overall intensification of upwelling after the 1999 regime shift. The inferred increase in upwelling is likely driven by an intensified Walker circulation during the global-warming hiatus. Upwelling in the Western Indian Ocean uncouples from the IOD. [ABSTRACT FROM AUTHOR]

The article provides information on the shallow-water and in situ observation of the genus Pseudothelogorgia. It states that the Pseudothelogorgia genus was described by L. P. van Ofwegen, in which the Lignella hartogi was included. It adds that live Pseudothelogorgia was first photographed under the Gulf of Oman.

Six common soft coral species ( Sarcophyton sp., Sinularia sp.1 and sp.2, Cladiella sp., Scleronephthya sp. and Dendronephthya sp.) from Bandar Al-Khayran (Sultanate of Oman) had significantly lower bacterial density in comparison with surfaces of empty shells. Methanol: chloroform (1:1) extracts of these species were tested against Gram positive ( Micrococcus luteus, Staphlococcus aureus, Bacillus subtilis, Bacillus sp.) and Gram negative ( Salmonella enterica, Pseudomonas aeruginosa, Escherichia coli, Cytophaga sp., Pseudomonas sp., Shewanella sp.) marine biofouling and pathogenic bacterial strains. All tested extracts had some activity against human pathogens and the highest antimicrobial activity was observed for extracts of Sinularia sp.1 and Cladiella sp. (inhibited 50% and 60% of the strains, respectively). Only ethyl acetate extracts of Cladiella sp. inhibited growth of biofouling bacteria. The active fraction was purified and identified as a mixture of hexadecyl palmitate and hexadecyl stearate. Pure hexadecyl palmitate inhibited growth ( Bacillus sp. and Psychrobacter sp.) and attachment ( Bacillus sp., Cytophaga sp., Pseudomonas sp., Psychrobacter sp., Shewanella sp.) of the marine biofouling bacteria. The results of this study suggest that soft corals have developed mechanisms to combat microbial infections and inhibit bacterial fouling. [ABSTRACT FROM AUTHOR]

Highlights: [•] Instrumental texture of dates was correlated with physico-chemical properties. [•] Principal component analysis identified six groups of variables to differentiate the dates. [•] Cluster analysis classified dates into three distinct groups. [•] Regression models for instrumental texture were developed. [Copyright &y& Elsevier]

Commercially available Omani halwa from the local market was classified based on its composition and instrumental texture profile. The products were grouped into four classes based on cluster analysis. None of the attributes of the instrumental Texture Profile Analysis (TPA) were correlated significantly with the ash, colour and pH values (p<0.05), while specific attributes did correlate with specific aspects of the chemical composition. All TPA attributes were significantly correlated with specific types of fatty acid. Hardness was correlated significantly with the moisture and sugar contents, while adhesiveness was correlated significantly with the moisture, sugar and non-sugar carbohydrate contents (p<0.05). Springiness was correlated with sugar and non-sugar carbohydrate. The firmness and chewiness were correlated with moisture and the total fat, saturated and unsaturated fat contents (p<0.05). Cohesiveness-1 was correlated only with the protein, total fat, saturated and un-saturated fat contents, while cohesiveness-2 was correlated with sugar, total fat, saturated and unsaturated fat (p<0.05). The resilience was correlated with the total fat, saturated and unsaturated fatty acids, while gumminess was only correlated with the moisture content. The link between TPA and physico-chemical characteristics was established using multivariate matrix correlations and revealed that the pattern of texture attributes was mostly linked to the moisture and fat contents. Principal component analysis was carried out to identify the main physico-chemical properties and TPA attributes of the four classes of halwa as determined by cluster analysis. The four classes of halwa could be characterised as soft-resilient, soft-springy-cohesive, soft-springy and hard-chewy. [ABSTRACT FROM AUTHOR]