Indian Ocean temperature anomalies predict long-term global dengue trends.

Despite identifying El Niño events as a factor in dengue dynamics, predicting the oscillation of global dengue epidemics remains challenging. Here, we investigate climate indicators and worldwide dengue incidence from 1990 to 2019 using climate-driven mechanistic models. We identify a distinct indicator, the Indian Ocean basin-wide (IOBW) index, as representing the regional average of sea surface temperature anomalies in the tropical Indian Ocean. IOBW is closely associated with dengue epidemics for both the Northern and Southern hemispheres. The ability of IOBW to predict dengue incidence likely arises as a result of its effect on local temperature anomalies through teleconnections. These findings indicate that the IOBW index can potentially enhance the lead time for dengue forecasts, leading to better-planned and more impactful outbreak responses.

Molecular diversity of black corals from the Saudi Arabian Red Sea: a first assessment.

Black corals occur as part of benthic assemblages from shallow to deep waters in all oceans. Despite the importance in many benthic ecosystems, where these act as biodiversity aggregators, antipatharians remain poorly studied, with 75% of the known species occurring below recreational SCUBA diving depth limits. Currently, information regarding the diversity and evolutionary history is limited, with most studies focusing on Hawaii and the South Pacific Ocean. Other regions of the world have received less attention, such as the Red Sea, where only two black coral families and four genera have been recorded. We provide the first analysis of the molecular diversity of black corals in the eastern Gulf of Aqaba and the northern and central Saudi Arabian Red Sea, based on a dataset of 161 antipatharian colonies collected down to 627 m deep. Based on specimen morphology, we ascribed our material to 11 genera belonging to 4 of the 7 known Antipatharia families, i.e. Antipathidae, Aphanipathidae, Myriopathidae and Schizopathidae. The genus level phylogeny of three intergenic mitochondrial regions, the trnW-IGR-nad2 (IgrW ), nad5-IGR-nad1 (IgrN ) and cox3-IGR-cox1 was reconstructed including previously published material. Overall, we recovered six molecular clades that included exclusively Red Sea sequences, with the highest diversity occurring at mesophotic depths. This study highlights that diversity of black corals in the Red Sea is much higher than previously known, with seven new generic records, suggesting that this basin may be a hotspot for antipatharian diversity as is known for other taxa. Our results recovered unresolved relationships within the order at the familial and generic levels. This emphasises the urgent need for an integration of genomic-wide data with a re-examination of informative morphological features necessary to revise the systematics of the order at all taxonomic levels.

An extensive investigation on human risk associated with PAHs in fish and sediment in Bushehr, Northern of Persian Gulf.

Here, a comprehensive study was designed to estimate the human risk assessment attributed to exposure of polycyclic aromatic hydrocarbons (PAHs)in sediment and fish in most polluted shore area in north of Persian Gulf. To this end, a total of 20 sediment and inhabitual Fish, as one of most commercial fish, samples were randomly collected from 20 different stations along Bushehr Province coastline. The 16 different components of PAHs were extracted from sediment and edible parts of inhabitual fish and measured with high-performance liquid chromatography (HPLC) and gas chromatography (GC), respectively. In addition, dietary daily intake (DDI) values of PAHs via ingestion Indian halibut and the incremental lifetime cancer risk (ILCR) attributed to human exposure to sediments PAHs via (a) inhalation, (b) ingestion, and (c) dermal contact for two groups of ages: children (1-11 years) and adults (18-70 years) were estimated. The results indicated that all individual PAHs except for Benzo(b)flouranthene (BbF) and Benzo(ghi) perylene (BgP) were detected in different sediment sample throughout the study area with average concentration between 2.275 ± 4.993 mg.kg-1 dw. Furthermore, Naphthalene (Nap) with highest average concentration of 3.906 ± 3.039 mg.kg-1 dw was measured at the Indian halibut. In addition, the human risk analysis indicated that excess cancer risk (ECR) attributed to PAHs in sediment and fish in Asaluyeh with high industrial activities on oil and derivatives were higher the value recommended by USEPA (10-6). Therefore, a comprehensive analysis on spatial distribution and human risk assessment of PAHs in sediment and fish can improve the awareness on environmental threat in order to aid authorities and decision maker to find a sustainable solution.

Rapid seagrass meadow expansion in an Indian Ocean bright spot.

The areal extent of seagrass meadows is in rapid global decline, yet they provide highly valuable societal benefits. However, their conservation is hindered by data gaps on current and historic spatial extents. Here, we outline an approach for national-scale seagrass mapping and monitoring using an open-source platform (Google Earth Engine) and freely available satellite data (Landsat, Sentinel-2) that can be readily applied in other countries globally. Specifically, we map contemporary (2021) and historical (2000-2021; n = 10 maps) shallow water seagrass extent across the Maldives. We found contemporary Maldivian seagrass extent was ~ 105 km2 (overall accuracy = 82.04%) and, notably, that seagrass area increased threefold between 2000 and 2021 (linear model, + 4.6 km2 year-1, r2 = 0.93, p < 0.001). There was a strongly significant association between seagrass and anthropogenic activity (p < 0.001) that we hypothesize to be driven by nutrient loading and/or altered sediment dynamics (from large scale land reclamation), which would represent a beneficial anthropogenic influence on Maldivian seagrass meadows. National-scale tropical seagrass expansion is unique against the backdrop of global seagrass decline and we therefore highlight the Maldives as a rare global seagrass 'bright spot' highly worthy of increased attention across scientific, commercial, and conservation policy contexts.

Assessment of parent and alkyl -PAHs in surface sediments of Iranian mangroves on the northern coast of the Persian Gulf: Spatial accumulation distribution, influence factors, and ecotoxicological risks.

Spatial patterns, potential origins, and ecotoxicological risk of alkylated (APAH) -and parent -(PPAH) polycyclic aromatic hydrocarbons (PAHs) were studied in mangrove surface sediments along the northern coasts of the Persian Gulf, Iran. The mean total concentrations (ngg-1dw) ∑32PAH, ∑PPAHs and ∑APAHs in sediments were 3482 (1689-61228), 2642 (1109-4849), and 840 (478-1273), respectively. The spatial variability was similar among these PAH groups, with the highest levels occurring in Nayband National Marine Park (NNMP). Physicochemical environmental factors, such as sediment grain size, and total organic carbon (TOC) contents, are significant factors of PAH distribution. These findings suggest that PAH pollution level is moderate-to-high, supporting the current view that mangrove ecosystems are under intensive anthropogenic impacts, such as petrochemical, oil and gas loads, port activities, and urbanization. Non-parametric multidimensional scaling (NPMDS) ordination demonstrated that NNMP mangrove is the critical site exhibiting high loading of PAH pollutants. Here, for the first time in this region, Soil quality guidelines (SQGs), Toxic equivalency quotient (TEQ), Mutagenic equivalency quotient (MEQ), and composition indices comprising Mean maximum permissible concentration quotient (m-MPC-Q), and Mean effect range median quotient (m-ERM-Q) methods were used to have a comprehensive risk assessment for PAH compounds and confirmed medium-to-high ecological risks of PAHs in the study area, particularly in the western part of the Gulf, highlighting the industrial impacts on the environment.

Roseihalotalea indica gen. nov., sp. nov., a halophilic Bacteroidetes from mesopelagic Southwest Indian Ocean with higher carbohydrate metabolic potential.

The pink-colored and strictly aerobic bacterium strain, designated as TK19036T, was isolated from mesopelagic layer of the Southwest Indian Ocean. This novel isolate can grow at 10-45 °C (optimum, 30 °C), pH 6.0-8.0 (optimum, pH 7.0), and 2-14% NaCl concentrations (w/v) (optimum, 6%). The predominant respiratory quinone was Menaquinone-7. Major polar lipid profiles contained two aminolipids, aminophospholipid, two glycolipids, phosphatidylethanolamine, and three unknown polar lipids. The preponderant cellular fatty acids were iso-C15:0, C16:1 ω5c and iso-C17:0 3-OH. Phylogenetic analyses based on 16S rRNA gene sequence uncovered that the strain TK19036T pertained to the family Catalinimonadaceae under phylum Bacteroidota, and formed a distinct lineage with the closed species Tunicatimonas pelagia NBRC 107804T. The up-to-bacteria-core gene phylogenetic trees also demonstrated a deep and novel branch formed by the strain TK19036T within the family Catalinimonadaceae. Based on chemotaxonomic, phylogenetic and genomic features presented above, strain TK19036T represents a novel species from a novel genus of the family Catalinimonadaceae, for which the name Roseihalotalea indica gen. nov. sp. nov. is proposed. The type strain is TK19036T (= CGMCC 1.18940T = NBRC 116371T).

Responses of the coral reef cryptobiome to environmental gradients in the Red Sea.

An essential component of the coral reef animal diversity is the species hidden in crevices within the reef matrix, referred to as the cryptobiome. These organisms play an important role in nutrient cycling and provide an abundant food source for higher trophic levels, yet they have been largely overlooked. Here, we analyzed the distribution patterns of the mobile cryptobiome (>2000 µm) along the latitudinal gradient of the Saudi Arabian coast of the Red Sea. Analysis was conducted based on 54 Autonomous Reef Monitoring Structures. We retrieved a total of 5273 organisms, from which 2583 DNA sequences from the mitochondrially encoded cytochrome c oxidase I were generated through sanger sequencing. We found that the cryptobiome community is variable over short geographical distances within the basin. Regression tree models identified sea surface temperature (SST), percentage cover of hard coral and turf algae as determinant for the number of operational taxonomic units present per Autonomous Reef Monitoring Structures (ARMS). Our results also show that the community structure of the cryptobiome is associated with the energy available (measured as photosynthetic active radiation), sea surface temperature, and nearby reef habitat characteristics (namely hard corals, turf and macroalgae). Given that temperature and reef benthic characteristics affect the cryptobiome, current scenarios of intensive climate change are likely to modify this fundamental biological component of coral reef functioning. However, the trajectory of change is unknow and can be site specific, as for example, diversity is expected to increase above SST of 28.5°C, and with decreasing hard coral and turf cover. This study provides a baseline of the cryptobenthic community prior to major coastal developments in the Red Sea to be used for future biodiversity studies and monitoring projects. It can also contribute to better understand patterns of reef biodiversity in a period where Marine Protected Areas are being discussed in the region.

Crown-of-thorns seastar (Acanthaster spp.) feeding ecology across species and regions.

The coral predators, crown-of-thorns starfish (COTS, Acanthaster spp.) remain a major cause of extensive and widespread coral loss in Indo-Pacific coral reefs. With increased phylogenetic understanding of these seastars, at least five species appear to be present across different regions. We compare the feeding ecology of these species. Where acroporid corals are prevalent, Acanthaster spp. often exhibit a preference for these corals, with Porites being least preferred, as seen in most species including Acanthaster planci in the northern Indian Ocean and Acanthaster cf. solaris in the west Pacific. In the eastern Pacific, where Acropora is largely absent, Acanthaster cf. ellisii prey on a range of coral species, including Porites. Coral predation by COTS is influenced by several factors including food availability, coral nutritional value, protective crustaceans and coral defenses, with differences in feeding ecology and behaviour emerging across the different COTS species. Feeding behaviour of COTS can act to increase coral species richness by reducing the dominance of fast-growing species. In outbreaking populations, COTS impacts reef systems by reducing live coral cover, eroding reef complexity and causing shifts in reef trophic structure. Where data are available, we synthesise and contrast the feeding preferences and foraging behaviour of Acanthaster species, and their impact on coral assemblages across the different species and regions. For areas where focal predation on Acropora occurs, also the fastest growing coral with the greatest recovery potential following mass mortality events, the combination of climate change and COTS outbreaks presents an imminent threat to coral reefs. This is exacerbated by the dietary flexibility of Acanthaster species. The impacts of heatwaves, COTS and other stressors are creating a negative feedback loop accelerating coral reef decline.

Circumtropical distribution and cryptic species of the meiofaunal enteropneust Meioglossus (Harrimaniidae, Hemichordata).

Hemichordata has always played a central role in evolutionary studies of Chordata due to their close phylogenetic affinity and shared morphological characteristics. Hemichordates had no meiofaunal representatives until the surprising discovery of a microscopic, paedomorphic enteropneust Meioglossus psammophilus (Harrimaniidae, Hemichordata) from the Caribbean in 2012. No additional species have been described since, questioning the broader distribution and significance of this genus. However, being less than a millimeter long and superficially resembling an early juvenile acorn worm, Meioglossus may easily be overlooked in both macrofauna and meiofauna surveys. We here present the discovery of 11 additional populations of Meioglossus from shallow subtropical and tropical coralline sands of the Caribbean Sea, Red Sea, Indian Ocean, and East China Sea. These geographically separated populations show identical morphology but differ genetically. Our phylogenetic reconstructions include four gene markers and support the monophyly of Meioglossus. Species delineation analyses revealed eight new cryptic species, which we herein describe using DNA taxonomy. This study reveals a broad circumtropical distribution, supporting the validity and ecological importance of this enigmatic meiobenthic genus. The high cryptic diversity and apparent morphological stasis of Meioglossus may exemplify a potentially common evolutionary 'dead-end' scenario, where groups with highly miniaturized and simplified body plan lose their ability to diversify morphologically.

Sources and pathways of carbon and nitrogen of macrophytes and sediments using stable isotopes in Al-Kharrar Lagoon, eastern Red Sea coast, Saudi Arabia.

Elemental ratios (δ13C, δ15N and C/N) and carbon and nitrogen concentrations in macrophytes, sediments and sponges of the hypersaline Al-Kharrar Lagoon (KL), central eastern Red Sea coast, were measured to distinguish their sources, pathways and see how they have been influenced by biogeochemical processes and terrestrial inputs. The mangroves and halophytes showed the most depleted δ13C values of -27.07±0.2 ‰ and -28.34±0.4 ‰, respectively, indicating their preferential 12C uptake, similar to C3-photosynthetic plants, except for the halophytes Atriplex sp. and Suaeda vermiculata which showed δ13C of -14.31±0.6 ‰, similar to C4-plants. Macroalgae were divided into A and B groups based on their δ13C values. The δ13C of macroalgae A averaged -15.41±0.4 ‰, whereas macroalgae B and seagrasses showed values of -7.41±0.8 ‰ and -7.98 ‰, suggesting uptake of HCO3- as a source for CO2 during photosynthesis. The δ13C of sponges was -10.7±0.3 ‰, suggesting that macroalgae and seagrasses are their main favoured diets. Substrates of all these taxa showed δ13C of -15.52±0.8 ‰, suggesting the KL is at present a macroalgae-dominated lagoon. The δ15N in taxa/sediments averaged 1.68 ‰, suggesting that atmospheric N2-fixation is the main source of nitrogen in/around the lagoon. The heaviest δ15N (10.58 ‰) in halophytes growing in algal mats and sabkha is possibly due to denitrification and ammonia evaporation. The macrophytes in the KL showed high C %, N %, and C/N ratios, but this is not indicated in their substrates due possibly to a rapid turnover of dense, hypersaline waters carrying most of the detached organic materials out into the Red Sea. The δ13C allowed separation of subaerial from aquatic macrophytes, a proxy that could be used when interpreting paleo-sea level or paleoclimatic changes from the coastal marine sediments.

Biodiversity patterns of the coral reef cryptobiota around the Arabian Peninsula.

The Arabian Peninsula accounts for approximately 6% of the world's coral reefs. Some thrive in extreme environments of temperature and salinity. Using 51 Autonomous Reef Monitoring Structure (ARMS), a standardized non-destructive monitoring device, we investigated the spatial patterns of coral reef cryptobenthic diversity in four ecoregions around the Arabian Peninsula and analyzed how geographical and/or environmental drivers shape those patterns. The mitochondrial cytochrome c oxidase subunit I (COI) gene was used to identify Amplicon Sequence Variants and assign taxonomy of the cryptobenthic organisms collected from the sessile and mobile fractions of each ARMS. Cryptobenthic communities sampled from the two ecoregions in the Red Sea showed to be more diverse than those inhabiting the Arabian (Persian) Gulf and the Gulf of Oman. Geographic distance revealed a stronger relationship with beta diversity in the Mantel partial correlation than environmental distance. However, the two mobile fractions (106-500 µm and 500-2000 µm) also had a significant correlation between environmental distance and beta diversity. In our study, dispersal limitations explained the beta diversity patterns in the selected reefs, supporting the neutral theory of ecology. Still, increasing differences in environmental variables (environmental filtering) also had an effect on the distribution patterns of assemblages inhabiting reefs within short geographic distances. The influence of geographical distance in the cryptofauna assemblages makes these relevant, yet usually ignored, communities in reef functioning vulnerable to large scale coastal development and should be considered in ecosystem management of such projects.

Health risk assessment of heavy metal toxicity in the aquatic environment of the Persian Gulf.

This study aims to explore the potential health risks linked to four heavy metals/metalloids (Pb, Cd, As, Hg) present in four commercially important fish species (Scombromorus commerson, Pseudorhombus elevatus, Thunnus tonggol and Otolithes ruber) in the Persian Gulf. Metals in fish muscle tissue were analyzed via ICP-MS. The analysis revealed that Scombromorus commerson (except for Pb) and Thunnus tonggol (except for As) exhibited the highest and lowest contamination levels, respectively. The Hazard Index findings highlighted arsenic and mercury as the most hazardous elements. However, the Target Hazard Quotient values for each metal and fish species remained within safe thresholds. The highest and lowest Total Carcinogenic Risk was concerning Pseudorhombus elevates (As: 7.41-E05), and Thunnus thonggol (Pb: 3.21-E07), respectively. TCR analysis suggests that the cancer risk of studied metals was below the negligible level (TCR < 10-6) or within the acceptable level (10-6 < TCR < 10-4), potentially not posing carcinogenic risks through extended consumption.

Microplastics in the Indian and South Atlantic oceans translocate to gills, digestive glands, and muscle of the chokka squid Loligo reynaudii.

Comparative microplastic (MP) data for cephalopods between oceans is scarce. Our aim was to quantify, characterise, and compare MPs in gills, digestive gland, and mantle of chokka squid from the South Atlantic Ocean (SAO) and Indian Ocean (IO) off the coast of South Africa. South African squid had more MPs compared with other studies (means = 2.0 and 0.4 in SAO and IO squid mantle, respectively). Blue fibres were dominant. Identifiable MPs were polyethylene. Despite IO water having higher MP concentrations than the SAO, SAO squid had higher MP concentrations. Dilution by growth is the likely reason for the lower MP concentrations. Fibres were shorter in SAO than IO squid. However, we could not explain why fibre and mantle lengths from both oceans were positively correlated. Squid may not be the best indicator of marine MPs. The characteristics of MPs in squid can be used to track stocks and migrations.

Sourcing aliphatic and polycyclic aromatic hydrocarbons (PAHs) in Jinga shrimp (Metapenaeus affinis) muscle tissues and surface sediments (study case: Northwest Persian Gulf).

This study addresses the sources of aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) in the surface sediments of the northwestern Persian Gulf and the muscle tissues of Jinga shrimp (Metapenaeus affinis), a commercially important aquatic species. In November 2018, 28 Jinga shrimp samples were systematically collected from four key fishing areas in Behrgan and Khormusi: Imam Khomeini Port (S1), Mahshahr Port (S2), Sejafi (S3), and Behrgan Wharf (S4). Additionally, sediment samples were collected from these locations, and AHs and PAHs concentrations were analyzed using gas chromatography-mass spectrometry (GC-MS). The average aliphatic concentration in Jinga shrimp was 4800.32 (µg g-1 DW), exceeding the sediment samples' 2496.69 (µg g-1 DW) estimate. Hydrocarbon component analysis revealed EPA priority list (PAH-16) and measured PAHs (PAH-29) concentrations in Jinga shrimp ranging from 1095.8 to 2698.3 (ng g-1 DW) and in sediments from 653.6 to 1019.5 (ng g-1 DW). Elevated AHs and PAHs in Jinga shrimp, compared to sediments, suggest a petrogenic source, notably at station S4 near Behrgansar and Nowruz oil fields. Low molecular weight (LMW) compounds dominated in both shrimp and sediment PAHs. Aliphatic composition profiles in shrimps closely mirrored sediment profiles, illustrating an even-to-odd carbon dominance gradient. Diagnostic ratio examinations of hydrocarbons indicated pervasive petroleum derivatives in the environment. This study establishes a direct correlation between hydrocarbon concentrations in shrimp and sediment samples and the corresponding aliphatic groups, PAH-16, and PAH-29. The findings underscore the potential of Jinga shrimp as a reliable indicator of hydrocarbon pollution in the northwestern Persian Gulf.

Effects of duty cycle on passive acoustic monitoring metrics: The case of blue whale songs.

Long-term fixed passive acoustic monitoring of cetacean populations is a logistical and technological challenge, often limited by the battery capacity of the autonomous recorders. Depending on the research scope and target species, temporal subsampling of the data may become necessary to extend the deployment period. This study explores the effects of different duty cycles on metrics that describe patterns of seasonal presence, call type richness richness, and daily call rate of three blue whale acoustics populations in the Southern Indian Ocean. Detections of blue whale calls from continuous acoustic data were subsampled with three different duty cycles of 50%, 33%, and 25% within listening periods ranging from 1 min to 6 h. Results show that reducing the percentage of recording time reduces the accuracy of the observed seasonal patterns as well as the estimation of daily call rate and call call type richness. For a specific duty cycle, short listening periods (5-30 min) are preferred to longer listening periods (1-6 h). The effects of subsampling are greater the lower the species' vocal activity or the shorter their periods of presence. These results emphasize the importance of selecting a subsampling scheme adapted to the target species.

A new species of branchial fish parasitic deep-sea isopod, Brucethoa Aneesh, Hadfield, Smit & Kumar, 2020 (Isopoda: Cymothoidae) from the Indian Ocean, with the transfer of two Elthusa Schioedte & Meinert, 1884 species.

Brucethoa isro n. sp., a new species of deep-sea cymothoid is described and illustrated from the host fish Spinyjaw greeneye, Chlorophthalmus corniger Alcock, 1894, at depths of 265 to 458 metres from the southwest coast of India. Brucethoa isro n. sp. is recovered from the base of the gill cavity, facing the head towards the anterior, and the dorsal body closely adpressed against the gill, while the ventral brood presses against the inner wall of the operculum. Brucethoa isro n. sp., the second species of the genus, is characterized by: head weakly immersed in pereonite 1, very elongated body (3.15 times as long as wide); body dorsum not vaulted, almost flat; all coxae short, 0.5 times as the length of corresponding pereonites; sternite 7 with prominent posterior lobes. All adult life stages of the new species are described [including females (ovigerous and non-ovigerous), males, transitional, and juvenile. The species is currently known from the southwest coast of India and is the type locality. Additionally, this research provides valuable ecological insights into Brucethoa isro n. sp. and its habitat. As part of the taxonomic contributions, two species, Brucethoa alvaradoensis (Rocha-Ramírez, Chávez-López & Bruce, 2005) comb. n. and Brucethoa epinepheli (Trilles & Justine, 2010) comb. n., are transferred from the Elthusa genus to the Brucethoa genus.

Chemical speciation and comprehensive risk assessment of metals in sediments from Nabq protectorate, the Red Sea using individual and synergistic indices.

The study evaluates metal concentrations, distributions, contamination, risk, sources, fractionation, and mobility in Nabq Protectorate sediments, revealing a metal content order of Fe, Mn, Pb, Ni, and Cd. Metals are dominated by residual fractions, with Cd (83.70 %) > Ni (82.98 %) > Pb (80.96 %) > Fe (80.31 %) > Mn (76.65 %) reflecting the natural sources of investigated metals. Mn (23.35 %) was the most abundant mobile metal, and the sediments of the protectorate had low toxicity and moderate risk according to the synergistic indices (1 ≤ mRAC<10 and ERM; 5-10). The results from the proposed individual indices showed that Mn, Fe, and Pb are the most bioavailable (BIM 0.1-0.4), Cd, Mn, Ni, Fe, and Pb are of moderate mobility (MIM 0.1-0.4), and Cd is the most available (ARIM 5-10), with Cd posing the most ecological risk. The total hazard quotient (THQ) for child was greater than one, exposure to manganese through ingestion and skin contact while swimming may endanger human health.

Using cell culture systems from the Persian Gulf Arabian yellowfin sea bream, Acanthopagrus arabicus, to assess the effects of dexamethasone on gonad and brain aromatase activity and steroid production.

Dexamethasone (DEX) is a synthetic glucocorticoid widely used as pharmaceutical and usually exists in effluents with varying degrees of concentrations. In this study, cultivated Brain, ovary and testis cells from Arabian Sea bream, Acanthopagrus arabicus, were treated by DEX at concentrations of 0, 0.3, 3.0, 30.0 and 300.0 µg/ml for 48 h. The aromatase activity and steroid (17-ß-estradiol (E2), progesterone (P) and testosterone (T)) production by cells were measured at 12, 24 and 48 h of the experiment. The results showed that the sensitivity of cultivated ovarian, testicular and brain cells to DEX increased dose dependently. DEX was potent inhibitor of aromatase activity at specially 30.0 and 300.0 µg/ml in the cultivated ovarian and testicular cells at different sampling time. On the other hand, DEX was found to stimulate the aromatase activity of fish brain. DEX also decreased E2, P and T production by cultivated ovarian and testicular cells during the experiment. While, DEX caused an increase in the production of E2 and P by brain cells, which seems logical considering the stimulating effect of this drug on brain aromatase activity. In conclusion, results highlight that DEX is able to change the activity of aromatase, and disrupt the biosynthesis of estrogens and thus affect reproduction in fish.

Occurrence and distribution of phycotoxins in the Antarctic Ocean.

Lipophilic phycotoxins (LPTs) and domoic acid (DA) in Antarctic seawater, as well as parts of the South Pacific and the Southern Indian Oceans were systematically investigated. DA and six LPTs, namely pectenotoxin-2 (PTX2), okadaic acid (OA), yessotoxin (YTX), homo-yessotoxin (h-YTX), 13-desmethyl spirolide C (SPX1), and gymnodimine (GYM), were detected. PTX2, as the dominant LPTs, was widely distributed in seawater surrounding Antarctica, whereas OA, YTX, and h-YTX were irregularly distributed across the region. The total concentration of LPTs in surface seawater ranged from 0.10 to 13.57 ng/L (mean = 2.20 ng/L). ∑LPT levels were relatively higher in the eastern sea areas of Antarctica than in the western sea areas. PTX2 was the main LPT in the vertical profiles, and the PTX2 concentration was significantly higher in the epipelagic zone than water depths below 200 m. The predominant sources of PTX2 and OA in Antarctic sea areas are likely to be Dinophysis.

Discernible decline in macroplastic litter inputs to the central eastern Red Sea shoreline during the COVID-19 lockdown.

Plastic debris accumulating on beaches pose a major threat to marine ecosystems. Unexpected events affecting human operations, such as the COVID-19 pandemic, which prompted governments to implement safety measures and restrictions, can serve as an unplanned investigation of anthropogenic pressure on the marine environment. This study aimed to explore deviations in macroplastic delivery rates to the central eastern Red Sea shoreline during three distinct population mobility periods: before, during, and after COVID-19 restrictions, spanning from January 2019 to June 2022. We observed a 50 % reduction in the estimated macroplastic delivery rates during the lockdown, followed by a 25 % increase after restrictions were eased. Seasonal variations in delivery rates were also observed, with higher values during the winter monsoon. Reduced shoreline litter delivery during the pandemic highlights human operations as a cause of macroplastic litter and suggests the potential of temporary measures to reduce plastic pollution in the coastal environment.