Neutral processes and taxonomic scale drive beta species-genetic diversity correlations in a submesophotic tropical reef fish.

If similar evolutionary forces maintain intra- and interspecific diversity, patterns of diversity at both levels of biological organization can be expected to covary across space. Although this prediction of a positive species-genetic diversity correlation (SGDC) has been tested for several taxa in natural landscapes, no study has yet evaluated the influence of the community delineation on these SGDCs. In this study, we focused on tropical fishes of the Indo-Pacific Ocean, using range-wide single nucleotide polymorphism data for a deep-sea fish (Etelis coruscans) and species presence data of 4878 Teleostei species. We investigated whether a diversity continuum occurred, for different community delineations (subfamily, family, order and class) and spatial extents, and which processes explained these diversity patterns. We found no association between genetic diversity and species richness (α-SGDC), regardless of the community and spatial extent. In contrast, we evidenced a positive relationship between genetic and species dissimilarities (ß-SGDC) when the community was defined at the subfamily or family level of the species of interest, and when the Western Indian Ocean was excluded. This relationship was related to the imprint of dispersal processes across levels of biological organization in Lutjanidae. However, this positive ß-SGDC was lost when considering higher taxonomic communities and at the scale of the entire Indo-Pacific, suggesting different responses of populations and communities to evolutionary processes at these scales. This study provides evidence that the taxonomic scale at which communities are defined and the spatial extent are pivotal to better understand the processes shaping diversity across levels of biological organization.

Endocrine-Disrupting Chemical Exposure Induces Adverse Effects on the Population Dynamics of the Indo-Pacific Humpback Dolphin.

Cetaceans play a pivotal role in maintaining the ecological equilibrium of ocean ecosystems. However, their populations are under global threat from environmental contaminants. Various high levels of endocrine-disrupting chemicals (EDCs) have been detected in cetaceans from the South China Sea, such as the Indo-Pacific humpback dolphins in the Pearl River Estuary (PRE), suggesting potential health risks, while the impacts of endocrine disruptors on the dolphin population remain unclear. This study aims to synthesize the population dynamics of the humpback dolphins in the PRE and their profiles of EDC contaminants from 2005 to 2019, investigating the potential role of EDCs in the population dynamics of humpback dolphins. Our comprehensive analysis indicates a sustained decline in the PRE humpback dolphin population, posing a significant risk of extinction. Variations in sex hormones induced by EDC exposure could potentially impact birth rates, further contributing to the population decline. Anthropogenic activities consistently emerge as the most significant stressor, ranking highest in importance. Conventional EDCs demonstrate more pronounced impacts on the population compared to emerging compounds. Among the conventional pollutants, DDTs take precedence, followed by zinc and chromium. The most impactful emerging EDCs are identified as alkylphenols. Notably, as the profile of EDCs changes, the significance of conventional pollutants may give way to emerging EDCs, presenting a continued challenge to the viability of the humpback dolphin population.

Temporal patterns in coral disease prevalences at Thudufushi Island, Maldives, 2010-2022.

Coral reefs are lately suffering a fast decline in biodiversity due to the coupled effect of climate change and disease outbreaks, which in recent decades have been reported with higher frequency and shorter intervals. Limited studies have been conducted on coral diseases in the Maldives resulting in the impossibility of assessing the temporal trend in their dynamics. In this context, we evaluated the change in the distribution, prevalence, and host range of 4 diseases, namely black band disease (BBD), brown band disease (BrB), skeletal eroding band (SEB) and white syndrome (WS), in the reef system around Thudufushi Island after an interval of 12 yr since the last assessment. In this period, the overall disease prevalence increased, except for BrB, with SEB showing the most severe increase in 2022 in comparison to 2010. The overall average prevalence of coral diseases is approximately 2%, indicating an increase of about 0.7% since 2010. Diseased coral colonies were found in all the investigated sites, with the east site being the most affected and SEB emerging as the most prevalent disease across all the investigated sites. The affected colonies belong to 13 genera, with Psammocora genus showing the highest overall mean disease prevalence. This study depicted a basic temporal trend in disease prevalence that confirms an increase in coral diseases in the region and calls for a dedicated national monitoring protocol to better understand and predict future coral disease dynamics at regional scales.

Limited trait responses of a tropical seagrass to the combination of increasing pCO2 and warming.

Understanding species-specific trait responses under future global change scenarios is of importance for conservation efforts and to make informed decisions within management projects. The combined and single effects of seawater acidification and warmer average temperature were investigated by means of the trait responses of Cymodocea serrulata, a tropical seagrass, under experimental conditions. After a 35 d exposure period, biochemical, morphological, and photo-physiological trait responses were measured. Overall, biochemical traits mildly responded under the individual exposure to high temperature and increasing pCO2 values. The response of C. serrulata was limited to a decrease in %C and an increase in the sucrose content in the rhizome under the high temperature treatment, 32 °C. This suggests that this temperature was lower than the maximum tolerance limit for this species. Increasing pCO2 levels increased %C in the rhizome, and also showed a significant increase in leaf δ13C values. The effects of all treatments were sublethal; however, small changes in their traits could affect the ecosystem services they provide. In particular, changes in tissue carbon concentrations may affect carbon storage capacity, one key ecosystem service. The simultaneous study of different types of trait responses contributes to establish a holistic framework of seagrass ecosystem health under climate change.

Long-Term Monitoring of Polybrominated Diphenyl Ethers (PBDEs) in Indo-Pacific Humpback Dolphins (Sousa chinensis) from the Pearl River Estuary Reveals High Risks for Calves due to Maternal Exposure.

Although many studies have documented the wide occurrence of polybrominated diphenyl ethers (PBDEs) in cetaceans, little evidence exists regarding the detrimental effects of PBDE exposure on calf death rates for free-ranging cetaceans. This study analyzed life-history-associated PBDE bioaccumulation patterns in 128 stranding Indo-Pacific humpback dolphin (Sousa chinensis) samples over an 18-year timespan from the Pearl River Estuary (PRE). In comparison to the records of PBDE levels in cetaceans worldwide, the median levels of PBDEs (median = 10600 ng g-1 lw, range = 721-50900 ng g-1 lw) in all samples were the highest to date. One-way analysis of variance (ANOVA) showed that adult males (median = 16100 ng g-1 lw, range = 4070-50900 ng g-1 lw) and calves (12000 ng g-1 lw, range = 1250-35300 ng g-1 lw) both had the highest levels of PBDEs compared to the rest of the age/sex groups (p < 0.05). Concentrations of PBDEs in noncalves significantly decreased over the studied period, while those in calves had a slightly increasing trend, which may be due to different exposure routes via fish or milk, respectively. A significant and positive relationship was found between annual calf stranding death rates and body-length-adjusted PBDE concentrations in calves (r = 0.62, p < 0.05), suggesting that maternal exposure of calves to elevated levels of PBDEs may have contributed to the high annual stranding death rates of calves in the last two decades.

Estimation of Per- and Polyfluorinated Alkyl Substance Induction Equivalency Factors for Humpback Dolphins by Transactivation Potencies of Peroxisome Proliferator-Activated Receptors.

The potential risks of per- and polyfluoroalkyl substance (PFAS) accumulation in nearshore dolphins are not well understood. Here, transcriptional activities of 12 PFAS on peroxisome proliferator-activated receptors (PPAR-α, -ß/δ, and -γ) in Indo-Pacific humpback dolphins (Sousa chinensis) were evaluated. All PFAS activated scPPAR-α in a dose-dependent manner. PFHpA exhibited the highest induction equivalency factors (IEFs). The order of IEFs for other PFAS was as follows: PFOA > PFNA > PFHxA > PFPeA > PFHxS > PFBA > PFOS > PFBuS ≈ PFDA ≫ PFUnDA and PFDoDA (not activated). The total induction equivalents (∑IEQs, 5537 ng/g wet weight) indicated that more attention should be paid to investigating contamination levels in dolphins, especially in PFOS (82.8% contribution to the ∑IEQs). The scPPAR-ß/δ and -γ were not affected by any PFAS, except for PFOS, PFNA, and PFDA. Furthermore, PFNA and PFDA could induce higher PPAR-ß/δ and PPAR-γ-mediated transcriptional activities than PFOA. Compared to human beings, PFAS might be more potent PPAR-α activators in humpback dolphins, suggesting that the dolphins may be more susceptible to the adverse effects of PFAS. Our results may be instructive for understanding the impacts of PFAS on marine mammal health due to the identical PPAR ligand-binding domain.

Reproductive biology, length-weight relationship and diet of co-occurring butterfly rays, Gymnura poecilura and Gymnura zonura, in Malaysian waters.

Recent IUCN assessments had resulted in up listing of the status of butterfly rays due to concerns of overfishing, but inadequate biological understanding of these rays prevents meaningful conservation and management measures. Therefore, this study was undertaken to address knowledge gaps in the reproductive biology and diet of longtail butterfly ray (Gymnura poecilura) and zone tail butterfly ray (Gymnura zonura) in Malaysian waters. From surveys of landing sites and fish markets from years 2017 to 2022, size (disc width, DW), weight and maturity were recorded, and stomachs were collected from 94 G. poecilura (N = 39 females and 55 males) and 20 G. zonura (N = 10 females and 10 males) specimens. The length-weight relationships were significantly different between sexes for G. poecilura. The size at maturity (DW50) was estimated to be 476.0 mm (females), 385.0 mm (males) for G. poecilura and 442.0 mm (combined) for G. zonura. The number of embryos ranged from 1 to 6, and the embryo size was between 73.90 to 130.44 mm DW. Dietary analysis of stomach contents revealed that fish prey was dominant in both G. poecilura [94.4% Index of Relative Importance (IRI)] and G. zonura (100% IRI). Ontogenetic shift was seen in G. poecilura that fed on more variety of prey items, including shrimps, squids and crabs with an increase in body size. Both species co-occur all along coastal Malaysia although G. zonura is rarely encountered from fisheries surveys along the Strait of Malacca. Given similar habitat associations and dietary habits, G. poecilura may be able to outcompete G. zonura across their shared habitat range. The validity of G. japonica and G. micrura records in Malaysia remains questionable and requires future investigation.

Connectivity and Order: an Analytical Framework.

IR literature has become inundated with different descriptions for the future of international order. The coming age is purportedly marked by China's ascendancy, American decline, a leaderless "no-one's world", or multiple competing modernities. Yet the global fight against climate change or shared COVID-19 strategies convey a different image of the world's predicament. The situation appears paradoxical: increasingly tense great-power relations are mixed with ever-strengthening interdependencies. This article contributes to these debates by exploring how global orders as well as regionalism today are increasingly defined by various types of connective functional links between intentional actors at various levels of social organisation. To enable a nuanced analysis, the article introduces an analytical framework composed of six connectivity logics, namely cooperation, copying, cushioning, contestation, containment, and coercion. These play out differently within material, economic, institutional, knowledge, people-to-people, and security spheres. The utility of this article's approach is demonstrated through empirical examples related to the policies of key actors in the Indo-Pacific region.

Introduction to the Special Issue: Theory and Practice of Connectivity in the Indo-Pacific-Spheres, Logics, and Regional Dynamics.

This short introduction to the Special Issue entitled "Theory and Practice of Connectivity in the Indo-Pacific - Spheres, Logics, and Regional Dynamics" serves four objectives. It first briefly outlines the rationale for theoretical and empirical engagement with the concept of connectivity, which has become a ubiquitous term in the policy parlance of key global actors in recent years. The introduction then provides a short leader on the connectivity initiatives of key players, specifically China, the USA, Japan, the European Union, and Russia, with a particular focus on the Indo-Pacific space. Third, the seven articles that comprise the Special Issue are summarised. The contributions include a theoretically and conceptually oriented lead article, which introduces an analytical framework for the study of connectivity, and six more empirically motivated contributions that draw upon the said framework. Finally, key takeaways arising from the articles with respect to a broader research agenda on connectivity are discussed.

Untangling the molecular basis of coral response to sedimentation.

Urbanized coral reefs are often chronically affected by sedimentation and reduced light levels, yet many species of corals appear to be able to thrive under these highly disturbed conditions. Recently, these marginal ecosystems have gained attention as potential climate change refugia due to the shading effect of suspended sediment, as well as potential reservoirs for stress-tolerant species. However, little research exists on the impact of sedimentation on coral physiology, particularly at the molecular level. Here, we investigated the transcriptomic response to sediment stress in corals of the family Merulinidae from a chronically turbid reef (one genet each of Goniastrea pectinata and Mycedium elephantotus from Singapore) and a clear-water reef (multiple genets of G. pectinata from the Gulf of Aqaba/Eilat). In two ex-situ experiments, we exposed corals to either natural sediment or artificial sediment enriched with organic matter and used whole-transcriptome sequencing (RNA sequencing) to quantify gene expression. Analysis revealed a shared basis for the coral transcriptomic response to sediment stress, which involves the expression of genes broadly related to energy metabolism and immune response. In particular, sediment exposure induced upregulation of anaerobic glycolysis and glyoxylate bypass enzymes, as well as genes involved in hydrogen sulphide metabolism and in pathogen pattern recognition. Our results point towards hypoxia as a probable driver of this transcriptomic response, providing a molecular basis to previous work that identified hypoxia as a primary cause of tissue necrosis in sediment-stressed corals. Potential metabolic and immunity trade-offs of corals living under chronic sedimentation should be considered in future studies on the ecology and conservation of turbid reefs.

Systematics and biogeography of the whistlers (Aves: Pachycephalidae) inferred from ultraconserved elements and ancestral area reconstruction.

The utility of islands as natural laboratories of evolution is exemplified in the patterns of differentiation in widespread, phenotypically variable lineages. The whistlers (Aves: Pachycephalidae) are one of the most complex avian radiations, with a combination of widespread and locally endemic taxa spanning the vast archipelagos of the Indo-Pacific, making them an ideal group to study patterns and processes of diversification on islands. Here, we present a robust, species-level phylogeny of all five genera and 85% of species within Pachycephalidae, based on thousands of ultraconserved elements (UCEs) generated with a target-capture approach and high-throughput sequencing. We clarify phylogenetic relationships within Pachycephala and report on divergence timing and ancestral range estimation. We explored multiple biogeographic coding schemes that incorporated geological uncertainty in this complex region. The biogeographic origin of this group was difficult to discern, likely owing to aspects of dynamic Earth history in the Indo-Pacific. The Australo-Papuan region was the likely origin of crown-group whistlers, but the specific ancestral area could not be identified more precisely than Australia or New Guinea, and Wallacea may have played a larger role than previously realized in the evolutionary history of whistlers. Multiple independent colonizations of island archipelagos across Melanesia, Wallacea, and the Philippines contributed to the relatively high species richness of extant whistlers. This work refines our understanding of one of the regions' most celebrated bird lineages and adds to our growing knowledge about the patterns and processes of diversification in the Indo-Pacific.

The first phylogenetic and species delimitation study of the nudibranch genus Gymnodoris reveals high species diversity (Gastropoda: Nudibranchia).

Nudibranchs are charismatic marine gastropods that lack a shell in the adult stage. While most nudibranchs feed on sessile animals such as sponges, bryozoans, and cnidarians, the nudibranch genus Gymnodoris Stimpson, 1855 evolved a more active and predatory lifestyle, including sea slug predation, cannibalism, and oddly enough, fish-fin parasitism. At the beginning of our work, no phylogenetic hypothesis existed for the genus, nor a clear picture of how Gymnodoris is related to other nudibranchs. Here we set out to reconstruct Gymnodoris phylogeny, investigate species diversity, and clarify the status of the genus name Analogium, which had been proposed for members of the genus with a linear gill filament arrangement. We present the first phylogenetic hypothesis for Gymnodoris, reconstructed by maximum likelihood and Bayesian inference using two mitochondrial and two nuclear loci, with gill filament arrangement plotted on the phylogeny. The backbone of the phylogeny remains unresolved with theseloci, however, we found that Gymnodoris comprises three main well-supported clades, which we refer to as the "subornata", "citrina" and "varied" clade, the latter two clades being comprised of several well-supported subclades. The sister group to Gymnodoris is a clade including the genera Vayssierea and Lecithophorus. Based on ABGD and PTP species delimitation methods, we conservatively estimate 65-70 species comprise our dataset. We further estimate that approximately 81% of the species we sampled are undescribed, and note that a linear gill filament arrangement has evolved multiple times within the genus. Gymnodoris is only monophyletic when the species with a linear gill arrangement are included. Therefore, at this time, we agree with the synonymy of Analogium striata with Gymnodoris striata by Rudman and Darvell (1990) and that the genus name Analogium is warranted as a junior synonym of Gymnodoris. Given the extensive undescribed diversity, and lack of resolution at some of the nodes in the phylogeny, patterns of diversification in diet are impossible to discern at this time and will require a large effort to both describe Gymnodoris species diversity and the diets of these candidate species.

Testing use of the first multi-partner cognitive enrichment devices by a group of male bottlenose dolphins.

Alliance formation plays a crucial part in male dolphins' lives. These partnerships may last for decades or even for a lifetime; thus, partner choice and the maintenance of these relationships are both considered key components of alliance formation. In our previous investigations, pairs of adult male dolphins showed a high success rate in cooperative manipulation of a cognitive enrichment device. Here, we introduced two novel cognitive enrichment devices to the group of five dolphins, facilitating simultaneous actions for not only pairs, but for three or even four dolphins. The devices were made of PVC tubes, fittings and caps equipped with rope handles, creating a three-way (T-shape) and a four-way (TT-shape) device. The devices were filled with fish and ice and were designed to be opened by simultaneous pull of the handles. Both devices were tested in 12 trials (each lasted for 15 min), separately. Only one of the caps could be opened, the others were affixed with the position of the openable cap counter-balanced over the trials. Although the dolphins received no training regarding the manipulation of the devices, they were successful in cooperatively opening the three-way devices in 10/12 of trials (70% by two and 30% by three dolphins) and the four-way devices also in 10/12 trials (50% by two, 40% by three and 10% by four dolphins). The dolphins interacted with the devices during the entire testing time, and this was mostly spent in cooperative play (77% and 56% of the test duration with the three-way and four-way device, respectively). The majority of the cooperative play was observed between one particular pair of dolphins that was temporarily associated with a third or sometimes even with a fourth dolphin. These findings demonstrate the first successful use of multi-partner cooperative enrichment devices, providing information on the social organization of a male dolphin group.

Blubber Cortisol-Based Approach to Explore the Endocrine Responses of Indo-Pacific Humpback Dolphins (Sousa chinensis) to Diet Shifts and Contaminant Exposure.

The detrimental effects of contaminant exposure and changes in the availability of food resources are still of concern for Indo-Pacific humpback dolphins (Sousa chinensis) of the Pearl River Estuary (PRE). Here, we validated and applied a blubber cortisol biomarker approach to assess the physiological responses of PRE dolphins to various pollutants and diet changes during 2008-2018 (n = 70). For calves, generalized additive models (GAMs) revealed that cortisol levels varied significantly by month and were positively correlated with the body length, owing to significant maternal transfer of hormones. The significantly positive correlation between length-adjusted cortisol levels in calf and the annual calf mortality ratios suggested that during years of high calf mortality, these animals were highly stressed before they die. For noncalves, blubber cortisol levels in diseased animals were significantly higher than those in "healthy" ones. Chromium (Cr) and dichlorodiphenyltrichloroethanes displayed a significant and positive relationship with blubber cortisol levels, suggesting that contaminant-mediated endocrine disruption effects may have occurred in noncalves. The GAMs indicated a decreasing trend of noncalf's blubber cortisol levels over an 11-year span, which can be explained by their declining contaminant accumulation levels due to a significant dietary shift from eating highly contaminated fishes to less polluted ones.

An Indo-Pacific humpback dolphin (Sousa chinensis) severely injured by vessel collision: live rescue at sea, clinical care, and postmortem examination using a virtopsy-integrated approach.

BACKGROUND: Vessel collision induces blunt and sharp force traumas to aquatic animals and is a leading anthropogenic impact affecting cetaceans worldwide. Vessel collision is an important threat affecting vulnerable coastal cetaceans such as the Indo-Pacific humpback dolphins (Sousa chinensis) which reside in coastal waters of Hong Kong amongst heavy marine traffic. CASE PRESENTATION: A severely injured subadult S. chinensis was sighted in the waters off southwestern Hong Kong with four gaping incision wounds on its dorsum. It was in poor body condition and seemed unable to use the fluke effectively. The deepest wound located at the caudal peduncle near the base of the fluke and exposed the underlying fractured caudal vertebrae. The dolphin was monitored in the field over three weeks and eventually captured for medical intervention as veterinary assessment indicated progressive and life-threatening deterioration. During rehabilitation, the dolphin demonstrated initial signs of improvement over the first 36 hours as supported by diagnostic tests but then deteriorated rapidly. It was humanely euthanised after three days of rehabilitation. Postmortem investigation was carried out using virtopsy (postmortem computed tomography and magnetic resonance imaging) and conventional necropsy, with special attention to the traumatic musculoskeletal injuries caused by vessel collision and also revealed acute gastrointestinal compromise and respiratory disease that further hampered the rehabilitation. CONCLUSION: In cetaceans, the prognosis for recovery from injuries caused by vessel collision depends on the extent, location, and gravity of the injuries (i.e., superficial, deep, penetrating, blunt vs. sharp, fresh vs. septic), as well as the health status of the individual and its ability to respond to the insult. Injuries extending deep into the vertebral column may lead to delayed death and associated welfare issues. The prognosis of this case was likely poor given the severity and location of the injuries, but the attempted rehabilitation and postmortem investigation provided valuable insights for clinical management if similar cases are encountered in the future. Being able to non-invasively assess and document traumatic injuries and other pathologies, diagnostic imaging is particularly useful in the clinical assessment and postmortem investigation (virtopsy) of cases with vessel-induced injuries.

Rainfall variations in central Indo-Pacific over the past 2,700 y.

Tropical rainfall variability is closely linked to meridional shifts of the Intertropical Convergence Zone (ITCZ) and zonal movements of the Walker circulation. The characteristics and mechanisms of tropical rainfall variations on centennial to decadal scales are, however, still unclear. Here, we reconstruct a replicated stalagmite-based 2,700-y-long, continuous record of rainfall for the deeply convective northern central Indo-Pacific (NCIP) region. Our record reveals decreasing rainfall in the NCIP over the past 2,700 y, similar to other records from the northern tropics. Notable centennial- to decadal-scale dry climate episodes occurred in both the NCIP and the southern central Indo-Pacific (SCIP) during the 20th century [Current Warm Period (CWP)] and the Medieval Warm Period (MWP), resembling enhanced El Niño-like conditions. Further, we developed a 2,000-y-long ITCZ shift index record that supports an overall southward ITCZ shift in the central Indo-Pacific and indicates southward mean ITCZ positions during the early MWP and the CWP. As a result, the drying trend since the 20th century in the northern tropics is similar to that observed during the past warm period, suggesting that a possible anthropogenic forcing of rainfall remains indistinguishable from natural variability.

Two new species of the butterflyfish genus Roa (Perciformes: Chaetodontidae).

Two new species of Roa (Chaetodontidae) are described. Roa semilunaris sp. nov., based on six specimens from the Mascarene Ridge (south-western Indian Ocean), is most similar to Roa jayakari (Norman, 1939), distributed in the Red Sea and the northern Indian Ocean, in having scales on the upper jaw, interrupted pale lines within the second dark body band, and similar coloration and shape of the pelvic fin. However, the former is readily distinguished from R. jayakari by a wider whitish interspace between the second and third black bands [width of interspace at lateral line level 15.9%-18.5% of standard length (SL) in R. semilunaris sp. nov. (vs. 5.1%-8.5% of SL in R. jayakari)], with 9 or 10 pored lateral-line scales in the interspace (vs. 3-5); an oval or semicircular ocellated blotch on the soft-rayed portion of the dorsal fin (vs. a circular blotch); the head higher and longer [head length 35.0%-36.7% of SL (vs. 40.8%-44.1% of SL), head height 48.1%-50.5% of SL (vs. 52.0%-56.9% of SL)], and postorbital length 14.0%-15.1% of SL (vs. 17.0%-20.5% of SL). Roa uejoi sp. nov., based on three specimens from Guam (Mariana Islands), is most similar to Roa excelsa (Jordan, 1921) (now restricted to the Hawaiian Islands and Johnston Island), but is distinguished from the latter by having a circular dorsal-fin ocellated spot (vs. spot distinctly oval in the latter) and a much more elongate, filamentous first pelvic-fin soft ray, of length 119.0%-123.4% of 2nd ray (vs. not obviously filamentous, 104.9%-105.8%). A key to the eight valid species of Roa is provided.

Investigating ocean deoxygenation and the oxygen minimum zone in the Central Indo Pacific region based on the hindcast datasets.

Deoxygenation is increasingly recognized as a significant environmental threat to the ocean following sea temperature rises due to global warming and climate change. Considering the cruciality of the deoxygenation impacts, it is important to assess the current status and predict the future possibility of ocean deoxygenation, for instance, within the Central Indo Pacific (CIP) regions represent climate-regulated marine areas. This study divided CIP into five regions then investigated the deoxygenation parameters (dissolved oxygen, temperature, salinity, and pH) collected from 1993 to 2021 sourced from in situ measurement and long-term hindcast data. The overall error statistics indicate a good accuracy of hindcast data and are comparable to the in situ values. The surface waters were identified to have the most fluctuated seasonal pattern of dissolved oxygen (DO) concentration compared to other water columns. However, DO fluctuation occurred in a different pattern in each region. The study shows ocean deoxygenation is accelerated in all five regions over decades. The strongest oxygen minimum zone (OMZ) is identified in the Bay of Bengal and the Arafura Sea with the lowest oxygen concentration less than 0.5 mmol/m3, while the weakest OMZ is located in the South China Sea with 60 mmol/m3 of DO concentration. The deoxygenation rates in CIP regions are varied by 0.09-2.75 mmol/m3/year depending on the different controlling factors that work in the five regions. Our results indicate that deoxygenation is attributed to ocean warming, seawater salinity increases, and ocean acidification and possibly continue in the future with continued global changes.

Realigning India's Vietnam Policy Through Cooperative Sustainable Development: a Geostrategic Counterbalancing to China in Indo-Pacific.

Vietnam is a key player in India's Act East Policy and is distressed due to China's overarching position in the South China Sea. China's expanding infrastructural investments in India's periphery have led to a regional security dilemma in Indian Ocean Region. India is steered to pursue opportunities to counter China in the latter's periphery, to which Vietnam fits as an apt ally. Hence, this paper examines the heightened need for realigning India's Vietnam policy in line with United Nations Sustainable Development Goals and explains how bilateral cooperation through sustainable trade, renewable energy production, and green investments can offer a "counter" to Chinese expansion in Indo-Pacific and its Belt and Road Initiative. This paper uses the theoretical framework of Balance of Power to enumerate how geostrategic policy decisions in India-Vietnam bilateral relations can create a "counterbalance" to the Chinese investments in India's neighborhood, especially in Pakistan.

Dispersal syndromes drive the formation of biogeographical regions, illustrated by the case of Wallace's Line.

AIM: Biogeographical regions (realms) reflect patterns of co-distributed species (biotas) across space. Their boundaries are set by dispersal barriers and difficulties of establishment in new locations. We extend new methods to assess these two contributions by quantifying the degree to which realms intergrade across geographical space and the contributions of individual species to the delineation of those realms. As our example, we focus on Wallace's Line, the most enigmatic partitioning of the world's faunas, where climate is thought to have little effect and the majority of dispersal barriers are short water gaps. LOCATION: Indo-Pacific. TIME PERIOD: Present day. MAJOR TAXA STUDIED: Birds and mammals. METHODS: Terrestrial bird and mammal assemblages were established in 1-degree map cells using range maps. Assemblage structure was modelled using latent Dirichlet allocation, a continuous clustering method that simultaneously establishes the likely partitioning of species into biotas and the contribution of biotas to each map cell. Phylogenetic trees were used to assess the contribution of deep historical processes. Spatial segregation between biotas was evaluated across time and space in comparison with numerous hard realm boundaries drawn by various workers. RESULTS: We demonstrate that the strong turnover between biotas coincides with the north-western extent of the region not connected to the mainland during the Pleistocene, although the Philippines contains mixed contributions. At deeper taxonomic levels, Sulawesi and the Philippines shift to primarily Asian affinities, resulting from transgressions of a few Asian-derived lineages across the line. The partitioning of biotas sometimes produces fragmented regions that reflect habitat. Differences in partitions between birds and mammals reflect differences in dispersal ability. MAIN CONCLUSIONS: Permanent water barriers have selected for a dispersive archipelago fauna, excluded by an incumbent continental fauna on the Sunda shelf. Deep history, such as plate movements, is relatively unimportant in setting boundaries. The analysis implies a temporally dynamic interaction between a species' intrinsic dispersal ability, physiographic barriers, and recent climate change in the genesis of Earth's biotas.