Search Results (119)

The Indo-Pacific region hosts several annual military exercises that involve the deployment of thousands of U.S. and partner-nation military personnel. Respiratory and diarrheal diseases pose a significant health risk to exercise participants and represent a substantial portion of medical encounters and lost duty days. We conducted surveillance for respiratory and diarrheal illness at the Cobra Gold and Balikatan military exercises in Thailand and the Philippines from 2023–2025. Through coordination with health providers in the field, military personnel that reported acute symptoms were asked to provide a nasopharyngeal swab or stool sample. These samples were transported to a field lab and tested by PCR for common respiratory and diarrheal pathogens. Follow-up analyses included bacterial culture, antimicrobial susceptibility testing, and viral whole-genome sequencing. From 84 respiratory and 61 diarrheal samples analyzed, we found that respiratory illness was primarily attributed to rhinoviruses/enteroviruses (23%), common coronaviruses (21%), and SARS-CoV-2 (11%) while diarrheal disease was attributed to a high rate of diarrheagenic E. coli (73%) and norovirus (20%), followed by Salmonella spp. (18%) and Campylobacter spp. (13%). Our findings highlight the distinct etiologies of respiratory and diarrheal disease in military field settings and demonstrate the feasibility of conducting real-time infectious disease surveillance in operational environments. Full article

Calcareous tropical green macroalgae of the genus Halimeda are key reef-builders, yet the drivers of their diversification and population dynamics remain poorly understood. This study analyzed the species diversity of Halimeda in the Xisha (Paracel) Islands based on tufA gene sequences, focusing on evaluating the genetic diversity, population structure, and historical dynamics of two widespread species—Halimeda discoidea and Halimeda macroloba. The results indicate new records of Halimeda cylindracea and Halimeda cf. stuposa in the Xisha (Paracel) Islands. More importantly, H. discoidea and H. macroloba exhibited significantly different evolutionary histories. Specifically, H. discoidea showed a highly fragmented population structure, restricted gene flow, and a multimodal mismatch distribution, suggesting a complex historical process or long-term stability. In contrast, H. macroloba exhibited lower population differentiation, extensive gene flow, and non-significant neutrality test results, indicating long-term demographic stability without recent, drastic population events. Further validation based on gene flow analysis and divergence time estimation revealed that the lineage divergence of H. discoidea is older, while H. macroloba represents a lineage with a relatively younger evolutionary origin restricted to the Indo-Pacific region. This striking dichotomy clearly illustrates the interplay between intrinsic species-specific traits (e.g., dispersal capacity) and extrinsic historical factors (e.g., paleo-oceanographic events), leading to contrasting evolutionary outcomes among widespread marine taxa. By elucidating how differing evolutionary histories influence patterns of genetic diversity, this study provides a predictive framework for evaluating the resilience and guiding conservation priorities for critical marine calcifiers in the context of rapid environmental change. Full article

While substantial eulimid diversity has been revealed in the Indo-West Pacific marine diversity hotspot, many neighbouring areas are still unexplored, including in Western Australia. The Houtman Abrolhos are a unique chain of islands in a well-characterised marine transition zone where tropical and temperate waters meet along the mid-west coast. During a biodiversity survey of the islands in 2025, sixty-two eulimids from 15 stations were collected, a family of marine gastropods never-before documented from this region. Here we incorporate newly collected and legacy material from the Western Australian Museum to illustrate 23 new eulimid morphospecies records for the Houtman Abrolhos. Sixteen hosts, representing all five classes of Echinodermata, were identified. Most eulimids were attached externally to their hosts, though Stilifer utinomii and two unidentified species of Melanella were found embedded in Disasterina longispina and Actinopyga mauritiana, respectively. Apicalia angulata, Peasistilifer nitidula and Stilifer utinomii are newly recorded for Western Australia, and Thyca ectoconcha and Vitreobalcis tripneusticola are new Australian records. The biogeographic affinities of these symbionts, like other marine life surveyed in the Houtman Abrolhos islands, are overwhelmingly tropical in nature, representing in many instances the southernmost records of otherwise widespread Indo-West Pacific species. Full article

It is known that the giant barrel sponge (GBS) Xestospongia spp. may provide shelter or a micro-environment for multi-species coral colonies both in the Indo-Pacific and Atlantic regions. An assessment of such interactions between Indo-Pacific GBS Xestospongia testudinaria and stony corals performed for two groups of small Vietnamese islands in the Gulf of Thailand revealed at least 12 species of scleractinians associated with GBS. An average of 21.7% of all observed GBSs were found to interact with stony corals. The phenomenon of positive GBS–coral interactions without any restrictions on coral development can be regarded as a form of ecological facultative commensalism and warrants further investigation. Full article

The Indonesian Throughflow (ITF) significantly influences global climate and interoceanic exchange. This review synthesizes recent findings on the Halmahera Sea’s role within the ITF, emphasizing its physical mechanisms, climatic modulation, and ecological consequences. Despite being a minor route, the Halmahera Sea transport volume is approximately 1.5 to 2.44 Sv, bringing water mass from the Southern Pacific Ocean. Seasonal and interannual variability, driven by monsoonal winds and phenomena like the El Niño-Southern Oscillation (ENSO), significantly affect the flow dynamics in this region. The Halmahera Sea also plays a pivotal role in nutrient cycling and marine biodiversity, influencing local ecosystems and fisheries. Understanding these dynamics is essential for predicting climate change impacts and managing marine resources in the Indo-Pacific region. This review highlights the need for enhanced observational efforts and high-resolution modeling to better understand the Halmahera Sea’s contribution to the broader ITF framework and its implications for regional and global climate systems. Full article

Varuna litterata is an estuarine crab species widely distributed across the Indo-Pacific region, commonly dwelling in brackish waters, mangrove forests, and tidal estuaries. In Bangladesh, while four Scylla species dominate the commercial crab market, the locally consumed V. litterata remains a biologically overlooked gem of the coastal waters. These crabs are frequently captured as a byproduct during shrimp fry collection from coastal estuaries. In this context, the current study investigates the reproductive biology, morphometric dynamics, and market potential of V. litterata collected from the Pasur River, a coastal mangrove forest-adjacent estuary of southern Bangladesh. A total of 75 individuals were collected from March to April 2023, comprising 35 males and 40 females, resulting in a sex ratio of 1:1.14 (♂:♀), with a predominance of females. A visual observation of ovary development revealed four distinct maturation stages, with Stage IV (fully mature) being the most prevalent (43%), indicating peak reproductive activity during the sampling period. Morphometric analysis revealed that the average carapace width (CW) was 31.2 ± 5.7 mm and 31.9 ± 5.8 mm and the mean carapace length (CL) was 29.3 ± 4.7 mm and 30.1 ± 4.9 mm in males and females, respectively. However, the mean body weight (BW) was 13.1 ± 4.3 g in males and 12.7 ± 3.8 g in female crabs. The dominant CW class ranges from 33 to 33.99 mm (males) and 28.99–29.99 mm (females), appear to be the most vulnerable to fishing pressure. BW-CW and CL-CW relationships demonstrated negative allometric growth, with high correlations in both sexes. Significant sexual dimorphism was observed, with males having larger cheliped dimensions, while females had broader abdomens, likely supporting reproductive functions that are essential to their conservation. The marketing of this crab remains largely informal, yet rising local demand and prices highlight its emerging commercial potential. Therefore, incorporation into aquaculture and coastal fishery development of this crab species could enhance food security, support livelihoods, and contribute to sustainable blue economy initiatives in Bangladesh. Full article

The occurrence of the bigfin reef squid Sepioteuthis lessoniana, a Lessepsian migrant, is documented for the first time from the coastal waters off Malta, based on the collection of a single specimen reported through citizen science. The presence of this species in the broader Strait of Sicily region is further confirmed by a morphometric assessment and genetic analysis of another individual captured off the Pelagian island of Lampedusa. Molecular identification using mitochondrial COI and 16S rRNA markers corroborates the taxonomic identification exercise as it aligns both specimens with Indo-Pacific clades of S. lessoniana. These records represent the first genetically verified occurrences of the species in both Maltese and Italian waters. The findings extend the known Mediterranean distribution of S. lessoniana, emphasizing the Strait of Sicily as an important monitoring region for Lessepsian migrants and highlighting the combined role of integrative taxonomy and citizen science in tracking non-indigenous species introductions. Full article

The crown-of-thorns starfish (CoTS, Acanthaster spp.), is responsible for a considerable amount of coral loss in the tropical Indo-Pacific region. After decimating coral populations through predation, it is expected that CoTS will face food scarcity before coral recovery. It is unclear how CoTS respond to starvation stress. Therefore, we conducted a four-month starvation stress experiment on CoTS, and analyzed the response characteristics of its stomach bacterial communities using high-throughput 16S rRNA sequencing. The results showed no significant differences in the α-diversity of the stomach bacterial community, but the β-diversity differed significantly between fed and starved CoTS. The bacterial community composition in the CoTS stomach changed dramatically, manifesting mainly from Tenericutes to Proteobacteria at the phylum level, and from a community dominated by digestive bacteria (Mycoplasma) to beneficial bacteria (Endozoicomonas) at the genus level. Furthermore, co-occurrence network analysis revealed that starvation reduced the network stability of the bacteria community, but improved network modularity, which may have contributed to the CoTS adaptation to chronic starvation. This study provides a basis for elucidating the mechanism of starvation resistance in the crown-of-thorns starfish. Full article

Tubastraea coccinea and T. tagusensis, commonly known as sun corals, are two species of stony corals (Scleractinia, Dendrophylliidae) native to the Indo-Pacific region (T. coccinea) and the Galapagos Islands (T. tagusensis), respectively. They are considered highly invasive species, particularly in the Western Atlantic Ocean, due to high adaptability to various ecological conditions and notable resilience. Given their demonstrated invasiveness, it is important to delve into their physiology and the molecular bases supporting their resilience. However, to date, only a few molecular tools are available for the study of these organisms. The primary objective of the present study was the development of an efficient RNA extraction protocol for Tubastraea coccinea and T.a tagusensis samples collected off Ilha Grande Bay, Rio de Janeiro (Brazil). The quantity of isolated RNA was evaluated using NanoDrop, while its purity and quality were determined by evaluating the A260/A280 and A260/230 ratios. Subsequently, based on genes known for T. coccinea, two housekeeping genes and seven stress response-related genes were isolated and characterized, for the first time for both species, using a molecular approach. An interactomic analysis was also conducted, which revealed functional interactions among these genes. This study represents the first report on gene networks in Tubastraea spp., opening new perspectives for understanding the chemical ecology and the cellular mechanisms underlying the invasiveness of these species. The results obtained will be useful for ecological conservation purposes, contributing to the formulation of strategies to limit their further expansion. Full article

Members of the genus Nemipterus are economically important fish species distributed in the tropical and subtropical Indo-West Pacific region. The majority of species in this genus inhabit waters with sandy–muddy substrates on the continental shelf, although different species are found at slightly varying water depths. In this study, we sequenced seven species within the genus Nemipterus after identifying the specimens using complementary morphological analysis and DNA barcoding. Each species yielded over 40,000,000 clean reads, totaling over 300,000,000 clean reads across the seven species. A total of 276,389 unigenes were obtained after de novo assembly and a total of 168,010 (60.79%) unigenes were annotated in the protein database. The comprehensive functional annotation based on the KOG, GO, and KEGG databases revealed that these unigenes are mainly associated with numerous physiological, metabolic, and molecular processes, and that the seven species exhibit similarity in these aspects. By constructing a phylogenetic tree and conducting divergence time analysis, we found that N. bathybius and N. virgatus diverged most recently, approximately during the Neogene Period (14.9 Mya). Compared with other species, N. bathybius and N. virgatus are distributed in deeper water layers. Therefore, we conducted selection pressure analysis using these two species as the foreground branches and identified several environmental-responsive genes. The results indicate that genes such as aqp1, arrdc3, ISP2, Hip, ndufa1, ndufa3, pcyt1a, ctsk, col6a2, casp2 exhibit faster evolutionary rates during long-term adaptation to deep-water environments. Specifically, these genes are considered to be associated with adaptation to aquatic osmoregulation, temperature fluctuations, and skeletal development. This comprehensive analysis provides valuable insights into the evolutionary biology and environmental adaptability of threadfin breams, contributing to the conservation and sustainable management of these species. Full article

The Belt and Road Initiative (BRI) is the first and currently the most expansive global infrastructure initiative, notably for its scale and emphasis on connectivity. In response, alternative initiatives such as the Partnership for Global Infrastructure and Investment (PGII) and Free and Open Indo-Pacific Strategy (FOIP), including their components the Blue Dot Network (BDN) and Partnership for Quality Infrastructure (PQI), as well as Global Gateway (GG) and the Three Seas Initiative (3SI), have emerged to counterbalance the BRI’s influence and promote more transparent, sustainable, and rules-based infrastructure frameworks. This review investigates how global and regional infrastructure initiatives—namely PGII/BDN, GG, FOIP/PQI, and 3SI—compare with the BRI in terms of development objectives, implementation models, institutional structures, and implications for developing economies. Adopting an inductive approach, this review identifies key themes from the literature to evaluate these initiatives across seven dimensions: (1) infrastructure objectives, (2) the quality and transparency of investments, (3) investment policy orientation, (4) trade policy orientation, (5) inclusivity and regional integration, (6) coordination mechanisms, and (7) environmental sustainability. While PGII/BDN, GG, FOIP/PQI, and 3SI appear well-positioned to address some of BRI’s shortcomings, the evidence does not clearly favour one model over another in terms of achieving welfare-enhancing outcomes and bridging development gaps. Nonetheless, strategic competition and complementarities among the connectivity policies of multiple initiatives can ultimately contribute to more accountable, multidimensionally sustainable, and socially inclusive infrastructure development. We also illustrate how stated preference methods, i.e., willingness to pay (WTP) and willingness to accept (WTA), can be used to quantify the value of soft infrastructure, particularly public preferences for sustainable investment and norm diffusion, which are central to evaluating the social welfare gains from participating in these initiatives. Full article

Giant clams are ecologically important coral reef animals, with many species facing imminent local extinction. While many regions have undertaken recent assessments of their biodiversity assets, persistent gaps remain even in otherwise well-surveyed areas. This study sought to understand the geographic distribution of smaller-bodied and morphologically similar giant clams, specifically Tridacna maxima and T. noae, in the eastern Indian Ocean. Due to the difficulties in reliably identifying these species using morphological characters, we confirmed species identity and investigated intraspecific variation using sequence data from the mitochondrial cytochrome C oxidase subunit I gene (COI). Seventy whole animal vouchers were newly sampled from a 1500 km span of remote northwestern Australian coastline over a decade, as part of an ongoing coral reef survey expedition of the Western Australian Museum and partners. Tridacna maxima had a limited distribution and was only genotyped from offshore oceanic reefs in the Rowley Shoals and Cocos Keeling Islands. In contrast, T. noae was well established beyond Ningaloo Reef, and was abundant at inshore sites throughout the Pilbara and Kimberley, and even offshore to Ashmore Reef. Phylogeographically, T. maxima did not group with conspecifics from the Western Pacific Ocean, including the east coast of Australia, but instead clustered with individuals from Malaysia, China, Taiwan, and Indonesia; T. noae exhibited a similar pattern. The affinity of Western Australian individuals with representatives from the Indo-Malay region and not eastern Australia will be an important consideration for these commercially important species. Novel haplotypes in both tested species occur in Western Australia. Continued sampling of eastern and central Indian Ocean giant clams, especially to continue to document the range of T. noae, is encouraged to understand connectivity in this basin. Together, these findings contribute to an improved baseline for conservation initiatives of these iconic coral reef animals in Western Australia. Full article

Understanding population genetic connectivity is crucial for the sustainability and persistence of marine biodiversity. As a fundamental reef-building macroalga of the coastal ecosystem, Halimeda macroloba Decaisne is one of the dominant intertidal seaweeds in the Indo-Pacific region. However, its genetic structure and population connectivity have been poorly recognized. Here, we explored the population genetic structure and genetic connectivity of H. macroloba using chloroplast tufA, rps3-rpl14, and rbcL. Our results indicated low genetic diversity and shallow population genetic structure at the intraspecific level, uncovering five genetic groups with six subdivided lineages in tufA and two genetic clusters in rps3-rpl14. We detected demographic expansion in the last glacial period of the Pleistocene and significantly asymmetric gene flow among different geographical units. We suggest that the southwestward ocean currents under the influence of northeast monsoon in the Indo-Pacific region are the main factor in shaping the present genetic structure, and the asexual reproduction of H. macroloba also plays an important role of the low genetic diversity pattern; in addition, the divergence between genetic clusters might be related to the historical isolation led by the paleoclimate oscillation in the Pleistocene. The Xisha Islands in the northern South China Sea might serve as a potential refugium of H. macroloba, which needs extra attention to conservation management. Given the limitation of sample size, we need to conduct more field work and carry out further research at a larger scale in the future. Our study provided new insights into the theory of population connectivity in the Indo-Pacific region and provided scientific basis for tropical costal seaweed conservation. Full article

Sea surface temperature (SST) is considered a strong indicator of climate change, being an essential parameter for long-range weather and climate forecasting. Another important indicator of climate change is sea level (SL), which has a longer history of systematic instrumental observations. This paper aims to examine the relationships between low-latitude variations in ocean characteristics (SST and SL) and surface air temperature (SAT) anomalies in the Arctic and mid-latitudes, and discuss the possibility of using SST and SL as predictors to forecast seasonal SAT anomalies. Archives of meteorological observations, atmospheric and oceanic reanalyses, and long-term series of tide gauge data on SL were used in this study. An analysis of relationships between seasonal SAT in different mid-to-high latitude regions and SST made it possible to identify areas in the ocean that have the greatest influence on SAT patterns. The most commonly identified area is located in the tropical North Atlantic. Another area was found in the Indo-Pacific warm pool. The predictive potential of the relationships identified between ocean characteristics (SST and SL) and SAT will be used to build deep learning models aimed at predicting climate variability in mid-to-high latitudes. Full article

Cymothoidae (Crustacea: Isopoda) infest fish in marine, brackish, and freshwater environments. Cymothoa pulchrum Lanchester, 1902 is a cymothoid commonly found in the buccal cavity of mainly Tetraodontiformes fishes, distributed in the central and western Indo-Pacific region. This study describes the morphology of each life cycle stage of C. pulchrum: adult female, transitional, adult male, juvenile, and manca. In addition, we obtained DNA sequences linked to the morphological information of this species. We compared it with the sequences in the database using the neighbor-joining tree based on cytochrome c oxidase subunit I (COI) and 16S rRNA. Prior to this study, morphological data on the immature stages of Japanese Cymothoa was limited to juveniles of Cymothoa indica Schioedte and Meinert, 1884. The research identified 12 distinct morphological features that differentiate juvenile C. pulchrum from juvenile C. indica. Molecular analysis revealed that the COI sequences obtained in this study matched some of the C. pulchrum sequences in the database, whereas other sequences in the database formed a clade with Cymothoa eremita (Brünnich, 1783). In the phylogenetic tree based on 16S rRNA, C. pulchrum was also divided into two groups. In the COI phylogenetic tree, C. pulchrum and C. eremita form a total of five groups, and these two species might need to be re-examined taxonomically and molecularly. Full article