ABSTRACT The Indian squid Uroteuthis duvaucelii (D’Orbigny) is widely distributed throughout the Indian Ocean, where it is extensively exploited and holds significant importance for the fisheries sector, particularly in Indian waters. Spawning aggregations are known to occur along the west coast of India during the post-monsoon months. However, the mating behaviour of this species remains poorly understood. Spermatangia implantation on the buccal membranes in female U. duvaucelii was examined from the Arabian Sea between January and December 2021. Of the 232 females analysed, 40% carried spermatangia on their buccal membranes, with occurrence recorded year-round and peaks in October. The number of spermatangia ranged from 64 to 385 (mean 178 ± 96), with implantation predominantly on the ventral buccal surface. Statolith analysis revealed ages of mated individuals between 98 and 162 days (110–162 mm, dorsal mantle length, DML), confirming rapid growth and short life spans. Typically, males transfer spermatophores to the female’s buccal region during copulation. However, the presence of spermatangia on the buccal membranes of single male individual provides evidence suggestive of same-sex sexual behaviour in U. duvaucelii. Overall, the widespread and seasonal occurrence of buccal spermatangia, including their presence in males, suggests a complex and previously unrecognised mating system in U. duvaucelii. These findings highlight the need for more detailed studies to fully understand the mating behaviour of loliginid squids in the Arabian Sea.

1. Chilo sacchariphagus is a major sugarcane pest, primarily affecting producing regions in Asia and around the Indian Ocean, yet little is known about the biotic and abiotic factors driving its population dynamics and associated crop damage. This study assesses, for the first time, the relative influence of meteorological conditions, farming practices, landscape context, and natural enemy communities on herbivory damage caused by this pest on Reunion Island. 2. In-field surveys were conducted at 60 sampling points during 2022 and 2023, recording crop damage and multiple explanatory variables across spatial scales, from the field to the landscape. Data were analyzed using generalized additive models and a multi-model inference framework. 3. Crop damage was primarily explained by meteorological conditions (36 % of deviance), farming practices (36 %), and landscape context within a 250 m buffer (27 %) , while natural enemy abundance had no significant effect. Five key predictors shaped damage: average temperature during the wettest season, agrochemical inputs (fertilizer and herbicides), landscape edge density, and sugarcane proportion within the 250 m buffer. Lower fertilizer and herbicide use was associated with crop damage, while edge density and sugarcane proportion showed non-linear relationships with damage. 4. This study underscores the value of an integrative, cross-scale approach to identify drivers of crop damage by C. sacchariphagus . Findings suggest that reduced agrochemical inputs, coupled with increased landscape fragmentation and lower host crop dominance, may mitigate pest damage. Future work should further examine the role of natural enemies and explore the ecological mechanisms behind the non-linear impacts of landscape structure on pest dynamics. • Pest damage are shaped by farming practices, temperature, and landscape structure. • Lower fertilizer and herbicide use reduced crop damage. • Edge density and sugarcane proportion non-linearly affected crop damage. • Agroecological farming and landscape planning could help managing C. sacchariphagus • Multiscale approach effectively rank key factors that explain herbivory patterns

Molecular cloning, expression and characterization analysis of p53, Bax, Caspase-3 and AIF genes from Portunus pelagicus under Vibrio parahaemolyticus challenge.

Inter- and intra-specific trophic niche partitioning, and cryptic speciation in three deep-sea predators in the Indian Ocean

This paper presents the integrated study of a distinctive bleach-decorated (bleached or etched) carnelian bead (S3074) discovered at the South Arabian port of Sumhuram (Dhofar, Sultanate of Oman), a Hadrami trading outpost active within regional and transoceanic trade networks between 100 BCE and 400 CE. Originating from a technology developed in the Greater Indus Valley during the 3rd millennium BCE, bleached carnelian beads remained markers of long-distance trade in the Early Historic and Medieval periods. Stylistic comparisons and SEM-based drilling diagnostics revealed that the Sumhuram specimen, the first securely identified example of this bead type in South-western Arabia, is consistent with production in north-western India. Its discovery in an urban context rather than a funerary assemblage raises interpretive questions about its circulation and meaning. While it may reflect structured trade flows linking Gujarat with South-eastern Arabia, the possibility that it was the personal possession of a South Asian individual temporarily residing in Sumhuram is equally plausible. This case ultimately exemplifies the entanglement of material culture, mobility, and identity in a cosmopolitan port city. Beyond economic exchange, the bead provides insight into personal histories and cross-cultural interactions across the Western Indian Ocean during the Late Iron Age. • First bleach-decorated carnelian bead identified in South-western Arabia. • Found at Sumhuram, a Hadrami port in Dhofar active in Indian Ocean trade. • Stylistic and SEM analysis indicates north-western Indian origin. • The find may represent structured trade or personal loss by a South Asian resident. • The case reflects mobility, identity, and cultural entanglement in the Western Indian Ocean.

Influence of sea surface temperature in the southern Indian and Atlantic Oceans on austral summer rainfall in southern Tanzania

Like many oceanic regions in the world, the Southwestern Indian Ocean (SWIO) is facing challenges to sustain economic growth, livelihoods and food security, while preserving essential habitats to safeguarding the marine ecosystems. Reaching the Global Biodiversity Framework targets and implementing the Blue Economy roadmaps developed in the SWIO region require reliable data and science-based strategies to manage the marine space as well as knowledge-based governance schemes at both national and regional levels. Monaco Explorations, as a platform committed to foster knowledge, sustainable management and protection of the ocean, organised a multidisciplinary expedition in 2022, in partnership with Mauritius and Seychelles, to advance the state of knowledge of unique sites in the SWIO and contribute to setting harmonised ocean governance in the region. This paper sets the general framework of the Monaco Explorations-Indian Ocean (ME-IO) Expedition and its grand objectives. It provides an outline of the projects developed during the expedition and summarizes the main results for an integrated understanding of the biophysical processes and ecological features in the Mascarene Basin, its underwater plateaus and the waters surrounding the islands.

Relative contribution of dark carbon fixation to total carbon uptake along a latitudinal transect in the Seychelles-Chagos thermocline ridge, western Indian ocean.

Early-Middle Pleistocene to recent paleoceanographic variability in the Agulhas system (southwestern Indian Ocean) induced by fluctuations in the Antarctic Circumpolar Current

Integrating physics-based modeling and deep learning for high-resolution vertical chlorophyll-a predictions in the ocean.

A novel framework for estimating probable maximum tropical cyclone parameters for ocean basins with sparse records

Seagrasses are essential blue carbon ecosystems that are increasingly threatened by the accumulation of emerging global pollutants, such as microplastics (MPs). However, in regions like Sri Lanka, MP contamination within seagrass beds remains critically understudied. This study investigated MP abundance in seagrass blades (Thalassia hemprichii), sediments, surface water, and sea cucumbers (Holothuria atra) and characteristics of isolated MPs from six selected sites along the Southern and Eastern coastlines of Sri Lanka (Indian Ocean). The average abundances of MPs in seagrass blades, Holothuria atra, surface water, vegetated sediments, and non-vegetated sediments were 1.59 ± 0.11 items/blade, 177.19 ± 53.28 items/kg, 9.60 ± 0.97 items/m3, 69.72 ± 8.38 items/kg, and 33.61 ± 2.15 items/kg, respectively. In this study, fibers were the most prevalent morphological type of MPs, while blue was the most dominant color. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed the predominant presence of low-density polyethylene (LDPE) in all types of samples, followed by polyethylene terephthalate (PET), high-density polyethylene (HDPE), polypropylene (PP), and polyamide or commonly known as nylon (PA) in variable amounts. A strong positive correlation between MPs on seagrass blades and those in sediments and surface water suggests that MPs from both water column and seabed contribute to their accumulation on seagrass. Furthermore, the ingestion of MPs by sea cucumbers indicates the potential for fragmentation and trophic transfer within the seagrass ecosystem, enabling MPs to enter and move through the marine food chain.

Marine heatwaves can interact across ocean basins through atmospheric teleconnections, but such inter-basin links remain poorly understood. Here we show that boreal spring and summer marine heatwaves in the Caribbean Sea are significantly connected to marine heatwaves in the Indian Ocean during the preceding winter. Using observational data and climate model simulations, we identify that boreal winter Indian Ocean marine heatwaves trigger atmospheric convection, generating an eastward-propagating Indo-Pacific-Atlantic Rossby wave train. This wave train alters the regional Hadley circulation and renders the overlying atmosphere warm, moist, and stable over the Caribbean Sea, reducing latent heat loss from the ocean, driving sea surface warming and promoting the intensification of marine heatwaves. These findings reveal a robust teleconnection pathway that allows climate signals from one basin to amplify marine heatwaves in another.

Maritime weather data from historical ship logbooks are used to assess 19th century surface wind conditions. Housed across several New England archives, logbooks of U.S. whaling voyages contain systematic weather observations (e.g., wind strength/direction, sea state, precipitation) at (sub-)daily temporal resolution. Here, qualitative wind descriptions by the whalers from ~200 ship logbooks are quantified to generate a dataset with ~81,000 daily records of wind strength and direction en route and covering key whaling grounds in the Atlantic, Pacific, Indian, and Southern Ocean during the period 1820-1900 CE. Following extensive quality control, we find good agreement in wind strength and direction for the whaling records when compared with 20th Century Reanalysis winds for mean and seasonal conditions. For the North Atlantic with the densest coverage of whaling records, interannual variations in the basin-wide wind field associated with different phases of the North Atlantic Oscillation are also captured in the whaling records. Our results demonstrate that the historical records provide an important long-term context for maritime wind patterns in ocean regions lacking direct observational data during the 19th century.

Exported and retained micronutrients from Indian Ocean fisheries

High coral thermal tolerance at a potentially climate-resistant reef.

Unlocking fine-scale temporal dynamics of coral reef health: a multi-kingdom microbial fingerprinting approach across seawater and sediment.

Abstract Paleoclimate records indicate substantial decreases in precipitation associated with the South Asian monsoon in response to Atlantic meridional overturning circulation (AMOC) perturbations, yet the underlying mechanisms remain poorly understood. In this study, we investigate the impacts of a collapsed AMOC on the South Asian monsoon using a suite of North Atlantic freshwater hosing simulations conducted with the NCAR Community Earth System Model, version 1 (CESM1), global climate model under preindustrial conditions. Our results show that a weakened AMOC leads to reduced monsoon rainfall and a southward shift of the Southern Hemisphere branch of the intertropical convergence zone (ITCZ). We also see a substantial increase in precipitation over the Indochina Peninsula, driven by enhanced winds across the Bay of Bengal. We show that these responses cannot be explained by global energy budget arguments and instead propose a local dynamical mechanism in which enhanced winds over the Bay of Bengal increase orographic precipitation across the Indochina Peninsula. These findings have important implications for both projections of future AMOC weakening or collapse under continued anthropogenic warming and for interpreting paleoclimate records of past monsoon variability. Significance Statement This study explores how the South Asian monsoon responds to a collapse of the Atlantic meridional overturning circulation (AMOC), a large-scale ocean circulation system in the climate system. This is important because climate models project that the AMOC will weaken due to increased anthropogenic warming. While much work has been done on how tropical precipitation changes at global scales, fewer studies have focused on local basins or monsoon systems. We find that the South Asian monsoon weakens in response to an AMOC collapse. However, we also show that the current leading framework of energy budget theory cannot fully explain the regional changes around the Indian Ocean. In particular, there is an increase in precipitation over the Bay of Bengal and the Indochina Peninsula which is driven by local dynamics rather than global energy shifts. These findings highlight the need for region-specific analysis and may help guide future research, including the interpretation of past climate records in this region.

ABSTRACT Australia claims the third largest maritime jurisdiction in the world, with a vast marine estate spanning 13.86 million square kilometres. With stakes in the management and security of waters in three of the four major oceans (Indian, Pacific and Southern Oceans), and the three seas located to its North (Timor, Arafura and Coral Seas), Australia’s national security depends on maintaining strong maritime borders, and ensuring a stable regional order and global maritime environment. This article discusses Australia’s security environment and examines how science and technology can support efforts to deter, prevent and defeat threats to its sovereignty, security and national interests. This article identifies core security imperatives for Australia, and the associated infrastructure, capabilities, technologies and tools required to defend its interests. It offers recommendations on how Australia could effectively leverage science and technology to enhance maritime security arrangements, and protect Australia’s sovereignty, resources and borders over the next decade.

Species of the gobionelline genus Oligolepis Bleeker, 1874 (Oxudercidae) are small gobies inhabiting muddy estuaries, coastal bays and lagoons, with some extending into freshwater systems. All recognised species occur in the western Pacific and eastern Indian oceans, except Oligolepis acutipennis (Valenciennes, 1837), previously considered widespread across the Indo-West Pacific to include the western Indian Ocean. Populations from the east African coast have traditionally been assigned to this species. Phylogeographic analysis of mitochondrial COI sequences reveals two deeply divergent lineages within O. acutipennis sensu lato: one distributed from the Indian subcontinent to the western Pacific, and another restricted to east African estuaries from South Africa to Kenya. The lineages differ by 5% sequence divergence and show allopatric distributions, with no confirmed records between Kenya and western India. Males of the Indo-Pacific lineage possess small black spots on the head, jaw membranes and anterior dorsal body, which are absent in the east African lineage. Based on genetic divergence, distributional isolation and several sex-specific differences (most notably the male colour pattern), the east African lineage is described as a new species, Oligolepis goni sp. nov. We further discuss the need for genus revision, considering that species diversity within Oligolepis may be overestimated, with several nominal taxa likely representing conspecific populations of O. acutipennis sensu stricto.