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We investigated dual carbon isotopes within the vertical water column at sites 67-1 and 67-2 of the western equatorial Indian Ocean to determine the source and age of particulate organic carbon (POC) and thus evaluated the contributions of modern and fossil (aged) POC. The concentration of POC ranged from 7 to 47.3 μgC L−1, δ13CPOC values ranged from -31.8 to -24.4‰, and Δ14CPOC values ranged from -548 to -111‰. Higher values of δ13CPOC and Δ14CPOC near the surface indicated an influence of autochthonous POC, whereas decreasing trends toward the bottom suggested a contribution of aged OC sources to the total POC pool. The contribution of fossil POC was lower near the surface, accounting for only 12% and 6% of the total POC at sites 67-1 and 67-2, respectively; however, in the deeper layers below 1,000 m, the contribution of fossil POC increased to 52% and 44% of the total POC at the two sites. Mechanisms for the increased contributions of fossil OC within deeper POC include the inflow of aged OC from sediments resuspended near slopes, the adsorption of old dissolved organic carbon in deep water masses, and the impact of aged OC that may originate from hydrothermal sources. This study highlights the importance of aged OC in the carbon cycle of the equatorial Indian Ocean.

The balmy islands of Seychelles couldn't feel farther from Antarctica, but their fossil corals could reveal much about the fate of polar ice sheets.

The balmy islands of Seychelles couldn't feel farther from Antarctica, but their fossil corals could reveal much about the fate of polar ice sheets.

Recent studies suggest that pelagic sediments can enrich rare-earth elements (REE) acting as a significant reservoir for the global REE budget as well as a potential resource for future exploitation. Although Ca-phosphate (e.g., bioapatite fossils) and Fe-Mn (oxyhydr)oxides (e.g., micronodule) have been considered important REE carriers in deep-sea sediments, the proportion of REE held by each mineral phase remains enigmatic. Here, we have investigated the sediments from two promising REE-rich prospective areas: the Tiki Basin in the Southeast Pacific (TKB) and the Central Indian Ocean Basin (CIOB). The mineral grains including bioapatite fossils and Fe-Mn micronodules have been inspected individually by in-situ microscale analytical methods. Correspondently, the REE bound to Ca-phosphate and Fe-Mn (oxyhydr)oxides have been sequentially extracted and quantified. The crucial role of Ca-phosphate is substantiated by sequential leaching which reveals its dominance in hosting ~69.3-89.4% of total REE. The Fe-Mn (oxyhydr)oxides carry ~8.2% to 22.0% of REE in bulk sediments, but they account for ~70.0-80.5% of Ce owing to their preferential adsorption of Ce over the other REE. Surface sediment on modern seafloor can accumulate high REE contents resulting from the REE scavenging by the host phases within the range of sediment-seawater interface. Differences between TKB and CIOB samples indicate that the REE enrichment in the deep-sea environment may be controlled by multiple factors including the productivity of overlying seawater (e.g., phosphorus flux), water depth relative to carbonate compensation depth (CCD), sedimentation rate, redox condition, and hydrothermal vent input (e.g., Fe-Mn precipitations).

The move could help protect this millions-of-years-old species.

The move could help protect this millions-of-years-old species.

This study represents the first ROV-based exploration of the Perth Canyon, a prominent submarine valley system in the southeast Indian Ocean offshore Fremantle (Perth), Western Australia. This multi-disciplinary study characterizes the canyon topography, hydrography, anthropogenic impacts, and provides a general overview of the fauna and habitats encountered during the cruise. ROV surveys and sample collections, with a specific focus on deep-sea corals, were conducted at six sites extending from the head to the mouth of the canyon. Multi-beam maps of the canyon topography show near vertical cliff walls, scarps, and broad terraces. Biostratigraphic analyses of the canyon lithologies indicate Late Paleocene to Late Oligocene depositional ages within upper bathyal depths (200-700 m). The video footage has revealed a quiescent 'fossil canyon' system with sporadic, localized concentrations of mega- and macro-benthos (∼680-1,800 m), which include corals, sponges, molluscs, echinoderms, crustaceans, brachiopods, and worms, as well as plankton and nekton (fish species). Solitary (Desmophyllum dianthus, Caryophyllia sp., Vaughanella sp., and Polymyces sp.) and colonial (Solenosmilia variabilis) scleractinians were sporadically distributed along the walls and under overhangs within the canyon valleys and along its rim. Gorgonian, bamboo, and proteinaceous corals were present, with live Corallium often hosting a diverse community of organisms. Extensive coral graveyards, discovered at two disparate sites between ∼690-720 m and 1,560-1,790 m, comprise colonial (S. variabilis) and solitary (D. dianthus) scleractinians that flourished during the last ice age (∼18 ka to 33 ka BP). ROV sampling (674-1,815 m) spanned intermediate (Antarctic Intermediate Water) and deep waters (Upper Circumpolar Deep Water) with temperatures from ∼2.5 to 6°C. Seawater CTD profiles of these waters show consistent physical and chemical conditions at equivalent depths between dive

Surfing geologist applies science to shark risk.

Kenya on Monday rebuked Somalia for dragging it before the UN's top court to defend a maritime border dispute that could decide the fate of potentially-lucrative Indian Ocean oil and gas reserves.

For years, Kenya and Somalia have argued over where their maritime boundary in the Indian Ocean runs. The International Court of Justice in The Hague could now decide who owns the sea, a decision that will only suit one.

Marine parks need to cover large swathes of ocean, but they also need to cover the right areas if they are to deliver the best conservation. New research off Australia's northwest suggests how.

Marine parks need to cover large swathes of ocean, but they also need to cover the right areas if they are to deliver the best conservation. New research off Australia's northwest suggests how.

South Asia Meet on Oil, Chemical Spill.

South Asia Meet on Oil, Chemical Spill.

Bangladesh: la mangrove en péril.

Chinese navy ships to be deployed at Gwadar: Pak navy official.

Iran wants stronger maritime capabilities, including an aircraft carrier.

Bangladesh coal plant threatens World Heritage mangrove: petition.

Bangladesh coal plant threatens World Heritage mangrove: petition.

A palaeontologist from The University of Manchester has taken part in a project to rebuild and redisplay the skeleton of a 200 million-year-old sea creature, 61 years after its bones were discovered in a field in Warwickshire. The Ichthyosaurus is the largest example ever found in the UK, and it is now available for the public to view for the first time.

A palaeontologist from The University of Manchester has taken part in a project to rebuild and redisplay the skeleton of a 200 million-year-old sea creature, 61 years after its bones were discovered in a field in Warwickshire. The Ichthyosaurus is the largest example ever found in the UK, and it is now available for the public to view for the first time.

Gliders are helping unlock the secrets of the Agulhas current.

Oil Spill in Tamil Nadu threatens marine life including turtles.

The Chennai Oil Spill: A Lesson for India's Maritime Agencies.

Énergie renouvelable : Maurice veut construire des parcs éoliens en mer.

L'océan Indien sera-t-il chinois ?