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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

Pocket beaches bound by headlands or other geologic features are common worldwide and experience constrained alongshore transport that influences their morphological changes. Pocket beaches fringed by shallow reefs have not been well-studied, yet can be commonly found throughout temperate and tropical regions. The presence of a reef is expected to drive distinct hydrodynamic processes and shoreline responses to offshore waves and water levels, which is investigated in this study. To examine the drivers of shoreline variability, a 20-month field study was conducted on a reef-fringed pocket beach in southwestern Australia (Gnarabup Beach), using a series of in situ wave and water level observations, topographic surveys, as well as video shoreline monitoring. The results indicate that the beach as a whole (alongshore averaged) was in a mostly stable state. However, we observed substantial spatial variability of the local shorelines in response to offshore wave and water levels across a range of time-scales (from individual storms to the seasonal cycle). We observed local regions of beach rotation within cells that were partitioned by the headlands and offshore reefs. The shoreline response was also dictated by the combination of offshore waves and water level which varied seasonally, with the shoreline generally eroding with lower water levels for the same wave height. Despite the contrasting responses in different alongshore locations of the beach, the overall beach volume of the pocket beach was largely conserved.

Age and growth data are central to management or conservation strategies for any species. Circumstantial evidence suggests that male whale sharks (Rhincodon typus) grow to asymptotic sizes much smaller than those predicted by age and growth studies and consequently, there may be sex-specific size and growth patterns in the species. We tested this hypothesis by using stereo-video and photo-identification studies to estimate the growth rates of 54 whale sharks that were resighted over a period of up to a decade at Ningaloo Reef. We found that male growth patterns were consistent with an average asymptotic total length (TL) of approximately 8-9 m, a size similar to direct observations of size at maturity at aggregation sites world-wide and much smaller than the sizes predicted by earlier modeling studies. Females were predicted to grow to an average asymptotic length of around 14.5 m. Males had growth coefficients of K = 0.088 year-1, whereas limited resighting data suggested a growth coefficient of K = 0.035 year-1 for females. Other data including re-sightings of an individual male over two decades, records of sex-specific maximum sizes of individuals captured in fisheries and data from juveniles growing in aquaria were also consistent with the suggestion of sex-specific growth profiles for the species. We argue that selection for sex-specific growth patterns could explain many of the otherwise enigmatic patterns in the ecology of this species including the tendency of the species to form aggregations of juvenile males in coastal waters.

Following a violent collision last Wednesday evening, British Vendee Globe skipper Sam DAVIES (Initiatives-Cœur) sustained significant damage to the framework supporting the keel of her IMOCA. In consultation with her team, she made the decision to stop in Cape Town (South Africa).This morning as she arrived in Cape Town she confirmed by video at 0900hrs UTC that she is officially retiring from the race. But she says she is determined to return - after making repairs with her team and experts - to complete the race course as 'hors course', unclassified on the solo race which forbids any kind of outside assistance.

The aim of this study was to document the composition and distribution of deep-water fishes associated with a submarine canyon-valley feature. A work-class Remotely Operated Vehicle (ROV) fitted with stereo-video cameras was used to record fish abundance and assemblage composition along transects at water depths between 300 and 900 metres. Three areas (A, B, C) were sampled along a submarine canyon-valley feature on the continental slope of tropical north-western Australia. Water conductivity/salinity, temperature, and depth were also collected using an ROV mounted Conductivity Temperature and Depth (CTD) instrument. Multivariate analyses were used to investigate fish assemblage composition, and species distribution models were fitted using boosted regression trees. These models were used to generate predictive maps of the occurrence of four abundant taxa over the survey areas. CTD data identified three water masses, tropical surface water, South Indian Central Water (centred ∼200 m depth), and a lower salinity Antarctic Intermediate Water (AAIW) ∼550 m depth. Distinct fish assemblages were found among areas and between canyon-valley and non-canyon habitats. The canyon-valley habitats supported more fish and taxa than non-canyon habitats. The fish assemblages of the deeper location (∼700-900 m, Area A) were different to that of the shallower locations (∼400-700 m, Areas B and C). Deep-water habitats were characterised by a Paraliparis (snail fish) species, while shallower habitats were characterised by the family Macrouridae (rat tails). Species distribution models highlighted the fine-scale environmental niche associations of the four most abundant taxa. The survey area had a high diversity of fish taxa and was dominated by the family Macrouridae. The deepest habitat had a different fish fauna to the shallower areas. This faunal break can be attributed to the influence of AAIW. ROVs provide a platform on which multiple instruments can be mounted and com

Deeper waters at remote Ashmore Reef off the Western Australian coast could be acting as a refuge for sea snake species not seen in shallow waters for more than a decade, new research led by the Australian Institute for Marine Science (AIMS) indicates.

The Java Trench is the only subduction trench in the Indian Ocean that extends to the hadal zone (> 6,000 m water depth), and except for sevenbenthic trawls acquired around the 1950s, there has been little to no sampling at hadal depths undertaken since. In 2019, we undertook a 5-day expedition comprising a scientific dive using a full ocean depth-rated submersible, the DSV Limiting Factor, seven hadal-lander deployments, and high-resolution bathymetric survey. The submersible performed a video transect from the deepest point of the trench, up a 150 m high near-vertical escarpment located on the forearc, and then across a plateau at a depth of ∼7,050 m to make in situ observations of the habitat heterogeneity and biodiversity inhabiting these hadal depths. We found the Java Trench hadal community to be diverse and represented by 10 phyla, 21 classes, 34 orders and 55 families, with many new records and extensions in either depth or geographic range, including a rare encounter of a hadal ascidian. The submersible transect revealed six habitats spanning the terrain. The deepest trench axis comprised fine-grained sediments dominated by holothurians, whereas evidence of active rock slope failure and associated talus deposits were prevalent in near-vertical and vertical sections of the escarpment. Sediment pockets and sediment pouring down the steep wall in "chutes" were commonly observed. The slope terrain was dominated by two species in the order Actiniaria and an asteroid, as well as 36 instances of orange, yellow, and white bacterial mats, likely exploiting discontinuities in the exposed bedrock, that may indicate a prevalence of chemosynthetic input into this hadal ecosystem. Near the top of the escarpment was an overhang populated by > 100 hexactinellid (glass) sponges. The substrate of the plateau returned to fine-grained sediment, but with a decreased density and diversity of epifauna relative to the trench floor. By providing the first visual insights of the h

Why the World's Biggest Sharks Love Mafia Island.