The body condition of animals is an important indicator of their habitats and the effects of anthropogenic activities and pollution. Body condition indices calculated from morphometric measurements have been widely employed as they are easy to use and inexpensive. In sea turtles, Fulton's condition index, calculated as the bodyweight divided by the cube of straight carapace length (SCL), has been commonly used and it has been proposed that an index of ≥1.2 indicates a good body condition. However, comparing Fulton's condition index between different species and size classes is problematic as it does not consider the mass-length relationship. In this study, we conducted a meta-analysis to evaluate the differences between sea turtles. A literature review indicated that most studies reported the SCL-based Fulton's condition index for green turtles (Chelonia mydas), followed by loggerhead turtles (Caretta caretta) and hawksbill turtles (Eretmochelys imbricata). Therefore, we compared the values reported for healthy turtles of these three species. Meta-analysis supported the adequacy of 1.2 as a threshold in juvenile and adult green turtles and large juvenile and adult loggerhead turtles. High Fulton's condition index values were found for hatchlings and post-hatchlings of all three species and small loggerhead turtle juveniles. Low Fulton's condition index values were found for hawksbill turtles, particularly small juveniles. The differences in the Fulton's condition index between species and size classes indicated that it should be used carefully as a threshold for health condition evaluation.

Jellyfish are a well-known component of marine ecosystems. Here, we aimed to assess whether populations of the jellyfish species Mastigias cf. papua and Cassiopea ornata inhabiting different marine lakes and jellyfish species from open water habitat host ‘core’ symbionts and if there is evidence of species-specific host-microbial associations. Compositionally, jellyfishes hosted prokaryotic communities distinct from those found in water samples. All jellyfish samples across habitats and species exhibited a core OTU, assigned to the genus Endozoicomonas. This OTU was particularly abundant (>90% of all sequences) in C. ornata from one Papuan marine lake. Additionally, an OTU assigned to the Entomoplasmatales order was found in all but two jellyfish specimens, and was particularly abundant in marine lake specimens from Berau and Papua, Indonesia. Given the well-known relationship between Endozoicomonas and Symbiodinium spp., we tested for Symbiodinium presence in pooled specimens of M. papua from Berau. Our results showed that OTUs assigned to the genus Symbiodinium accounted for >99% of all sequences in jellyfish-associated microeukaryotic communities; these were closely related to organisms from Symbiodinium clade C. These results suggest the existence of a widespread and abundant jellyfish core symbiont, which may interact with symbiotic Symbiodinium populations to influence host fitness.

Deep-sea ecosystems are generally oligotrophic because they lack photosynthesizing producers. On deep-sea slopes near land, however, various terrestrial plant remains flow to and are deposited on near-shore deep bottoms. From a depth of 300 m off the Pacific coast of Owase, central Japan, we collected an onuphid polychaete, Anchinothria cirrobranchiata (Annelida: Onuphidae), which lives in a dorsoventrally flattened portable tube. The polychaete tubes were made of sand, as well as leaves and twigs of terrestrial evergreen trees. The leaves glued on the portable tubes were chartaceous, blackish and tough; they belonged mainly to two genera of Fagaceae, Castanopsis and Quercus, which are dominant components of coastal evergreen oak forests. In aquaria, the polychaetes fed on the leaves on their tubes, as well as autochthonous sedimented leaves, suggesting utilization of terrigenous plant litter as food. As to the evolution of Anchinothria, a molecular phylogenetic analysis suggests that Anchinothria is monophyletic with other Hyalinoeciinae (Nothria, Leptoecia, Hyalinoecia).

One shark was landed at the Naval Base Pasha Liman, Bay of Vlore, Albania, the Adriatic Sea. Photographic records only enabled the specimen to be placed in family Odontaspididae or Carchariidae. Later examination of the preserved head, dry jaw and dentition identified the specimen as Odontaspis ferox. This is a rare record and the northernmost Mediterranean observation of this species, and the first Adriatic record for several decades.

This report provides the first confirmed identifications of wahoo (Acanthocybium solandri) and striped marlin (Kajikia audax) in the Red Sea, expanding the known ranges of these species into the basin. Potential mechanisms responsible for the lack of regional documentation of the two species are further discussed. These findings illustrate the need for systematic biodiversity surveys of pelagic fish assemblages in the Red Sea.

Deep-water shrimps are recognized as non-conventional culinary delicacies owing to the presence of high-quality polyunsaturated fatty acids, even though they remain one of the predominantly unexplored marine fishery resources. In this study, variation of fatty acid profiles of Aristeus alcocki, Solenocera choprai, Heterocarpus chani and Plesionika quasigrandis, caught along the south-west coast of India (Arabian Sea) during the months spanning from September 2018–April 2019, were compared. Among the deep-water shrimps studied, A. alcocki contained a greater amount of n-3 fatty acids, such as docosahexaenoic and eicosapentaenoic acid along with optimal n-3/n-6 polyunsaturated fatty acid ratios beneficial for human nutrition (up to 8 during the winter months) when compared with other shrimps. In general, fatty acid concentrations exhibited variations, particularly with regard to polyunsaturated fatty acids, such as eicosapentaenoic acid and docosahexaenoic acid. These n-3 fatty acids were predominant during December–February of the studied year, but concentrations were noticeably lower during March and April. Females had considerably higher (P < 0.05) C20–22 n-3 fatty acid concentrations along with nutritionally balanced polyunsaturated/saturated fatty acid ratio than males. Results of the two-way multivariate analysis of variance (MANOVA) revealed statistically significant differences in the fatty acid profiles between the species and months. The interaction effects of months with species were also highly significant (Wilk's lambda = 0.000001; F = 187.7, P < 0.0001). Lesser atherogenicity (<3) and thrombogenicity (<0.5) indices coupled with considerably greater n-3/n-6 fatty acid ratios recognized these deep-water species as a possible source of highly nutritional human food.

Scomberomorus koreanus was originally described from a single specimen from the west coast of Korea. In 1964 the species was synonymized with S. guttatus during the systematic review of the scombroid fishes of India. Subsequently, S. koreanus was discovered in Palk Bay in 1976, confirming its first record from India and the Indian Ocean. Since then, no such detailed taxonomic studies have been undertaken for the species along the Indian coast. Although the species is distributed in the Indo-West Pacific region and forms a commercially important fishery in part of its range, S. koreanus is poorly known and very limited taxonomic studies have been carried out in detail which usually results in misidentifications at field level. The present morpho-genetic investigation and previous molecular study by the authors confirmed the occurrence of the species in the coastal waters of both the Bay of Bengal and the Arabian Sea. The exact characteristics of S. koreanus are detailed here, and their comparison was made here with the related species S. guttatus found in the northern part of the east coast of India, based on a thorough morphological study, including the radiographs of 13 fresh specimens (334–588 mm FL), colour photographs of S. koreanus collected in 2019–2021 and DNA barcoding.

We present the first record of the very large deep-sea mytilid Gigantidas horikoshii Hashimoto & Yamane, 2005 outside of its type distribution, based on a juvenile specimen collected by fishermen at the Tashi fishing grounds east of Taiwan. This record extends the distribution of the species in about 20 latitudinal degrees to the west (about 1916 km), and it is the first record for this species outside the Izu-Ogasawara Island-arc, southern Japan, representing the westernmost geographic limit of this species and the first record in Taiwanese waters.

The coral reefs of the Pitcairn Islands are in one of the most remote areas of the Pacific Ocean, and yet they are exposed to the impacts of anthropogenic climate change. The Pitcairn Islands Marine Protected Area was designated in 2016 and is one of the largest in the world, but the marine environment around these highly isolated islands remains poorly documented. Evidence collated here indicates that while the Pitcairn Islands' reefs have thus far been relatively sheltered from the effect of warming sea temperatures, there is substantial risk of future coral decalcification due to ocean acidification. The projected acceleration in the rate of sea level rise, and the reefs' exposure to risks from distant ocean swells and cold-water intrusions, add further uncertainty as to whether these islands and their reefs will continue to adapt and persist into the future. Coordinated action within the context of the Pitcairn Islands Marine Protected Area can help enhance the resilience of the reefs in the Pitcairn Islands. Options include management of other human pressures, control of invasive species and active reef interventions. More research, however, is needed in order to better assess what are the most appropriate and feasible options to protect these reefs.