Explore the vast range of titles available.

The early life stages of Octopus vulgaris face significant challenges in sandy environments, where shelter is limited and predation risk is high. This study examines how juvenile octopuses adapt to these conditions, focusing on their use of empty bivalve shells as shelters. Between May 2022 and June 2023, through four SCUBA diving expeditions in the Cíes Islands, NW Spain, nine juvenile octopuses were found inhabiting bivalve shells. The juveniles preferentially selected shells that fit their body size, providing protection and minimizing exposure. They manipulated the shells for security and positioned themselves strategically for optimal visual surveillance. Additionally, they used camouflage techniques, blending with the sandy substrate. When threatened, some octopuses displayed bipedal locomotion to enhance their escape. This study highlights the adaptive flexibility of juvenile O. vulgaris in response to predation pressures in sandy habitats, adding to the growing but limited knowledge of habitat-specific behaviors that can help contribute to the conservation strategies of wild populations

Horse mussels (Modiolus modiolus) create complex beds (aka reefs) that provide a range of vital ecosystem services. Unfortunately, these ecologically significant habitats are highly sensitive to human activity and are very slow to regenerate (if at all). As an example, there are cases in the Irish Sea and Strangford Lough where extensive beds have been severely declined or destroyed by fishing activity. Whilst individuals are widespread, beds are rare and are given a range of international statuses and protections. Marine Scotland indicates that a horse mussel bed is located within the Berwickshire and North Northumberland Coast (BNNC) Special Area of Conservation (SAC), which encompasses the Berwickshire Marine Reserve (BMR), although, no details are available as to its size or location. This study aimed to conducted preliminary surveys to gain a better understanding of horse mussel presence within the BMR. Historical data, public sightings, and scuba diving and Remotely Operated Vehicle (ROV) survey data were collected. This study expanded our knowledge of horse mussels within the BMR with over 200 recorded. Whilst most of the sightings were of individuals, five locations were highlighted as possibly meeting the requirements for a Scottish Priority Marine Feature (PMF). Further research is required to gain a full picture of horse mussel distribution and health within the area.

Hermit crabs are common and abundant members of the intertidal community and in sublittoral bottoms, where they play a fundamental role in the trophic chain. This study aimed to determine the composition of the hermit crab fauna, to quantify the density in the natural environment, and to register shells use by main species from subtidal boulder fields, in an island off the southeastern Brazilian coast. Monthly samples were taken from March 2010 to February 2011 on boulder fields on Couves Island, Ubatuba, Brazil, during scuba diving daytime sessions. Three hundred and eighty-three crabs were collected by hand, in a quadrat of 20 [m.sup.2] belonging to five species: Calcinus tibicen, Dardanus venosus, Pagurus brevidactylus, Paguristes tortugae, and Petrochirus diogenes. The highest densities were recorded for P. brevidactylus and P. tortugae. Hermit crabs occupied shells of 15 gastropod species. Cerithium atratum, Gemophos auritulus, and Morula nodulosa comprised more than 80% of the occupation. The heterogeneity of boulder fields of Couves Island, composed almost entirely of small refuges and crevices, favors the exploration of hermit crab species recorded here, which are characterized by small size. These results, combined with the findings of further studies, can contribute to the development of effective monitoring programs for decapod crustacean species.

The noble pen shell (Pinna nobilis) is a key bivalve species found in the Mediterranean that has suffered dramatic declines due to mass mortality events (MMEs) caused by pathogens like Haplosporidium pinnae. This study looks at the historical population structure of P. nobilis in Malo jezero, a coastal lagoon in Mljet National Park, Croatia, using data collected before the MME. During a field survey in 2018, data on the population density, size, and age of 3800 individuals, using a grid-based transect method, were collected. The population density ranged from 7.50 to 55.83 individuals per 100 m2, with an average of 25.42 individuals per 100 m2, over 11 520 m2, reflecting a high abundance compared to other populations. All individuals were mature, with no juveniles or signs of recent recruitment. The estimated ages ranged from 8.00 to 44.34 years, with 20 individuals exceeding the expected maximum size. The population was comprised of older individuals, making it vulnerable to sudden events, due to a lack of younger individuals. The isolation of Malo jezero may limit larval exchange with other populations, contributing to recruitment challenges. This study provides important information for understanding P. nobilis populations and supports the potential of Malo jezero for future conservation and reintroduction efforts.

The aim of this work is to update the checklist of the marine malacofauna of the Culuccia Peninsula (NW Sardinia, Italy), based on research carried out over two years by SCUBA and free diving in all the main marine habitats of the peninsula. We provide here new records, all accompanied by in situ images of living animals or photographs of shells. In some cases, ecological and systematic notes are provided. With the new records of 39 species (27 gastropods and 12 bivalves), a total of 295 taxa belonging to the classes Bivalvia (84), Gastropoda (199), Polyplacophora (11), and Scaphopoda (1) have been listed from this Sardinian high-biodiversity spot. Two alien species already reported, Pinctada radiata (Leach, 1814) and Bursatella leachii Blainville, 1817, can now be considered to be well established.

Rhodoliths are non-geniculate, free-living coralline red algae that can accumulate on the seafloor and form structurally complex benthic habitats supporting diverse communities known as rhodolith beds. We combined in situ rhodolith collections and imagery to quantify variability, over 9 months and at two sites, in the structural complexity and biodiversity of a subarctic Lithothamnion glaciale rhodolith bed. We show that the unconsolidated rhodolith framework is spatially heterogeneous, yet provides a temporally stable habitat to an abundant and highly diverse macrofauna encompassing 108 taxa dominated by brittle stars, chitons, bivalves, gastropods, polychaetes, sea urchins, and sea stars. Specific habitat components, including large bivalve shells, affect rhodolith morphology and resident macrofauna, with increasingly large, non-nucleated rhodoliths hosting higher macrofaunal density, biomass, and diversity than increasingly large, shell-nucleated rhodoliths. The present study’s fine taxonomic resolution results strongly support the notion that rhodolith beds are biodiversity hotspots. Their spatial and temporal domains provide clear quantitative evidence that rhodolith beds provide a stable framework under the main influence of biological forcing until sporadic and unusually intense physical forcing reworks it. Our findings suggest that shallow (<20 m depth) rhodolith beds are vulnerable to ongoing and predicted increases in the frequency and severity of wave storms.

A new marine sponges, Mycale (Carmia) ieoensis n. sp., of the family Mycalidae was collected SCUBA diving in June 2017 from Ieodo Ocean Research Station, Korea. M. (C.) ieoensis n. sp. is encrusting to irregular massive type, yellow in life. This new species is similar to M. nullarosette Hoshino, 1981 in color and growth form but it differs in spicule size and sigma shape. Spicule size of M. (C.) ieoensis n. sp. smaller than that M. nullarosette. Also, M. (C.) ieoensis n. sp. has two size toxa, but M. nullarosette is not. The new species are compared to other Mycale species from the Korean region, and similar species from elsewhere.

The vocal repertoire of walruses has been widely described in the bioacoustic literature. These marine mammals produce several distinct types of vocalizations for intraspecific communication during the breeding season. In this study, we provide the first evidence of walrus-generated sounds during foraging dives when they feed on bivalves. We recorded two types of sounds that we associated to different feeding mechanisms. The first sound type was brief and low in frequency that we relate to the suction of soft parts from the bivalves’ shells through the use of walrus powerful tongues, which is the common feeding behavior reported in the walrus literature. We also recorded a second sound type composed of multiple broadband pulse trains. We hypothesize the latter were associated with bivalve shell cracking by walruses, which would represent a new feeding mechanism in the walrus literature. This new feeding mechanism is either related to bivalves’ ecology or to walruses removing the sediment when searching for food. During this study, we observed bivalves lying on the seafloor instead of being buried in the sediment in walrus feeding areas while scuba diving. As a result, walruses cannot use suction to feed on soft body part of bivalves and have to use another strategy, mastication. Our findings provide a first step towards using passive acoustics to quantify walrus behavior and feeding ecology.

Beach rocks are located along many coasts of the Mediterranean basin. The early diagenesis environment and the mean sea level along the shoreline make these landforms useful in the reconstruction of relative sea-level changes and, in particular, as SLIPs (sea-level index points). The beach rocks surveyed along the Ionian coast of Apulia were found to be well preserved at three specific depth ranges: 6–9 m, 3–4 m, and from the foreshore to about 1.20 m. Morpho-bathymetric and dive surveys were performed to assess both the geometries and the extension of the submerged beach rocks. Samples were collected at these different depths in the localities of Lido Torretta, Campomarino di Maruggio, San Pietro in Bevagna, and Porto Cesareo. Bivalve shells were identified and isolated from the beach rock samples collected at a depth of 7 m; AMS dating provided a calibrated age of about 7.8 ka BP. Their morphology and petrological features, along with the time constraints, enabled us to (i) reconstruct the local sea-level curve during the Holocene, (ii) corroborate acquired knowledge of the relative sea-level history, and (iii) identify possible local vertical land movement (VLM).