Quaternary Coastal Landscape Evolution and Sea-Level Rise: An Example from South-East Sicily

Coastal depositional environments are the site of complex interactions between continental and marine processes. Barrier islands are highly dynamic coastal systems, typical of these transitional environments, and are affected by sea level changes and the accumulation of transgressive deposits with the landwards migration of the coast. The offshore of Marzamemi (Syracuse Province, Sicily), in the south-eastern portion of the Hyblean foreland, represents an excellent site for the study of transgressive deposits and their connection with the sea-level changes. The available dataset consisted of new high-resolution bathymetry (Multibeam), whose description and interpretation through a Digital Elevation Model (DEM) was integrated with a grid of eighteen seismic profiles (SPARKER). In the investigated bathymetric range, from about −5 m to −60 m, a sensibly different morphological setting between the northern and southern sectors was evident. Within the whole study area, three bathymetric contours (−45 m, −35 m and −20) were identified and assumed as the markers of the main locations of the paleo-coastlines during the recent changes in the sea level. Along the northern sector, three submerged barrier-lagoon systems developed on a calcarenite substratum, marking important steps of the Late Quaternary sea-level rise. They coexisted with numerous karst forms (poljes and dolines). In the southern sector the transgressive environmental evolution was significantly different and submerged lagoons did not form. Here the outcropping calcarenite substratum was affected by the development of paleo-rivers and karsts structures, a tract in common along with many Mediterranean carbonate coastal areas.

All post- Cambrian ichnospecies of Psammichnites Torell, 1870 belong to Olivellites Fenton and Fenton, 1937a

The ichnogenus Psammichnites herein restricted to Psammichnites gigas is based on comparison of morphology, feeding behaviour, contrast between the burrows and the host rock and possible producers. The record of siphonal activity as a “snorkel device” is discussed. The diagnosis of the ichnogenus Olivellites now is amended and includes all the records of Psammichnites in the post-Cambrian. Olivellites is now documented in successions other than the classical tidal flat deposits facies of the Carboniferous of the USA. We propose that the producer of Olivellites was an animal with capacity for displacement to different shallow infaunal levels for different feeding strategies. An interpretation of detritus feeding behavior with sediment displacement (pasichnia) is favoured here. The producer of Olivellites was likely to have been a bivalved mollusc that evolved after the Late Ordovician mass extinction. It was euryhaline and lived in a broad bathymetric range, and is recorded in temperate to glacially related successions. The material of Olivellites implexus from western Argentina is the youngest record of the ichnogegenus from Western Gondwana.

Annotated and updated checklist of marine crabs (Decapoda: Brachyura) of Mozambique supported by morphological and molecular data from shelf and slope species of the “MOZAMBIQUE” surveys

An updated checklist of Mozambican marine brachyuran crabs is generated based on an exhaustive revision of the existing literature, together with the additional records provided by the specimens collected throughout the three “MOZAMBIQUE” surveys carried out in Mozambican waters during three consecutive years (2007–2009) by the Instituto Español de Oceanografía, (Spanish Institute of Oceanography, IEO). A total of 269 species, grouped in 15 superfamilies, 26 families and 172 genera are reported in the checklist, and a detailed inventory is produced with the list and remarks about the brachyuran species collected. Thirty-nine crab species belonging to 19 families were identified based on morphological characteristics and/or genetic tools. DNA barcode sequences (16S rRNA and/or COI) were obtained for 37 species, including 16S and COI sequences that are new for 26 and 14 species, respectively. Colour photographs of fresh specimens illustrate the comments about most species, being the first time that the original colour pattern is described for some of them. New records in Mozambican waters are reported for the species Paromolopsis boasi, Mursia aspera, Carcinoplax ischurodous, Tanaoa pustulosus, Euclosiana exquisita, Oxypleurodon difficilis, Naxioides robillardi, Samadinia galathea, Cyrtomaia gaillardi, Paramaja gibba, Pleistacantha ori, Parathranites granosus, Parathranites orientalis, Ovalipes iridescens and Charybdis smithii, and second records for Moloha alcocki, Samadinia pulchra and Charybdis africana. In addition, Raninoides crosnieri, S. galathea and P. ori were collected for the first time after their descriptions. The female of Samadinia galathea is described for the first time, and a potential new species of Mursia is reported. Some records expand the known bathymetric range of certain species and/or their general distribution. New molecular and morphological data suggest the necessity of the revision of P. boasi, R. crosnieri, C. africana and the genera Platymaia and Carcinoplax. The variability and taxonomic validity of some morphological characters in brachyuran systematic is discussed.

The Reef Check Mediterranean Underwater Coastal Environment Monitoring Protocol

Since 2001, trained snorkelers, freedivers, and scuba diver volunteers (collectively called EcoDivers) have been recording data on the distribution, abundance, and bathymetric range of 43 selected key marine species along the Mediterranean Sea coasts using the Reef Check Mediterranean Underwater Coastal Environment Monitoring (RCMed U-CEM) protocol. The taxa, including algae, invertebrates, and fishes, were selected by a combination of criteria, including ease of identification and being a key indicator of shifts in the Mediterranean subtidal habitats due to local pressures and climate change. The dataset collected using the RCMed U-CEM protocol is openly accessible across different platforms and allows for various uses. It has proven to be useful for several purposes, such as monitoring the ecological status of Mediterranean coastal environments, assessing the effects of human impacts and management interventions, as well as complementing scientific papers on species distribution and abundance, distribution modeling, and historical series. Also, the commitment of volunteers promotes marine stewardship and environmental awareness in marine conservation. Here, we describe the RCMed U-CEM protocol from training volunteers to recording, delivering, and sharing data, including the quality assurance and control (QA/QC) procedures.

Better Alone Than in Bad Company: New Species of Caudofoveate Limifossorid (Mollusca, Aplacophora) Unravels Patterns of Distribution Hidden in the Deep Atlantic

Aplacophorans are common inhabitants of the deep-sea, where many places remain unexplored regarding their biodiversity. Filling a gap in knowledge about these animals from the South Atlantic, Scutopus variabilis sp. nov. (Caudofoveata, Limifossoridae) is described; further, species distribution modelling (SDM) was performed to elucidate the distribution patterns of Atlantic species of Scutopus. The type materials of S. megaradulatusSalvini-Plawen (1972) and S. chilensisSalvini-Plawen (1972), were examined and a search was performed for specimens of Scutopus held in museum collections. Scutopus variabilis sp. nov. has a slender and highly variable body form and a very distinct suture line is present midventrally. Two dominant types of trunk sclerites were observed by Scanning Electron Microscopy (SEM): one elongated with lateral margins slightly concave in medial portion, and another longer, with narrower base; its radula bears up to eight rows of heavily sclerotized teeth bearing 12–16 small denticles. The species occurs in a wide bathymetric range (40–1300 m), being more abundant at the edge between the continental shelf and upper slope. Outside the areas from where these samples were obtained, suitable areas for S. variabilis sp. nov. were found in the Southern Caribbean Sea (from where S. megaradulatus is recorded) and in the Brazilian Northern coast; the Gulf of Mexico and the Brazilian Northeastern coasts were found as unsuitable. Species of Scutopus appear to exhibit different patterns of geographical distribution: the European S. ventrolineatusSalvini-Plawen (1968) and S. robustusSalvini-Plawen (1970) are known as widely distributed, while non-European representants, the American S. megaradulatus, S. chilensis and S. variabilis sp. nov., and the Japanese S. schanderiSaito and Salvini-Plawen (2014) and S. hamatamiiSaito and Salvini-Plawen (2014) have more restricted distributions. However, clear and definite patterns of distribution of some of these species are probably blurred by sampling bias, for the European area is better studied. In the Atlantic, the SDM showed that species of Scutopus occur in a way that overlapping is minimized. Great sampling efforts combined with detailed descriptions based on SEM have revealed an interesting, abundant and up to now undescribed Brazilian deep-sea malacofauna.

Eurythenes atacamensis sp. nov. (Crustacea: Amphipoda) exhibits ontogenetic vertical stratification across abyssal and hadal depths in the Atacama Trench, eastern South Pacific Ocean

Eurythenes S.I. Smith in Scudder, 1882 (Crustacea: Amphipoda) are prevalent scavengers of the benthopelagic community from bathyal to hadal depths. While a well-studied genus, molecular systematic studies have uncovered cryptic speciation and multiple undescribed lineages. Here, we apply an integrative taxonomic approach and describe the tenth species, Eurythenes atacamensis sp. nov., based on specimens from the 2018 Atacamex and RV Sonne SO261 Expeditions to the southern sector of the Peru-Chile Trench, the Atacama Trench (24–⁠21°S). Eurythenes atacamensis sp. nov. is a large species, max. observed length 83.2 mm, possesses diagnostic features, including a short gnathopod 1 palm and a chelate gnathopod 2 palm, and a distinct genetic lineage based on a 16S rRNA and COI phylogeny. This species is a dominant bait-attending fauna with an extensive bathymetric range, spanning from 4974 to 8081 m. The RV Sonne SO261 specimens were recovered along a 10-station transect from abyssal to hadal depths and further examined for demographic and bathymetric-related patterns. Ontogenetic vertical stratification was evident across the trench axis, with only juveniles present at abyssal depths (4974–6025 m). Total length-depth analysis revealed that the size of females was unrelated to depth, whereas juveniles followed a sigmoidal relationship with a step-up in size at depths >7200 m. Thus, these bathymetric trends suggest that juveniles and females employ differing ecological strategies in subduction trench environments. This study highlights that even dominant and ecologically important species are still being discovered within the abyssal and hadal environments. Continued systematic expeditions will lead to an improved understanding of the eco-evolutionary drivers of speciation in the world’s largest ecosystem.

Stylasterids (Hydrozoa: Stylasteridae) from Mar del Plata submarine canyon and adjacent area (southwestern Atlantic), with a key to the species off Argentina

The Argentine continental margin is a poorly explored area as regards its benthic biodiversity. Few works have been made near the Brazil-Malvinas confluence (around 38° S) regarding corals, especially in deep waters (over 1000 m). Hitherto 17 species of stylasterids are known from southwestern Atlantic (SWA) off Argentina. Fourteen species of stylasterids collected from the Mar del Plata submarine canyon and adjacent area in years 2012 and 2013 at depths between 800 and 2200 m are discussed, including the descriptions of 13 of them. The geographic distribution of six species and bathymetric range of occurrence of two species are broadened in this work. Stations where most specimens were collected are located in areas where sedimentation is known to be scarce. Species in common between the study area and the Antarctic region, south of Chile, South Africa, New Zealand and New Caledonia suggest the Circumpolar Antarctic Current and the Malvinas Current are the means for dispersion. A key of identification of all stylasterid species off Argentina is included.

First report of Alvania scuderii Villari, 2017 (Gastropoda: Mollusca) from Tyrrhenian Sea: Some biogeographic implications

The cryptic gastropod Alva-nia scuderii Villari, 2017, recently described from the Strait of Messina as new species inside the A. scabra (Philippi, 1844) group, was known by restricted areas of eastern and southern Sicily. Some records from the type locality and south-eastern Tyrrhenian sea, which pro-vided new data on habitat and bathymetric range, also enlarged northward, in a further basin, the known ar-eal. Such areal, that over-laps a Mediterranean west-ern-eastern biogeographic boundary, may be consid-ered a further clue of an hy-drological front that is re-sponsible of a West-Mediterranean footprint more marked than in nearby North-westernmost areas.

Intertidal to Abyss: Crustaceans and Depth

Crustaceans occur from the shelf to hadal depths, but the immense environmental change that occurs along this depth gradient results in significant faunal change. One well-established pattern is the dramatic decline in biomass with depth, a result of an exponential decline in food availability. Average body size becomes smaller, despite observations of deep-sea gigantism in some crustaceans. Crustacean species tend to occupy a limited depth range, resulting in high faunal turnover. The depths of the greatest faunal turnover vary widely throughout the oceans, and there do not appear to be distinct bathymetric “zones” at ocean-wide scales. Molecular research at the species level confirms that small bathymetric changes are often more significant at promoting population differentiation than geographic distance. Observation of crustaceans in the laboratory demonstrates that the interaction between pressure and temperature is likely to act together in limiting the bathymetric range of many species. Debate continues around species richness and diversity gradients, and it remains unclear whether there are more crustacean species on the shelf compared to bathyal depths. Diversity patterns vary between taxa. Decapods are species rich on the shelf and upper slope and less so in the abyss. Isopods show high bathyal diversity, although this pattern varies between regions. For other crustaceans, it is difficult to make generalizations on diversity gradients as there are fewer studies, and results vary depending on geographic region and the method used to estimate diversity and richness. In cumaceans, amphipods. and harpacticoids, species richness is often highest on the shelf, while maximum species diversity occurs in deeper water. Food availability and temperature are good correlates for depth-diversity gradients.