Search Results (28)

The authors propose considering the structure and evolutionary changes in the biosphere from the standpoint of a biogeomics approach. It is necessary to study biogeomes as systems of ecosystems that are similar in their structural and functional organization. Biogeomes are structural units of the biosphere and elements of biospheromerons. Based on an analysis of the concept of the “biome”, it is concluded that its primary use is limited, since it is only based on the phytocenotic approach; however, it should be noted that it is this aspect that is currently developing most successfully. The authors note that A. Tansley (1935), critically examining the concept of the biome, essentially introduced the concept of the biogeome, which is broader than the concept of the “ecosystem”. The authors consider the characteristics of five main terrestrial and atmobiontic biogeomes (hylea, grass biogeome, tundra, and desert biogeome), as well as seven hydrosphere biogeomes (shelf, pelagic ocean biogeome, bathyal–abyssal bottom, hydrothermal, bioherm, limnobiogeome, and rheobiogeome). They are grouped, based on the physiognomic approach and an analysis of the “biogeomic formulas”, into the following three types: biotic (the appearance of ecosystems is determined by the biome), oligobiotic (the appearance of ecosystems is determined by both the biome and abiotic elements, as well as the geome), and nanobiotic, where the general appearance of ecosystems is determined by the elements of the geome. The biogeomic approach allows us to consider the organization of terrestrial and hydrosphere ecosystems in a general way and to introduce important elements into the structure of the Earth’s biosphere, which has gone through complex and lengthy stages during its evolution. Full article

The Chaoshan Depression, situated in the northern South China Sea, is a Mesozoic residual depression beneath the Cenozoic Pearl River Mouth Basin. Borehole LF35-1-1 has confirmed the existence of marine Jurassic layers rich in organic carbon within this depression. However, the understanding of petroleum geology in this area is limited due to the complex interplay of Mesozoic and Cenozoic tectonic activities and the poor quality of seismic imaging from previous surveys, which have obstructed insights into the characteristics of Mesozoic reservoirs and the processes of oil and gas accumulation. Recent quasi-3D seismic data have allowed for the identification of Mesozoic bioherms and carbonate platforms in the Middle Low Uplift of the Chaoshan Depression. This research employs integrated geophysical data (MCS, gravity, magnetic) and well data to explore the factors that influenced Middle Jurassic reef development and their implications for reservoir formation. The seismic reflection patterns of reefs and carbonate platforms are primarily characterized by high-amplitude discontinuous to chaotic reflections, with occasional blank reflections or weak, sub-parallel reflections, as well as significant high-velocity, high Bouguer gravity and low reduced-to-pole (RTP) magnetic anomalies. Atolls, stratiform reefs, and patch reefs are located on the local topographic highs of the platform. Three vertical evolutionary stages have been identified based on the size of atolls and fluctuations in relative sea level: initiation, growth, and submergence. The location of bioherms and carbonate platforms was influenced by paleotectonic topography, while their horizontal distribution was affected by variations in relative sea level. Furthermore, the reef limestone reservoirs from the upper member of the Middle Jurassic, combined with the mudstone source rocks from the Lower Jurassic and the lower section of the Middle Jurassic, as well as the bathyal mudstone caprocks from the lower part of the Late Jurassic, create highly favorable conditions for hydrocarbon accumulation. Full article

This study deals with the biostratigraphic determination and paleoenvironmental reconstruction of the middle–upper Eocene sediments along the northwestern and northeastern banks of the Nile Valley, Egypt. The studied successions are classified into four rock units as follow: The Qarara (Lutetian–Bartonian), the El Fashn (Bartonian), the Gehannam, and the Beni Suef (Bartonian–Priabonian) formations. A total of eighty planktonic foraminifera species belonging to twenty-two genera and eight families are identified, and their vertical distribution enabled us to recognize four planktonic biozones, namely the Morozovelloides lehneri Zone (late Lutetian–early Bartonian), Orbulinoides beckmanni Zone (early Bartonian), Morozovelloides crassatus Zone (late Bartonian), and Globigerinatheka semiinvoluta Zone (late Bartonian–early Priabonian). The faunal assemblages characterizing these zones showed a great similarity with those recorded in the lower latitudes (tropical and sub-tropical) regions and correlated with the planktonic zones in the northern and southern Tethyan provinces. The appearance of Orbulinoides beckmanni distinguishes the early Bartonian period, its lowest occurrence defines the upper boundary of the Morozovelloides lehneri Zone, and its highest occurrence marks the lower boundary of the Morozovelloides crassatus Zone. The disappearance of the spinose forms of morozovellids and the large acarininids, besides the highest occurrence of Morozovelloides crassatus, defines the lower boundary of the Globigerinatheka semiinvoluta Zone. The middle/upper Eocene boundary is traced based on the last and first appearance of the marker planktonic species and located herein within the Globigerinatheka semiinvoluta Zone. The paleontological data, including the planktonic to benthic foraminiferal ratio (P/B), statistical analyses of different foraminiferal groups, and ternary plot diagrams in conjunction with the sedimentological features, indicate changes in the depositional settings, fluctuating between the inner to middle and outer neritic environment and the uppermost bathyal environment at some levels. Full article

Echinoderms are among the most charismatic megabenthic taxa in mesophotic and deep waters. However, they generally have a scattered distribution and are difficult to collect, especially on hardgrounds, so defining their abundance, distribution and ecological preferences is challenging. The largest available Italian remotely operated vehicle dataset, including 624 dives carried out between 2006 and 2022 in coastal and offshore areas in the depth range of 40–1825 m, was used to assess echinoderm diversity and large-scale geographic and bathymetric distributions. Thirty-nine taxa were identified, including three rarely reported from the Mediterranean basin. The maximum diversity and occurrence of the deep-sea echinoderm fauna were reported from the northern areas, and generally, they decreased with depth and distance from the coast. Species, mostly of Atlantic origin, were mainly distributed according to their thermic preferences. The recorded species occurred in a large variety of habitats, including some in which, differently from what was reported in the literature, they formed dense aggregations. The high densities of individuals were hypothesised to be related, in some cases, to reproductive, feeding or stress situations. Environmental predictors were considered in order to both investigate patterns in community composition and the response of the studied community to them. This work enhances the knowledge of deep-sea Mediterranean echinoderms, fundamental to implementing more effective monitoring and conservation strategies for the habitats in which they thrive. Full article

The Alboran Sea is the westernmost sub-basin of the Mediterranean Sea, and it is connected to the Atlantic Ocean through the Strait of Gibraltar. The Alboran Ridge is located in the middle of the Alboran Sea and represents a hotspot of biodiversity in the Mediterranean Sea. Besides their critical importance, there are few studies on the communities and changes in biodiversity, and they mostly concentrate on infralittoral and circalittoral bottoms. In this work, the composition, structure and bathymetric and temporal changes of megafauna of the Alboran Ridge were examined. Samples were collected from MEDITS surveys carried out between 2012 and 2022 at depths ranging from 100 to 800 m. Analyses were performed separately for each of the taxonomic groups: osteichthyes, chondrichthyes, crustaceans, molluscs, echinoderms and “other groups”. There was no common spatial organization for each of the faunistic groups studied, although most of them displayed differences between the shelf and the slope. The continental shelf was characterized by the highest values of community metrics such as abundance, biomass, species richness and mean weight of species for all groups except for chondrichthyes and crustaceans. Decreasing trends of some community metrics were detected in some of the faunistic groups throughout the study period. Full article

The arrival of a new invasive alga, Rugulopteryx okamurae, in the Strait of Gibraltar (SoG) in 2015 marked an unprecedented milestone in the North African and, later, in the European marine ecosystems. Nowadays, it is colonising vast infralittoral areas and significantly modifying some habitats and associated communities of the southern Iberian Peninsula. In recent expeditions, a high amount of free drifted thalli of this alga has been detected in different circalittoral and bathyal habitats of the northern SoG and the Alboran Sea. The present study combines quantitative data of this alga obtained with the use of a remotely operated vehicle (ROV) and a bottom otter trawl. The coverage–entanglement level of the drifted thalli on circalittoral and bathyal benthic invertebrates (e.g., not covering, covering only the basal part, covering one-third of the invertebrate, etc.) was also annotated from picture frames taken in locations with abundant drifted thalli. In underwater images, drifted thalli were mainly detected in circalittoral and bathyal bottoms of the northern SoG and the north-western Alboran Sea, between 50 to ca. 450 m depth. Nevertheless, abundant drifted thalli were also detected in bottom otter trawl samples from circalittoral bottoms of the north-central and north-eastern Alboran Sea. Small benthic organisms (e.g., encrusting sponges, hydrozoans, etc.) generally displayed low coverage–entanglement levels of drifted thalli. Nevertheless, large sessile and colonial benthic organisms with a complex three-dimensional morphology (e.g., gorgonians, colonial scleractinians) reached high levels of R. okamurae thalli entangled in different parts of their colonies. The drifted R. okamurae thalli entangled in these colonial suspension feeding organisms may hinder their feeding capability in the long term, resulting in habitat deterioration in the near future. Full article

The Kuril–Kamchatka Trench (North-West Pacific Ocean) is included in the deepest trenches (>9000 m). This study is the first that aims at uncovering the bathyal prokaryotic diversity (1000–2000 m) of this fascinating extreme environment. The analysis of α-diversity revealed that bacterial communities showed greater diversity than archaeal communities and that both communities were characterized by poor evenness (indicative of the presence of few dominant OTUs). The metabarcoding analysis showed that Proteobacteria (65.5–90.7%), Bacteroidetes (2.4–10.7%), and Actinobacteria (2.5–9.6%) were the highly represented phyla of bacteria, with Acinetobacter (21.5–62.5%) as the most abundant genus. Moreover, the recently described Pseudofrancisella genus, which has been isolated from estuarine environments, has been found among the major bacterial taxa. This work represents the first report stating the presence of this genus in bathyal waters. The archaeal communities were dominated by the phylum Thaumarchaeota (53.6–94.0%), with Nitrosopumilus (53.6–94%) as its representative genus. The functional diversity analysis revealed that overall, the bacterial communities had a higher involvement in the carbon and nitrogen biogeochemical cycles, with chemoheterotrophy (mostly aerobic), aromatic compound degradation, and nitrate reduction as the most represented functions. In the archaeal communities, the most represented ecological function was the aerobic oxidation of ammonia (first stage of nitrification), a functional feature characteristic of Nitrosopumilus. Full article

The diversity and evolution of the Red Sea invertebrates in mesophotic and deep-water benthic ecosystems remain largely unexplored. The Palaemonidae is a diversified family of caridean shrimps with numerous taxa in need of taxonomic revisions based on recent molecular analyses. The Red Sea mesophotic and bathyal palaemonid shrimps are largely unstudied. During recent expeditions off the Red Sea coast of Saudi Arabia, several palaemonid specimens were collected at a depth range of 88–494 m, spanning the mesophotic and bathyal zones. This material was examined morphologically and genetically to infer phylogenetic relationships among the Red Sea taxa and several other palaemonid genera. The concordant morphological and genetic data led to the description of two new genera and two new species. Moreover, one species was recorded in the Red Sea for the first time, with a new host record, whereas three further deep-water species, which do not occur in the Red Sea, were formally transferred to a different genus. As more exploration efforts are deployed, research on the diversity and evolutionary relationships among marine invertebrates from the Red Sea will further underline the uniqueness of its mesophotic and bathyal fauna. Full article

Gymnesigobius medits is reported for the first time after a recent description recorded from the Balearic Islands and from the slope of the Gulf of Vera on the Iberian Peninsula coast. The record from the Emile Baudot seamount on the Balearic Islands represents the deepest positive benthic gobiiform species record in general. The presence of the membrane connection between the pelvic fins in Gymnesigobius medits, presumed on the damaged fin in the original description, was confirmed. The recently described Gobius xoriguer is the first record from the Pitiusas and Columbretes islands and from the Iberian Peninsula coast. It appears to be widely distributed in the circalittoral bottoms, preferentially in red algae beds. Morphological identification of both species was confirmed using molecular analyses based on the sequencing of the mitochondrial cytochrome c oxidase subunit I (DNA barcode) gene. The deepest records of gobiiform fishes in oceans and seas are reviewed. The European seas, a well-studied area with eight gobiid species recorded deeper than 200 m, show high bathyal gobiid species richness compared to other areas. The real worldwide diversity of bathyal gobies, although only a fraction of the shallow water species richness of this taxon, is probably much larger than presently known. Full article

Competitive interactions come in a variety of forms and may be modulated by the size and number of individuals involved, and/or the resources available. Here, intra- and interspecific competitive behaviours for food (i.e., foraging/food search and feeding/food ingestion) were experimentally characterized and quantified in four co-existing deep-sea benthic species. Three sea stars (Ceramaster granularis, Hippasteria phrygiana, and Henricia lisa) and one gastropod (Buccinum scalariforme) from the bathyal Northwest Atlantic were investigated using video trials in darkened laboratory conditions. A range of competitive or cooperative behaviours occurred, depending on species (conspecific or heterospecific), comparative body size, and the number of individuals involved. Contrary to expectations, small individuals (or smaller species) were not always outcompeted by larger individuals (or larger species) when foraging and feeding. Moreover, faster species did not always outcompete slower ones while scavenging. Overall, this study sheds new light on scavenging strategies of co-existing deep-sea benthic species in food-limited bathyal environments, based on complex behavioural inter- and intraspecific relationships. Full article

Geryon longipes is a crab species that inhabits the muddy bottoms of the middle and lower slopes, as well as bathyal bottoms ranging from 400 to 2000 m in depth. To assess its molecular diversity, a fragment of 572 bp of the COI (Cytochrome Oxidase subunit I) mitochondrial gene was sequenced in eight Western Mediterranean locations. Within the studied area, two oceanographic fronts are present (Almeria-Oran Front and Ibiza Channel). From the 124 sequences obtained, only 7 distinct haplotypes were identified. The population distribution indicated three well-differentiated regions: the Alboran Sea, the Gulf of Vera and the Levantine/Catalan coasts. The molecular diversity was compared with that obtained in the same year for the same gene in Liocarcinus depurator, a crab species that is captured on the continental shelf and upper slope (40 to 500 m). The estimates of molecular diversity parameters for the COI gene fragment were rather similar between both species, but the number of haplotypes was higher for L. depurator. Finally, the obtained COI sequences of G. longipes were compared to those from other populations of the species distribution range, recovered from the DNA repository. Only one additional, different haplotype was reported (Sicily), whereas all the rest were common with those described in our study. Therefore, the COI gene fragment would indicate that all the sequences analysed in the Mediterranean and NE Atlantic belong to the same species, G. longipes. Full article

The genus Abyssopathes Opresko, 2002, comprises deep-sea black corals known almost exclusively from lower bathyal and abyssal depths, mainly from seamounts covered by cobalt-rich crusts and areas of polymetallic nodules. The taxonomical position of the genus and its placement in the family Schizopathidae has been repeatedly questioned, but fruitlessly. Known only in extremely deep habitats, these corals have rarely been collected in a state suitable for morphological or molecular studies that could help to clarify their status. Recently, increasing attention has been paid to the study of fauna associated with deep-sea minerals. Using material of Abyssopathes lyra (Brook, 1889) sampled during these studies, we transfer the genus Abyssopathes from the family Schizopathidae to the family Cladopathidae based on morphological and molecular data. Morphological data includes six mesenteries in the polyps, a unique pinnulation pattern found only in genera within the Cladopathidae, and relatively short polyp tentacles, a feature typical of some cladopathids. Sequencing data, consisting of 626 bp from the mitochondrial cox1 gene, showed that Abyssopathes is 99% identical to Chrysopathes Opresko, 2003, Cladopathes Brook, 1889, Heteropathes Opresko, 2011, and Trissopathes Opresko, 2003 (all Cladopathidae), in this gene region. Full article

Sea-bottom sampling at bathyal depths off the Apulian margin (southwestern Adriatic Sea) recovered shelly biogenic sediments rich in mollusk remains. Noteworthy is the occurrence in such taphocoenoses of loose chiton valves, rarely reported in these environments. We identified four species of Polyplacophora, Leptochiton asellus (Gmelin, 1791), Belknapchiton alveolus (M. Sars MS, Lovén, 1846), Hanleya hanleyi (Bean in Thorpe, 1844), and the new species Leptochiton antondohrni. L. asellus (Gmelin, 1791) and B. alveolus are primarily of North Atlantic (boreo-celtic) affinity and thus considered to belong to last Pleistocene glacial assemblages, whose presence in the study area has long been ascertained. The same could be true for the valves of H. hanleyi and, possibly, Leptochiton antondohrni n. sp. Finally, we updated the list of mollusks found thus far in the deep-sea taphocoenoses of this area, including new records of North Atlantic-type taxa considered at present extinct in the Mediterranean basin. Full article

In this paper, we report on the discovery of the hidden biodiversity of the genus Dendronotus (Gastropoda: Nudibranchia) in bathyal areas of the North Pacific (the Sea of Okhotsk and the Kuril Islands). We also test different scenarios of Dendronotus expansion to deeper waters. An integrative analysis was implemented based on morphological data (light microscopy and SEM) and molecular data, which included molecular phylogenetic analysis of four markers (COI, 16S, H3, and 28S), molecular species delimitation analyses, and ancestral area reconstruction. Our results indicated the presence of seven species new to science, five of which are described herein. The phylogenetic reconstructions show that these new species are members of different Dendronotus lineages. Ancestral area reconstruction indicates the shallow-water origin of the genus, while the invasion of deep waters occurs independently multiple times. Full article

Compared to their fossil counterparts, living brachiopods are investigated far less often, due to their occurrence in remote environments such as dark caves or deep environments. Due to the scarcity of studies targeting in situ brachiopods’ populations, large-scale information on their distribution and ecological preferences is still lacking, especially on hardgrounds. The extensive employment of remotely operated vehicles (ROVs), however, has opened up the chance to better explore this taxon’s diversity and ecology in the mesophotic and bathyal zones. The analysis of over 600 h of video footage collected from 624 sites, from 40 m to 1825 m, located along the Ligurian and Tyrrhenian coasts of Italy and the Sicily Channel, allowed for a large-scale investigation. The four identified species, Novocrania anomala, Gryphus vitreus, Megerlia truncata and Terebratulina retusa, emerged as common macrofaunal components of the explored habitats, especially between 150 m and 250 m, with high occurrences in the northern areas, especially on offshore seamounts. All species can form dense aggregations of individuals, with M. truncata showing the densest populations on steep rocky terraces (up to 773 individuals m⁻²). Except for G. vitreus, the only species also recorded on soft bottoms, the others were found exclusively on hardgrounds, with N. anomala showing a peculiar ability to exploit anthropogenic substrates such as terracotta amphorae. No stable species-specific associations were noted, even if numerous species were frequently observed together. Although brachiopods do not show the conspicuous tridimensionality of large filter-feeders, their substrate occupancy and their role in pelagic–benthic processes support their importance in deep-sea Mediterranean ecosystems. Full article