78 research outputs found

    Schackoinella Spina, a new benthic foraminiferal species from cold-water coral ecosystems of the alboran sea and the gulf of CĂĄdiz

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    Schackoinella spina n. sp. has been found in the eastern Alboran Sea at five different stations in water depths ranging from 258–330 m, as well as in one 532 m deep station in the Gulf of Cádiz, north-eastern Atlantic Ocean. Three stations have been sampled with a giant box core (BC) and two stations with a gravity core (GC) system. The sediments of the BCs and the GCs are characterized by cold-water coral (CWC) debris and a high abundance of biogenic components (e.g., bryozoans, echinoderms, bivalves, gastropods, serpulids, foraminifera). The surface samples from the BCs were treated with an ethanol-rose Bengal solution following standardized sampling protocol. In the BC samples the specimens of Schackoinella spina n. sp., were collected from the surface (0–1 cm). In particular, one BC sample (MD13-3456BC) contained six live (stained) specimens and an abundance of non-stained specimens (46 per 50 cm3 sediment). The new species was found at several sediment depth intervals corresponding to a Holocene age.The occurrence of this small (60–140 mm) species in the Alboran Sea and Gulf of Cádiz has likely been overlooked in this region. Although not straightforward, the presence of this species in association with cold-water coral fragments and its absence in fine-grained pelagic sediments may indicate a relationship with this ecosystem

    Late glacial and Holocene Ostracoda from the Melilla cold-water coral mound field

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    The ostracod assemblages from sediment core TTR17-401G recovered from the Melilla cold-water coral mound field in the eastern Alboran Sea spanning the last 13 ka are analysed quantitatively, taxonomically and palaeoecologically. The core can be subdivided in three distinct assemblages linked to environmental shifts during the Younger Dryas and the Bþlling–Allerþd interstadial. A total of 9 ostracod species is recorded, Paracypris polita is dominant throughout the core. Common accessory taxa Cytherella robusta, Echinocythereis vidua and Macromckenziea ligustica characterize the well-oxygenated ostracod assemblage 2 affected by the Younger Dryas. Favourable growth conditions for ostracods during the latter are indicated by large- sized Krithe praetexta specimens

    Fossil and genetic evidence for the polyphyletic nature of the planktonic foraminifera ‘Globigerinoides’, and description of the new genus Trilobatus

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    Planktonic foraminifera are one of the most abundant and diverse protists in the oceans. Their utility as paleo proxies requires rigorous taxonomy and comparison with living and genetically related counterparts. We merge genetic and fossil evidence of “Globigerinoides”, characterized by supplementary apertures on spiral side, in a new approach to trace their “total evidence phylogeny” since their first appearance in the latest Paleogene. Combined fossil and molecular genetic data indicate that this genus, as traditionally understood, is polyphyletic. Both datasets indicate the existence of two distinct lineages that evolved independently. One group includes “Globigerinoides” trilobus and its descendants, the extant “Globigerinoides” sacculifer, Orbulina universa and Sphaeroidinella dehiscens. The second group includes the Globigerinoides ruber clade with the extant G. conglobatus and G. elongatus and ancestors. In molecular phylogenies, the trilobus group is not the sister taxon of the ruber group. The ruber group clusters consistently together with the modern Globoturborotalita rubescens as a sister taxon. The re-analysis of the fossil record indicates that the first “Globigerinoides” in the late Oligocene are ancestral to the trilobus group, whereas the ruber group first appeared at the base of the Miocene with representatives distinct from the trilobus group. Therefore, polyphyly of the genus "Globigerinoides" as currently defined can only be avoided either by broadening the genus concept to include G. rubescens and a large number of fossil species without supplementary apertures, or if the trilobus group is assigned to a separate genus. Since the former is not feasible due to the lack of a clear diagnosis for such a broad genus, we erect a new genus Trilobatus for the trilobus group (type species Globigerina triloba Reuss) and amend Globoturborotalita and Globigerinoides to clarify morphology and wall textures of these genera. In the new concept, Trilobatus n. gen. is paraphyletic and gave rise to the Praeorbulina / Orbulina and Sphaeroidinellopsis / Sphaeroidinella lineages

    High-resolution monitoring of water temperature and oxygen concentration in Lake Murten (Switzerland)

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    Lake Murten is located in the Lake District in western Switzerland and so far, it has been poorly investigated. The Environmental Service of Fribourg (SEn) has monitored this lake once a month for several years by water profiles (water temperature, pH, dissolved oxygen, conductivity) at its deepest part. The SEn identified the stratification of water masses as one of the main causes for oxygen consumption in the hypolimnion. In the present study, a Lander System was deployed in Lake Murten from April to September 2015 at 20 m depth at the northwestern part of the lake to monitor water temperature and dissolved oxygen at higher resolution (30 s interval). These records were compared with time series of atmospheric parameters like atmospheric temperature, wind speed and precipitation. A clear correlation of lake temperatures with wind speed was observed during the Spring and Autumn. The water mass stratification evolved through the season and reached its peak during Summer, preventing surface turbulences to reach the deeper part (20 m) of the water column and to partially oxygenate the metalimnion

    The genus Amphistegina (benthic foraminifera): distribution along the southern Tunisian coast

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    The benthic foraminiferal genus Amphistegina is currently expanding its range in the Mediterranean Sea after being introduced through the Suez Canal from the Red Sea. Over the previous decade, Amphistegina spp. has colonized the eastern part of the Mediterranean Sea including the Egyptian and Libyan coasts, but the present southern limit in the Mediterranean Sea is along the southern Tunisian coast. However, this limit has never clearly been defined, and existing models predict an expansion along the entire Tunisian coastline. The Gulf of Gabes, in the southern part of Tunisia, is heavily polluted by local phosphate industries that discharge untreated waste directly into the sea. Amphistegina spp. is sensitive to water quality and marine pollution. Based on our surveys and recent investigations, the present distribution area of Amphistegina spp. along the south Tunisian coast includes the coastline east of Djerba Island, located in the Gulf of Gabes. Possible limiting factors for Amphistegina spp. expansion in the Gulf of Gabes may be the unfavourable environmental conditions generated by the phosphate industry
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