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Wisshak M.,Senckenberg Institute | Berning B.,Oberosterreichisches Landesmuseum | Jakobsen J.,Rebikoff Niggeler Foundation | Freiwald A.,Senckenberg Institute
Marine Biodiversity | Year: 2015

The diversity of calcareous epiliths along a bathymetrical transect spanning the intertidal to bathyal (0–500 m) was investigated during a two-year carbonate cycling experiment deployed in the Faial Channel, Azores. The epilith inventory comprises 47 taxa of bryozoans, 9 serpulids, 3 bivalves, 3 cirripeds, 3 foraminiferans, 2 vermetid gastropods, and 1 scleractinian coral, along with 6 rhodophyte morphotypes. Colonised surface area, carbonate accretion rates, and biodiversity peak in the deeper euphotic zone (15 and 60 m), where mature biocoenoses were established after 2 years exposure, whereas colonisation was retarded at dysphotic and aphotic depths. Particularly in the photic zone, colonised surface area, accretion rates, as well as species richness and abundance were higher on down-facing compared to up-facing surfaces. Analyses of similarity (ANOSIM) and non-metrical multidimensional scaling (NMDS) of species abundance data revealed that water depth and substrate orientation were the dominant factors controlling the community structure as a result of direct (photosynthesis) and indirect (bioerosion pressure; nutrient supply) effects of the light regime, while exposure time and substrate type had little influence. The same hierarchy applies for the ichnodiversity of bioerosion traces, but with an inverse pattern in case of substrate orientation, reflecting the interaction of encrustation and bioerosion. Positive net carbonate production rates support the development of oyster bioherms and heterozoan-dominated carbonate/volcaniclastic sediments accumulating in the Faial Channel and adjacent slope. A comparison with biogenic sediments from other Macaronesian archipelagos and seamounts demonstrates the abundance and diversity of non-tropical heterozoan carbonates in oceanic islands. © 2014, Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg. Source


Avila S.P.,University of Porto | Avila S.P.,University of The Azores | Ramalho R.S.,University of Bristol | Ramalho R.S.,Lamont Doherty Earth Observatory | And 21 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015

Massive fossil shell accumulations require particular conditions to be formed and may provide valuable insights into the sedimentary environments favouring such concentrations. Shallow-water shell beds appear to be particularly rare on reefless volcanic oceanic islands on account of narrow, steep and highly-energetic insular shelves where the potential for preservation is limited. The occurrence of an exceptional coquina (Pedra-que-pica) within the Miocene-Pliocene deposits of Santa Maria Island (Azores), therefore provides a rare opportunity to understand the conditions that led to the formation and preservation of a massive shell bed at mid-ocean insular setting. This study provides a detailed analysis regarding a 10-11-m-thick bivalve-dominated fossil assemblage exposed at Pedra-que-pica on Santa Maria Island in the Azores. Integration of taphonomical, palaeoecological and sedimentological observations are used to reconstruct the genesis of the coquina bed and related events, and to discuss why such exceptional sedimentary bodies are so rare on shelves around reefless volcanic oceanic islands.The sequence at Pedra-que-pica demonstrates a complex succession of sedimentary environments in response to the drowning of an existing coastline during a period of rapid sea-level rise. The Pedra-que-pica shell bed incorporates storm-related materials and possible debris falls that originated nearby in a shallow and highly productive carbonate factory. Deposition took place below fair-weather wave base, at around 50. m depth, as inferred from the overlying volcanic succession. The preservation of this coquina was favoured by deposition on a platform laterally protected by a rocky spur, combined with rapid burial by water-settled volcanic tuffs and subsequent volcanic effusive sequences. The recent exhumation of the deposit is the result of island uplift and subsequent erosion. © 2015 Elsevier B.V. Source


Avila S.P.,University of The Azores | Melo C.,University of The Azores | Berning B.,Oberosterreichisches Landesmuseum | Cordeiro R.,University of The Azores | And 3 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2016

The family Strombidae is one of the twenty-three families and subfamilies of gastropods associated with tropical environmental conditions, and therefore useful as a biogeographical and paleoclimatic proxy. Today, the strombid genus Persististrombus is represented in the NE Atlantic by a single species restricted to the tropical Mauritanian-Senegalese Province. This work reports the occurrence of Persististrombus coronatus from the lower Pliocene of Santa Maria Island in the Azores Archipelago. Based on this occurrence, and on the Mio-Pliocene fossil record of the NE Atlantic oceanic islands, paleoclimatological considerations are discussed, which allow, for the first time, to include the Azores and the other Macaronesian islands in a wider context of the NE Atlantic paleobiogeographical molluscan provinces. Late Miocene to present day molluscan biogeographic units, ranging in latitude from 60°N down to 17°S, are here defined and the boundaries of the proposed climatic zones are outlined. We suggest that during the upper Miocene-lower Pliocene, the paleoclimate at Santa Maria Island was drastically different from that seen at those latitudes today, with mean annual sea surface temperatures (SSTs) about 3.7 °C to 6.3 °C higher than the present-day 20.6 °C, and with mean monthly SSTs ranging from 20 °C to 28 °C, with six months with mean SSTs over 24 °C, conditions typical of a tropical setting. © 2015 Elsevier B.V. Source


Rebelo A.C.,University of The Azores | Rasser M.W.,SMNS Staatliches Museum fur Naturkunde Stuttgart | Kroh A.,Geologisch palaontologische Abteilung | Johnson M.E.,Williams College | And 10 more authors.
Facies | Year: 2016

Rhodoliths are a common producer of carbonates on modern and ancient shelves worldwide, and there is growing evidence that they thrive on volcanic insular shelves. However, little is still known on how rhodoliths cope with the demands of this particularly dynamic environment. In this study, the focus is placed on fossil rhodoliths from a Pliocene sequence at Santa Maria Island, Azores, in order to gain further insight into the life cycle (and death) of rhodoliths living within a mid-ocean active volcanic setting. These rhodoliths occur as a massive accumulation within a larger submarine volcano-sedimentary sequence that was studied from the macro- to the micro-scale in order to reconstruct the paleoenvironmental conditions under which the rhodolith accumulation was deposited and buried. All fossil rhodoliths from this setting are multi-specific and demonstrate robust growth forms with a lumpy morphology. Moreover, taphonomical analyses show the succession of several destructive events during rhodolith growth, suggesting life under a highly dynamic system prior to stabilization and burial. The rhodoliths therefore tell a story of an eventful life, with multiple transport and growth stages, owing to the environment in which they lived. Transport and deposition to their final resting place was storm-associated, as supported by the general sedimentary sequence. In particular, the sequence features an amalgamation of tempestites deposited under increasing water depths, sediment aggradation, and before burial by volcanic activity. This transgressive trend is also attested by the overall characteristics of the volcano-sedimentary succession, which exhibits the transition to subaerial environment in excess of 100 m above the rhodolith bed. © 2016, Springer-Verlag Berlin Heidelberg. Source


Zagorsek K.,Brno University of Technology | Ramalho L.V.,Grande Rio University | Berning B.,Oberosterreichisches Landesmuseum | De Araujo Tavora V.,Federal University of Para
Zootaxa | Year: 2014

Pirabasoporella gen. nov. is introduced for three new bryozoan species from the Early Miocene of the tropical western Atlantic. The genus is placed in the family Jaculinidae Zabala, a peculiar group of cheilostome bryozoans characterised by reticulate colonies formed by uni- or biserial branches that are connected by kenozooidal struts. This colonial morphology superficially resembles colonies of the Paleozoic order Fenestrata (Stenolaemata) and some Recent Cyclostomata. As jaculinid colonies are anchored to soft sediments via rhizoids, however, they differ in life habit from Paleozoic and modern fenestrate colonies, which are firmly attached to stable substrata by an encrusting base. The three new species are Pirabasoporella atalaiaensis n. sp. from the Brazilian Pirabas Formation, Pirabasoporella baitoae n. sp. from the Baitoa Formation (Dominican Republic), and Pirabasoporella chipolae n. sp. from the Floridan Chipola Formation. Their presence in the Early Miocene western Atlantic represents the earliest record of Jaculinidae, and suggests that the origin of the family, the only living species of which are known from the eastern Atlantic and Mediterranean Sea, extends well into the Paleogene. The Jaculinidae is here transferred from the lepraliomorph superfamily Schizoporelloidea Jullien to the umbonulomorph Lepralielloidea Vigneaux owing to the partly umbonuloid frontal shield and non-schizoporelloid ovicell. Copyright © 2014 Magnolia Press. Source

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