Sérgio P. Ávila

Non-indigenous marine species of the Azores

Marine benthic species introduced to the Azores are collated from scientific publications, internal reports and own data. Twelve algae and 21 invertebrates are classified as non-indigenous species, 18 as cryptogenic. Two species of algae and two ascidians are regarded as particularly invasive along the shores of this oceanic archipelago.

Emergence and evolution of Santa Maria Island (Azores)—The conundrum of uplifted islands revisited

The growth and decay of ocean-island volcanoes are intrinsically linked to vertical movements. While the causes for subsidence are better understood, uplift mechanisms remain enigmatic. Santa Maria Island in the Azores Archipelago is an ocean-island volcano resting on top of young lithosphere, barely 480 km away from the Mid-Atlantic Ridge. Like most other Azorean islands, Santa Maria should be experiencing subsidence. Yet, several features indicate an uplift trend instead. In this paper, we reconstruct the evolutionary history of Santa Maria with respect to the timing and magnitude of its vertical movements, using detailed field work and 40Ar/39Ar geochronology. Our investigations revealed a complex evolutionary history spanning ∼6 m.y., with subsidence up to ca. 3.5 Ma followed by uplift extending to the present day. The fact that an island located in young lithosphere experienced a pronounced uplift trend is remarkable and raises important questions concerning possible uplift mechanisms. Localized uplift in response to the tectonic regime affecting the southeastern tip of the Azores Plateau is unlikely, since the area is under transtension. Our analysis shows that the only viable mechanism able to explain the uplift is crustal thickening by basal intrusions, suggesting that intrusive processes play a significant role even on islands standing on young lithosphere, such as in the Azores.

Patterns of Diversity of the Rissoidae (Mollusca: Gastropoda) in the Atlantic and the Mediterranean Region

The geographical distribution of the Rissoidae in the Atlantic Ocean and Mediterranean Sea was compiled and is up-to-date until July 2011. All species were classified according to their mode of larval development (planktotrophic and nonplanktotrophic), and bathymetrical zonation (shallow species—those living between the intertidal and 50 m depth, and deep species—those usually living below 50 m depth). 542 species of Rissoidae are presently reported to the Atlantic Ocean and the Mediterranean Sea, belonging to 33 genera. The Mediterranean Sea is the most diverse site, followed by Canary Islands, Caribbean, Portugal, and Cape Verde. The Mediterranean and Cape Verde Islands are the sites with higher numbers of endemic species, with predominance of Alvania spp. in the first site, and of Alvania and Schwartziella at Cape Verde. In spite of the large number of rissoids at Madeira archipelago, a large number of species are shared with Canaries, Selvagens, and the Azores, thus only about 8% are endemic to the Madeira archipelago. Most of the 542-rissoid species that live in the Atlantic and in the Mediterranean are shallow species (323), 110 are considered as deep species, and 23 species are reported in both shallow and deep waters. There is a predominance of nonplanktotrophs in islands, seamounts, and at high and medium latitudes. This pattern is particularly evident in the genera Crisilla, Manzonia, Onoba, Porosalvania, Schwartziella, and Setia. Planktotrophic species are more abundant in the eastern Atlantic and in the Mediterranean Sea. The results of the analysis of the probable directions of faunal flows support the patterns found by both the Parsimony Analysis of Endemicity and the geographical distribution. Four main source areas for rissoids emerge: Mediterranean, Caribbean, Canaries/Madeira archipelagos, and the Cape Verde archipelago. We must stress the high percentage of endemics that occurs in the isolated islands of Saint Helena, Tristan da Cunha, Cape Verde archipelago and also the Azores, thus reinforcing the legislative protective actions that the local governments have implemented in these islands during the recent years.

The Palaeontological Heritage of Santa Maria Island (Azores: NE Atlantic): a Re-evaluation of Geosites in GeoPark Azores and Their Use in Geotourism

The application of geoconservation concepts and methodologies to the Azores archipelago led to the implementation of the Geopark Azores, recognized as such by the European and Global Geoparks Network. The current work re-evaluates and stresses the scientific and touristic value of the palaeontological sites of Santa Maria Island. Two new geosites (the Ponta do Castelo tempestite deposit and the Pedra-que-pica coquina) are proposed for classification as ‘Regional Natural Monuments’ by the Regional Government of the Azores, due to their international relevance. The tempestite deposit of Ponta do Castelo was overlain by a contemporary coastal lava delta, which enables the inference of the precise water depth of the geosite at the time of deposition, a very rare condition worldwide; and Pedra-que-pica is the most extensive multispecific fossiliferous coquina ever reported in the literature from the shelf of any of the ∼20,000 known volcanic oceanic islands in the world. Relevant geosites reported for this island are increased from 15 to 26. Additional palaeontological heritage contributions to the sustainable tourism of Santa Maria are suggested, with a focus on two recent projects: the ‘Fossil Trail’ and the future ‘PalaeoPark Santa Maria’.

New records for the shallow-water chiton fauna (Mollusca, Polyplacophora) of the Azores (NE Atlantic)

Abstract Published records, original data from recent field work on all of the islands of the Azores (NE Atlantic), and a revision of the entire mollusc collection deposited in the Department of Biology of the University of the Azores (DBUA) were used to compile a checklist of the shallow-water Polyplacophora of the Azores. Lepidochitona cf. canariensis and Tonicella rubra are reported for the first time for this archipelago, increasing the recorded Azorean fauna to seven species.

The shallow marine ostracod communities of the Azores (Mid- North Atlantic): taphonomy and palaeoecology

This is the first palaeoecological and taphonomical study of the Recent marine ostracods from the Azores. The aims of this work were to address the following questions: i) to establish the typical ostracod assemblages from the shallow waters of the Azores; ii) to determine the bathymetric ranges for each ostracod species; iii) to investigate the time span and depth in which significant transport occurs; iv) to quantify the amount of out of habitat transport between sandy beaches, tide pools and the sublittoral; v) to determine distinctive taphonomic features that can be used to recognize the amount of temporal resolution in ostracod assemblages. Fifteen species were recovered, representing 8 families and 12 genera (Loxoconcha, Neonesidea, Xestoleberis, Aurila, Urocythereis, Heterocythereis, Carinocythereis, Callistocythere, Leptocythere, Semicytherura, Lanceostoma and Cylindroleberis). The living assemblages are dominated by specimens of the Loxoconchidae, Xestoleberidae and Hemicytheridae, whereas the dead assemblages are dominated by specimens of the Loxoconchidae, Hemicytheridae, Bairdiidae, Xestoleberidae and Trachyleberidae. The shift from life-dominated assemblages in the shallower depths to death-dominated assemblages at greater depths is a consequence of significant transport downwards. The abundance of ostracods is higher in the first 10-20 m depth, especially in fine to medium sandy substrates. Considerable differences among islands were supported by the Bayesian model, as a consequence of the physical and hydrodynamic factors that differently affect each of the Azorean islands. Large-scale (sea-surface currents, Holocene relative sea-level, storms) and small-scale processes are responsible for shaping the Azorean Recent marine ostracod communities. No living specimens were found in the samples collected at the beach faces, thus reinforcing former interpretations of one of the authors (S. Avila) that advocate that at a global scale, sandy beaches in oceanic islands located at temperate latitudes are almost or even completely devoid of life due to historical reasons related with the sea level changes.

Reproductive cycle of the rissoid Alvania mediolittoralis Gofas, 1989 (Mollusca, Gastropoda) at São Miguel Island (Azores, Portugal)

Summary The reproductive cycle of an Alvania species is studied for first time. Alvania mediolittoralis Gofas, 1989 is an endemic Azorean rissoid very common in sheltered places and particularly abundant among the algal turf covering the lower half of the intertidal and upper subtidal rocky shores. This species reproduces throughout the year, with two spawning peaks, one during early spring and the other in late autumn. In an attempt to relate to current paleobiogeographical studies, inferences are made regarding the ecological advantages of species with a continuous type of reproduction, on Azorean shores, during glacial episodes.

Comparison of the community structure of the marine molluscs of the “Banco D. João de Castro” seamount (Azores, Portugal) with that of typical inshore habitats on the Azores archipelago

D. João de Castro Bank (DJC) is a shallow seamount with hydrothermal activity located between the islands of Terceira and São Miguel, Azores (Portugal). A survey of the molluscan fauna was conducted in this peculiar habitat. We found a smaller number of molluscan taxa and a different community structure compared to shore environments on the Azores. This coincides with impoverished environmental settings at this location. Possible reasons such as the degree of isolation (inshore vs. offshore locations), geological age, and special ecological conditions related to seamounts and hydrothermal vents are discussed.

Diagenetic history of lower Pliocene rhodoliths of the Azores Archipelago (NE Atlantic): Application of cathodoluminescence techniques

The diagenetic history of calcareous fossils is required for their application as palaeoenvironmental indicators. In this study, cathodoluminescence-microscopy (CL microscopy) and back scatter electron image-energy dispersive X-ray spectroscopy (BSE-EDS microscopy) were applied to Pliocene rhodoliths from the Azores Archipelago (NE Atlantic) in order to gain additional insight regarding the trace element content distribution throughout the algae thalli, and to ascertain palaeoenvironmental interpretations. Two types of luminescence were obtained: (1) high and (2) low luminescence. Rhodoliths with high luminescence are related with high concentrations of Mn(2+) in seawater and low luminescence rhodoliths are related with low concentrations of Mn(2+) in seawater. When the rhodoliths were deposited at about 4.0-4.5 Ma, the shoreline configuration of Santa Maria Island was much different than today. The influence of volcanic activity due to the extrusion of lavas and associated products and/or the presence of active shallow-water hydrothermal vents, was reflected in the sea water chemistry, with penecontemporaneous palaeoshores of the island featuring a high sea water concentration of Mn(2+), which mirrored on the rhodolith Mn(2+) high concentration. By contrast, rhodoliths located about 2.8 and 2.9 km from the shore, in areas with low seawater Mn(2+) concentration, had low luminescence, reflecting the low Mn(2+) concentration in seawater. Rhodoliths chemical data and the geological history of the island proved to be congruent with the palaeogeographical reconstruction of Santa Maria Island at the time of the formation of the rhodoliths.

New records for the opisthobranch fauna of the Archipelago of the Azores (north-east Atlantic Ocean)

ricardo cordeiro, manuel anto’nio e. malaquias, guillem mas, irene figueroa, jose’ p. borges and se’rgio p. a’vila CIBIO, Centro de Investigacao em Biodiversidade e Recursos Geneticos, InBIO Laboratorio Associado, Polo dos Acores, Universidade dos Acores, Campus de Ponta Delgada, Apartado 1422, 9501-801 Ponta Delgada, Acores, Portugal, Departamento de Biologia, Universidade dos Acores, Campus de Ponta Delgada, Apartado 1422, 9501-801 Ponta Delgada, Acores, Portugal, Phylogenetic Systematics and Evolution Research Group, University Museum of Bergen, Natural History Collections, University of Bergen, PB 7800, 5020-Bergen, Norway, Grup de Recerca d’Opistobranquis de Catalunya, Mas Castellar, s/n, Pontos 17773, Girona, Spain, CREAF, 08193 Cerdanyola del Valles, Spain, Instituto Portugues de Malacologia, Zoomarine, EN 125 km 65, Guia, 8200-864 Albufeira, Portugal