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In the Azores, a remote archipelago of nine volcanic oceanic islands located in the northeastern Atlantic Ocean, the most striking differences in assemblage composition in relation to mainland European Atlantic shores are the absences of topshells, Mytilus species and the predator Nucella lapillus in the intertidal zone (Hawkins et al., 1990, 2000; Ávila et al., 2005). Although occasionally reported for the Azores (Ávila et al., 1998, 2000) Mytilus species have not, so far, been able to maintain viable populations on these islands, probably due to low productivity of the oceanic waters that surround them, (with primary production ,150 mg C/m2 year; Raymont, 1980) or to Allee effects associated with broadly dispersive larvae (Lewis & Kareiva, 1993). Biological assemblages on volcanic oceanic islands are commonly regarded as fragile ecosystems with local communities highly susceptible to alien species (Elton, 1958; Simberloff, 1995; Meyer & Florence, 1996; Jousson et al., 2000; Sax & Brown, 2000; Provan, Murphy & Maggs, 2005). In recent years, the status of the recorded nonindigenous marine species, and the threats posed by them—some with the status of ‘invasive’ sensu Falk-Petersen, Bøhn & Sandlund (2006)—have been assessed for the Azores (Cardigos et al., 2006; Amat, Cardigos & Santos, 2008; Amat & Tempera, 2009; Torres, Costa & Dionísio, 2012). A total of 59 taxa have been reported as introduced in the Azores, including five species of marine molluscs: the gastropods Hexaplex trunculus and Pollia dorbgnyi and the bivalves Hiatella arctica (considered as cryptogenic, i.e. of unknown origin), Ruditapes decussatus and Pinctada radiata. The shores of the Azores islands and nearby seamounts have been surveyed extensively for the last 20 years by teams from the University of the Azores, with over 900 dives done from the intertidal down to 50 m depth and over 100 dredges from 50 to about 300 m depth. In addition, in the last decade, a large number of scientific campaigns have been made in the archipelago and, as a consequence, new records of marine molluscs keep being added to the Azores checklists (Ávila, 2000, 2005; Malaquias et al., 2009, 2011; Martins et al., 2009; Pedro et al., 2011; Ávila, Goud & Martins, 2012; Geiger, 2012; Ávila & Sigwart, 2013; Cordeiro et al., 2013). Ávila, Borges & Martins (2011) revised the systematics of the Azorean Trochidae and Calliostomatidae. No Phorcus species (Trochidae) have hitherto been reported for the Azores. In their detailed account of the phylogenetic relationships of herbivorous intertidal grazers, Donald et al. (2012: 44) stated that “The distribution of Phorcus sauciatus includes Madeira, the Canaries and the African mainland, with negligible genetic differentiation between them, suggesting either recent or continuing dispersal among these areas. Interestingly this species has not yet reached the Azores.” Our study documents for the first time the occurrence of P. sauciatus (Koch, 1845) in the Azores and discusses the diferences in size structure between the Azorean and mainland Iberian populations, as well as an estimation of colonization time and the expected impact of this species on the ecology of local intertidal communities.

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... After that, continuing uplift at an estimated rate of about 60 m/Ma (Ramalho et al., 2014) and erosion were the main factors affecting the volcanic edifice from the early Pleistocene to the present. Many of the sediments in outcrops such as Pedreira do Campo, Figueiral, Malbusca, Pedra-que-pica and Ponta do Castelo, were deposited at depths around 40–60 m (Cachão et al., 2003; Meireles et al., 2013; Ávila et al., 2015) or even deeper (Cré; Jansen et al., 2008). In the present-day, these outcrops are exposed at different altitudes, ranging from the intertidal (e.g., Pedra-que-pica; Ávila et al., 2015) to 95 m above sea-level (Figueiral; Ávila et al., in press-b) due to the uplift of the island (Ramalho et al., 2014). ...
... Many of the sediments in outcrops such as Pedreira do Campo, Figueiral, Malbusca, Pedra-que-pica and Ponta do Castelo, were deposited at depths around 40–60 m (Cachão et al., 2003; Meireles et al., 2013; Ávila et al., 2015) or even deeper (Cré; Jansen et al., 2008). In the present-day, these outcrops are exposed at different altitudes, ranging from the intertidal (e.g., Pedra-que-pica; Ávila et al., 2015) to 95 m above sea-level (Figueiral; Ávila et al., in press-b) due to the uplift of the island (Ramalho et al., 2014). ...
... As typical shallowwater species, the shells of these large strombids would be prone to be swept ashore post-mortem in large numbers by spring tides or storm events, as can be seen in the present times at Ponta Braço de Sirena (Sal Island, Cape Verde Archipelago; Zazo et al., 2010), or in the upper Pleistocene (MIS 5e) deposits at Matas Blancas (Fuerteventura Island, Canaries; Meco et al., 2002) and at La Marina, Alicante (East Spain) (Goy et al., 2006), where specimens of the congeneric P. latus occur in large numbers. However, at Santa Maria Island, no similar deposits were found, all P. coronatus specimens representing shells transported downslope into deeper marine environments, as at Pedra-que-pica or at Baía de Nossa Senhora outcrops (Fig. 2F–H) (Ávila et al., 2015). The common occurrence of Strombidae in the fossil record, apart from the fact that they usually have large and sturdy shells, may also be related with the usual discrete aggregation pattern of the animals, e.g., L. gigas, which may reach hundreds or even thousands of specimens/ha (McCarthy, 2007). ...
... Nowadays, although documented (cf. Afonso et al., 2013;Avila et al., 2015c), dispersal among Macaronesian archipelagos or to/from continental shores is rare, as currents and upwelling systems constitute effective ecological barriers. Moreover, as present-day SSTs are still lower than during MIS 5e in the northern archipelagos (e.g., Azores, Madeira), the individuals associated with the rare events of dispersal of tropical species are usually not able to establish viable, reproductive populations. ...
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... Phorcus sauciatus, a common temperate-subtropical grazer that inhabits extensive and gently sloping rocky shore platforms in the eastern Atlantic, including the Macaronesian archipelagos of Madeira, the Canaries and the Azores, reaches its northern boundary in the Iberian Peninsula (Rubal et al., 2014;Ávila et al., 2015). The life history traits of this species vary intraspecifically due to genetic differences and environmental effects. ...
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This work was done on 1996 and 1997, and presents an extremely valuable baseline to compare the recent and future changes on the insular shallow habitats of the Azorean islands. We examined the structure of the molluscan communities of the macroalgae Halopteris scoparia in São Miguel Island (Azores, Portugal). This island was chosen because it is the largest and the most populated of the archipelago, with polluted sites which are not common in the Azores. The relationship between the epifaunal assemblages and a set of environmental factors – geographical location (orientation), seawater temperature, depth, algal volume, degree of disturbance, and degree of exposure to the wave action – was investigated using distance-based redundancy analysis and significant variation in the distribution of richness of assemblages was found. Four environmental predictors were common to all the four analyses implemented (richness and assemblage structure using both AIC and BIC): algal volume (that correlates with algal dry weight), seawater temperature, coastal orientation and depth. Finally, the application in the Azores of this methodology favours a sampling program in Spring-Summer (when disturbance seems to be more susceptible to detection), and the use of H. scoparia in the subtidal zone, as the target alga is recommended due to its large covering of rocky shore substrates.
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Solen marginatus Pulteney, 1799 was reported from São Miguel Island (Azores Archipelago, central North Atlantic) by Drouet in 1858, but the occurrence of this species in the archipelago was questioned by authors. We herein report a novel population from Terceira Island, located in the central island group of the Azores Archipelago. This new record increases the number of non-native marine mollusc species reported from the Azores to six. Our preliminary data gives insight on a population that we infer to have settled about ten years ago and provides a first populational assessment that will be crucial for future studies. So far, specimens occur in a restricted area which is subjected to freshwater, in the northern section of Praia da Vitória bay, reaching maximum sizes of nearly 15 cm. We discuss the most likely vectors of introduction and the probable origin of the colonizers of this non-native species that reached the archipelago. We predict that, given the opportunity, this razor shell will expand its geographic range and colonize other suitable habitats on other islands in the Azores. Finally, we urge the Azorean authorities to implement a monitoring program for this, until now, small and confined population.
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Interactions in the Marine Benthos - edited by Stephen J. Hawkins August 2019
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Harvesting of intertidal grazers such as topshells is known to affect negatively the exploited populations by altering population structure and decreasing abundance. Phorcus sauciatus has a wide geographic distribution in the Northeastern Atlantic Ocean and is subject to increasing levels of harvesting pressure due to the expansion of human population on coastal areas. The effect of proximity to human settlements and coastal accessibility on the size structure and abundance of P. sauciatus populations was examined in Madeira archipelago. Mean size, proportion of reproductive individuals, and abundance of this species were generally smaller in areas closer to human settlements and in more accessible coastal areas. Marine protected areas returned the highest mean sizes evidencing their effectiveness in preserving the size structure of this species. The results highlight the necessity to regulate the harvest of P. sauciatus in Madeira archipelago, as well as the implementation of management measures aiming at the sustainable exploitation and conservation of this species, exploited in this region since the early 15th century. K E Y W O R D S Atlantic Ocean, harvesting, human-induced pressure, intertidal, mollusks, Phorcus sauciatus
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A complete inventory of the known Recent vetigastropod fauna of South Africa is provided. Bibliographic citations to works discussing the taxonomy, synonymy and distribution of the species in a southern African or south-western Indian Ocean context are provided. Additional explanatory notes are given where pertinent. New genus records for South Africa: Acremodontina B.A. Marshall, 1995; Choristella Bush, 1879; Cocculinella Thiele, 1909; Conjectura Finlay, 1926; Crosseola Iredale, 1924; Falsimargarita Powell, 1951; Lepetella Verrill, 1880; Profundisepta McLean & Geiger, 1998; Stomatella Lamarck, 1816; Stomatia Helbling, 1779; Stomatolina Iredale, 1937; Synaptocochlea Pilsbry, 1890; Tibatrochus Nomura, 1940; Visayaseguenzia Poppe, Tagaro & Dekker, 2006; Zetela Finlay, 1926. New species records for South Africa: Acremodontina aff. carinata Powell, 1940; Anatoma finlayi (Powell, 1937); Anatoma munieri (P. 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New name: Oxystele antoni is proposed as a new name for Trochus (Turbo) variegatus (non Gmelin, 1791 =Heliacus) Anton, 1838. Revised taxonomy: Cyclostrema semisculptum Martens, 1904 is an earlier name for Solariella intermissa Thiele, 1925, and is referable to the genus Zetela Finlay, 1926; Margarita bicarinata A. Adams & Reeve, 1850 is considered to be a senior synonym of Solariella undata G.B. Sowerby (II), 1870, and is referable to the genus Ilanga Herbert, 1987. Validation of the name Trochus tigrinus Chemnitz, 1781 is credited to Dillwyn (1817) rather than Anton (1838). New synonyms: Clanculus exquisita Turton, 1932 =Calliostoma africanum Bartsch, 1915; Cyclostrema alfredensis Bartsch, 1915 =Parviturbo alfredensis (Bartsch, 1915); Cynisca gloriosa Bartsch, 1915 =Cinysca spuria (Gould, 1861); Herbertina hayesi Herbert, 1995 =Bruceina chenoderma (Barnard, 1963); Ilanga millardi Herbert, 1987 =Ilanga humillima (Thiele, 1925); Leptothyra africana Bartsch, 1915 =Cinysca spuria (Gould, 1861); Leptothyra albocincta Turton, 1932 =Tricolia striolata (Turton, 1932); Solariella undata G.B. Sowerby (II), 1870, S. gratiosa Thiele, 1925 and S. valdiviae Thiele, 1925 =Ilanga bicarinata bicarinata (A. Adams & Reeve, 1850); Solariella chuni Thiele, 1925, S. intermissa Thiele, 1925, S. gilchristi Barnard, 1963 and S. macleari Barnard, 1963 =Zetela semisculpta (Martens, 1904); Turbo (Collonia) armillatus G.B. Sowerby (III), 1886 =Cinysca spuria (Gould, 1861). New combinations: Basilissa (Ancistrobasis) compsa Melvill, 1904 is transferred to Visayaseguenzia; Calcar rhysopoma Barnard, 1964 is transferred to Bothropoma; Calliostoma glaucophaos Barnard, 1963 is transferred to Falsimargarita; Calliotropis chenoderma Barnard, 1963 is transferred to Bruceina; Collonia bicarinata Martens, 1902 is transferred to Cinysca; Crossea agulhasensis Thiele, 1925 is transferred to Conjectura; Cyclostrema semisculptum Martens, 1904 is transferred to Zetela; Cyclostremella farica Bartsch, 1915 is transferred to Dikoleps; Cynisca africana Bartsch, 1915 is transferred to Homalopoma; Leptogyra africana: Bartsch, 1915 is transferred to Cirsonella; Leptothyra agulhasensis Thiele, 1925 is transferred to Homalopoma; Leptothyra alfredensis Bartsch, 1915 is transferred to Parviturbo; Leptothyra sola Barnard, 1963 is transferred to a Parviturbo; Liotia (Cynisca) semiclausa Thiele, 1925 is transferred to Cinysca; Monilea spuria Gould, 1861 is transferred to Cinysca; Monodonta gibbula Thiele, 1925 is transferred to Cantrainea; Puncturella voraginosa Herbert & Kilburn, 1986 is transferred to Profundisepta; Solariella fuscomaculata G.B. Sowerby (III), 1892 is transferred to Skenea; Solariella turbynei Barnard, 1963 is transferred to Zetela; Turbo boswellae Barnard, 1969 is transferred to Cantrainea; Turbo foveolatus Barnard, 1963 is transferred to Crosseola; Turbo ponsonbyi G.B. Sowerby (III), 1897 is transferred to Bothropoma; Vitrinella agulhasensis Thiele, 1925 is transferred to Parviturbo; Vitrinella (Docomphala) arifca Bartsch, 1915 is transferred to Lodderena; Vitrinella inclinans Barnard, 1963 is transferred to Skenea.
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Prefácio O trabalho que agora se apresenta de Sérgio Ávila e colaboradores é mais um precioso contributo para a divulgação científica que emerge de trabalho de investigação académica da Universidade dos Açores. É um trabalho que procura conciliar um rigor e uma descrição exaustiva e profusamente ilustrada dos elementos factuais paleontológicos e geológicos associados à jazida da Prainha, com uma obra apelativa e agradável de desfolhar, ler e consultar. Este tipo de produtos académicos para a comunidade, de extensão universitária como agora se fala, é de extrema importância para a Região Autónoma dos Açores, em particular, e para Portugal, em geral, por três ordens de razões. Em primeiro lugar porque, contrariamente aos ditados e sabedoria popular, as rochas e outros elementos do património geológico, são frágeis e efémeros. Um dos aspectos de maior fragilidade são os fósseis, propriamente ditos, o que é mais fácil de entender. Mais difícil é reconhecer que as próprias jazidas fossilíferas, fósseis e seu enquadramento geológico, o qual pode incluir filões, falhas, minerais, seixos rolados, etc., são igualmente bastante frágeis quer a acções de erosão e alteração naturais quer a acções antrópicas. Quanto às primeiras a única e melhor atitude é proceder ao seu estudo e registo documental, nomeadamente fotográfica, como generosamente se apresenta nesta obra. Quanto às segundas, o modo mais eficaz de as preservar é dar a conhecer às populações, em geral, e às autarquias e entidades de gestão do território, em particular, no sentido de prevenir o licenciamento de obras ou infra-estruturas que poderão comprometer irremediavelmente esse Património Natural. Efectivamente, numa região balnear como a da Praia Formosa, uma eventual pressão urbanística pode levar à destruição destes seus elementos patrimoniais únicos. Únicos, não só no contexto da Ilha de Santa Maria, como no contexto da Região Autónoma dos Açores, ou mesmo do Continente. Em segundo lugar, estão em curso vários esforços no sentido de que o conjunto das nove ilhas açorianas venham a ser integradas na Rede Europeia de Geoparques e, como tal, sejam reconhecidas pela UNESCO como mais um elemento da Global Network of Geoparks. Tal galardão é consagrado pela excelência do seu Património geológico e paleontológico, o qual encontra neste livro um excelente aliado e um repositório de informação da qual se irão retirar elementos necessários à subsequente produção de textos de divulgação em língua estrangeira, fundamentalmente anglo-saxónica. Por outro lado, ficam bem expressos, os argumentos da necessidade desta jazida se converta em mais um dos magníficos e bem sucedidos exemplos de geoconservação e valorização ambiental que estão a registar-se por todo o arquipélago açoriano. Em terceiro lugar, obras como a que agora se edita ajudam à interiorização por parte da população de Santa Maria, e por todos quantos a visitam, da singularidade geológica desta ilha e do valor científico e patrimonial que as suas unidades fossilíferas representam. Elas ilustram de modo particularmente exuberante as alterações climáticas que o nosso Planeta tem vindo a sofrer, actualmente acompanhadas com maior acuidade pela sociedade e os media. Estes afloramentos particularmente ricos em conteúdo fóssil, intercalados ou embutidos em sequências de rochas vulcânicas e sedimentares, são os únicos testemunhos que restam das comunidades bióticas que povoaram as águas superficiais e as regiões costeiras insulares do Atlântico Norte, há milhares de anos (no caso da Prainha ou Lagoinhas) ou mesmos há milhões de anos, como as jazidas do Monumento Natural Regional da Pedreira do Campo, Pedreira da Cré, “Pedra que Pica” ou Ponta da Malbusca, para citar só algumas. Todas elas são singulares excepções que complementam os registos sedimentares das bacias oceânicas envolventes, os quais têm sido, e continuarão a ser, alvo de investigação paleoceanográfica do Global Change. No entanto, estas jazidas, são os únicos testemunhos das comunidades costeiras pretéritas, com as quais é possível estabelecer comparações e mapas de distribuição biogeográfica, um dos temas fortes presentes nesta obra. Terminava salientando que esta obra integra-se num vasto conjunto de outros trabalhos e iniciativas de divulgação e valorização do património natural, geológico e biológico, realizados por esta mesma equipa. Resulta dum esforço notável não só de investigação em áreas especializadas do conhecimento científico, mas também de gestão de recursos. Criar e financiar expedições científicas com mais de uma dezena de especialistas não só em ciência (investigadores pluridisciplinares, nacionais e internacionais) mas também em comunicação (fotógrafos, operadores de câmara), autarquias e cargos públicos de gestão do território e áreas protegidas, exige muito tempo e esforço pessoal. Que todos os envolvidos encontrem neste trabalho o merecido reconhecimento público do seu empenho. Mário Cachão Professor Auxiliar com Agregação Centro e Departamento de Geologia (GEO/FCUL) Faculdade de Ciências Universidade de Lisboa 8 Julho 2010
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Os principais resultados deste trabalho são os seguintes: a) sistematizou-se a informação dispersa em bibliografia variada, sobre a família Rissoidae no Oceano Atlântico e Mediterrâneo, daqui resultando o cerne de uma futura base de dados a ser brevemente disponibilizada na internet. Nela constarão a distribuição geográfica, o tipo de desenvolvimento embrionário e a zonação batimétrica de cada espécie; b) apresentação de uma nova regra biogeográfica, com forte impacto em estudos de índole biogeográfico, relacionando pela primeira vez três conceitos: a zonação batimétrica típica de espécies abundantes e com desenvolvimento não-planctotrófico, a dispersão destas espécies em objectos flutuantes e a sua distribuição geográfica; c) apresentação de uma hipótese de trabalho relacionando a zonação batimétrica e a actual distribuição geográfica de espécies insulares com desenvolvimento não planctotrófico, com a idade geológica das espécies; d) estudo sistemático das jazidas Plistocénicas das Lagoinhas e Prainha existentes na ilha de Santa Maria, com a interpretação paleoecológica sugerindo uma certa estabilidade geológica na ilha de Santa Maria, no que a oscilações tectono-eustáticas diz respeito; e) apresentação de uma possível explicação para o desaparecimento dos bivalves bentónicos litorais associados a substrato arenoso, que é patente no registo fóssil das jazidas Plistocénicas investigadas em Santa Maria; f) estabelecimento das relações paleobiogeográficas Plistocénicas (com menos de 130.000 anos) e discussão destas; g) discussão da influência que as glaciações poderão ter tido sobre a fauna marinha litoral dos Açores, sugerindo prováveis rotas de colonização deste arquipélago; h) sugestão de uma origem comum da fauna Açoreana e Mediterrânea, por forma a explicar o aparente paradoxo biogeográfico que é a maior semelhança faunística dos Açores com a Europa, ao invés de com a América/Caraíbas, em virtude do (actual) regime global de correntes marinhas no Atlântico Norte e no Estreito de Gibraltar.
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An ecological study of the malacological composition of the intertidal zone, at a rocky shore, was performed. Three transects with quadrats of 25x25 cm were surveyed and profiles were made for two transects. A total of 12.285 molluscs were collected within a very sheltered lagoon. Preliminary results indicate that the dominant species is Cingula trifasciata (J. Adams, 1800) and, in a much lesser degree, Ovatella vulcani (Morelet, 1860), Onchidella celtica (Forbes & Hanley, 1853) and Auriculinella bidentata (Montagu, 1808). Juveniles of Ovatella vulcani, a species endemic to the Azores, are quite common near the channel that connects the lagoon with the open sea. Rissoidae is the best represented family, with 7 species: Alvania cancellata (da Costa, 1778), Alvania mediolittoralis Gofas, 1989, Cingula trifasciata, Manzonia unifasciata Dautzenberg, 1889, Botryphallus ovummuscae (Gofas, 1990), Rissoa guernei Dautzenberg, 1889 and Setia subvaricosa Gofas, 1990. Four species of Ellobiidae were found -Ovatella vulcani, Auriculinella bidentata, Pseudomelampus exiguus (Lowe, 1832) and Pedipes pedipes (Gmelin, 1790). A total of 29 species were recorded. Ellobiidae make the transition between terrestrial and marine environment,. followed by Onchidella celtica, a large species, abundant in the middle of the lagoon. The inferior half of the intertidal zone is dominated by Cingula trifasciata. Near low-tide level, Lasaea adansoni (Montagu, 1808) appears. SUMÁRIO Levou-se a efeito um estudo ecológico da composição malacológica da zona intertidal, numa costa rochosa. Três transectos com quadrados de 25x25 cm foram inspeccionados e perfis executados para dois transectos. Dentro da lagoa muito abrigada foi recolhido um total de 12.285 moluscos. Resultados preliminares indicam que Cingula trifasciata (J. Adams, 1800) é a espécie predominante e, em grau menor, Ovatella vulcani (Morelet. 1860), Onchidella celtica (Forbes & Hanley, 1853) e Auriculinella bidentata (Montagu, 1808). Juvenis de Ovatella vulcani, espécie endémica para os Açores, são bastante comuns perto do canal que liga a lagoa corn o mar aberto. A família Rissoidae é a melhor representada, com 7 espécies: Alvania cancellata (da Costa, 1778), Alvania mediolittoralis Gofas, 1989, Cingula trifasciata, Manzonia unifasciata Dautzenberg, 1889, Botryphallus ovummuscae (Gofas, 1990), Rissoa guernei Dautzenberg, 1889 e Setia subvaricosa Gofas, 1990. Encontraram-se quatro espécies de Ellobiidae: Ovatella vulcani, Auriculinella bidentata, Pseudomelampus exiguus (Lowe, 1832) e Pedipes pedipes (Gmelin, 1790). Registou-se um total de 29 espécies.
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A two-year systematic survey was conducted in a rocky exposed shore located at Porto dos Baleias (S60 Vicente, Capelas) in the north coast of Sdo Miguel Island and suppos-edly representative of the Azorean rocky shores. Zonation of the littoral molluscs (Gas-tropoda, Bivalvia and Polyplacophora) was established for the most abundant species and possible molluscs/algae biological associations were studied. Seventy-one taxa (56 Gastropoda, 13 Bivalvia and 2 Polyplacophora) were found in the
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Seasonal changes in the rate of shell formation frequently affect the surface morphology of molluscan shells, with reductions in feeding activity and calcification rates at low temperatures producing winter rings that can be used for age determination. Such annuli are well-known in lamellibranchs and have greatly facilitated studies on their growth, longevity and other age-related processes (as reviewed by Wibur & Owen, 1964; Rhoads & Panella, 1970; Comfort, 1957, 1979). However, they occur less frequently in gastropods and many species that do show such checks are relatively short-lived, or else their growth ceases or becomes erratic on sexual maturity.
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It is paradoxical that exotic species invade and displace native species that are well adapted to local environments. Yet, even those exotics that eventually become abundant and widespread, often do so only after having failed to establish following multiple earlier introductions. The first pattern, while not generally discussed in this context, is usually explained by exotic species pre-adaptations for human-altered environments and by a release from enemies. It can be under-stood further by examining the superior quality of colonists from large species-rich regions and the historical contingency of evolution. The second pattern is generally explained by invoking demo-graphic and environmental stochasticity; how-ever, it can be understood further by examining the role of environmental variation over space and by metapopulation dynamics. These pro-cesses provide a context in which these patterns of invasion are not paradoxical, but instead, expected.
Article
La flore indigène des îles océaniques tropicales est connue pour être particulièrement sensible à un déplacement voire à une extinction d'espèces, suite à l'invasion d'organismes étrangers. #Miconia calvescens DC (Melastomataceae), d'abord introduit à Tahiti (Polynésie française, Pacifique Sud) en 1937 comme plante ornementale, recouvre actuellement plus des deux-tiers de l'île. En formant des couverts monospécifiques denses qui ont étouffé progressivement les forêts naturelles, cette plante est un danger direct pour la flore indigène riche de Tahiti. Entre 40 et 50 espèces des 107 plantes endémiques de Tahiti sont supposées être en voie d'extinction. #M. calvescens a finalement été déclarée espèce nuisible en Polynésie française en 1990. Sans des efforts de lutte et une législation sur la conservation et la protection des plantes en danger efficaces, #M. calvescens$ peut transformer Tahiti et toutes les îles hautes de Polynésie française en déserts écologiques. (Résumé d'auteur)
Article
Aim Recent colonization of northern Portuguese shores by Patella rustica Linnaeus, 1758, led to the bridging of a historical gap in the distribution known since the 1900s. Long-term oceanographic data collected over the last half-century were examined in order to detect possible mechanisms for the observed change in its distribution. Location This study was carried out along the entire Portuguese coastline, from 41°50′ to 37°06′ N. Time-series of hydrographical variables (sea surface temperature and salinity) were derived for the Atlantic coast of the Iberian Peninsula. Methods Abundance and size-frequency distributions of the newly observed limpet populations were compared with those from well-established populations in southern Portugal. Anomalies were computed for sea surface temperature (1950–2000) and sea surface salinity (1958–2001) data, covering the whole Atlantic coast of the Iberian Peninsula. An upwelling index (1967–2005) was derived for a single location within the distributional gap of P. rustica. Split moving window analysis was performed to detect significant discontinuities in hydrographical data sets. Results Patella rustica has gradually been expanding in northern Iberia, and in the late 1990s the historical gap in distribution in northern Portugal was bridged. Size-frequency distribution differed between historical and recent populations, the latter lacking small-sized individuals. At the same time, several anomalous oceanographic events occurred off the Portuguese coast and were probably related to this expansion. Main conclusions Although sea surface temperature might be a major determinant of the reproductive success of P. rustica and hence its dispersal potential, it is more likely that a coincidence of several factors occurring in the late 1990s provided exceptional conditions that allowed the geographical expansion of this species.
Article
Aim The development of accurate models predicting species range shifts in response to climate change requires studies on the population biology of species whose distributional limits are in the process of shifting. We examine the population biology of an example system using the recent northward range expansion of the marine neogastropod Kelletia kelletii (Forbes, 1852). Location This is a marine coastal shelf neogastropod species whose range extends from Isla Asuncion (Baja California, Mexico) to Monterey (CA, USA). Research sites spanned the extent of the range. Methods We examine abundance distributions and size frequency distributions of K. kelletii for evidence of factors determining historic and contemporary distributional patterns. Population studies were supplemented by historic and contemporary hydrographic data, including seawater temperature data from California Cooperative Oceanic Fisheries Investigations (CalCOFI ) and National Data Buoy Center (NDBC), and seawater circulation data. Results The structure of recently established populations varied dramatically from that of historic populations. Markedly low densities and irregular size frequency distributions characterized recently established populations and suggested only occasionally successful recruitment. The point of transition between historic and recently established populations also corresponded to the location of a gradient in seawater temperature and the confluence of two major oceanic currents. The accumulated data suggest that temperature and/or barriers to dispersal could have set both contemporary patterns in population structure as well as the former northern range limit. Main conclusions Early life stages play a critical role in determining distributional patterns of K. kelletii . Dispersal barriers and temperature limitation are two plausible mechanisms that could determine both contemporary and historic distributional patterns. Future studies on this species should attempt to tease apart the relative importance of these factors in maintaining the populations at the northern edge of the range.
Article
The study of biological invasions has triggered the production of a diversity of concepts. The terminology has, however, often been applied inconsistently and inaccurately. This article lists and assesses the most commonly used terms and concepts in invasion ecology. In each case the most coherent definition and use is suggested.
Article
We examine how an Allee effect in local population dynamics (reduced reproductive success at low densities) influences the spatio-temporal dynamics of ecological invasions. Our approach is to use a partial differential equation model of dispersal and population growth, and then ask whether we can identify "rates of spread" for an invading organism subject to an Allee effect. Results indicate that an Allee effect may substantially reduce the rate at which the invader moves into a new environment. Analysis of spread in two spatial dimensions entails application of a singular perturbation theory approach. Here the two-dimensional spread velocity is given in terms of the one-dimensional asymptotic spread rate and the curvature of a boundary between invaded and non-invaded regions. Using this result, we show that invasions cannot propagate unless they initially exceed a critical area. This prediction is verified by numerically solving the original model. Numerical solutions are used throughout in demonstrating the nature of the two-dimensional spread.
Article
Island biotas are viewed popularly as much more fragile than those of mainland areas and much more prone to damage from invaders. There are far too few data to assess this view thoroughly; for example, failed invasions are often unrecorded, and claims that an introduced species has displaced a native one are often based on correlated population changes rather than experiment and/or detailed field observations. If there is a tendency for invasions to affect island communities more than mainland ones, it is far from universal; virtually every kind of damage wrought by invaders on islands has also been wrought in mainland areas. It is unlikely that, by virtue of their reduced species richness alone, island communities pose less "biotic resistance" to invaders than mainland communities do. Rather, certain entire groups of species, like terrestrial mammals, are often missing from islands, and these absences can predispose certain invaders to be especially likely to survive and to produce particular impacts.
Article
The new occurrence of the bryozoan Zoobotryon verticillatum Della Chiaje, 1822 is herein recorded in multiple places throughout Azores archipelago. Where introduced, this species has caused important ecological and economical damage and therefore is regarded as invasive. In the Azores, no detrimental effects have yet been noted. The species is so far restricted to marinas (Horta, Faial Island; Vila Franca do Campo, São Miguel Island) and a natural coastal pool located near a secondary harbour (Lajes do Pico, Pico Island). A total of 29 colonies were counted during a specific survey conducted in August 2008 in the marina of Horta. The distribution of the species throughout the eastern and central island groups denotes a wide dispersion area and offers control or eradication measures a low probability of success together with the lack of harbour management practices that could effectively prevent the arrival, settlement and dispersal of non-native species transported by human-assisted means.
Article
The spread of nonindigenous species into new habitats is having a drastic effect on natural ecosystems and represents an increasing threat to global biodiversity. In the marine environment, where data on the movement of invasive species is scarce, the spread of alien seaweeds represents a particular problem. We have employed a combination of plastid microsatellite markers and DNA sequence data from three regions of the plastid genome to trace the invasive history of the green alga Codium fragile ssp. tomentosoides. Extremely low levels of genetic variation were detected, with only four haplotypes present in the species' native range in Japan and only two of these found in introduced populations. These invasive populations displayed a high level of geographical structuring of haplotypes, with one haplotype localized in the Mediterranean and the other found in Northwest Atlantic, northern European and South Pacific populations. Consequently, we postulate that there have been at least two separate introductions of C. fragile ssp. tomentosoides from its native range in the North Pacific.
Crimora papillata (Nudibranchia: Triophinae), a new record for the shallow marine molluscs of the Azores Tracking the invasive history of the green alga Codium fragile subsp. tomentosoides
  • N C Pedro
  • M A E Malaquias
  • A C Costa
  • S P Vila
  • E
  • J Provan
  • S Murphy
  • C A Maggs
PEDRO, N.C., MALAQUIAS, M.A.E., COSTA, A.C. & A ´ VILA, S.P. 2011. Crimora papillata (Nudibranchia: Triophinae), a new record for the shallow marine molluscs of the Azores. Marine Biodiversity Records, 4: e37. PROVAN, J., MURPHY, S. & MAGGS, C.A. 2005. Tracking the invasive history of the green alga Codium fragile subsp. tomentosoides. Molecular Ecology, 14: 189–194.
we envisage a significant ecological impact on the present-day intertidal assemblages of the Azores due to this new invasion by P. sauciatus. Although neither local disappearances nor extinc-tions are anticipated (for a review on the reasons of marine mol-luscs extinctions see A
  • Hawkins
As the biodiversity of the shallow Azorean malacofauna is lower than its European counterparts (Hawkins et al., 1990, 2000; A ´ vila, 1998, 2003; Morton et al., 1998; A ´ vila et al., 2005), we envisage a significant ecological impact on the present-day intertidal assemblages of the Azores due to this new invasion by P. sauciatus. Although neither local disappearances nor extinc-tions are anticipated (for a review on the reasons of marine mol-luscs extinctions see A ´ vila et al., 2008a, b; A ´ vila, 2013), the reduced limpet stocks in the Azores (which are the result of over-exploitation;
Monograph of the little slit shells, vols 1 and 2. Santa Barbara Museum of Natural History A description of the zonation patterns of molluscs and other important biota on the south coast of Saõ Miguel
  • D L Geiger
  • Santa Barbara
  • S J Hawkins
  • L P Burnay
  • A I Neto
  • R T Cunha
  • A M F Martins
GEIGER, D.L. 2012. Monograph of the little slit shells, vols 1 and 2. Santa Barbara Museum of Natural History, Santa Barbara. HAWKINS, S.J., BURNAY, L.P., NETO, A.I., CUNHA, R.T. & MARTINS, A.M.F. 1990. A description of the zonation patterns of molluscs and other important biota on the south coast of Saõ Miguel, Azores. Aç, Suppl. 2: 21– 38.
Zonac¸a˜o intertidal de uma comunidade malacolo´gica numa lagoa costeira localizada na costa sul da ilha do Pico
  • Á Vila
Á VILA, S.P. 1998. Zonac¸a˜o intertidal de uma comunidade malacolo´gica numa lagoa costeira localizada na costa sul da ilha do Pico, Ac¸ores. Açoreana, 8: 436-486.