Ranking the Azorean Natural Forest Reserves for conservation using their endemic arthropods

Copyright © 2000 Kluwer Academic Publishers.Endemic arthropods were used to evaluate the conservation value of the 16 Natural Forest Reserves (NFRs) of the Azores (Macaronesia). For each of the 280 known Azorean endemic species of arthropods, a rarity index was calculated, using distribution and abundance data obtained from the literature. In addition, several scoring indices were used to rank the 16 NFRs. Frequency distributions of the rarity index indicated that there was a tendency for a greater proportion of the commonest species being represented in the NFRs in contrast with a lower representation of the rarest species. About 60% of the endemic arthropod species that were recorded from the NFRs are single NFR endemics , that is, are known from only one of the 16 NFRs. Species richness was considered to be a very good surrogate measure of the conservation value of the 16 NFRs under study. The fact that the six highest ranked NFRs (using a composite multi-criteria index) are located in different islands has some important conservation management implications; to preserve a large proportion of the Azorean arthropod biodiversity there is a need to protect sites in all islands. If the five highest ranked NFRs are correctly managed in terms of conservation, then at least 80% of the endemic arthropods known from the NFRs could be protected. Most of the tested taxa (Acari-Oribatei; Lepidoptera; Diptera; Coleoptera) are good surrogates of the overall total set of species present in the 16 NFRs when using a species richness index

Evidence for late Pleistocene volcanism at Santa Maria Island, Azores?

Santa Maria Island constitutes the oldest volcanic island within the Azores Archipelago, with no onshore record of eruptions younger than ≈2.8 Ma. A recent high-resolution multibeam bathymetric survey, however, revealed the presence of a seemingly young submerged wide volcanic edifice at approximately −70/−80 m, on the northeastern sector of the island shelf. The outer flanks of this volcanic edifice are partially eroded by marine erosion, but its general morphology is largely preserved, attesting to its relative youth. The edifice's aspect ratio and crater size are typical of a tuff ring formed by very violent surtseyan to taalian eruptions (with water/magma interaction ratios close to 1), implying extrusion at sea level or in very shallow waters, conditions that are incompatible with the present-day water depth at which this structure occurs. A detailed geomorphological analysis – coupled with a correlation with a modified reference eustatic curve – allowed the formulation and discussion of a formation model for the tuff ring, which involves extrusion during a period immediately preceding a rapid relative sea-level drop, most likely at ≈43 ka. Extrusion during such a period would have allowed for the subaerial consolidation and palagonitization of the tuff ring, increasing its resistance to erosion, before being finally submerged during the Last Glacial Termination. Submersion during the Last Glacial Termination – a period characterised by extremely fast sea-level rise – also helps to explain why this tuff ring was submerged without being completely razed by marine erosion. Our study offers insights on the formation and preservation of tuff rings in coastal environments, and in relation to sea-level oscillations, suggesting that consolidation plays a crucial role in the process. Crucially, our study suggests that Santa Maria's volcanism might have extended well into the very late Pleistocene, raising important hazard implications. Future work is scheduled to confirm this hypothesis, including sampling of the volcanic products by dredging and/or by remote operated vehicle. Our study also emphasises the importance of available high-resolution bathymetric surveys to the formulation of solid volcanic hazard assessments on volcanic islands.info:eu-repo/semantics/publishedVersio

Hazard potential of volcanic flank collapses raised by new megatsunami evidence

Large-scale gravitational flank collapses of steep volcanic islands are hypothetically capable of triggering megatsunamis with highly catastrophic effects. Yet, evidence for the generation and impact of collapse-triggered megatsunamis and their high run-ups remains scarce or is highly controversial. Therefore, doubts remain on whether island flank failures truly generate enough volume flux to trigger giant tsunamis, leading to diverging opinions concerning the real hazard potential of such collapses. We show that one of the most prominent oceanic volcanoes on Earth—Fogo, in the Cape Verde Islands—catastrophically collapsed and triggered a megatsunami with devastating effects ~73,000 years ago. Our deductions are based on the recent discovery and cosmogenic 3He dating of tsunamigenic deposits found on nearby Santiago Island, which attest to the impact of this giant tsunami and document wave run-up heights exceeding 270 m. The evidence reported here implies that Fogo’s flank failure involved at least one fast and voluminous event that led to a giant tsunami, in contrast to what has been suggested before. Our observations therefore further demonstrate that flank collapses may indeed catastrophically happen and are capable of triggering tsunamis of enormous height and energy, adding to their hazard potential

Interplay of deep-marine sedimentary processes with seafloor morphology offshore Madeira Island (Central NE-Atlantic)

The deep-water sedimentary processes and morphological features offshore Madeira Island, located in the Central-NE Atlantic have been scantly studied. The analysis of new multibeam bathymetry, echo-sounder profiles and few multichannel seismic reflection profiles allowed us to identify the main geomorphologies, geomorphic processes and their interplay. Several types of features were identified below 3800 m water depth, shaped mainly by i) the interplay between northward-flowing Antarctic Bottom Water (AABW) and turbidity currents and ii) interaction of the AABW with oceanic reliefs and the Madeira lower slope. Subordinate and localized geomorphic processes consist of tectono-magmatic, slope instability, turbidity currents and fluid migration. The distribution of the morphological features defines three regional geomorphological sectors. Sector 1 represents a deep seafloor with its abyssal hills, basement highs and seamounts inherited from Early Cretaceous seafloor spreading. Sector 2 is exclusively shaped by turbidity current flows that formed channels and associated levees. Sector 3 presents a more complex morphology dominated by widespread depositional and erosional features formed by AABW circulation, and localized mixed contourite system developed by the interplay between the AABW circulation and WNW-ESE-flowing turbidite currents. The interaction of the AABW with abyssal hills, seamounts and basement ridges leads to the formation of several types of contourites: patch drifts, double-crest mounded bodies, and elongated, mounded and separated drifts. The patch drifts formed downstream of abyssal hills defining an previously unknown field of relatively small contourites. We suggest they may be a result of localized vortexes that formed when the AABW’s flow impinges these oceanic reliefs producingthe erosional scours that bound these features. The bottom currents in the area are known to be too weak (1–2 cm s− 1) to produce the patch drifts and scours. Therefore, we suggest that these features could be relics at present, having developed when the AABW was stronger than today, as during glacial/end of glacial stages

Canopy insect herbivores in the Azorean Laurisilva forests: key host plant species in a highly generalist insect community

Copyright © ECOGRAPHY 2005.This article explores patterns of insect herbivore distribution in the canopy of the Laurisilva forests on seven islands in the Azores archipelago. To our knowledge, this is one of the first extensive studied of this type in tree or shrub canopies of oceanic island ecosystems. One of the most frequently debated characteristics of such ecosystems is the likely prevalence of vague, ill-defined niches due to taxonomic disharmony, which may have implications for insect-plant interactions. For instance, an increase in ecological opportunities for generalist species is expected due to the lack of predator groups and reduced selection for chemical defence in host plants. The following two questions were addressed: 1) Are specialists rare species, and insect herbivore species randomly distributed among host plant species in the Azores? 2) Are the variances in insect herbivore species composition, frequency and richness explained by host plants or by regional island effects? We expect a proportional distribution of herbivore species between host plants, influenced by host frequency and distinct island effects; otherwise, deviation from expectation might suggest habitat preference for specific host tree crowns. Canopy beating tray samples were performed on seven islands, comprising 50 transects with 1 to 3 plant species each (10 replicates per species), giving 1320 samples from ten host species trees or shrubs in total. From a total of 129 insect herbivore species, a greater number of herbivore species was found on Juniperus brevifolia (s=65) and Erica azorica (s=53). However, the number of herbivore species per individual tree crown was higher for E. azorica than for any other host, on all islands, despite the fact that it was only the fourth more abundant plant. In addition, higher insect species richness and greater insect abundance were found on the trees of Santa Maria Island, the oldest in the archipelago. Insect species composition was strongly influenced by the presence of E. azorica, which was the only host plant with a characteristic fauna across the archipelago, whereas the fauna of other plant crowns was grouped by islands. The great insect occurrence on E. azorica reflects strong habitat fidelity, but only four species were clearly specialists. Our findings indicate a broadly generalist fauna. The simplicity of Azorean Laurisilva contributed to the understanding of insect-plant mechanisms in canopy forest habitats

Evidencias acústicas de procesos paralelos al talud asociados con depósitos de movimiento en masa en el talud inferior de la Isla de Madeira (Atlántico Central Oriental)

The Madeira Island lower slope has been build-up mostly by along slope-processes associated with mass movement deposits as seen in GEBCO bathymetry, multibeam bathymetry, Parasound echosounder profiles and multichannel seismic reflection profiles. A plastered contourite drift (Madeira Drift) developed on this lower slope, being composed of seismic units D1, D2 and D3. The most probable water mass responsible for its deposition is the Antarctica Bottom Water (AABW). The youngest sediments of seismic units D2 and D3 are affected by gravity-driven processes, probably slumps and debris flows, which moved downslope towards west. Parasound profiles show evidences of such mass movements on present-day seabottom (e.g. diffraction hyperbolae echoes) but also of past-events buried within the contourite sediments. These older debris flows are recognized by semitransparent/transparent acoustic facies and lenticular shape.Versión del edito

Contourite drift off Madeira Island (Northeast Atlantic) and implications to Cenozoic bottom-current circulation

EUROPEAN GEOPHYSICAL UNIO

Relação entre o número de espécies e o número de táxones de alto nível para a fauna de artrópodes dos Açores

Nesta contribuição pretendemos avaliar a aplicação dos modelos RESTAN, "Relação entre o número de Espécies e o número de Táxones de Alto Nível", à fauna de artrópodes de vários habitats das ilhas dos Açores. Utilizámos várias bases de dados recentemente obtidas baseadas em amostragens estandardizadas de artrópodes epígeos do solo em florestas de áreas protegidas, artrópodes fitófagos e predadores de pastagens semeadas e semi-naturais e artrópodes da copa da árvore endémica Juniperus brevifolia. Os modelos RESTAN são aplicados não só usando dados puramente taxonómicos, mas igualmente agrupando os taxa em termos de estratégias ecológicas (e.g. herbívoros, predadores) e de colonização das ilhas (e.g. endémicos). Deste modo pensamos poder avaliar a aplicabilidade destes modelos em estudos de estrutura de comunidades e de conservação. Para os Açores, a aplicação dos modelos RESTAN constitui uma forma muito prática e eficaz de obter estimativas de diversidade. De facto, em todas as matrizes de dados analisadas a riqueza de espécies pode ser estimada eficazmente usando apenas a riqueza em géneros, sendo a relação linear. Ao nível da família, os modelos estimadores possuem um menor poder explicativo e são melhor explicados por uma função exponencial. O escalonamento de Reservas Florestais Naturais dos Açores em termos de biodiversidade de artrópodes endémicos pode ser efectuado usando informação taxonómica ao nível do género. A aplicação de métodos de estimativa rápida de biodiversidade fica assim facilitada, podendo usar-se parataxonomistas bem treinados para o processo de triagem do grande número de amostras geralmente necessárias em estudos ecológicos. Discute-se igualmente a aplicabilidade dos modelos RESTAN a dados de diversidade alfa, beta e gama.ABSTRACT: In this contribution we examine the predictive power of numbers of higher taxa (orders, families and genera) as surrogates of species richness ("RESTAN" models – models based on linear relationship between species and higher taxa numbers) for the Azorean arthropod fauna. Recently, two large entomological and ecological studies were performed in the Azores, using standardized sampling protocols to estimate the diversity of arthropods in grassland and native forests. We use datasets available from those studies to address a few technical questions: A. what is the impact of using several measures of diversity (alpha, gamma and beta species diversity; Shannon-Wiener index of diversity; Evenness) based on numbers of families and genera for canopy arthropods? For instance, could be predicted that values of beta-diversity decrease with the use of higher-taxa estimates. All the measures of diversity could be used, being the genera the best predictor; B. how well behave the RESTAN models for functional groups of species like grass-feeding and web-building spiders in grasslands? The predictive power of higher-taxa is low using web-building spiders, due to few families being envolved and some genera having many species locally represented; C. assuming at least one sample with no species then there will be also no highertaxa in that sample. Consequently, the curve of the relationship between highertaxa richness and species richness should be anchored to the origin (y= bx). What is the predictive value of this model in comparison with the linear (y =a + bx), log-log (log y = a + b log x) and exponential (y = A • e b x) models? The best fit was obtained with the linear model for the genus-species relationship, but the variables are not normally distributed and the log-log model should be preferable. For the family-species relationship the exponential model is the best. The linear model anchored to the origin (y =bx) has some statistical pitfalls and was of less predictive value; D. in conservation studies what is the predictive value of higher-taxa in ranking protected areas? We found that the numbers of arthropod genera could successfully rank the Natural Forest Reserves as well as numbers of species (using endemic species dataset). We found that in the Azores the predictions of species richness using higher-taxa are quite reasonable, mainly because of low levels of diversity. Therefore, costeffective studies could use only genera, since the species richness of arthropods could be predicted reasonably closely from their genus-level richness. Family and order-level data were less informative for all datasets. We suggest that in the Azores as a consequence of the low levels of species diversification with a great proportion of monospecific genera, the use of parataxonomists trained in genus-level identification could be appropriate for sorting large numbers of ecological samples

Updated Checklist of Arthropods from Azores (Portugal)

The data we present consists in an updated checklist of the Azorean arthropods. The checklist compile known records based on published literature, unpublished data, and new records at archipelago and island levels. This publication represents the most recent information about distribution of introduced, native and endemic arthropods in the Azores archipelago. Currently the total number of terrestrial arthropod taxa (species and subspecies) in the Azores is estimated of about 2417 belonging to 14 classes, 53 orders, 438 families, 1554 genera and 2397 species and 149 individual subspecies. The most diverse orders of Azorean arthropods are: Coleoptera (585 taxa), Diptera (422 taxa), Hemiptera (338 taxa), Hymenoptera (162 taxa), Lepidoptera (159 taxa) and Araneae (132 taxa). A total of 275 endemic taxa are currently known (231 species and 44 subspecies), belonging to 8 classes and 22 orders. São Miguel, Terceira and Pico are the islands with higher number of endemic species and subspecies. Compared to the other nearest Macaronesian archipelagos (Madeira and Canaries), the Azorean arthropod fauna is characterized by a lower percentage of endemism and a high proportion of exotic introduced species.FUNDING: This work was financed by two main projects: FEDER - AZORESBIOPORTAL –PORBIOTA (ACORES-01-0145-FEDER-000072) and Portal da Biodiversidade dos Açores (2022-2023) - PO Azores Project - M1.1.A/INFRAEST CIENT/001/2022. Open access was funded by the project FCT-UIDB/00329/2020-2024 (Thematic Line 1 – integrated ecological assessment of environmental change on biodiversity).info:eu-repo/semantics/publishedVersio

Environmental representativity in marine protected area networks over large and partly unexplored seascapes

Converting assemblages of marine protected areas (MPAs) into functional MPA networks requires political will, multidisciplinary information, coordinated action and time. We developed a new framework to assist planning environmental representativity in a network across the marine space of Portugal, responding to a political commitment to protect 14% of its area by 2020. An aggregate conservation value was estimated for each of the 27 habitats identified, from intertidal waters to the deep sea. This value was based on expert-judgment scoring for environmental properties and features relevant for conservation, chosen to reflect the strategic objectives of the network, thus providing an objective link between conservation commitments and habitat representativity in space. Additionally, habitats' vulnerability to existing anthropogenic pressures and sensitivity to climate change were also scored. The area coverage of each habitat in Portugal and within existing MPAs (regionally and nationally) was assigned to a scale of five orders of magnitude (from 10%) to assess rarity and existing representation. Aggregate conservation value per habitat was negatively correlated with area coverage, positively correlated with vulnerability and was not correlated with sensitivity. The proposed framework offers a multi-dimensional support tool for MPA network development, in particular regarding the prioritization of new habitats to protect, when the goal is to achieve specific targets while ensuring representativity across large areas and complex habitat mosaics. It requires less information and computation effort in comparison to more quantitative approaches, while still providing an objective instrument to scrutinize progress on the implementation of politically set conservation targets.Agência financiadora Número do subsídio Oceanic Observatory of Madeira M1420-01-0145-FEDER-000001-OOM national funds through FCT UID/BIA/00329/2013 UID/Multi/04326/2013 Fundacao para a Ciencia e a Tecnologia SFRH/BPD/95334/2013 CESAM - FCT/MEC through national funds UID/AMB/50017 - POCI-01-0145-FEDER-007638 FEDER FCT SFRH/BPD/94320/2013 MARE - UID/MAR/04292/2019 EU through the Cohesion Fund POSEUR-03-2215-FC-000046 POSEUR-03-2215-FC-000047 FCT national funds ECO/28687/2017info:eu-repo/semantics/publishedVersio