DCA - Artigos em Revistas Internacionais / Articles in International Journals
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- Absorption coefficients by aerosols in remote areas: a new approach to decouple dust and black carbon absorption coefficient using seven-wavelength Aethalometer dataPublication . Fialho, Paulo; Hansen, Anthony; Honrath, RichardWe present a new approach to decouple aerosol absorption coefficients due to iron oxide in Sahara dust from those due to black carbon (BC) particles. Absorption coefficients, σaerosol(λ,t), were measured at the summit of Pico mountain (2225 m ASL) in the Azores Islands using a seven-wavelength Aethalometer. Measurements between 27th July and 1st August, 2001, are analyzed here. Variations in aerosol absorption coefficients were uncorrelated to those of CO during the latter part of this period, suggesting the presence of non-combustion-derived aerosol, apparently African dust. To differentiate between BC and other absorbing particles, we analyzed the wavelength dependence of σaerosol(λ,t) and determined a best-fit exponent during the later period equal to -2.9±0.2, somewhat lower than previously reported for soil dust. Using this method, it is possible to estimate the aerosol absorption due to BC and that due to soil dust separately through the full period analyzed.
- Abundance, spatial variance and occupancy: arthropod species distribution in the AzoresPublication . Gaston, Kevin J.; Borges, Paulo A. V.; He, FangLiang; Gaspar, Clara1. The positive abundance-occupancy and abundance-variance relationships are two of the most widely documented patterns in population and community ecology. 2. Recently, a general model has been proposed linking the mean abundance, the spatial variance in abundance, and the occupancy of species. A striking feature of this model is that it consists explicitly of the three variables abundance, variance and occupancy, and no extra parameters are involved. However, little is known about how well the model performs. 3. Here, we show that the abundance-variance-occupancy model fits extremely well to data on the abundance, variance and occupancy of a large number of arthropod species in natural forest patches in the Azores, at three spatial extents, and distinguishing between species of different colonization status. Indeed, virtually all variation about the bivariate abundance-occupancy and abundance-variance relationships is effectively explained by the third missing variable (variance in abundance in the case of the abundance-occupancy relationship, and occupancy in the case of the abundance-variance relationship). 4. Introduced species tend to exhibit lower densities, less spatial variance in these densities, and occupy fewer sites than native and endemic species. None the less, they all lie on the same bivariate abundance-occupancy and abundance-variance, and trivariate abundance-variance-occupancy, relationships. 5. Density, spatial variance in density, and occupancy appear to be all the things one needs to know to describe much of the spatial distribution of species.
- Adapting the IUCN red listing criteria for invertebratesPublication . Cardoso, Pedro; Borges, Paulo A. V.; Triantis, Kostas A.; Ferrández, Miguel A.; Martín, José L.The IUCN Red List is the most useful list of species that are at risk for extinction worldwide, as it relies on a number of objective criteria. Nevertheless, there is a taxonomic bias that excludes species with small body sizes, narrow distribution ranges and low dispersal abilities, which constitute the vast majority of the planet’s biota, particularly local endemics. By evaluating each IUCN criterion separately, we (i) identify the shortcomings for invertebrate applications, (ii) explain how risk categories may be wrongly applied due to inapplicable and/or misleading thresholds, (iii) suggest alternative ways of applying the existing criteria in a more realistic way and (iv) suggest possible new criteria that were not considered in the current evaluation framework but that could allow a more comprehensive and effective assessment of invertebrates. By adapting the criteria to rely more explicitly on the Area of Occupancy and the Extent of Occurrence, their respective trends and by using ecological modelling methods, the criteria’s applicability would be increased. The change in some thresholds or, eventually, the creation of sub-categories would further increase their adequacy. Additionally, co-extinction could be introduced as an explicit part of the classification process. As a case study, we evaluated 48 species of Azorean arthropods and Iberian spiders according to the current criteria. More than one-quarter (27%) of all evaluated species were classified as Critically Endangered, 19% as Endangered, 6% as Vulnerable and 8% as Least Concern. The remaining 40% did not have enough data to reach a classification.
- Aerosol chemical elemental mass concentration at lower free tropospherePublication . Freitas, Maria do Carmo; Dionísio, Isabel; Fialho, Paulo; Barata, FilipeThis paper shows the use of Instrumental neutron activation analysis (INAA) technique to determine elemental masses collected by a seven-wavelength Aethalometer instrument at the summit of Pico mountain in the Azorean archipelago, situated in the Central North Atlantic Ocean. Each sample corresponds to air particulate matter measured continuously for periods of approximately 24 h taken from 14th July 2001 through 14th July 2002. The statistical analysis of the coefficients of correlation between all the elements identified, permitted to establish six groups that could potentially be associated with the type of source responsible for the aerosol sampled in the lower free troposphere at the Azorean archipelago. Calculation of the synoptic back trajectories helped to corroborate the use of the iron/cesium relation as a tracer for the Saharan dust aerosol. It was demonstrated that INAA constituted an important tool to identify these events.
- Agonistic and predatory behaviour of the lizardfish Synodus saurus (Linnaeus, 1758) (Actinopterygii: Synodontidae) from the AzoresPublication . Soares, Marta S. C.; Barreiros, João P.; Sousa, Luis; Santos, Ricardo S.The behaviour of the lizardfish Synodus saurus, a common demersal predator in Azorean waters, is described. A total of 25 hours’ qualitative diurnal underwater observations were carried out between July 2000 and January 2001. Behavioural aspects are presented, illustrated with diagrams based on in situ observations. S. saurus is a cryptic predator that feeds mainly of small pelagic, gregarious fish; it is primarily associated with soft bottom substrate. Besides remaining camouflaged buried beneath the sand, S. saurus is a highly mobile predator capable of rapidly swimming more than five meters to capture its prey. S. saurus maintains a territory through agonistic interactions, and also interacts non-agonistically with heterospecifics such as Bothus podas maderensis.
- Analysis of Atmospheric Aerosols Using the Lisbon Nuclear MicroporePublication . Rita, E. M.; Alves, L. C.; Reis, M. A.; Rodrigues, A. F.; Fialho, Paulo; Soares, J. C.The nuclear microprobe installed at Instituto Tecnológico e Nuclear, in Lisbon, was used in the analysis of aerosols collected at the Azores islands. Samples from two different aerosol groups were analysed. One referred to aerosols that were carried from North America and the other one contained aerosols that were carried from the Sahara desert and crossed over Europe. Coarse and fine fractions were analysed for each aerosol group and two-dimensional elemental maps were constructed, which allowed the identification of several individual particles. For particles of interest, elemental spatial correlations and dimensions were determined and point analysis was also carried out (depth information was achieved by fitting Rutherford backscattering spectra). Some of these particles are quite interesting. For instance, in the fine fraction of the aerosols that were carried from North America, particles were found with Cu and Cl in the atomic proportion 1:2 and with dimensions 15 x 15 x 15 μm³, and in the corresponding coarse fraction a particle with K and S was identified, with dimensions 28 x 35 x 30 μm³. Some differences were found between the aerosols groups. One example of these are Ti particles (fine fraction) and Rb (coarse fraction) that were identified in one group (Sahara desert and Europe), but not in the other.
- The application of a multi-wavelength Aethalometer to estimate iron dust and black carbon concentrations in the marine boundary layer of Cape VerdePublication . Fialho, Paulo; Cerqueira, Mário; Pio, Casimiro; Cardoso, João; Nunes, Teresa; Custódio, Danilo; Alves, Célia A.; Almeida, S. M.; Almeida-Silva, M.; Reis, M. A.; Rocha, F.The two-component model (Fialho et al., 2006) was used to decouple the contributions of black carbon (BC) and iron oxides, present in dust, to the aerosol attenuation coefficient, measured with a multiwavelength Aethalometer. The model results were compared with the elemental carbon (EC) and iron concentrations determined in the laboratory from the analysis of aerosol particles collected with conventional samplers. The comparison was based on one year of data obtained at Praia, Santiago Island, Cape Verde, after side by side operation of the aerosol monitoring instruments. The linear regression equation that best describes the relationship between BC concentrations, derived from the Aethalometer, and EC concentrations, derived from a PM10 high-volume sampler after filter analysis with a thermal optical method, presents a slope of 1.01 ± 0.05 and a correlation coefficient (r) of 0.90, showing that the model worked as intended to describe BC concentrations without interferences from iron dust. On the other hand, the linear regression equation that best describes the relationship between the iron concentrations derived from the Aethalometer and elemental iron concentrations, derived from a PM10 lowvolume sampler after filter analysis by k0 e Instrumental Neutron Activation Analysis, presents a slope of 0.495 ± 0.014 and a correlation coefficient (r) of 0.96. These results show that the two-component model underestimated the iron concentrations in dust aerosol, which was explained by differences in the size range of particles sampled with the Aethalometer and the PM10 low-volume sampler together with differences in the size distribution of iron oxides.
- Are island and mainland biotas different? Richness and level of generalism in parasitoids of a microlepidopteran in MacaronesiaPublication . Santos, Ana M. C.; Fontaine, Colin; Quicke, Donald L. J.; Borges, Paulo A. V.; Hortal, JoaquínIsland communities are exposed to several evolutionary and ecological processes that lead to changes in their diversity and structure compared to mainland biotas. These phenomena have been observed for various taxa but not for parasitoids, a key group in terms of community diversity and functioning. Here we use the parasitoid communities associated with the moth Acroclita subsequana (Lepidoptera: Tortricidae) in the Macaronesian region, to test whether species richness differs between islands and mainland, and whether island parasitoid faunas are biased towards generalist species. Host larvae were collected on several islands and adjacent mainland, carefully searched for ectoparasitoid larvae and dissected to recover any endoparasitoids. Parasitoids were classified as idiobionts, which usually have a wide host range (i.e. generalists), or koinobionts that are considered specialists. Mainland species richness was lower than expected by chance, with most of the species being koinobionts. On the other hand, island communities showed a greater proportion of idiobiont species. Overall parasitism rates were similar between islands and mainland, but islands had higher rates of parasitism by idiobionts than expected by chance, and mainland areas showed the highest koinobiont parasitism rates. These results suggest that island parasitoid communities are dominated by generalists, in comparison to mainland communities. Several hypotheses may explain this pattern: (1) generalist parasitoids might have better dispersal abilities; (2) they may be less constrained by ‘sequential dependencies’; and (3) island parasitoids probably have fewer competitors and/or predators, thus favouring the establishment of generalists. New studies including multiple hosts, other habitats, and/or more islands are necessary to identify which of these processes shape island parasitoid communities.
- Are species-area relationships from entire archipelagos congruent with those of their constituent islands?Publication . Santos, Ana C.; Whittaker, Robert J.; Triantis, Kostas A.; Borges, Paulo A. V.; Jones, Owen R.; Quicke, Donald L. J.; Hortal, JoaquínAIM To establish the extent to which archipelagos follow the same species–area relationship as their constituent islands and to explore the factors that may explain departures from the relationship. LOCATION Thirty-eight archipelagos distributed worldwide. METHODS We used ninety-seven published datasets to create island species–area relationships (ISARs) using the Arrhenius logarithmic form of the power model. Observed and predicted species richness of an archipelago and of each of its islands were used to calculate two indices that determined whether the archipelago followed the ISAR. Archipelagic residuals (ArcRes) were calculated as the residual of the prediction provided by the ISAR using the total area of the archipelago, standardized by the total richness observed in the archipelago. We also tested whether any characteristic of the archipelago (geological origin and isolation) and/or taxon accounts for whether an archipelago fits into the ISAR or not. Finally, we explored the relationship between ArcRes and two metrics of nestedness. RESULTS The archipelago was close to the ISAR of its constituent islands in most of the cases analysed. Exceptions arose for archipelagos where (i) the slopes of the ISAR are low, (ii) observed species richness is higher than expected by the ISAR and/or (iii) distance to the mainland is small. The archipelago's geological origin was also important; a higher percentage of oceanic archipelagos fit into their ISAR than continental ones. ArcRes indicated that the ISAR underpredicts archipelagic richness in the least isolated archipelagos. Different types of taxon showed no differences in ArcRes. Nestedness and ArcRes appear to be related, although the form of the relationship varies between metrics. MAIN CONCLUSIONS Archipelagos, as a rule, follow the same ISAR as their constituent islands. Therefore, they can be used as distinct units themselves in large-scale biogeographical and macroecological studies. Departure from the ISAR can be used as a crude indicator of richness-ordered nestedness, responsive to factors such as isolation, environmental heterogeneity, number and age of islands.
- Are underwater archaeological parks good for fishes? Symbiotic relation between cultural heritage preservation and marine conservation in the AzoresPublication . Garcia, Catarina; Barreiros, João P.The Underwater Archaeological Parks (UAP) of the Azores are a cultural heritage protection initiative and an opportunity to promote fruition between archaeological sites and biodiversity. Respecting UNESCO’s “Convention on the Protection of the Underwater Cultural Heritage” principles, the UAPs were classified for the first time in 2005 and are unique in the Portuguese context. Due to the autonomy that this ultra-peripheral European Region has in terms of cultural heritage management, this structure arises from a specific law in 2005 formulated by initiative of the Azores Regional Government. At the same time, the archipelago’s marine biodiversity richness has become one of the most attractive elements for tourism in the islands. The main goal of this paper is to reflect on these two important identity elements of the Azores: on a cultural and environmental level. We try to understand if there is any interaction and symbiotic relation between the UPAs and their growing biodiversity due to the classification. For this purpose, the Angra UAP in Terceira and Dori UAP in S. Miguel will be presented. In both cases, the cultural element was mandatory for the classification and protection of the sites. This first attempt to combine marine biota data together with archaeological data proposes to create a precedent. In fact, the empirical perception of archaeologists, biologists and divers who visit the parks is that the biodiversity has increased with the protection measures. However, we need elements that are more accurate in order to define that. The main goal of this paper is to identify the marine species present in Angra for the first time. It will also create a reference for future evaluation regarding the symbiotic relation between the two UAP dimensions. We believe this has a positive effect on the defence of the natural and cultural heritage of the Azores.