Browsing by Author "Costa, Tarso"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- Frondose and turf-dominated marine habitats support distinct trophic pathways: evidence from ¹⁵N and ¹³C stable isotope analysesPublication . Hipólito, Cláudia; Neto, Raul M. A.; Costa, Tarso; Dionísio, Maria Ana; Prestes, Afonso L.; Azevedo, José M. N.; Martins, Gustavo M.; Neto, Ana I.Marine vegetation plays an important structuring role, delivering key functions and services to coastal systems the extent of which depends on the foundation species and their architecture. In increasingly urbanised coastlines, turf-forming macroalgae are replacing frondose morphotypes. Trophic relationships within these systems can be studied through stable isotope analysis of the different food web compartments. In the present study, we investigated trophic pathways in two distinct macroalgal assemblages: one dominated by small brown frondose algae, and one dominated by low-lying turf-forming species. ¹⁵N and ¹³C isotopic signatures were determined for selected macroalgae and sedentary animals from distinct trophic levels, collected from two habitats on São Miguel Island (Azores, Portugal). In frondose habitats macroalgae appeared to make up the primary carbon source for the entire food web, whilst in turf-dominated habitats there was a decouple between macroalgae and higher trophic levels. Because canopy replacement by algal turf may affect the structure of the littoral food webs, coastal biodiversity conservation strategies should give priority to natural areas rich in canopy-forming algae.
- Guia do Ilhéu de Vila Franca do CampoPublication . Faria, João; Álvaro, Nuno V.; Costa, Tarso; Azevedo, José M. N.; Neto, Ana I.O ilhéu de Vila Franca do Campo é uma cratera vulcânica afundada e quase circular que está localizada a 400 metros de Vila Franca do Campo, na costa sudeste da ilha de São Miguel. [...]. Em 1983 a área terrestre do Ilhéu foi declarada Reserva Natural pelo Governo Regional dos Açores. Em 2004 a área de reserva foi incrementada para incluir a zona marítima adjacente num perímetro de 350 metros. Atualmente integra o Parque Natural de Ilha de São Miguel como área protegida para a gestão de habitats e espécies. O seu estatuto de conservação prevê a proteção do património florístico (nomeadamente as espécies endémicas), a conservação da fauna (em especial das aves marinhas que utilizam o local para nidificação e rota migratória), a proteção dos valores geológicos e a preservação do património paisagístico e cultural. [...].
- How Many Azores Bullfinches (Pyrrhula murina) Are There in the World? Case Study of a Threatened SpeciesPublication . Costa, Tarso; Gil, Artur José Freire; Timóteo, Sérgio; Ceia, Ricardo S.; Coelho, Ruben; De La Cruz Martín, AzucenaThe Azores bullfinch (Pyrrhula murina Godman, 1866) is a rare Passeriformes endemic from the eastern part of São Miguel Island, Azores, Portugal. This bird was almost considered extinct in the first half of the 20th century, but due to recent conservation measures, it has experienced a recovery since the beginning of the 2000s. Despite the attention given to this bird, the size of its population is still controversial, and the most recent studies present significant divergences on this behalf. The purpose of the present study is to present data from the long-term monitoring and results of the third single-morning survey of the Azores bullfinch to update information about the population size and range of this species. In addition, we performed a literature review to highlight the limitations and advantages of the different approaches for monitoring this species. The Azores Bullfinch records during the single-morning survey indicated a reduction in the extent of occurrence and area of occupancy of this species in comparison with the previous studies, despite the increase in bird detection. However, we suggest that the distribution range of this species needs further analysis concerning its area to exclude non suitable habitats from this analysis. In this study, we conclude that the most likely size of the Azores bullfinch population is 500 to 800 couples, with a slow population growth tendency and an area of distribution of 136.5 km2.
- Limited effects of marine protected areas on the distribution of invasive species, despite positive effects on diversity in shallow-water marine communitiesPublication . Cacabelos, Eva; Martins, Gustavo M.; Faria, Joao; Prestes, Afonso L.; Costa, Tarso; Moreu Badia, Ignacio; Neto, Ana I.Marine protected areas (MPAs) can be an effective tool for the conservation and management of marine coastal habitats. MPAs have been shown to halt habitat degradation, enhance the biomass of exploited species and diversity in general. Yet, we still know little about its role in halting the spread of non-native species. In this study, we assessed the role of MPAs in the structure of shallow subtidal communities around Sao Miguel Island, in general, and particularly on distribution of the two species of genus Asparagopsis: A. armata and A. taxiformis. In the Azores, the former is a well-established invasive species, whereas the status of A. taxiformis is still questionable. Overall, there was a significant greater diversity in terms of both species richness and number of macroalgal functional groups within MPAs. However, when considering the relative abundance of the various macroalgal functional groups, or the assemblage as a whole (multivariate analysis), there was no significant difference between areas within and outside MPAs. The cover of A. taxiformis was significantly greater within MPAs but not its biomass, whereas no significant variation was observed for A. armata. Overall, results suggest that surveyed MPAs had a positive effect on the diversity of shallow-water macroalgal communities. However, they have a limited role on the distribution of both Asparagopsis spp. and negligible effects when considering the relative abundances of macroalgal functional groups.
- Priolo, resultado de duas décadas de conservação.Publication . Costa, Tarso; Botelho, R.; Teodósio, J.; Figueiredo, F.; Amaral, A.; Mendonça, A.; De la Cruz, A.Outrora abundante na Vale das Furnas e na parte Este da ilha de São Miguel, a história do Priolo (Pyrrhula murina) começou a mudar no século XIX. Esta ave, endémica dos Açores, vivenciou uma redução drástica no tamanho de sua população no século XIX. Uma aparente incompatibilidade entre a coexistência do Priolo com as atividades humana neste período quase levaram esta espécie à extinção.