Browsing by Author "Neves, Pedro A."
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- “Pink round stones”—rhodolith beds: an overlooked habitat in Madeira ArchipelagoPublication . Neves, Pedro A.; Silva, João; Peña, Viviana; Ribeiro, CláudiaDespite its worldwide distribution in sedimentary infralittoral and circalittoral bottoms, rhodolith beds have been the subject of fewer studies than other nearshore communities, like kelp forests and coral reefs. This is also the case in Madeira archipelago (Eastern Atlantic), where until recently our knowledge on rhodolith beds was limited to a few references to its occurrence and species composition. In the course of an ongoing habitat-mapping project developed in Madeira, observations revealed that rhodolith beds are more common and extensive than previously supposed. The habitat maps for these beds in Madeira archipelago here presented are the first ever produced for the region. They reveal a total of 46 rhodolith beds at eleven different locations spread across three islands (Madeira, Desertas and Porto Santo), with areas ranging from 776 to 101,081 m(2) and at depths between 12 and 35 m. Author's observations, as well as the results suggest that more rhodolith beds are likely to exist in the archipelago, particularly at greater depths and unexplored locations. The application of molecular systematic tools for the identification of rhodolith-forming species revealed the occurrence of four species belonging to the genera Lithothamnion and Phymatolithon. This latter genus is represented by a single species which is commonly found in rhodolith beds of the archipelago. Genetically, our results show similarities both with the rhodolith communities from the Canary islands and the Algarve (south of Portugal) and highlight the singularities of the archipelago's marine flora. The new array of data here presented is deemed essential for an effective management and conservation of these important and sensitive habitats.
- Population density, reproduction cycle and nutritional value of Sphaerechinus granularis (Echinodermata: Echinoidea) in an oceanic insular ecosystemPublication . Lourenço, Sílvia; José, Ricardo; Neves, Pedro A.; Góis, André; Cordeiro, Nereida; Andrade, Carlos; Ribeiro, CláudiaSea urchins play an important role in island coastal ecosystems as keystone species and as potential resources for harvesting and aquaculture. In Southern Europe, the most valuable and harvested species is the European purple sea urchin Paracentrotus lividus, but there is a growing interest to explore other edible species like the blunt sea urchin Sphaerechinus granularis. The echinoderms biodiversity of Madeira archipelago was previously described, but their local habitat, population densities and size distribution, important to establish their harvest and aquaculture potential, are poorly known. The present study aimed to evaluate S. granularis population in the oligotrophic and narrow insular shelf of Madeira archipelago, mainly regarding its habitat, densities, reproduction season and roe marketable characteristics. Sphaerechinus granularis was found in low densities (0.01 ind./m(2)) from shallow to deep reefs (5-30 m). The highest densities occurred in shallow waters and breakwaters in association to encrusting algae, turf and erect brown macroalgae. Here, the low primary productivity ecosystem influenced the long reproductive season of the local population. This population showed a relatively high gonadosomatic index (maximum GI of 8), high gonad weight (5.00-12.19 g) with high proportion of bright yellow and orange gonads (37.5-60%) between February and November. Additionally, the high level of total carotenoids, the high PUFA (particularly EPA) content, and the ratio n-6/n-3 close to one support the high nutritional value of S. granularis roe. The trend of incremental GI between September and November and the increasing content of PUFA in autumn suggests this could be the preferential harvesting season. This information is key to evaluate a sustainable exploitation of this living marine resource.