Browsing by Author "Vasconcelos, P."
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Are non-indigenous species hitchhiking offshore farmed mussels? A biogeographic and functional approachPublication . Piló, David; Pereira, F.; Carvalho, A.N.; Vasconcelos, P.; Cunha, A.M.; Gaspar, MiguelThe epifauna associated to farmed mussels in southern Portugal coast was analysed, aiming at identifying the species with spreading potential through commercial transport. The presence of a relevant number of the species here found is not reported to at least one of the common mussel export/transposition countries. Indeed, important species biogeographic dissimilarities between the mussel farm area and the Greater North Sea and Western Mediterranean Sea sub-regions were detected, suggesting the potential transport of non-indigenous species (NIS) into other countries. Among them, fouling species such as the anemones Paractinia striata and Urticina felina, the acorn barnacles Balanus glandula and Balanus trigonus or the bryozoans Bugulina stolonifera and Schizoporella errata exhibit functional attributes that allow them to colonise and spread in new areas. This combined biogeographic and functional approach may contribute to clarify the role of aquaculture on the transport of NIS and to predict and prevent their spreading worldwide.
- Depth segregation phenomenon in Donax trunculus (Bivalvia : Donacidae) populations of the Algarve coast (southern Portugal)Publication . Gaspar, Miguel; Chicharo, Luis; Vasconcelos, P.; Garcia, A; Santos, A. R.; Monteiro, C. C.A study was undertaken to evaluate the existence of depth segregation between size classes of Donax trunculus populations that occur along the Algarve coast (southern Portugal). Five collecting areas were sampled in the Ria Formosa barrier islands, namely in the Culatra, Barreta and Armona Islands, between March and June 1998. The study was based on size frequency distribution analysis and shell biometric relationships, The size frequency distribution showed the predominance of smaller individuals (<25 mm) in the renewal area (0.5-1.0 m depth) and the prevalence of larger individuals (greater than or equal to25 mm) at greater depths (4.0-6.0 in depth). The biometric study revealed the existence of significant differences in the type of growth between size classes in relation to depth distribution and burrowing activity. On the basis of these results, some specific management measures were proposed for this important bivalve fishery, taking into account the distinct fishing strategies and operations (manual and boat-operated dredging) performed at different depths.