Alexandre M. Pereira

Larval hatching and development of the wedge shell ( Donax trunculus L.) under increased CO 2 in southern Portugal

Noticeable changes in global temperatures, climate and ocean carbon chemistry are the result of carbon dioxide increase in the atmosphere. This increase has been mitigated by the oceans capacity to absorb one-fourth of the carbon dioxide in the atmosphere, although this CO2 intake affects oceans carbonate chemistry [i.e., ocean acidification—(OA)]. The detrimental effect of OA in the development and shell formation has been studied in several species of bivalves, although no information is available on the wedge shell Donaxtrunculus, a gastronomically appreciated species and an important economical resource in several southern European countries. We evaluated the effect of pCO2 increase on hatching and early life stages of D.trunculus, considering two ocean acidification scenarios (ΔpH −0.3 and ΔpH −0.6). Our results showed that elevated pCO2 caused a delay in hatching into D-larvae and reduced larvae survival. In the extreme scenario (ΔpH −0.6), some trochophore larvae persisted to day 9 of the experiment and more abnormal larvae were produced than in the ΔpH −0.3 and control treatments. At day 5, normal veligers under extreme acidification were smaller than in other treatments, but by day 9, these differences were attenuated and the average size of normal D-larvae varied inversely to the pH gradient. Possible underlying mechanisms for these complex response patterns are discussed, including the existence of phenotypic plasticity or genetic pre-adaptive capacity in this D.trunculus population to cope with future environmental changes.

Morphometric relationships and relative growth of 20 uncommon bivalve species from the Algarve coast (southern Portugal)

This study reports the morphometric relationships and relative growth of 20 uncommon bivalve species collected along the Algarve coast (southern Portugal). Morphometric relationships were established between three linear variables (shell length, height and width) and one ponderal variable (total weight) and the relative growth between variables (isometry vs allometry) was analysed in order to assess their variation throughout ontogeny. In addition, morphometric indices (elongation, compactness, convexity and density) based on ratios of those linear and ponderal variables were calculated in order to further characterize morphologically the bivalve species. A total of 2512 individuals belonging to nine bivalve families were analysed, comprising specimens with broad ranges in both shell length (11.8–109.0 mm SL) and total weight (0.2–354.6 g TW). All morphometric relationships were highly significant ( P r = 0.727–0.998). Among a total of 60 morphometric relationships, 27 isometries, 25 positive allometries and 8 negative allometries were registered. The morphometric indices displayed a remarkable variation among taxa, reflecting the high morphological diversity of these miscellaneous bivalve species. Discriminant analysis provided a spatial visualization of the species morphometric variables that further evidenced their main shape features, the distinctness between some species and families (e.g. Pharidae and Cardiidae) and the morphological resemblance among some species belonging to other families (e.g. Veneridae and Tellinidae). Overall, this information is useful and has practical application in diverse research fields, including studies on systematics and taxonomy, physiology, biology, ecology, fisheries assessment and management.

First record of Albunea carabus (Decapoda, Anomura, Hippidea) from the Algarve coast, South Portugal

Abstract During an annual bivalve dredge survey undertaken in April 2005 along the Portuguese coast, one specimen of the sand crab Albunea carabus was collected. This is the first record of this species on the Portuguese continental shelf. The individual found was a male with 11.31 mm carapace length and was collected off Faro at 3 m depth in a sandy area considerably hydrodynamic during winter. This occurrence is one of the few records outside the Mediterranean Sea. A short review of previous findings on this species is presented.