Browsing by Author "Coelho, Pedro Duarte"
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- Evidence for contrasting accumulation pattern of cadmium in relation to other elements in Senilia senilis and Tagelus adansoni from the Bijagós archipelago, Guinea-BissauPublication . Catry, Teresa; Figueira, Paula; Carvalho, Lina; Monteiro, Rui J. R.; Coelho, Pedro Duarte; Lourenço, Pedro Miguel; Catry, Paulo; Tchantchalam, Quintino; Catry, Inês; Botelho, Maria J.; Pereira, Eduarda; Granadeiro, José Pedro; Vale, CarlosShellfish harvesting in intertidal areas is a widespread and economically important activity in many countries across West Africa. However, in some areas, there is virtually no information concerning the levels of contaminants (and other elements related to nutritional aspects) in the harvested species. We collected sediments and several individuals of the West African bloody cockle Senilia senilis and of the razor clam Tagelus adansoni during the dry season of 2015 nearby three islands in the Bijagós archipelago, Guinea-Bissau. Aluminium, Ca, Fe, Mg, As, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn were determined in sediments and whole soft tissues of the two bivalves. Sediments showed uniformly low trace element concentrations, pointing to an ecosystem with low levels of trace element contamination. T. adansoni presented higher concentrations of most elements than S. senilis, with the exception of Cd that showed up to 40 times higher values in S. senilis than in T. adansoni from the same sites. Furthermore, Cd concentrations (25±8.7 mg kg(-1), dw) in S. senilis are clearly above the maximum level established for human consumption. Future studies should clarify whether biological factors are the major responsible for this unusual situation.
- Home sweet home: evidence for nest-fidelity in the rocky intertidal fish, the shanny Lipophrys pholisPublication . Martins, Joana; Almada, Frederico José Oliveira de; Gonçalves, Ana Sofia Ribeiro; Coelho, Pedro Duarte; Jorge, PauloThe ability to be faithful to a particular area or site was analysed in the shanny Lipophrys pholis. Using passive integrated transponders, adults from a population of L. pholis at Cabo Raso, Portugal, were followed over a period of 3 years. The findings showed that site fidelity is a consistent behaviour during the breeding season with specific breeding males being found only in particular sectors within the area, and in specific nests throughout the years. The fact that, in general, L. pholis individuals were absent from the study area during the non-breeding season and breeding males were recorded returning to the same nests and sectors for consecutive breeding seasons suggests that they have developed excellent homing abilities. Translocation data corroborate this idea showing that breeding males successfully returned to their nests after a displacement of >100 m. Altogether, these findings highlight the relevance of life-history traits (e.g. nesting) in the conditioning of site fidelity and homing for this species of rocky intertidal fish, and more importantly, provide evidence for the need of a well-developed navigational system.
- Homing in rocky intertidal fish. Are Lipophrys pholis L. able to perform true navigation?Publication . Jorge, Paulo; Almada, Frederico José Oliveira de; Gonçalves, Ana Sofia Ribeiro; Coelho, Pedro Duarte; Almada, Vítor CarvalhoAlthough navigation is common in many animals, only a few perform true navigation, meaning that they have the ability to return to a given place by relying on indirect cues obtained at the release site (i.e., by relying on information from a ‘‘map and compass’’ mechanism). The common intertidal fish, Lipophrys pholis, is thought to have homing abilities through a mechanism that primarily makes use of familiar landmarks (i.e., piloting). Anecdotal reports that individuals return to their home pools after release at unfamiliar sites suggest that L. pholis might use cues collected at the release site to find their way back (i.e., they might use map and compass information). Using a completely artificial setup, we tested the homing abilities of L. pholis as a function of age, sex, and familiarity with the release site. The findings showed that motivation for homing is present only in the adult phase and is independent of sex and/or familiarity with the release site. Moreover, adults released at a completely unfamiliar place oriented themselves in a direction roughly similar to that of their home pools. The fact that L. pholis were tested in a complete artificial environment means that hydrodynamic cues can be excluded as playing a role in this process and restricts the candidate options (e.g., magnetic cues). The ability to perform navigation based on a ‘‘map and compass’’ mechanism raises many interesting questions about the learning process, once these individuals have restricted home ranges during their lives. In vertebrate navigation, the cues used during the navigation process are a question of debate, and L. pholis offers an outstanding model to test hypotheses and ultimately provide answers.
- Identification of adult and juvenile Atherina presbyter Cuvier, 1829 in a marine coastal area adjacent to Tagus estuary (NE Atlantic): A molecular tool for an ecological questionPublication . Almada, Frederico José Oliveira de; Carpi, Piera; Carlos, Fábio Ferreira; Francisco, Sara Martins; Faria, Ana Margarida; Lungu, Ruxanda; Coelho, Pedro Duarte; Neto, José; Gonçalves, Emanuel João; Robalo, Joana IsabelA simple PCR-RFLP consisting in the digestion of a fragment of the 12S ribosomal RNA (12SrRNA) with species-specific restriction enzymes (MboII and HinfI) was developed to distinguish northeastern Atlantic species in the genus Atherina. Unambiguous identification of morphologically similar sympatric species is frequently difficult, especially when younger specimens are included in the analysis. Genetic and morphological analysis of a total of 123 atherinids collected near the mouth of the Tagus estuary (west Portugal) confirmed that only Atherina presbyter (sand smelt) adults and juveniles are recurrently using these marine rocky habitats as spawning and nursery grounds, respectively. The importance of applying non-destructive methods is emphasized. In the future, the conditions involved in the transition from marine A. presbyter to estuarine/ riverine A. boyeri should be further evaluated along with the ability of larvae and juveniles to cope with river flow and tidal currents drift.
- Tidal variation in a rocky inter-tidal fish population : The case of white seabream Diplodus sargus juvenilesPublication . Gonçalves, Ana Sofia Ribeiro; Sousa, Liliana Carvalho; Coelho, Pedro Duarte; Almada, Vítor CarvalhoThe rocky inter-tidal habitat is a harsh and fluctuating environment, subject tofrequent disturbances. Field observations of juvenile white seabream Diplodussargus in inter-tidal rocky habitats were conducted to analyse the spatial distri-bution and feeding activity of this species in relation to the tidal cycle. Thedepth at which fish were observed did not change in most tidal phases whilefeeding activity changed with tidal level, showing the occurrence of tidal migra-tions and that feeding may be limited by habitat availability in shallow watersand thus be dependent on tidal changes. The present results show the exploita-tion of available feeding areas in the rocky inter-tidal by juvenile white seab-ream, which corroborates the importance of these habitats for the firstdevelopmental stages of this fish species.