Browsing by Author "Faria, Ana M."
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- Benthic food webs support the production of sympatric flatfish larvae in estuarine nursery habitatPublication . Dias, Ester; Morais, Pedro; Faria, Ana M.; Antunes, C.; Hoffman, Joel C.Identifying nursery habitats is of paramount importance to define proper management and conservation strategies for flatfish species. Flatfish nursery studies usually report upon habitat occupation, but few attempted to quantify the importance of those habitats to larvae development. The reliance of two sympatric flatfish species larvae, the European flounder Platichthys flesus and the common sole Solea solea, on the estuarine food web (benthic versus pelagic), was determined through carbon and nitrogen stable isotope analysis. The organic matter sources supporting the production of P.flesus and S.solea larvae biomass originates chiefly in the benthic food web. However, these species have significantly different C-13 and N-15 values which suggest that they prey on organisms that use a different mixture of sources or assimilate different components from similar OM pools (or both).
- Effects of starvation on swimming performance and body condition of pre-settlement Sparus aurata larvaePublication . Faria, Ana M.; Gonçalves, Emanuel J.; Chicharo, AlexandraBody condition in larval fishes is an important determinant of survival in the natural environment. However, few studies correlate body condition with behavioural traits critical for survival, such as swimming performance. In the present study, we compared normally fed larvae of gilthead seabream Sparus aurata Linnaeus, 1758, at various intervals post-hatch with larvae which were starved for 1 to 3 d (for Ucrit) or 2 d (for swimming endurance). Feeding treatment (fed and or unfed) had no effect on the relationship between Ucrit and larval size. However, in the endurance experiment, fed individuals swam twice as far as unfed larvae (19.7 km for fed larvae and 9.5 km for unfed larvae). The RNA/DNA ratio was higher in fed larvae in the Ucrit experiment, but significant effects were only detectable after a 3 d period of starvation. Fulton’s condition factor was significantly higher in fed larvae in the endurance trial, which suggests that growth (in weight) of starved larvae was affected by long-term swimming. Taken together, these results suggest that for aging and orientation behaviours (activities in which critical speeds might be involved) are not affected by reduced feeding over a few days, but that sub-lethal effects of starvation may affect dispersal potential (for which endurance swimming is critical) and therefore compromise subsequent recruitment to the adult population.
- Influence of starvation on the critical swimming behaviour of the Senegalese sole (Solea senegalensis) and its relationship with RNA/DNA ratios during ontogenyPublication . Faria, Ana M.; Muha, T.; Morote, E.; Teodosio, MariaFood availability can affect larval survival directly through starvation and indirectly through the effects on larval growth rate, swimming performance and vulnerability to predators. In the present study we evaluate the effects of starvation on growth, nutritional condition and swimming behaviour of the Senegalese sole (Solea senegalensis) throughout ontogeny (8 to 14 days after hatching). Biochemical analysis (RNA/DNA ratios) and behavioural experiments (critical swimming speed, Ucrit) were conducted on larvae reared under 3 feeding treatments: fed ad libitum, deprived of food for 48 hours and deprived of food for 96 hours. Growth was significantly affected by feeding treatment, while only slight decreases in RNA/DNA ratio and swimming performance were registered. Late stage larvae of the three feeding treatments had slower critical speeds than the pre-flexion and flexion stages, which is probably related to the benthic lifestyle acquired by the species at the end of the larval period. These physiological and behavioural changes are in accordance with previous results, which show that flatfish larvae are more resistant to starvation than pelagic species and that they become less active later in development.
- Ontogeny of critical swimming speed of wild-caught and laboratory-reared red drum Sciaenops ocellatus larvaePublication . Faria, Ana M.; Ojanguren, Alfredo F.; Fuiman, Lee A.; Gonçalves, Emanuel J.Critical swimming speed (U,,it) provides a useful estimate of maximum swimming performance for fish larvae that can be used to assess transport and migratory potential. We measured U,it of red drum Sciaenops ocellatus larvae through its ontogeny and compared the swimming performance of laboratory-reared larvae to that of wild-caught individuals. U-crit increased with ontogeny (size), even though variability in U-crit at any ontogenetic state was large. U-crit for wild-caught larvae increased from 9.7 to 22.2 cm s(-1) over the range of 8.3 to 16.3 mm TL and from 1.1 to 20.5 cm s(-1) over the range of 3.0 to 19.1 mm TL for reared larvae. The ontogenetic increase in critical swimming speed occurred in 2 phases-an early phase of rapid improvement, and a later phase of slower improvement. This sharp change in the trajectory of swimming performance coincided with important changes in ecology, morphology, and hydrodynamics. During the early phase, larvae were pelagic, their growth was highly allometric, especially in the caudal region, and they swam in the inertial hydrodynamic regime. The onset of the later phase coincided with settlement into seagrass beds, isometric growth, and inertial effects on locomotion. Wild larvae generally exhibited greater values of U,it than reared larvae of a comparable size, but the difference was not statistically significant. The results of this comparison imply that research on reared larvae may provide naturalistic results for swimming performance and that hatchery-produced larvae may perform certain behaviours well when released into the wild.
- Ontogeny of swimming behaviour of two temperate clingfishes, Lepadogaster lepadogaster and L-purpurea (Gobiesocidae)Publication . Faria, Ana M.; Gonçalves, EmanuelGobiesocids are typically reef-dwelling species whose larvae have been found in several nearshore rocky environments; this suggests a possible retention pattern for these species. Retention may occur due to the physical features of an area and/or active larval behaviour, such as swimming abilities. In the laboratory, we measured the ontogeny of swimming behaviour (routine speed and critical speed, U-crit) of 2 clingfish species, Lepadogaster lepadogaster and L. purpurea. L. lepadogaster larvae swam better than L. purpurea larvae, but this difference might be related to differences in water temperature, since the former is a spring spawner, whereas the latter spawns during winter. It is well known that water viscosity increases with decreasing temperature, making swimming more difficult. Routine and critical swimming speeds of larvae of both species increased with ontogeny (size) despite high variability at any ontogenetic state. U-crit ranged from 1 to 9.4 and 1.2 to 6.5 cm s(-1) in L. lepadogaster and L. purpurea, respectively. Routine speeds were similar to 18 to 19% of the maximum U-crit registered for both species. Interestingly, swimming speed started to decrease as settlement size (10 to 11 mm total length) was approached, concurrent with the development of a ventral sucking disk that allows individuals to attach to the bottom of the swimming chamber and counteract strong currents. This shift in swimming behaviour that is associated with settlement is probably an adaptation to the cryptobenthic mode of life of these fish.