Browsing by Author "Borges, Rita Alexandra"
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- Androgens and social behaviour in a cichlid fish, Oreochromis mossambicusPublication . Oliveira, Rui Filipe; Carneiro, Luís Alberto; Borges, Rita Alexandra; Canário, Adelino V. M.The relationship between androgen levels and social behaviours of males of the cichlid fish Oreochromis mossambicus (Peters) was investigated. Firstly, males were kept socially isolated for a week prior to placing them together in groups of only males. Urinary androgen (testosterone and 11-ketotestosterone) levels immediately after social isolation were not correlated to a dominance index obtained after male–male interactions in the newly formed groups. In contrast the dominance index obtained immediately after groups formation was a good predictor of androgen levels measured after male–male interactions. Secondly, receptive females were introduced in tanks of isolated males and the pair was followed for 6 h. Although male androgen levels measured prior to the introduction of the females were not correlated to their behavioural (agonistic and sexual) response towards the female, behavioural indices were good predictors of 11-ketotestosterone levels at the end of the trial. In a third experiment, the relationship between aromatase activity in the brain, social status and sexual behaviour was investigated. Brain aromatase activity was not correlated to any of the social behaviours measured but there was a variation in the enzyme activity with sex and gonadosomatic index. These results suggest a short-term social modulation of androgen levels both by male–male and by male–female interactions. Unlike in higher vertebrates, androgendependent activation of male social behaviours in cichlid fishes appears not to be controlled by brain aromatase activity.
- Biomares, a LIFE project to restore and manage the biodiversity of Prof. Luiz Saldanha Marine ParkPublication . Cunha, Alexandra H.; Erzini, Karim; Serrão, Ester A.; Gonçalves, Emanuel João; Borges, Rita Alexandra; Henriques, Miguel; Henriques, Victor; Guerra, Miriam; Duarte, Carlos M.; Marbá, Núria; Fonseca, MarkThe Marine Park Prof. Luiz Saldanha, in the coast of Arrábida, is the first marine park in continental Portugal. This area is a Nature 2000 site and is considered to be a hotspot for European marine biodiversity. In 2005, the management plan of the park was implemented, ending several habitat menaces, thereby allowing an application to the LIFE—NATURE Programme. The LIFE-BIOMARES project aimed at the restoration and management of the biodiversity of the marine park through several actions. The restoration of the seagrass prairies that were completely destroyed by fishing activities and recreational boating, was one of the most challenging. It included the transplanting of seagrasses from donor populations and the germination of seagrass seeds for posterior plantation to maintain genetic diversity in the transplanted area. One of the most popular actions was the implementation of environmental friendly moorings to integrate recreational use of the area with environmental protection. Several dissemination and environmental education actions concerning the marine park and the project took place and contributed to the public increase of the park acceptance. The seabed habitats were mapped along the park and a surrounding area to 100 m depth in order to create a habitat cartography of the park and to help locate alternative fishing zones. Biodiversity assessments for macrofauna revealed seasonal variations and an effect of the protection status. Preliminary results are presented and show that the marine park regulations are having a positive effect on biodiversity conservation and sustainable fisheries, thereby showing that these kind of conservation projects are important to disseminate coastal conservation best practices. The Biomares project is a model project that can be followed in the implementation of marine reserves and the establishment of the Natura 2000 marine network.
- Critical swimming speeds of wild-caught sand-smelt Atherina presbyter larvaePublication . Faria, Ana Margarida; Borges, Rita Alexandra; Gonçalves, Emanuel JoãoSwimming abilities of wild-caught sand-smelt Atherina presbyter larvae were assessed as critical swimming speed (Ucrit) throughout ontogeny. The mean Ucrit increased with size, ranging from 3⋅6 to 18⋅7 cms−1, over the size range of 6⋅6–21⋅0mm LT. This indicates that at hatching A. presbyter larvae, far from being passive floaters, are already capable of active behaviours, which may influence their dispersal patterns.
- Depth distribution of nearshore temperate fish larval assemblages near rocky substratesPublication . Beldade, Ricardo; Borges, Rita Alexandra; Gonçalves, Emanuel JoãoIn this study, we compare the composition, abundance and structure of a temperate fish larval assemblage at different depth intervals (0–4, 4–8 and 8–12 m) in the extreme nearshore environment. We used a plankton net attached to an underwater scooter to sample in close proximity to the rocky substrate (<50 cm). A total of 868 larvae from 27 taxa in 13 families were caught. The majority of larvae belonged to benthic reef-associated species (Blenniidae, Gobiidae, Gobiesocidae and Tripterygiidae), the four most abundant comprising 76% of the total larvae caught. A non-metric multidimensional scaling analysis (MDS) showed that there was a single multispecific larval patch near the substrate in the extreme nearshore up to 12 m depth. Nonetheless, distinct larval abundances were found in this relatively small depth range, with the majority of species being more abundant at the deepest interval, particularly Pomatoschistus pictus and Gobius xanthocephalus. Tripterygion delaisi was an exception being more abundant at the shallowest depth as young larvae. The density of pre-flexion larvae was not significantly different across depth intervals, but post-flexion larval density increased with depth. The full size range (from hatching to settlement) of P. pictus was present at the extreme nearshore. The innovative sampling technique used here revealed high densities of larvae close to the bottom, and depth was found to be an important factor influencing the distribution of several taxa and ontogenetic stages. The nearshore component of coastal fish larval assemblages near rocky substrates has been poorly studied, and our results suggest that the high densities of larvae found to aggregate in these environments must be taken into account when studying distribution and functional aspects of these assemblages.
- Early development of the red mouthed goby, Gobius cruentatus (Pisces: Gobiidae)Publication . Gil, Fátima; Borges, Rita Alexandra; Faria, Cláudia Barreiros Macedo de; Gonçalves, Emanuel JoãoThe full developmental embryonic sequence of Gobius cruentatus is described for the first time. Embryonic development lasted 13 days (14·0–15·0°C). The newly hatched larvae (3·3 mm total length) presented pigmented eyes, the yolk is fully absorbed, and the mouth and anus were opened allowing the onset of exogenous feeding almost after hatching.
- Early life history of larvae and early juvenile atlantic horse mackerel trachurus trachurus off the portuguese west coastPublication . Beveren, Elisabeth Van; Klein, Maria; Serrão, Ester A.; Gonçalves, Emanuel João; Borges, Rita AlexandraEarly life history traits (ELHTs) are key to understand recruitment patterns in marine animals. However, for reef fishes, studies on ELHTs are mainly focused on tropical systems and little is known for temperate reefs. In this study we used SMURFs (Standard Monitoring Units for the Recruitment of Reef Fishes) to collect fish in a temperate rocky reef system (Arrábida Marine Park, Portugal) on a weekly basis for three months during the recruitment period. Six sub-surface SMURFs sampled 2490 Atlantic horse mackerel (Trachurus trachurus) postlarvae and juveniles. Sagittal and lapilli otoliths were extracted from a subsample of 296 fish and ELHTs, such as size and age at settlement, growth rate and age at first secondary growth formation were examined. Additionally, we tested three growth curves and selected the best suited to back-calculate the hatching pattern based on the lengths of all sampled fish. Standard length ranged from 6.13 mm to 48.56 mm and subsampled fish were aged between 19 days to 44 days. Age and size at settlement were estimated between 19 days and 36 days for individuals of 6.13 mm and 24.95 mm, respectively. Otolith shape changed clearly with increasing age and, on average, secondary growth started to form on day 33 (±3 days). Age/length relationship was well described by a Gompertz growth model which was used to back-calculate hatching dates. Four distinct hatching cohorts were identified with fish of the earliest cohort showing a faster body and otolith growth. This study indicates that the nearshore environment might have an important role in the early growth, development and hence recruitment of Atlantic horse mackerel. Information on the early life history of Atlantic horse mackerel is key to understand recruitment processes for this economically and biologically important species.
- Embryonic and larval development of Gobius paganellus (Pisces: Gobiidae)Publication . Borges, Rita Alexandra; Faria, Cláudia Barreiros Macedo de; Gil, Fátima; Gonçalves, Emanuel João; Almada, Vítor CarvalhoThe full developmental sequence from egg to juvenile of Gobius paganellus under controlled conditions is described. Embryonic development lasted 9-10 days at 18.5-20.0ºC and 10-11 days at 15.0-16.5ºC. Newly hatched larvae measured 3.90 mm, had the mouth and anus opened, pigmented eyes and almost no yolk. They ¢rst settled 25 days after hatching (10.0-10.5mm total length [TL]) and showed juvenile behaviour and body form 36 days after hatching (14.0mmTL). However, they only showed full juvenile pigmentation patterns 15 days later (17.0mmTL) (16.0-16.5ºC). In addition, a preliminary di¡erentiation between the newly hatched larvae of the most common Gobius species of south-western European shores is presented.
- Embryonic and larval development of Lipophrys pholis (Pisces: Blenniidae)Publication . Faria, Cláudia Barreiros Macedo de; Borges, Rita Alexandra; Gil, Fátima; Almada, Vítor Carvalho; Gonçalves, Emanuel JoãoInformation on the early ontogeny of Lipophrys pholis is scattered and incomplete. In this paper we describe for the first time the full developmental sequence from egg to juvenile in controlled conditions. In addition, some notes on the spawning behaviour of adults and the behaviour of larvae are provided. During oviposition, the female follows the male´s path, suggesting that the male may apply sperm on the nest before spawning. Embryonic development lasted 16 days (17ºC) and larval development to settlement lasted 29 days (15.5-17.5ºC). At hatching, mean larval total length was 5.0 mm. The larvae hatched with the mouth and anus opened, with pigmented eyes and almost no yolk, and started to feed within one day. They first settled 29 days after hatching (13-14 mm TL) and showed full juvenile pigmentation and behaviour 8 to 9 days later (17-19 mm TL).
- High interannual variability in connectivity and genetic pool of a temperate clingfish matches oceanographic transport predictionsPublication . Klein, Maria; Teixeira, Sara; Assis, Jorge; Serrão, Ester A.; Gonçalves, Emanuel João; Borges, Rita AlexandraAdults of most marine benthic and demersal fish are site-attached, with the dispersal of their larval stages ensuring connectivity among populations. In this study we aimed to infer spatial and temporal variation in population connectivity and dispersal of a marine fish species, using genetic tools and comparing these with oceanographic transport. We focused on an intertidal rocky reef fish species, the shore clingfish Lepadogaster lepadogaster, along the southwest Iberian Peninsula, in 2011 and 2012. We predicted high levels of self-recruitment and distinct populations, due to short pelagic larval duration and because all its developmental stages have previously been found near adult habitats. Genetic analyses based on microsatellites countered our prediction and a biophysical dispersal model showed that oceanographic transport was a good explanation for the patterns observed. Adult sub-populations separated by up to 300 km of coastline displayed no genetic differentiation, revealing a single connected population with larvae potentially dispersing long distances over hundreds of km. Despite this, parentage analysis performed on recruits from one focal site within the Marine Park of Arrábida (Portugal), revealed self-recruitment levels of 2.5% and 7.7% in 2011 and 2012, respectively, suggesting that both long- and short-distance dispersal play an important role in the replenishment of these populations. Population differentiation and patterns of dispersal, which were highly variable between years, could be linked to the variability inherent in local oceanographic processes. Overall, our measures of connectivity based on genetic and oceanographic data highlight the relevance of long-distance dispersal in determining the degree of connectivity, even in species with short pelagic larval durations.
- Horizontal spatial and temporal distribution patterns of nearshore larval fish assemblages at a temperate rocky shorePublication . Borges, Rita Alexandra; Ben-Hamadou, Radhouan; Chícharo, Maria Alexandra; Ré, Pedro; Gonçalves, Emanuel JoãoThere have been no previous studies of the composition of nearshore larval fish assemblages along the coast of Portugal. We aimed to describe the composition and horizontal distribution patterns of larval fish assemblages and their temporal dynamics near a rocky reef at depths shallower than 13 m (inshore) and at two miles (3.70 km) from shore (offshore), as well as along transects perpendicular to the shoreline, from the reef to 10 miles offshore (18.52 km). Samples were taken using 5 min sub-surface trawls at the rocky shore of the Arra´bida Marine Park (W Portugal). A total of 1021 larvae were collected, belonging to 61 taxa inshore and to 29 taxa offshore. Along transects, 626 larvae of 52 taxa were collected. Most larvae belonged to coastal species associated with rocky reefs. Total larval abundance and diversity were higher from May to July, which is consistent with the spawning activity of adults. Diversity and total larval abundance decreased significantly with increasing distance from shore, both in the inshore/offshore comparison and in the transects, where this decrease was evident at a very small spatial scale (within the first mile from the reef). Species assemblages differed in the pattern of distribution, with most species clearly associated to the extreme nearshore. The distribution patterns obtained were independent of the spawning mode of species. Results are discussed in the light of the possible physical mechanisms that can potentially act at the Arra´bida Marine Park to facilitate larvae retention and the role of larval behaviour.