UIE-E - Actas de reuniões cientificas
Permanent URI for this collection
Browse
Recent Submissions
- Hormonas e comportamento - Aspectos actuais da endocrinologia comportamentalPublication . Oliveira, Rui FilipeNo presente trabalho o autor propõe-se analisar, com base na literatura existente, a relação existente entre hormonas e comportamento. São de salientar os seguintes pontos: (1) Não existe uma hormona específica para determinado comportamento; os comportamentos expressam sim o «resultado final» de um estado fisiológico momentâneo no qual podem estar envolvidas várias hormonas; (2) A relação entre hormonas e comportamento é biunívoca. Não só as hormonas influenciam comportamentos como também estes modulam determinados estados hormonais; (3) AS hormonas podem estar envolvidas no comportamentoa a dois níveis diferentes: durante a ontogenia com um papel organizacional e no animal adulto com um papel activacional. Em ambos os níveis as hormonas podem actuar em quatro sistemas diferente: mecanismos sensoriais, mecanismos motivacionais, mecanismos motores e sobre características somáticas com valor social (e.g., caracteres sexuais secundários). (4) Os estudos de endocrinologia comportamental cometem frequentemente dois tipos de erros: a) Utilizam unidades comportamentais grosseiras, muitas vezes afastadas da realidade biológica da espécie em estudo; b) Na maior parte dos trabalhos em que se recorre à administração de hormonas utilizam-se dosagens farmacológicas e não fisiológicas; (5) Os resultados positivos obtidos com administração de hormonas devem ser encarados cuidadosamente uma vez que a maior parte das hormonas tem um tempo de vida muito curto e os seus metabólitos podem ser biologicamente activos.
- 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.
- Use of temperate reef fish community to identify priorities in the estabilishment of a marine protected areaPublication . Gonçalves, Emanuel João; Henriques, Miguel; Almada, Vítor CarvalhoFew studies have dealt with biodiversity, composition and dynamics of temperate reef fish. The present study area is a 25 km stretch of coastline (53 km2) on the west Portuguese coast that has recently been assigned as a Marine Park (Marine Park of the Arrábida Nature Park), for which basic information on composition of the marine communities is very scarce. From a biogeographical perspective, mainland Portugal is in a transitional zone where many species of cold- and warm-water fish reach their southern and northern limits of distribution respectively. This situation contributes strongly to a high level of biodiversity in the Lusitanian province, and also makes it very sensitive to climatic oscillations such as those predicted as part of global warming. This study analysed the fish community composition in the marine park and ascribed a hierarchical importance for the coastal sectors and the different habitats present. The results reflect the heterogeneous nature of the substrata present and their significant differences in biodiversity values and in the occurrence of rare species. For each species, dispersion and abundance indexes were calculated and species that require particular attention are noted. Appropriate management measures are suggested. Procedures for the implementation of these measures must be suited to a situation where basic biological information is scarce. This research is included in a broader project aimed at building a long-term database of the fish communities in this area, assessing the main factors influencing their structure and distribution patterns, and monitoring reserve effects in the long term.
- Influence zones of pile-drive noise on a resident population of bottlenose dolphins in the Sado estuary, PortugalPublication . Luís, Ana Rita; Silva, C.; Andrade, Fabiana Fontenelle de; Santos, Manuel Eduardo dosInexistente