UIE-E - Artigos em revistas internacionais
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- Some features of the territories in the breeding males of the intertidal blenny Lipophrys pholis (Pisces: Blenniidae)Publication . Almada, Vítor Carvalho; Gonçalves, Emanuel João; Oliveira, Rui Filipe; Barata, Eduardo NunoIn this paper we present data on the organization of the territories in males of Lipophrys pholis during the breeding season. Data were collected during high tides by skin- and scubadiving and during low tides by direct inspection of nests. Our study area was located at Arrébida, Portugal. The main results are: (i) The territories of the breeding males of this species are temporary, being established each breeding season, (ii) The guarding males stay in the nest holes with the egg masses while the tide is low and are subjected to several hours of emersion in each tidal cycle, (iii) Even when the nests are submerged the fishes stay inside the nest for an average of 92% of the time. All the activities performed outside the nest correspond to an average of 27 minutes per day. (iv) There was a low frequency of territorial intrusions. Conspecific intruders released a significantly higher frequency of agonistic responses than did Coryphoblennius galerita. (v) Removal experiments showed that vacated territories are not occupied by other males during the same breeding season, (vi) Without the presence of the guarding male the eggs are slowly destroyed by predation and infection, but some eggs can still survive and hatch up to five days after the removal of the parental male. The results are discussed in terms of the probable costs and benefits of breeding intertidally.
- Growth of sprat Sprattus sprattus larvae in the German Bight (North Sea) as inferred by otolith microstructurePublication . Ré, Pedro; Gonçalves, Emanuel JoãoGrowth of sprat larvae was studied in the German Blght of the North Sea and 2 different statlons (stratlfled and mixed water masses) were compared. Sprat larvae were aged using dally growth increments in sagittal otoliths. The daily nature of otolith growth increments was corroborated using the marginal increment technique. The data presented are consistent with the deposition of one complete increment per 24 h period, indicating that at least larvae with lengths greater than 11.0 mm form daily growth increments in their otoliths. There was some evidence that daily growth increments are deposited on the otoliths of sprat larvae only after the onset of exogenous feeding. Integrated somatic growth rate was 0.406 mm d-'. This value is comparable to others obtained for similar pelaglc clupeoid species. There were no significant differences between growth rates at the 2 stations.
- On the occurrence of Parablennius sanguinolentus (Pisces: Blenniidae) on the portuguese coastPublication . Gonçalves, Emanuel João; Almada, Vítor Carvalho; Almeida, Armando J.; Oliveira, Rui FilipeIn this paper we report for the first time the occurrence of Parablennius sanguinolentus in mainland Portuguese waters. Since this species is common in the Mediterranean and in the Bay of Biscay, there appears to be a distributional gap along the Portuguese coast. The present finding, together with recent data on the occurrence of several other blenniids in the Atlantic coast of the Iberian Peninsula, formerly supposed to be Mediterranean endemics, stresses the urgent need for detailed zoogeographical investigations on the inshore fish fauna of south-west Europe.
- The reproductive behavior of the longspine snipefish, Macrorhamphosus scolopax (Syngnathiformes, Macrorhamphosidae)Publication . Oliveira, Rui Filipe; Almada, Vítor Carvalho; Gil, Maria de FátimaAbout two hundred Macrorhamphosus scolopax were observed in a large tank and their behavior was videotaped for subsequent analysis. When not disturbed, the fish moved slowly in a head-down position. Spawning in the tank took place in the last two hours before dark. Courting males change color and actively interact aggressively with other males. They push against each other while swimming in parallel or they charge their opponents with their erected dorsal spine directed at them. Courtship begins near the bottom. After following and swimming parallel to the female the two fish unite tightly by their caudal peduncle, with their ventral regions in close proximity and rise slowly in the water column. During the ascent, the genital papilla of the female extends repeatedly and contacts the genital region of the male.
- Breeding ecology and nest aggregations in a population of Salaria pavo (Pisces: Blenniidae) in an area where nest sites are very scarcePublication . Almada, Vítor Carvalho; Gonçalves, Emanuel João; Santos, António José; Baptista, Maria CéuIn this paper we present data on the breeding ecology and patterns of nest aggregation in a population ofSalaria pavo (Pisces: Blenniidae), in an area where hard substrates are very scarce. The study site was at Ria Formosa, an extensive littoral lagoon on the south coast of Portugal. The only hard materials available are bricks, tiles, stones and debris that clam culturists use to delimit their fields. The males of S. pavo establish nests intertidally in the holes of the bricks where they guard the eggs. Data were collected at low tide inspections of these artificial ridges and underwater behavioural observations during high tide. The main results are: (i) the same male can establish sequentially more than one nest in the same breeding season; the number of males that stay within the bricks increases before the start of the breeding season and declines towards its end; (ii) there is a large excess of mature males that do not establish nests and they are significantly smaller than the nesting males, suggesting very strong competition for nest sites; (iii) the nests of several males occur in adjacent holes of the same brick, sometimes being entirely surrounded by other nests. Thus, in this population, there is virtually no defended territory around the nest, a situation not known for other blenniid species. This pattern of nest aggregation implies both strong competition among males and reduction of aggression between neighbour parental fishes. This can be explained by the extreme scarcity and spatial distribution of available nest sites.
- Sexual dimorphism and allometry of external morphology in Oreochromis mossambicusPublication . Oliveira, Rui Filipe; Almada, Vítor CarvalhoSexual dimorphism in growth of conventional morphometric characters was investigated in juveniles and young adults (size range: 31 to 91 mm) of Oreochromis mossambicus. A closely associated set of traits was identified that shows sexually dimorphic growth, which was positively allometric in the males. These traits correspond to two different morphological complexes: jaw structure and anal/dorsal fins. The best sex discriminators among this set of traits were premaxilla width, anal fin height and snout length. These findings may be explained in terms of intra- and inter-sexual selection acting together and favouring males with strong and large mouths and high dorsal and anal fins, traits that are important in agonistic displays (jaw and fins), fighting and nest digging (jaw).
- Courting females: Ecological constraints affect sex roles in a natural population of the blenniid fish Salaria pavoPublication . Almada, Vítor Carvalho; Gonçalves, Emanuel João; Oliveira, Rui Filipe; Santos, António JoséInexistente
- Social modulation of sex steroid concentrations in the urine of male cichlid fish Oreochromis mossambicusPublication . Oliveira, Rui Filipe; Almada, Vítor Carvalho; Canário, Adelino V. M.The relationship between urinary concentrations (free + sulfates + glucuronides) of the steroids testosterone (T), 11-ketotestosterone (11KT), 17α, 20β-dihydroxy-4-pregnen-3-one (17,20β-P) and 17α,20α-dihydroxy-4-pregnen-3-one (17,20α-P), and the social behavior of males of the cichlid fishOreochromis mossambicuswas investigated. After 8 days of isolation none of the steroids were good predictors of social dominance developed after subsequent formation of all-male groups. One day after group formation dominance indexes were good predictors of the urine concentrations of all sex steroids. Dominance indexes and androgen concentrations measured after all-male group formation were positively correlated with territoriality, courtship rate, and nest size. Similar relationships were found for progestins with the exception that they were not correlated with courtship rate. All-male group formation was also accompanied by an increase in urinary sex steroid concentrations in fish that became territorial and a decrease in non-territorial fish with the exception of T, which increased in both groups. Addition of ovulating females caused steroid concentrations to return to levels near isolation, except for 17,20α-P in territorials, which underwent a large increase. Thus, social interactions may have an important modulatory effect on sex steroid concentrations in O. mossambicus.
- Cetaceans of the cape verde archipelagoPublication . Reiner, Francisco; Santos, Manuel Eduardo dos; Wenzel, Frederick W.; Whale, Alliedinexistente
- On the (in)stability of dominance hierarchies in the cichiid fish Oreochromis mossambicusPublication . Oliveira, Rui Filipe; Almada, Vítor CarvalhoDominance hierarchies were studied during 8 weeks in eight heterosexual captive groups of Oreochromis mossambicus at Ihe unset of sexual maturity. Linearity was assessed for each group on a weekly basis based on the Landau's index (h) and on the procedure described by Appleby [Appleby MC (1983): Animal Behaviour 31:600-6081. Week-toweek stability of the hierarchical structures was measured using the Burk's stability index (b) and Spearman rank correlation coefficients for the ranks of fishe.s in consecutive weeks. The two measures of stability showed a high level of concordance but the Spearman rank correlations were more conservative in detecting cases of stability. Although most dominance structures were linear they were unstable frum week to week. Dominant individuals were less likely to experience rank reversals than subordinates. Rank reversals were especially likely among hierarchical neighbors. Dominance hierarchies did not -Stabilize in tbe time span of tbis study.