Percorrer por autor "Santos, Ricardo Serrão"
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- Contrasting movements and residency of two serranids in a small Macaronesian MPAPublication . Afonso, P.; Abecasis, D.; Santos, Ricardo Serrão; Fontes, JorgeProtection inside marine reserves and the desired ‘reserve effect’ depend directly on the home rangeand sedentary behaviour of fishes throughout their lives. Benthic territorial predators are typically seenas major candidates to beneficiaries, but empirical evidence of short-versus long term residency is stillsurprisingly rare. We studied the inter-annual patterns of site fidelity and finer scale movements in twoof the most abundant benthic predators of the NE Atlantic coastal reefs, the dusky grouper (Epinephelusmarginatus) and the blacktail comber (Serranus atricauda), using passive acoustic telemetry inside andaround a small marine reserve in the Azores islands, central North Atlantic. Individuals of both speciesresided in the reserve year-round, occupying stable core activity areas within relatively small homeranges. Groupers were detected nearly every day (n = 11, median = 5.0 years) while combers were stilldetected in 2/3 of the days (n = 9, median = 2.0 years). Some dusky groupers underwent daily short-rangeforays during the summer, most probably related to spawning events, whereas combers appeared toforay for longer periods with no direct relation with reproductive activity. The two species also contrastin their diel pattern, strictly diurnal in the comber but crepuscular in the grouper. This study evidencesthat even small reserves within the size range of most coastal reserves can accommodate the multiple-scale patterns of space use of exploited benthic territorial species, and promote the recovery of theirlocal exploited populations in the long-term via the ‘reserve effect’ and, potentially, via the ‘larval export’effect.
- Endocrine correlates of male polymorphism and alternative reproductive tactics in the Azorean rock-pool blenny, Parablennius sanguinolentus parvicornisPublication . Oliveira, R. F.; Canario, Adelino V. M.; Grober, M. S.; Santos, Ricardo SerrãoIn the Azorean rock-pool blenny male sexual polymorphism occurs. Larger and older males (M1 males) fully express male secondary sex characters (SSC), particularly an anal gland that produces a sex pheromone, whereas smaller and younger sexually active males do not express SSC (M2 males). Two mating tactic types can be identified among M1 males: nest-holders that establish nests and court females and floaters that move around in the breeding area and try to achieve parasitic fertilizations and/or to take over nests. Two behavioral tactic types can also be identified within M2 males: satellites that are associated with particular nests and actively participate in territorial defense (when females go inside the nest to spawn they try to enter to fertilize some of the eggs) and sneakers that do not help nest holders (when spawning occurs they also try to enter the nest to fertilize eggs). It was found that M1 males have significantly higher levels of 11-ketotestosterone (KT), but not testosterone (T), than M2 males [M1 male androgen levels (mean 6 SE): total T 5 11.6 6 3.0 ng ml21, total KT 5 4.5 6 1.1 ng ml21; M2 male androgen levels (mean 6 SE): total T 5 9.6 6 1.0 ng ml21, total KT 5 2.5 6 1.1 ng ml21]. There were no differences in plasma T or KT among individuals using different mating tactics within the same male morph; that is, among M1 males, nest-holders did not differ in androgen levels from floaters [nest-holder androgen levels (mean 6 SE): total T 5 12.3 6 4.4 ng ml21, total KT 5 4.3 6 1.4 ng ml21; floater androgen levels (mean6SE): total T55.960.8 ng ml21, total KT 5 3.4 6 0.3 ng ml21], and among M2 males, satellites did not differ in androgen levels from sneakers [satellite androgen levels (mean 6 SE): total T 5 7.7 6 1.5 ng ml21, total KT51.360.3 ng ml21; sneaker androgen levels (mean6SE): total T58.361.6 ng ml21, total KT 5 1.4 6 0.3 ng ml21]. Thus, the observed differences appear to be correlated with the expression of different male morphotypes and not with the expression of different behavioral tactics within the morphotype. Androgen levels were not correlated with the behavior activity of nest-holders, except for a negative correlation between KT levels and parental behavior. Furthermore, nestholder males that succeeded in having females spawn in their nests during the observation period had significantly lower KT levels than unsuccessful males. Since behavioral observations preceded blood sampling in time, it is suggested that these results indicate a negative relationship between KT and parental care, since successful males were parenting when blood samples were collected. Male SSC were better correlated with KT than with T and the use of total blood levels (i.e., free 1 conjugates) yielded higher correlation coefficients than when only the free fraction of each steroid was considered. Since conjugates are nonactive metabolites of the free androgen they should reflect active free steroids in a previous time. Thus, their incorporation into the hormonal measurements increases the time frame captured, and because steroids are released in a pulsatile way, this time-integrated measure can be more meaningful than the free steroids, which represent a snapshot of the hormone levels at a given point in time.
- Metal interactions between the polychaete Branchipolynoe seepensis and the mussel Bathymodiolus azoricus from Mid-Atlantic-Ridge hydrothermal vent fieldsPublication . Bebianno, Maria João; Cardoso, Cátia; Gomes, Tânia; Blasco, Julian; Santos, Ricardo Serrão; Colaço, AnaThe vent blood-red commensal polynoid polychaete Branchipolynoe seepensis is commonly found in the pallial cavity of the vent mussel Bathymodiolus azoricus, the dominant bivalve species along the Mid-Atlantic-Ridge (MAR) and is known to be kleptoparasitic. Mussels were collected from three hydrothermal vent fields in the MAR: Menez Gwen (850 m depth, MG2, MG3 and MG4), Lucky Strike (1700 m depth, Montségur-MS and Eiffel Tower-ET) and Rainbow (2300 m depth). Polychaetes were absent in all Menez Gwen vent mussels, while the highest percentage was detected in mussels from Lucky Strike, where more than 70% of the mussels had at least one polychaete in their mantle cavity, followed by Rainbow with 33% of mussels with polychaetes. Total metal concentrations (Ag, Cd, Co, Cu, Fe, Mn, Ni and Zn) were determined in polychaetes whole body and in the mussel tissues (gills, digestive gland and mantle). To understand the possible metal interactions between symbiont and host, the activity of antioxidant defence (catalase (CAT), metallothioneins (MTs)), biotransformation enzymes (glutathione-s-transferases (GST)) activities and lipid peroxidation (LPO) were determined in polychaete whole soft tissues and in mussel tissues (gills, digestive gland and mantle). Metal concentrations in polychaetes and mussels tissues indicated that the accumulation patterns were species specific and also influenced by, and possibly dependent upon, the inter- and intra-variation of vent physico-chemistry between hydrothermal fields. Despite not detecting any strong correlations between metal and enzymes activities in polychaetes and mussels, when in presence of polychaetes, mussels presented less metal concentrations in the gills and digestive gland and lower activity of enzymatic biomarkers. This leads to infer that the polychaete plays a role on the detoxification process, and the interaction between the polychaete mussel association is probably an adaptation to metals concentrations at the vent sites.
- Molecular insights indicate that Pachycara thermophilum (Geistdoerfer, 1994) and P. saldanhai (Biscoito and Almeida, 2004) (Perciformes: Zoarcidae) from the Mid-Atlantic Ridge are synonyms speciesPublication . Stefanni, S.; Porteiro, F. M.; Bettencourt, R.; Gavaia, Paulo J.; Santos, Ricardo SerrãoThe genus Pachycara comprises of 20 species distributed across the globe. Due to difficulties in collecting these fish, most of the species were described from single or few individuals. Until now, the systematics for these species has been based on traditional taxonomy and the only studies with molecular interest were performed on the Circum Antarctic Pachycara brachycephalum.
- The role of androgens in the trade-off between territorial and parental behavior in the Azorean rock-pool blenny, Parablennius parvicornisPublication . Ros, A. F. H.; Bruintjes, R.; Santos, Ricardo Serrão; Canario, Adelino V. M.; Oliveira, R. F.Androgen hormones have been shown to facilitate competitive ability in courtship and territorial behavior, while suppressing paternal behavior. The rock-pool blenny, Parablennius parvicornis, provides an excellent model to study the proximate regulation of such a trade-off between territorial and parental behavior, because nest-holder males of this species display these behaviors simultaneously. A field study was carried out in which territorial nest holder males were either treated with long-lasting implants filled with 11-ketotestosterone (11-KT) or with control implants. Males treated with 11-KT showed a higher frequency of aggressive behavior, were more responsive to aggressive challenges, and were more persistent in aggressive behavior than control males. In addition, territories were larger in males treated with 11-KT than in controls. We found evidence for incompatibility between defense of a large territory and high levels of parental behavior. However, contrary to expectation, 11-KT did not suppress parental behavior. We suggest that trade-offs between territorial and parental behavior may not be regulated by androgen hormones but may result from a time constraint in the individual’s activity budget.