O conhecimento científico do mar

Os mares e oceanos têm um papel vital para a vida do planeta Terra. Para além de fonte importante de recursos vivos, minerais e energéticos têm assegurado a reciclagem e o depósito de numerosos contaminantes com que as sociedades modernas, após a revolução industrial, vêm poluindo os ecossistemas do planeta que habitamos. Deste modo, têm vindo a adiar, mas não a eliminar, cenários de catástrofe ambientais. Os estudos actuais em ciências do mar são assim importantes não só em termos estritamente científicos mas também dada a relevância e urgência social, económica, política e de gestão. Portugal está particularmente bem posicionado para o desenvolvimento e aplicação da investigação naquele domínio científico. Portugal, que detém uma das maiores Zonas Económicas Exclusivas da Europa, na qual grande parte é oceano aberto e mar profundo, tem assim condições especiais, mas também obrigações para desenvolver a investigação em ciências do mar. A investigação científica nacional em ciências do mar, apesar de tardia no âmbito do sistema científico mundial e nacional, tem vindo a fazer progressos acentuados em comparação com outros domínios disciplinares. Na última década, o ranking de publicações científicas indexadas internacionalmente em domínios das ciências marinhas passou para o 13ª lugar, quando na década passada ocupava o 30ª lugar entre os diferentes tópicos identificados pelo portal Web of Knowledge. Neste artigo são analisados alguns dos progressos alcançados e encarado com optimismo o progresso científico nacional para o século XXI agora que o país está dotado de uma estratégica nacional para os Oceanos, de uma estratégia nacional para o Mar e que dispõe de dois navios oceanográficos de alto mar e um ROV que pode explorar os oceanos até à profundidade de 6000 metros

Comportamento e evolução

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Sobre a questão das estratégias alternativas em biologia

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Padrões de actividade e estrutura dos territórios dos machos parentais de Parablennius pilicornis cuvier (Pisces: Blenniidae) da costa portuguesa

Observações sub-aquáticas do comportamento territorial e parental de machos de P. pilicornis, realizadas durante os meses de Junho e Julho na Baía de Sesimbra, permitiram registar as suas actividades tendo em consideração a sua localização no espaço, por referência ao ninho. Estas observações revelam que: 1) ao contrário do que é conhecido para outras blenídeos um território pode conter pelo menos dois ninhos em cavidades distintas vigiadas e cuidados pelo mesmo macho; 2) grande parte das actividades do peixe são realizados fora do ninho. Incluem um patrulhamento muito activo e frequentes permanências num ponto de observação nas imediações do ninho. As actividudes, no seu conjunto, concentram-se numa área a partir do ninho (ou ninhos) cujo raio não exceda 20 a 30 cm; 3) ao contrário de outros blenídeos só muito raramente observámos ventilação caudal dos ovos. As actividades relativas ao ninho e aos ovos são a limpeza, a remoção de materiais e um movimento semelhante ao roçar dos ovos de outros blenídeos, mas frequentemente realizado em natação; 4) os comportamentos agonísticos inter-específicos são predominantes em relação aos intra-específicos, sendo muito raras as interações com outros machos parentais. Lepadogaster sp. parece ser um predador importante dos ovos desta espécie, invadindo com frequência os ninhos quando o macho se afasta. ------- ABSTRACT ------- Underwater observations of territorial and parental behaviour of males of P. pilicornis in the bay of Sesimbra made possible to note their activities and the spacial distribution of activities with referençe to the nests. The results can be summarized as follows: 1) one territory may contain two separate nests, guarded by the same male, which is rare in blennids; 2) a large proportion of the activities are performed outside of the nest, and include a very active territorial patrolling and frequent use of an observation site in the vicinity of the nest. The great majority of activities are performed in an area less than 20 to 30 cm around the nest (or nests); 3) in contrast to other blennids, egg ventilation with the tail was very rare. Predomminant parental activities were: nest cleaning, removal of materials, and an egg rubbing movement similar to that observed in other blennies, but often performed in association with swimming; 4) interspecific agression was more frequent than intraspecific agression, and interactions betwen parental males were very rare. Lepadogaster sp. seems to be an important egg predator, and intruds the nests when the males are out

Historical population dynamics and demography of the eastern Atlantic pomacentrid Chromis limbata (Valenciennes, 1833)

Recent studies have focused on the relationship between the marine fauna of the eastern Atlantic and the Mediterranean Sea, but within the Atlantic, little is known about genetic relationships between populations of the Macaronesian islands. In this study, we tested whether the paleo-climatology and paleo-oceanography of the region could predict the genetic relationships among three eastern Atlantic populations (Azores, Madeira, and Canaries) of a damselWsh, Chromis limbata, and compared our results with its Mediterranean and adjacent Atlantic sister species, Chromis chromis. We combined phylogeographic and coalescent approaches using the fast evolving mitochondrial control region gene. No population structure was found for the three archipelagos. The coalescence time estimated for C. limbata (0.857–1.17Mya) was much greater than that estimated for C. chromis. We propose that this diVerence reXects diVerences in glaciating extents in the Northeastern Atlantic and the Mediterranean. Diversity indexes (Hd and genetic distances) together with historical demographic parameters of C. limbata ( and g) revealed a more stable population history when compared to C. chromis. Our results suggest that the Macaronesian populations of C. limbata have probably been less aVected by the last glaciation than the Mediterranean populations of C. chromis. Migration across the three archipelagos was estimated and a prevailing northwest trend was detected. This result supports the idea of a colonization of the Azores by warm water Wsh from Madeira or the westernmost Canary islands which acted as major glacial refugia for the tropical and subtropical marine fauna during the glaciations

Phylogeography and demography of the Blenniid Parablennius parvicornis and its sister species P. sanguinolentus from the northeastern Atlantic Ocean and the western Mediterranean Sea

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Phylogeography and evolution of the triplefin Tripterygion delaisi (Pisces, Blennioidei)

The genus Tripterygion (Risso 1826) is restricted to the eastern Atlantic and the Mediterranean, and comprises only three species. T. melanuros and T. tripteronotus are essentially endemic to the Mediterranean, while Tripterygion delaisi occurs in the Atlantic and in the Mediterranean. Two subspecies of T. delaisi have been described (T. d. xanthosoma in the Mediterranean and T. d. delaisi in the Atlantic). Several scenarios have been proposed for the evolution of T. delaisi subspecies, but so far its subspeciation process is not clear. In this study we present a population survey of T. delaisi including specimens from the two recognized subspecies. We combined a phylogeographic approach with estimates of the direction of migration (between the Atlantic and the Mediterranean) and of the coalescence time of the two subspecies, using polymorphic mitochondrial and nuclear genes. The results of this study clearly support the existence of two Tripterygion delaisi clades, one in the eastern Atlantic islands and another in the Atlantic coasts of Europe and in the Mediterranean. Historical migration between the islands and Western Europe plus Mediterranean was restricted, and showed a westbound trend, with a higher number of migrants going from the Western Europe plus Mediterranean into the islands. We estimated the time of coalescence of both groups of T. delaisi to be more recent than the onset of Pleistocene glaciations (1.7 Mya). Our results are consistent with previous hypothesis that consider successive dispersal events of a Tripterygion ancestor from the western African coast colonizing the Atlantic islands and the Mediterranean, promoting the evolutionary divergence between these areas

Mitochondrial and nuclear markers reveal isolation by distance and effects of Pleistocene glaciations in the northeastern Atlantic and Mediterranean populations of the white seabream (Diplodus sargus, L.)

Phylogeography of Diplodus sargus from the northeastern Atlantic and the Mediterranean was assessed using sequences from the mitochondrial control region and the first intron of the S7 ribosomal protein gene. The relationship between genetic and geographic distances supported an isolation by distance model, with the Azores having a peripheral position. The geographic distribution of the genetic diversity, together with the historical demography of the populations studied can be explained by the effect of the Pleistocene glaciations in the northeastern Atlantic warm water fauna. D. sargus might have disappeared from western Europe during glacial peaks and suffered considerable demographic reductions in the Canaries and Mauritania, surviving in less affected areas such as Madeira, Azores and the Mediterranean. The mismatch analysis and the Fu's Fs values provide clear evidence of expansion in western Iberia (S. Pedro), Canaries, Mauritania and also in the eastern Mediterranean. Atlantic and Mediterranean populations of D. sargus showed no signs of genetic differentiation. D. sargus are active swimmers that can undergo extensive movements along the shores. This and the presence of planktonic eggs and larvae would allow rapid mixing between Mediterranean and Atlantic fish, erasing signs of population differentiation

Regulation of immunocompetence by different androgen metabolites in a blenny with alternative reproductive tactics

In Parablennius parvicornis, small reproductive males with relatively low expression of secondary sexual characters (M morphotype) parasite on the parental investment of the larger nest-holder males which have fully developed secondary sexual characters (M1 morphotype). In comparison with M1 males, M males have relatively low levels of androgens while having high blood cell percentages of lymphocytes and antigen responsiveness. Here we test the hypothesis that androgens are a causal factor for these differences in immunocompetence between morphotypes. After drawing an initial blood sample, males received a silastic implant containing either oil only (C), or oil with testosterone (T) or 11-ketotestosterone (KT). Males were re-caught 2 weeks later for drawing of the final blood sample. KT but not T induced the development of secondary sexual characters in M males. M males treated with KT showed lower swimming activity than the males treated with T or C implants, suggesting that KT also mediates behavioral changes in M males. As expected, blood cell percentages of lymphocytes, but not of granulocytes, were higher in M males than in M1 males. Overall, lymphocyte percentages increased in the C group which might have been a response to the surgery/treatment. In concordance with the hypothesis, lymphocyte percentages were suppressed in males treated with T in comparison with controls. However, no significant change was found in KT-treated males. This suggests that androgens modulate central, morphological and immunological traits by partly independent androgen mechanisms in P. parvicornis

A comparison between the ontogeny of two related blenniid species Parablennius gattorugine and Parablennius ruber (Pisces: Blenniidae)

Parablennius gattorugine and Parablennius ruber are closely related sympatric western European species. In this note, traits that distinguish the larvae of both species are presented and it is demonstrated that conflicting descriptions reported in the literature on the larvae of P. gattorugine stem from confusion between the two species