Biologia Marinha
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- A simple method using a single video camera to determine the three-dimensional position of a fishPublication . Pereira, Pedro; Oliveira, Rui FilipeIn the present paper, we describe a method for recording the coordinates of a fish in an aquarium in a three-dimensional space, using a single video camera and a mirror. Weuse photogrammetic equations for this, considering the image obtained in the mirror as a virtual image obtained by a second camera. Atransformation of the coordinate system is required to express the obtained coordinates in an x, y, z system defined by the edges of the aquarium. The accuracy of the proposed method was estimated, and errors in extreme conditions were found to be 0.8% to 1.2 %, compared with the dimensions of the aquarium used in the test.
- Watching fights raises fish hormone levels: Cichlid fish wrestling for dominance induce an androgen surge in male spectators.Publication . Oliveira, Rui Filipe; Lopes, Marco; Carneiro, Luís Alberto; Canário, Adelino V. M.Inexistente
- A new species of Calma Alder & Hancock, 1855 (Gastropoda: Nudibranchia) with a review of the genusPublication . Calado, Gonçalo; Urgorry, VictorianoThis paper presents the description of a new species of the genus Calma (Alder & Hancock, 1855). To date only one valid species, Calma glaucoides (Alder & Hancock, 1854), has been assigned to this genus, which feeds exclusively upon eggs of littoral teleost fishes. New morphological and ecological data, and review of the literature on the species attributed to this genus, lead us to conclude that there are two distinct species previously put together under the same specific name. Calma gobioophaga new species is described based upon consistent morphological differences, such as the diameter and position of the eyes, the size of the propodial tentacles, and the size of the metanefridium. Whereas Calma gobioophaga feeds on spawn of Gobius niger, Calma glaucoides feeds on eggs of Lepadogaster lepadogaster, Lepadogaster purpurea, Lepadogaster candollei, Parablennius gattorugine, and Parablennius pilicornis.
- 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.
- A new species of Calma Alder & Hancock, 1855 (Gastropoda:Nudibranchia) with a review of the genusPublication . Calado, Gonçalo; Urgorri, VictorianoThis paper presents the description of a new species of the genus Calma (Alder & Hancock, 1855). To date only one valid species, Calma glaucoides (Alder & Hancock, 1854), has been assigned to this genus, which feeds exclusively upon eggs of littoral teleost fishes. New morphological and ecological data, and review of the literature on the species attributed to this genus, lead us to conclude that there are two distinct species previously put together under the same specific name. Calma gobioophaga new species is described based upon consistent morphological differences, such as the diameter and position of the eyes, the size of the propodial tentacles, and the size of the metanefridium. Whereas Calma gobioophaga feeds on spawn of Gobius niger, Calma glaucoides feeds on eggs of Lepadogaster lepadogaster, Lepadogaster purpurea, Lepadogaster candollei, Parablennius gattorugine, and Parablennius pilicornis.
- Whistles of bottlenose dolphins (Tursiops truncatus) in the Sado Estuary, Portugal: Characteristics, production rates, and long-term contour stabilityPublication . Santos, Manuel Eduardo dos; Louro, Sónia; Couchinho, Miguel Nogueira; Brito, Cristina MariaThis study focuses on the whistle characteristics and production patterns of bottlenose dolphins (Tursiops truncatus) resident in the Sado Estuary, Portugal. Recordings and observations were conducted inside the estuary and in adjacent coastal waters using single hydrophones between 1987 and 2000. In the groups sampled, the mean number of whistles emitted per minute per animal was 0.28. The acoustic characteristics of a sample of 735 whistles were measured and compared with data from other Tursiops populations, showing that, in a pattern of overall similarity, the whistles recorded in the Sado are relatively long and the frequency range used is relatively wide. Mean peak frequency was 9.2 kHz. About 30% of the whistles were stereotyped, and remarkable stability was found in several contours over a 12-year period. No relation was found between dolphin group size and whistle rate, suggesting some restriction in production; and no relation was found between dolphin group size and the emission of different contours. Significant variation was found between episodes of simple travel and more aroused activities in terms of the production of whistles in general and also of different whistle contours.
- Estimating the size of "Uca tanger" (Crustacea: Ocypodidae) without massive crab capturePublication . Lourenço, Rita; Paula, José R.; Henriques, MiguelUca tangeri (Eydoux, 1835) is the only species of fiddler crab that occurs in Portugal, where it mainly inhab-its salt marshes in the south and southwest coasts. Individuals spend most of their time on and around their galleries, bur-rowing structures which they typically create and maintain in muddy substrate. Capturing fiddler crabs in nature is extreme-ly difficult and can be destructive for their habitat. Once disturbed, U. tangeri tend to hide in their burrow, and their capture usually involves the destruction of the upper part of the burrow. In the present study, a method for estimating the carapace length of the fiddler indirectly, using the diameter of the burrow opening, is proposed. Significant sex-specific relationships between the diameter of the burrow opening and the occupant’s length were found. Although the mean length of the cara-pace was not significantly different between sexes,
- Phylogeography and demographic history of Atherina presbyter (Pisces: Atherinidae) in the North-eastern Atlantic based on mitochondrial DNAPublication . Francisco, Sara Martins; Castilho, Rita; Soares, Miguel; Congiu, Leonardo; Brito, Alberto; Vieira, Maria Natividade; Almada, Vítor CarvalhoA fragment of the mitochondrial control region was used to assess phylogeographic patterns and historical demography of the sand-smelt Atherina presbyter in the North-eastern Atlantic, covering its geographical range. A striking result is the highly marked diVerentiation between the Canary Islands population and western European ones. A genetic structure among European populations of A. presbyter was revealed, with a pattern of isolation-by-distance or a gradient eVect at a scale of hundreds kilometres, an uncommon pattern likely related to the biological and life-history traits of the sand-smelt. The northern European populations present a much lower genetic diversity when compared to southern populations, which is consistent with a recent colonization from southern populations. The results showed signs of Pleistocene signatures, with the population age estimates for the European populations being clearly older than the Last Glacial Maximum (18,000 years bp). Nevertheless, paleotemperature reconstructions show that the sand-smelt could not have inhabited the western European shores during the last glacial phase.
- Tactile stimulation lowers stress in fishPublication . Soares, Marta C.; Oliveira, Rui Filipe; Ros, Albert F. H.; Grutter, Alexandra S.; Bshary, RedouanIn humans, physical stimulation, such as massage therapy, reduces stress and has demonstrable health benefi ts. Grooming in primates may have similar effects but it remains unclear whether the positive effects are due to physical contact or to its social value. Here we show that physical stimulation reduces stress in a coral reef fi sh, the surgeonfi sh Ctenochaetus striatus . These fi sh regularly visit cleaner wrasses Labroides dimidiatus to have ectoparasites removed. The cleanerfi sh infl uences client decisions by physically touching the surgeonfi sh with its pectoral and pelvic fi ns, a behaviour known as tactile stimulation. We simulated this behaviour by exposing surgeonfi sh to mechanically moving cleanerfi sh models. Surgeonfi sh had signifi cantly lower levels of cortisol when stimulated by moving models compared with controls with access to stationary models. Our results show that physical contact alone, without a social aspect, is enough to produce fi tness-enhancing benefi ts, a situation so far only demonstrated in humans.
- Phylogeography of the shanny Lipophrys pholis (Pisces: Blenniidae) in the NE Atlantic records signs of major expansion event older than the last glaciationPublication . Francisco, Sara Martins; Faria, Cláudia Barreiros Macedo de; Lengkeek, W.; Vieira, Maria Natividade; Velasco, Eva Maria; Almada, Vítor CarvalhoThe study of the phylogeography of inshore fish from West Europe is revealing diverse geographical and demographical patterns. Some species conform to the phylogeographic patterns typical of terrestrial organisms, with marked signatures of the last glaciation and a decline of genetic diversity to the north of the species range. Other species, however, reveal no decline in diversity with latitude and signatures of expansions older than the last glaciation. The shanny Lipophrys pholis is a common intertidal resident fish in west European rocky shores. It is unable to leave the rocky stretch where it settled as a juvenile, so that dispersal depends entirely on the planktonic larval stage. These life-history and behavioural traits make the shanny an interesting species for phylogeographical analysis, as long-range movements by adults, which could blur historical signals, are absent. In this paper the phylogeography of L. pholis was studied using a fragment of the mitochondrial control region and one from the first intron of the S7 ribosomal protein gene. The European samples (ranging from SW Spain to the Netherlands) did not display population differentiation, isolation-by-distance or latitudinal declines in genetic diversity. Iberia was proposed as having operated as the main glacial refugium for the shanny. The genealogy of the European population showed that the largest expansion detected was older than the last glaciation, with lineages persisting from the early Pleistocene, which does not conform to colonisation by a few founders in the current interglacial. It is argued that if fishes have very large population sizes and high dispersal rates, populations can efficiently track climatic shifts so that little or no genetic structure remains after each range expansion and latitudinal gradients of genetic diversity tend to be weak or non-existent.