Browsing by Author "Caldeira, Rui"
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- O papel do Observatório Oceânico da Madeira na promoção da literacia do oceanoPublication . Costa, Sónia; Caldeira, RuiA Literacia do Oceano é definida como a compreensão da influência que o oceano tem em nós e da nossa influência no oceano. Muitas instituições desenvolvem iniciativas nesta área. Na Região Autónoma da Madeira, o Observatório Oceânico da Madeira (OOM) tem atuado como facilitador e promotor deste tipo de literacia. Para isso, tem contado com o contributo de investigadores de várias áreas das ciências marinhas: Biodiversidade, Pescas e Maricultura, Modelação e Previsão Meteo-Oceanográfica, Teledeteção e Seguimento Remoto de animais marinhos. Entre 2016, ano em que iniciou ações educativas e de divulgação de ciência de forma regular, e 2019, o OOM contabilizou mais de 5500 alunos em cerca de 140 palestras, atividades teórico-práticas e lúdico-didáticas, foram ministrados 7 módulos formativos para professores e participou e organizou diversas iniciativas de aproximação da ciência ao público.
- Surface behavior of pelagic juvenile loggerhead sea turtles in the eastern North AtlanticPublication . Freitas, Carla; Caldeira, Rui; Dellinger, ThomasSea turtles bask at the ocean surface, but little is known about the patterns and ecological context of surface behavior in the wild. This study investigated the surface behavior of ten juvenile loggerhead sea turtles (34 - 58 cm straight carapace length) satellite tagged in Madeira, in the pelagic eastern North Atlantic. During a total of 2273 tracking days, turtles moved through oceanic areas with a mean depth of ~3400 m. On average, turtles spent one third of the time at the surface (0 - 1 m depth), spending 43% of the time at the surface during the day and 29% of the time during the night. Generalized linear mixed modelling showed that the proportion of time at the surface was significantly larger during the day, particularly during spring and summer. Time spent at the surface during the day increased with elevated air temperatures and weak winds, probably to maximize the benefits of solar absorption. Conversely, the probability of being at the surface during the day decreased as horizontal search effort increased, suggesting a trade-off between basking and daytime foraging activities. At night, time spent at the surface was not associated with air temperature or wind speed but was instead positively associated with moon illumination. As turtles tend to dive deeper during clear nights, increased surface time may be needed to recover from deeper dives. This study presents important aspects of the behavioral ecology of the species during the oceanic juvenile phase. The findings reported here may be relevant for species management and conservation, including correction of census data and management of interactions with surface fishing gear and other anthropogenic activities.
- The effect of a transient frontal zone on the spatial distribution of extant coccolithophores around the Madeira archipelago (Northeast Atlantic)Publication . Narciso, Áurea; Caldeira, Rui; Reis, Jesus; Hoppenrath, Mona; Cachão, Mário; Kaufmann, ManfredIn order to characterize the coccolithophore community around the Madeira archipelago and to understand the effect of a transient frontal zone on its distribution, 149 seawater samples from the first 150 m were collected in 37 stations, during the research cruise POS466 of RV Poseidon. The present study revealed the occurrence of two biogeographic domains, NE and SW, during the late winter of 2014, with distinct physical-chemical and cal careous nannoplankton characteristics. The NE sector was characterized by higher coccolithophore cell densities (mean of 56 × 103 cell L−1) and a slightly lower diversity (Margalef diversity index of 1.80) when compared with the SW sector (mean of 47 × 103 cell L−1; Md index of 1.86). The more productive sector, NE, was asso ciated with colder, less saline and higher nutrient content water masses, linked to the injection of a westerly flow with origin in the Azores frontal system. Total cell densities ranged between 12 × 103 and 112 × 103 cell L−1, being Emiliana huxleyi the dominant species followed by small Gephyrocapsa. The most common and subordinate taxa, in order of decreasing abundance, were: Gephyrocapsa oceanica, Michaelsarsia spp., Syracosphaera spp., Umbilicosphaera spp. and Algirosphaera robusta. Relationships between environmental conditions and spatial and vertical variability in coccosphere abundance, associated E. huxleyi and small Gephyrocapsa with the more productive water mass conditions, linked to the thermohaline transient front. G. oceanica distribution indicated its preference for warmer and less turbulent coastal waters, when compared to E. huxleyi and small Gephyrocapsa. Michaelsarsia spp. and A. robusta revealed preference for the northwest coast of Madeira, associated with mesotrophic con ditions of the water column. Syracosphaera spp. and Umbilicosphaera spp. were well distributed throughout the archipelago and along the sampled depths, from the coast to open ocean conditions, as well as from lower to higher productive zones, displaying affinities for the meso to oligotrophic conditions, typical of these subtropical waters. The broad depth range of several taxa and the nonexistence of the coccolithophore vertical succession were the result of homogeneous and generalized well-mixed surface layer during the present survey.