Associações de peixes de uma zona costeira artificializada:o Porto de Recreio de Oeiras

Tese de mestrado, Ecologia e Gestão Ambiental, 2010, Universidade de Lisboa, Faculdade de CiênciasForam realizados censos visuais em mergulho com escafandro autónomo durante a Primavera e Verão de 2009 com o objectivo de caracterizar as associações de peixes do Porto de Recreio de Oeiras. Nestes mergulhos foram identificadas 46 espécies de peixes pertencentes a 20 famílias diferentes. A maioria das espécies amostradas é característica de zonas marinhas de substrato rochoso, sendo as espécies mais comuns e com distribuição mais ampla no interior do Porto de Recreio: Atherina presbyter, Diplodus sargus, Diplodus vulgaris, Ctenolabrus rupestris e espécies da família Mugilidae. Compararam-se as abundâncias e frequências de ocorrência em três zonas distintas no interior do Porto de Recreio: A (zona do molhe de abrigo na entrada do Porto); B (zona de pontões flutuantes) e C (zona de enrocamento abrigada). O índice de Shannon- Wiener revelou uma diversidade decrescente da zona A para a zona C, apresentando a zona C uma diversidade significativamente mais baixa do que as zonas A e B. Realizou-se uma análise de correspondência (CA) que revelou uma clara separação entre a zona B e as zonas A e C. Espécies especialmente abundantes, como A. presbyter e D. vulgaris, posicionaram-se entre as zonas A e C, enquanto G. gasteveni, D. cervinus, D. bellottii e G. cobitis apresentam uma fraca associação em qualquer dos grupos formados, ocupando uma posição afastada em relação às zonas consideradas.Underwater surveys were carried out in the Oeiras Harbor along the spring and summer of 2009 in order to identify the fish assemblages present inside this artificial structure. During these months 46 species belonging to 20 different fish families were identified. Most species are typically marine rocky subtidal species. The most common and widely distributed species inside the Oeiras Harbor were: Atherina presbyter, Diplodus sargus, D. vulgaris, Ctenolabrus rupestris and several Mugilidae species. Relative abundances and frequencies were estimated in three distinct areas inside the study area: A (artificial rocky area near the entrance of the harbor); B (floating piers) and C (sheltered artificial rocky area). Analysis of the Shannon-Wiener index revealed a decreasing diversity from area A to area C, with the diversity in C being significantly lower when compared with A and B. Correspondence analysis (CA) revealed the distinctiveness of area B, when compared with areas A and C. Species A. presbyter and D. vulgaris, were particularly abundant and were mainly found in areas A and C while G. gasteveni, D. cervinus, D. bellottii e G. cobitis were not associated to any of these groups

Area Estimation of Deep-Sea Surfaces from Oblique Still Images

Estimating the area of seabed surfaces from pictures or videos is an important problem in seafloor surveys. This task is complex to achieve with moving platforms such as submersibles, towed or remotely operated vehicles (ROV), where the recording camera is typically not static and provides an oblique view of the seafloor. A new method for obtaining seabed surface area estimates is presented here, using the classical set up of two laser devices fixed to the ROV frame projecting two parallel lines over the seabed. By combining lengths measured directly from the image containing the laser lines, the area of seabed surfaces is estimated, as well as the camera’s distance to the seabed, pan and tilt angles. The only parameters required are the distance between the parallel laser lines and the camera’s horizontal and vertical angles of view. The method was validated with a controlled in situ experiment using a deep-sea ROV, yielding an area estimate error of 1.5%. Further applications and generalizations of the method are discussed, with emphasis on deep-sea applications

Early development and larval behaviour of two clingfishes, Lepadogaster purpurea and Lepadogaster lepadogaster (Pisces: Gobiesocidae)

The recent revision on the taxonomic status of Lepadogaster lepadogaster resulted in the division of this species into L. lepadogaster and L. purpurea, the clarification of each species’ distribution ranges and the elimination of L. zebrina (now in synonymy with L. lepadogaster). This new taxonomic status led to the need of clarifying the early development of the two species. Embryonic development lasted 21 days in L. purpurea at a mean temperature of 14.2°C, and 16 days in L. lepadogaster at a mean temperature of 16.5°C. Newly hatched larvae of both species measured 5.2 mm, had the mouth and anus opened, pigmented eyes and almost no yolk. At hatching and throughout development the two species can be distinguished by the ventral pigmentation which is absent in L. purpurea. The change to a benthic mode of life was gradual in both species, with larvae increasingly spending more time close to the bottom until definitely settling. Larval development lasted 33 days in L. purpurea at a mean temperature of 14.6°C and 18 days in L. lepadogaster at a mean temperature of 16.5°C. Locomotion and foraging behaviours are described for both species. L. lepadogaster showed a higher frequency of swimming and foraging behaviour when compared with L. purpurea

Ludwig Koch and the Music of Nature

Ludwig Koch was a pioneer of outside broadcast, natural history recording in the first half of the 20th century. This programme explores his methods, techniques and personality through archive recordings and interviews, and includes attempts t recreating his experiments using modern equipment

High-resolution multibeam bathymetry of the northern Mid-Atlantic Ridge at 45–46° N: the Moytirra hydrothermal field

This work presents a new high-resolution multibeam bathymetric map of a segment of active deep sea-floor spreading in the Atlantic Ocean, the northern Mid-Atlantic Ridge (MAR) at 45–46º N. New high-resolution bathymetry data were acquired using an Atlas multibeam echosounder onboard the research vessel Sarmiento de Gamboa during the EXPLOSEA-2 survey in 2019. The final map of the MAR (50 m cell grid size) at the original scale of 1:200,000 shows a segment of 140 × 35 km of the MAR, at water depths from 715 to 3700 m. This new high-resolution bathymetric map allows to better defining the submarine morphology of the Moytirra hydrothermal active field, the only high-temperature field identified between the Azores Archipelago (Portugal) and Iceland. ROV submarine observations reaching the deepest part of the system for the first time show giant anhydrite-sulfide chimneys up to 20 m high, active strong black smokers and polymetallic massive sulfides

Multidisciplinary Scientific Cruise to the Northern Mid-Atlantic Ridge and Azores Archipelago

This work presents the preliminary result of the multidisciplinary cruise EXPLOSEA2 surveying the northern Mid-Atlantic Ridge and Azores Archipelago from 46 300 N to 38 300 N aboard the R/V Sarmiento de Gamboa and ROV Luso over 54 days (June 11 to July 27, 2019). In this cruise report, we detail the geophysical, hydrographic, geological, oceanographic, ecological, and microbiological data acquired and a brief of main findings. The cruise addressed the exploration and comprehensive characterization of venting sites, including the water column, the sediments and rocks that host the hydrothermal activity, and the associated mineralizations, biology, and microbiology. Deep hydrothermal chimneys and massive sulfide deposits (up 3,000 m in depth) within the Moytirra hydrothermal active field were identified on slopes that had not been explored previously. Another striking finding made during the EXPLOSEA2 cruise was the field of carbonate chimneys named the “Magallanes-Elcano” field, a potentially relict ultramafic-hosted hydrothermal site sourced by abiotic methane. This field is related to a serpentinite and gabbro rock outcropping on a dome-shaped massif named the “Iberian Massif.” An outstanding finding of the EXPLOSEA2 survey was the identification of the first garden of soft corals growing after active submarine eruptions were reported in the Azores Archipelago composed by a high density of soft corals the suborder Alcyoniina at the summit and flanks of a recent volcanic cone at 160 m water depth developed during the 1957–1958 eruption of Capelinhos. Several cold-water coral habitats formed by colonial scleractinians (e.g., Lophelia pertusa and Madrepora oculata), coral gardens composed of mixed assemblages of black corals (Leiopathes sp.), and octocorals and dense aggregations of the glass sponge Pheronema carpenteri that may be classified as vulnerable marine ecosystems (VMEs) have been discovered during the EXPLOSEA2 cruise along the northern Mid-Atlantic Ridge. This work reveals the importance of multidisciplinary surveys to the knowledge of deep-sea environments

On a hexactinellid sponge aggregation at the Great Meteor seamount (North-east Atlantic)

Hexactinellids or glass sponges constitute a predominantly deep-sea sponge group typically occurring at bathyal and abyssal depths. Some species form dense populations along the European and African continental slope but the distribution and extent of these populations remains ill known and the driving factors behind their occurrence poorly understood. Here we report an aggregation of the hexactinellid sponge Poliopogon amadou Thomson, 1878 at ~2700 m depth on the Great Meteor seamount, a large seamount located southern of the Azores archipelago. A description of the species, along with scanning electron microscopy of its spicules, is provided

Estimation of Seabed Surface Areas from ROV Oblique Still Images

Since 2008, the Portuguese Task Group for the Extension of the Continental Shelf has been operating the ROV “Luso” (rated for 6000m depth) for geological sampling of the deep North Atlantic seabed, performing surveys on, e.g., seamounts and hydrothermal vent fields. Amongst other sensors, the ROV is equipped with a full HD video camera with which still images of the deep ocean floor are recorded. Fixed on the ROV’s frame are two underwater “line” lasers, each generating a sharp green line (532nm) over the seabed. The two lasers are paralleled and calibrated at a set distance. Provided that the camera’s angle of view is known, numerical values for seabed surface area may be calculated using direct measurements taken from the pictures containing the laser lines. We present the corresponding main mathematical formulas, which are derived from simple geometrical considerations, and discuss how to generalize these results for an arbitrary camera tilt or pan. We present an example of application of our method by estimating values for percent coverage of rock substrate versus sediment. Our results are also relevant for determining seabed polymetallic nodule abundances from still images obtained during ROV surveys

3D chemoecology and chemotaxonomy of corals using fatty acid biomarkers: Latitude, longitude and depth

With the objective of uncovering differences in the fatty acid (FA) composition of hexa- and octocorals from different climatic zones (equatorial, subtropical and tropical) and distinct habitats (e.g. rock and coral reefs; intertidal to deep-sea environments), the FA composition of 36 hexa- and octocoral species (132 specimens) was analysed (including the first characterization of organisms from the order Zoantharia and deep-sea gorgonians). PCA was applied in a FA matrix of the ten major PUFAs to detect differences among coral groups. Fatty acid profile analysis confirmed that C24 polyunsaturated FAs are suitable chemotaxonomic biomarkers to separate hexa- and octocorals. The polyunsaturated FA 22:6n-3 was identified as a useful biomarker to distinguish between zoantharians and scleractinians. Also, we discuss the role of food availability (type of phytoplankton assemblage) in relation to autotrophic carbon significance and in the establishment of FA profiles of octocorals from the West and East coasts of the Atlantic Ocean. Furthermore, we show that the occurrence of high levels of primary productivity hinder the use of FA profiles to distinguish between zooxanthellate and azooxanthellate octocorals. Finally, we present and discuss the particular traits of the FA profile of deep-sea gorgonians while comparing it with that of shallow species.info:eu-repo/semantics/publishedVersio

Surface and underwater view of the camera and laser optical system installed on the ROV.

<p>(a): Test launch of the ROV “Luso”. (b): Front view of the ROV, illustrating the HD camera (red circle) and the two laser devices (green circles). (c): Horizontal seabed still image containing the two (parallel) green laser lines; the trapezoid [A’B’D’C’] defines the surface area over the seafloor to be estimated.</p