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Characterisation of fish communities in different marine coastal habitats from southern Italy by using BRUVS
Publication . Grödl, Vincent Tobias Manuel; Vinagre, Catarina; Sperone, Emilio
This study characterizes the fish community structure of the coast of Calabria in the Ionian and the Tyrrhenian Sea regarding their habitats (rocky, sandy and seagrass) and their location in either one of the seas. The communities were located in 18 sites that are part of the 13 SACs of the Natura 2000 network identified according to the “Habitat” directive. The sites were examined with the use of BRUVS. The fish communities were mainly characterized by their respective habitat and secondarily by their location in either the Ionian or the Tyrrhenian Sea. Communities in the Tyrrhenian Sea had a higher detectability of fish and a higher species richness then species in the Ionian Sea. The detectability and number of species in the habitats was highest in rocky habitats, followed by seagrass and sandy habitats with the lowest number of species and the lowest detectability. Species richness is correlated with the benthic complexity of the habitats as well as their food availability. The benthic complexity is highest in rocky habitats followed by seagrass habitats and sandy habitats with the lowest complexity in its benthic structure. The detectability is mainly influenced by the availability of food. The food availability is influenced by the productivity of the habitat and other factors like upwelling or nutrient input by estuaries. The most productive habitat in this study was the rocky habitat, another influence in the productivity of the habitats is the upwelling of the Sicilian coast fuelling the production of the waters of the Tyrrhenian coast. On the Ionian site a similar effect can be seen in habitats located at an estuary increasing the production of the surrounding habitats
Swimming capacity of the post-larvae of the little fish of São Tomé
Publication . Bastos, Jerónimo da Graça; Baptista , Vânia; Maia, Hugulay
Little fish from São Tomé is the name attributed to a set of Gobiid post-larvae that includes the species: Sicydium bustamantei, Sicydium brevifile and Awaous lateristiga, which are caught at the mouths of the island's rivers. It represents a source of animal protein and one of the main financial resources for fishing communities. These species, during the breeding season the adults form pairs and lay their eggs in the lower parts of the rocks and crevices. After hatching in fresh water, the larvae are dragged by the currents to the ocean where they develop into planktonic post-larvae and make the
migration back to the rivers. In this sense, the present study sought to identify whether there is variation in the swimming capacity of these little fish. For this purpose, tests were carried out in laboratories using the swimming chamber. The swimming capacity of the post-larvae of A. lateristriga ranged from 7 to 23 cm.s-1 reaching the critical
swimming speed (Ucrit) of 5.42 minimum and 22.08 maximum. S. brevifile with 8 to 23 cm.s-1 and (Ucrit) of 7.32 minimum, 22.02 maximum and S. bustamantei ranged from 4 to 23 cm.s-1 and (Ucrit) of 2.09 minimum and 22.0 maximum in the swimming chamber . It was found with this study that the variation of the critical swimming speed is not homogeneous between the species. There was a slight difference between the critical swimming speed of A. lateristiga in relation to other species, so the swimming capacity of the species is not influenced by their length. However, this study contributes to the
understanding of the variation of the swimming capacities of the post-larvae little fish and the dynamics of their migratory flow.
In situ and satellite characterization of Meddies' structures in open Ocean NE Atlantic: NA-Vice Cruise (2012), Azores to iceland
Publication . Serpa, Tiago Luís; Martins, Ana Maria de Pinho Ferreira da Silva Fernandes; Almeida, Paulo José Relvas de
A meddy was found at 41.3º N 27.1º W during the R/V Knorr cruise KN207-03 that took place from the Azores to Iceland in the summer of 2012 within the framework of the international project NA-VICE. The meddy’s main physical properties and characteristics were identified using in situ data (CTD and ADCP) and salinity and temperature anomalies of 0.24 and 2.18ºC, respectively, were found as well as azimuthal velocities up to 0.35 m s-1 . These values were compared with criteria described by previous authors to ensure that this structure, which was further north than most observations, could be classified as a meddy. Meanwhile, a cyclonic eddy with characteristics from Mediterranean Water (MW) was also found to interact with the meddy, and their relationship was discussed. Afterwards, the meddy’s surface expression was analysed using altimetry data combined with an eddy detection algorithm, and it was found that its Sea Level Anomaly (SLA) was 15 cm, and it presented a 100 km radius. This data was used to track the meddy’s path, giving a general idea of the generation and dissipation dates and locations, leading to the hypothesis that the locations previously identified by other authors do not encompass all the possible meddy generation sites. A new method was tested using satellite Ocean Colour (OC) images to identify meddies surface expression. Despite the previously known Sea Surface Temperature (SST) surface expression, the results show that other valuable parameters such as Chlorophyll-a (Chlor-a), kd_490, Particulate Organic Carbon (POC), and Particulate Inorganic Carbon (PIC) are equally important, emphasising the vital role of the meddies in the mixing and transport of biogeochemical properties in the ocean and how this has been underestimated.
Structural enrichment promotes natural behaviour and welfare of captive gilthead seabream broodstock
Publication . Oliveira, Ana Rita; Cabrera-Álvarez, María José; Soares, Florbela; Diáz-Gil, Carlos; Candeias-Mendes, Ana; Saraiva, João; Arechavala-Lopez, Pablo
The intensification of aquaculture practices in the last decade can compromise the welfare of farmed fish. However, one strategy to be considered to improve the welfare of captive fish is the implementation of structural enrichment in the rearing environment. The behavioural and physiological effects of suspended ropes inside rearing tanks were experimentally assessed on gilthead seabream (Sparus aurata) breeders, evaluating the potential use of such structures in production units. Over the course of six months, 60 adult gilthead seabreams, were reared in cylindrical tanks with and without structural enrichment. Fish were video recorded regularly before, during and after feeding. Biometry and blood samples for biochemical analyses of plasma (cortisol, glucose and lactate) were taken throughout the experiment. Suspended ropes modified the horizontal distribution of fish after feeding, influencing the swimming activity and social interactions throughout the experimental period. In addition, structural enrichment promoted foraging and anticipatory behaviour of gilthead seabream. No effects of structural enrichment were detected on gilthead seabream condition or growth, although there was an apparent positive yet fading effect of enrichment on plasma cortisol and glucose. In general, structural enrichment had diverse positive effects on the behaviour diversity and natural repertoire of captive gilthead seabream, and therefore, on fish welfare. This type of structural environmental enrichment can be easily incorporated into land-based flow-through and recirculating aquaculture systems, both for experimentation and commercial purposes.
Development of 3d cell cultures and testicular organoid transplantations: potential tools for reproductive biology
Publication . Ferreira, João Gil Gomes; Cabrita, Elsa; Pšenička, Martin
Researchers in the last decade have struggled to increase the number of offspring of species with economic importance or endangered status, reducing aquaculture growth. The primary obstacles are spermatozoa's low number and motility and the long maturation period in some fish species. Germ cell transplantation and cryopreservation techniques enable researchers to surpass problems related to the quality and quantity of spermatozoa. However, the most significant bottlenecks are the low number of spermatogonia germ cells and the incapability to cryopreserve oocytes. Organoids are cell structures only produced in 3D cell mediums, capable of maintaining functionality and structure similar to in vivo. Cell proliferation and differentiation in organoids is the most critical part of their development and an essential step in transplanting them into recipients since there is a probability of increasing the colonisation of the gonadal tissue and decreasing the gonadal maturation period. Therefore, the study and usage of organoids to study epigenetics, cell-cell communication, and cell differentiation are recent strategies in fish biology. The current project aims to reach a consensus on the definition of organoids and be the steppingstone for future work done with fish organoids. Two protocols were produced during these experiments, one for organoid development utilising vitrogel and a second for organoid development through aggrewell plates. The aggrewell procedure was more efficient than any vitrogel, producing more organoids during a smaller period. Despite both mediums achieving organoid-like structures, histology proved that only the aggrewell successfully created organoids with a single membrane and niche structure similar to the donor organ. Preliminary tests with transplanted organoids showed positive results, with observable organoids after 45 days. In summary, the performed experiments will facilitate any work related to future works with fish organoids, surpassing any difficulties in organoid development.