Search results for "Actinopterygii"
showing 10 items of 210 documents
Diversity of vertebrate remains from the Lower Gogolin Beds (Anisian) of southern Poland
2020
Middle Triassic (Muschelkalk) limestones and dolostones of southern Poland contain vertebrate remains, which can be used for palaeoecological and palaeogeographical analyses. The results presented concern vertebrate remains uncovered at four localities in Upper Silesia and one on Opole Silesia, a region representing the south-eastern margin of the Germanic Basin in Middle Triassic times. The most abundant remains in this assemblage are fish remains, comprising mostly actinopterygian teeth and scales. Chondrichthyan and sauropsid remains are less common. Reptilian finds include vertebrae, teeth and fragments of long bones, belonging to aquatic or semi-aquatic reptiles, such as nothosaurids, …
Contrasting neurochemical and behavioral profiles reflects stress coping styles but not stress responsiveness in farmed gilthead seabream (Sparus aur…
2020
In fish, as well as in other vertebrates, contrasting suites of physiological and behavioral traits, or coping styles, are often shown in response to stressors. However, the magnitude of the response (i.e. stress responsiveness) has been suggested to be independent of stress coping style. One central neurotransmitter that has been associated with both stress responsiveness and differences in stress coping styles is serotonin (5-hydroxytryptamine, 5-HT). In this study, we investigated to what extent stress responsiveness reflects differences in stress coping, and the potential involvement of the 5-HT system in mediating such differences in farmed Gilthead seabream. Initially, fish were class…
The orbito-nasal area ofAsterolepis ornata, a Middle Devonian placoderm fish
2001
The structure of the orbito-nasal cavity in the antiarchan placoderm fish Asterolepis ornata has been studied, providing a detailed description of the premedian, rostral, and pineal plates, and bones of the sclerotic ring. Both eyes and nostrils were directed antero-latero-dorsally in Asterolepis. Eyes were enclosed within the sclerotic capsule. Nasal cavities were not opened into a so called “prenasal slit,” but directly above the head of fish. A new reconstruction of the nasal openings and position of the nasal sacs shows broader similarities between various antiarchs than was previously claimed, and allows the evaluation of the differences in the structure of the orbito-nasal cavities in…
Corynosoma acanthocephalans in their paratenic fish hosts in the northern Baltic Sea
2003
En 1996-1997, nous avons etudie les stages cystacanthes de trois especes de Corynosoma (Acanthocephala), C. strumosum et C. semerme, ainsi qu'une nouvelle espece C. magdaleni parasite du chabot a quatre cornes (Myoxocephalus quadricornis) dans le golfe de Bothnie. Les longueurs du tronc et du proboscis permettent de differencier les trois especes de parasites. La stabilite temporelle de l'infection par Corynosoma est etudiee en comparant nos resultats a ceux obtenus dans la meme zone geographique centrale et cotiere) en 1977-1982 (Valtonen, 1983a). Comme C. magdaleni et C. strumosum n'etaient pas differenciees a cette epoque, elles ont ete groupees sous l'appellation "C. strumosum" pour les…
Response of captive seabass and seabream as behavioural indicator in aquaculture
2010
Welfare of cultivate fish at high-density represents an important concern for modern aquaculture. The behaviour of European seabass (Dicentrarchus labrax) and seabream (Sparus aurata) reared in cages was studied in a fish farm of northern Sardinia (Italy) in autumn 2006 to test whether captive condition had an effect on the movement patterns of these two species.Video images recorded before, during and after the manual feeding distribution allowed us to collect data on different behaviours of captive fish. Thus, behaviours indicating the position of fish in the water column, swimming direction and possible aggressive behaviours (aggression, direction change and collision) showed juveniles a…
Pinger affects fish catch efficiency and damage to bottom gill nets related to bottlenose dolphins
2009
There is some evidence that the presence of Tursiops truncatus in fishing areas represents a real economic threat to fishermen due the dolphin feeding on the entangled fish, damaging the nets and reducing the fish catch. We have carried out experiments to assess the efficiency of a pinger in decreasing the interaction between the dolphins and fishing nets, in a fishing area off the coast of southern Italy, where Tursiops truncatus is frequently observed to interact with bottom gill nets. Two identical monofilament bottom gill nets (900 m long), one equipped with pingers and the other without, were used to measure the effect of these pingers on the abundance of the catch and net damage. For …
Polyculture as a tool to increase the economic income: a study case in the Gulf of Castellammare
2010
Polyculture is a practice involving integration between organisms of different trophic levels (i.e. fish with low-trophic-level organism like molluscs and/or algae). This paper, reporting on a field experiment carried out during 2004 in the Gulf of Castellammare (South Tyrrhenian), showed that mussels transplanted in areas under fish farm influence grew up better than mussels transplanted far from fish farm. Thus, results pointed out polyculture as a reliable tool for i) increasing local bivalve production, ii) obtaining the reduction of importation from other countries and iii) increasing the environmental sustainability of fish aquaculture.
Fish diversity associated with gas platforms: Evaluation of two underwater visual census techniques
2007
Se estudiaron las comunidades ícticas asociadas con plataformas extractivas mediante dos técnicas de censos visuales submarinos: transectos y conteos de puntos móviles. Los datos se tomaron a cuatro profundidades en tres diferentes plataformas situadas en el Mar Jónico (Crotone, Italia). Se registraron un total de 25 especies de peces pertenecientes a 12 familias. Se observaron diferencias significativas entre ambos métodos de muestreo y las profundidades en cuanto a la estructura de la comunidad íctica, la riqueza de especies y la abundancia de peces. El promedio de peces registrado con el método de transectos siempre fue mayor que el registrado mediante puntos móviles, mientras que lo con…
Biochemical Responses of European Sea Bass (Dicentrarchus labrax L.) to the Stress Induced by Off Shore Experimental Seismic Prospecting
1999
The paper reports the results of an experimental seismic survey in the open sea by an air gun, carried out to evaluate the effects of air gun acoustic waves on marine animals. Air gun blast exposition was found to have a marked influence on confined Dicentrarchus labrax. Our data, in fact, demonstrated a biochemical response to acoustic stress induced by air gun blasts. Variations of cortisol, glucose, lactate, AMP, ADP, ATP and cAMP in different tissues of D. labrax, indicate that fish have a typical primary and secondary stress response after air gun detonations. Radiography indicates that air gun blasts do not induce any macroscopic effect on skeletal apparatus. The variations of biochem…
Ventastega curonica and the origin of tetrapod morphology.
2008
The gap in our understanding of the evolutionary transition from fish to tetrapod is beginning to close thanks to the discovery of new intermediate forms such as Tiktaalik roseae. Here we narrow it further by presenting the skull, exceptionally preserved braincase, shoulder girdle and partial pelvis of Ventastega curonica from the Late Devonian of Latvia, a transitional intermediate form between the 'elpistostegids' Panderichthys and Tiktaalik and the Devonian tetrapods (limbed vertebrates) Acanthostega and Ichthyostega. Ventastega is the most primitive Devonian tetrapod represented by extensive remains, and casts light on a part of the phylogeny otherwise only represented by fragmentary ta…