High PCB levels were recorded in porpoises and common dolphins from European coasts. AbstractConcentrations of polychlorinated biphenyls (PCBs) in blubber of female common dolphins and harbour porpoises from the Atlantic coast of Europe were frequently above the threshold at which effects on reproduction could be expected, in 40% and 47% of cases respectively. This rose to 74% for porpoises from the southern North Sea. PCB concentrations were also high in southern North Sea fish. The average pregnancy rate recorded in porpoises (42%) in the study area was lower than in the western Atlantic but that in common dolphins (25%) was similar to that of the western Atlantic population. Porpoises that died from disease or parasitic infection had higher concentrations of persistent organic pollutants (POPs) than animals dying from other causes. Few of the common dolphins sampled had died from disease or parasitic infection. POP profiles in common dolphin blubber were related to individual feeding history while those in porpoises were more strongly related to condition.
In North Atlantic European waters, the nasal mite Halarachne halichoeri has been described affecting Grey seals (Halichoerus grypus) producing different levels of respiratory disease. This study provides data on the prevalence, clinical signs and produced macro-pathology of this parasite mite infecting juvenile wild Grey seals stranded in North-Western Spanish coast. Among the 25 seals examined during the study, a total of 19 had nasal mites in their respiratory upper ways, including adult and larval stages. This represented a percentage of prevalence of 76 ± 8.37. All the live positive seals presented a typical clinical symptomatology associated to upper respiratory tract infections. In dead positive seals, a light to intense sinusitis could be diagnosed macroscopically. The presence of the parasite in the nasal sinuses appears as the primary cause of the high respiratory tract symptomatology presented in most of the juvenile seals stranded in the north coast of Spain. Ultrastructural characterization by scanning electronic microscopy (SEM) has confirmed the taxonomic status of the mite. This identification of H. halichoeri represents the first description of the occurrence of this parasite in Southern Europe.
Describing the auditory periphery of odontocetes is a key conservation issue to further assess the effect of acoustic pollution. Because all odontocetes produce species-specific frequency ranges, differences in echolocation signals should reflect anatomical differences in the auditory pathways. Here, we studied the ears of 15 odontocete species through 3D reconstructions from computerized tomography scans to extract standard measurements (bullae lengths/volumes and cochlear volume) and investigate the discriminatory weight of each of these variables as well as their relation to the species' hearing specificity. Any of the measurements appeared to be a good indicator of the species and could therefore be used to classify them. All the ear lengths and most volumes were strongly linearly correlated (r >0.9) in all species and the proportion between the tympanic and periotic bones appeared to remain constant. This constant ratio could be an indication of a functional relationship between both structures, and might suggest an active role of the odontocete middle ear during target acoustic detection, providing new information on the odontocete sound reception mechanism. Our results are generally consistent with previous studies, although here the coefficients of correlation between animal lengths and the total volume and lengths of the bullae were lower (0.77< r <0.86), indicating that the length of the animals may not be a primary parameter to take into account when defining ear measurements. These results suggest that the measurements described characterize standard ears which could be used as a morphological basis for further species-specific acoustic comparison.
The aim of this study was to provide a detailed anatomical description of the thoracic region features in normal common (Delphinus delphis) and striped dolphins (Stenella coeruleoalba) and to compare anatomical cross-sections with computed tomography (CT) and magnetic resonance imaging (MRI) scans. CT and MRI were used to scan 7 very fresh by-caught dolphin cadavers: four common and three striped dolphins. Diagnostic images were obtained from dolphins in ventral recumbency, and after the examinations, six dolphins were frozen (-20°C) and sliced in the same position. As well as CT and MRI scans, cross-sections were obtained in the three body planes: transverse (slices of 1 cm thickness), sagittal (5 cm thickness) and dorsal (5 cm thickness). Relevant anatomical features of the thoracic region were identified and labelled on each section, obtaining a complete bi-dimensional atlas. Furthermore, we compared CT and MRI scans with anatomical cross-sections, and results provided a complete reference guide for the interpretation of imaging studies of common and striped dolphin's thoracic structures.
Computed tomography (CT) and low-field magnetic resonance imaging (MRI) were used to scan seven by-caught dolphin cadavers, belonging to two species: four common dolphins (Delphinus delphis) and three striped dolphins (Stenella coeruleoalba). CT and MRI were obtained with the animals in ventral recumbency. After the imaging procedures, six dolphins were frozen at -20°C and sliced in the same position they were examined. Not only CT and MRI scans, but also cross sections of the heads were obtained in three body planes: transverse (slices of 1 cm thickness) in three dolphins, sagittal (5 cm thickness) in two dolphins and dorsal (5 cm thickness) in two dolphins. Relevant anatomical structures were identified and labelled on each cross section, obtaining a comprehensive bi-dimensional topographical anatomy guide of the main features of the common and the striped dolphin head. Furthermore, the anatomical cross sections were compared with their corresponding CT and MRI images, allowing an imaging identification of most of the anatomical features. CT scans produced an excellent definition of the bony and air-filled structures, while MRI allowed us to successfully identify most of the soft tissue structures in the dolphin's head. This paper provides a detailed anatomical description of the head structures of common and striped dolphins and compares anatomical cross sections with CT and MRI scans, becoming a reference guide for the interpretation of imaging studies.
The study of the organ of Corti is essential to assess the impact of underwater noise on cetaceans. While classical histology techniques (including EDTA decalcification) have been previously considered, the process is time consuming. Independently from the histological technique, one of the challenging steps after extraction and fixation of the samples is to decalcify the bone envelope to access the cochlea without damaging the soft tissues. Here, we propose to use a fast commercial decalcifier (RDO®). 93 ears from 11 different odontocetes species stranded in the Mediterranean, Spanish North Atlantic and North Sea were used to precisely determine the decalcification time. Depending on the tympanic-periotic volume of the species, the decalcification time ranged from several hours to a few days, allowing a subsequently faster observation of the cochlear structures through routine microscope techniques.
The fish farming industry has an interest in the rearing of triploids as a means to prevent 26 sexual maturation in fish before they reach their optimal commercial size (Felip et al., 27 1999). Additionally, the production of triploid fish ensures that any that escapees from 28 aquacultural facilities are not able to reproduce in the wild. However, the production of 29 triploid fish has often been associated with an increased incidence of morphological 30 malformations, including abnormal jaws and fins (Sutterlin et al., 1987; Jungalwalla, 31 1991; McGeachy et al., 1996;Sadler et al., 2000;Oppedal et al., 2003), abnormal tail 32 and trunk proportions (Swarup, 1959), facial deformities (Tave et al., 1993) female by application of a cold-shock shortly after fertilization, as described by Piferrer 49 et al. (2000Piferrer 49 et al. ( , 2003. 50 3 The triploidy ratio within each progeny group was estimated by flow cytometric 51 analysis of embryos from 120 eggs sampled 48 hours post-fertilization using an FC500 52 flow cytometer (Beckman Coulter, Ca, U.S.A.), and following a modified version of the 53 method described by Lecommandeur et al. (1994). The triploidy ratios achieved in each 54 progeny were 87, 94, 95 and 97%). Only the progeny from the mating producing the 55 highest triploid rate (97%) were examined further. Thereafter, treated (3n) and control 56 (2n) larvae were reared separately in four 1000-l tanks. When they were 2 months old, 57 fish were vaccinated against Vibrio sp. by immersion in Gava-3 (100mL/L) 58 (Laboratorios HIPRA, Girona, Spain). Periodic OX-CTA (OX Laboratories, Barcelona, 59Spain) baths (50mg/L) were administered throughout the experiment to prevent the 60 presence of parasites. At 5 months of age, random samples of diploid and triploid fish 61were placed into four 3800-l tanks (2 tanks per ploidy group and 50 fish per tank). The 62 tanks were provided with flow-through water (40 l/min), and the fish were reared under 63 natural photoperiod and temperature conditions. The fish were fed by automatic feeders 64 providing dry pellets of increasing size (Skretting, Burgos, Spain) 7 days a week until 65 they reached 12 months of age. 66At both 6 and 12 months, 10 fish were sampled from each tank. The fish were 67 euthanized with an overdose of the anaesthetic MS-222 (500 mg/l, Sigma-Aldrich, 68Madrid, Spain). The ploidy level of each fish was determined by measurement of the 69 individual mean length of the erythrocyte major axis (30 erythrocytes per fish) in a 70 blood sample, stained with Hemacolor (E. Merck. Darmastadt., Germany), as 71 previously described by Piferrer et al. (2003). The individual mean length was then 72 compared with the overall mean length for diploids and triploids. The mean erythrocyte 73 major axis length was 11.5 ± 0.51 µm (mean±SD) in control diploids and 15.3 ± 0.29 74 4 µm in cold-shock treated triploid fish (P<0.001). All fish were confirmed to be of the 75 ploidy level appropriate to their corresponding test group. 76Fish were photographed with ...
The study of the organ of Corti is essential to assess the impact of underwater noise on cetaceans. While classical histology techniques (including EDTA decalcification) have been previously considered, the process is time consuming and artifacts, probably directly deriving from the protocol, often appear and difficult the analysis. However, no matter the choice of the analysis technique, one of the challenging step after extraction and fixation of the samples is to decalcify the bone envelope to access the cochlea without damaging the soft tissues. Here, we propose to use a fast commercial decalcifier (RDO®). 103 ears from 12 different odontocetes species stranded in the Mediterranean, Spanish North Atlantic and North Sea have been used to precisely determine the decalcification time. Specifically, the species processed were: Phocoena phocoena (n=45), Stenella coeruleoalba (n=12), Stenella frontalis (n=12), Tursiops truncatus (n=13), Delphinus delphis (n=4), Kogia simus (n=3), Kogia breviceps (n=2), Globicephala macrorhynchus (n=3), Globicephala melas (n=2), Steno bredanensis (n=4), Lagenodelphis hosei (n=2) and Ziphius cavirostris (n=1). Depending on the species, the decalcification time ranged from several hours to a few days, allowing a subsequently faster observation of the cochlear structures through routine microscope techniques.
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