Clara Boglione

Skeletal descriptors and quality assessment in larvae and post-larvae of wild-caught and hatchery-reared gilthead sea bream (Sparus aurata L. 1758)

Gilthead sea bream from different Mediterranean hatcheries show a consistent number of skeletal anomalies, mainly in the hemal and caudal body regions. Four hundred and twenty-two hatchery-reared sea bream from Italy, France and Spain were checked for skeletal malformations and meristic counts. The same skeletal descriptors were examined in 72 wild-caught sea bream. Correspondence analysis (CA) was performed to rank groups of hatchery-reared sea bream according to their skeletal abnormalities. The position of each group on the first correspondence axis with respect to the wild-caught specimens was used as a larval quality indicator. Wild phenotype similarity was also tested performing meristic counts and inter-groups meristic differences were illustrated. Results highlighted a quality gap between wild-caught and hatchery-reared specimens, with the only exception being sea bream larvae that were reared in semi-intensive conditions. This larval monitoring method is proposed as a tool for evaluating hatchery larval quality at a morpho-anatomical level.

Normal and abnormal osteological development of caudal fin in Sparus aurata L. fry

Normal osteological development of the caudal fin in gilthead sea bream is described at the larval and juvenile stages. It was used as a standard for the study of a sea bream larval population with characteristic osteological deviations which give rise to abnormal juveniles. Normal specimens were reared under extensive rearing conditions, and abnormal specimens under intensive rearing conditions. The first hypural elements appearing in the abnormal preflexion larvae were deformed and displaced. With development, all elements related to the caudal region (parhypural, hypuralia, epuralia, vertebra centra, neural and haemal processes) formed abnormally. The abnormalities were extra-numerous elements, fusions, deformities and displacements of the elements.

Skeletal quality assessment of reared and wild sharpsnout sea bream and pandora juveniles

In this study, skeletal descriptors of wild and reared juveniles of sharpsnout sea bream (Diplodus puntazzo) and pandora (Pagellus erythrinus) were compared to assess the quality of farmed individuals. A total of 1016 wild and reared juveniles of sharpsnout sea bream and pandora were inspected for skeletal abnormalities and a qualitative evaluation of aquaculture production was achieved. The applied approach was based on the analysis of meristic character counts, and incidence and pattern of skeletal anomalies. Correspondence Analysis (CA), Multi-Response Permutation Procedure (MRPP) and Indicator Species Analysis were performed on a data matrix. Such methodology allowed the identification of different levels of disturbance generated by the captive conditions.

Geometric morphometrics and internal anatomy in sea bass shape analysis (Dicentrarchus labrax L., Moronidae)

Abstract The effects of different conditions of larval and postlarval rearing on the external morphology and internal anatomical characters were studied in juvenile and adult specimens of Dicentrarchus labrax L. (Teleostea, Moronidae) in order to assess the potential of a combined methodology in the assessment of finfish quality. Differences in the external morphology between two samples were analysed before their introduction into floating cages and after 15 months of common rearing. Shape differences were studied with geometric morphometrics. Significant differences in shape were found in juveniles. In adults, at the end of the common rearing, differences were smaller but still significant. The importance of larval rearing conditions in determining sea bass juvenile and adult shape is evident as well as a phenomenon of morphological resilience. On the same specimens, internal anatomical data were collected from X-rays. In this way, it was possible to correlate fish shape with internal anatomical data. Characteristic shapes were associated with particular cadres of internal anatomical anomalies, such as head shape and anomalies in the cephalic region, a bent body shape and lordosis of the haemal and prehaemal regions, the shape of the caudal region and lordosis of the caudal vertebral axis. Streamlined wild-like profiles were associated with light anomaly cadres. The use of the combined approach proposed is, thus, recommended in the description and quantification of shape features and particularly in the context of fish quality assessment.

An Advanced Colour Calibration Method for Fish Freshness Assessment: a Comparison Between Standard and Passive Refrigeration Modalities

Freshness represents a pivotal aspect in fish product for both security and quality. Its evaluation still represents the key factor driving the consumer’ choices. Fish appearance is affected by many different factors that demand the contribution of different disciplines to be understood: from the physical and optical properties to the slaughtering and post-slaughtering conditions. An innovative preservation system is represented by the Passive Refrigeration PRS™ developed for the preservation and transport of perishable food products. Scientific methods for product freshness evaluation may be conveniently divided into two categories: sensorial and instrumental. In this study, an instrumental method of colour calibration and discrimination is proposed at pilot scale for automatic evaluation of gilthead seabream (Sparus aurata) freshness. We propose a non-destructive method based on the colorimetric imaging of the whole external body of seabreams to evaluate through multivariate partial least squares which approach the differences in the freshness preservation under four refrigeration modalities. The matrix of the independent variables is represented by RGB values for each pixel belonging to an extracted region of interest (129,633 values). The dependent variable is composed by two dummy variable corresponding to fresh (T0) or non-fresh (T2) individuals. T1 individuals were used as external test. The results quantified significant colorimetric differences between fresh and non-fresh fish. All fish used to create the model (T0 and T2) were correctly classified as fresh or non-fresh, while external test individuals (T1) were all classified as fresh. The proposed imaging method merges different image analysis techniques: (a) colorimetric calibration, (b) morphometric superimposition and (c) partial least square discriminant analysis modelling. This innovative and non-destructive approach allows the automatic assessment of fish freshness.

Environmental Conditioning of Skeletal Anomalies Typology and Frequency in Gilthead Seabream (Sparus aurata L., 1758) Juveniles

In this paper, 981 reared juveniles of gilthead seabream (Sparus aurata) were analysed, 721 of which were from a commercial hatchery located in Northern Italy (Venice, Italy) and 260 from the Hellenic Center for Marine Research (Crete, Greece). These individuals were from 4 different egg batches, for a total of 10 different lots. Each egg batch was split into two lots after hatching, and reared with two different methodologies: intensive and semi-intensive. All fish were subjected to processing for skeletal anomaly and meristic count analysis. The aims involved: (1) quantitatively and qualitatively analyzing whether differences in skeletal elements arise between siblings and, if so, what they are; (2) investigating if any skeletal bone tissue/ossification is specifically affected by changing environmental rearing conditions; and (3) contributing to the identification of the best practices for gilthead seabream larval rearing in order to lower the deformity rates, without selections. The results obtained in this study highlighted that: i) in all the semi-intensive lots, the bones having intramembranous ossification showed a consistently lower incidence of anomalies; ii) the same clear pattern was not observed in the skeletal elements whose ossification process requires a cartilaginous precursor. It is thus possible to ameliorate the morphological quality (by reducing the incidence of severe skeletal anomalies and the variability in meristic counts of dermal bones) of reared seabream juveniles by lowering the stocking densities (maximum 16 larvae/L) and increasing the volume of the hatchery rearing tanks (minimum 40 m3). Feeding larvae with a wide variety of live (wild) preys seems further to improve juvenile skeletal quality. Additionally, analysis of the morphological quality of juveniles reared under two different semi-intensive conditions, Mesocosm and Large Volumes, highlighted a somewhat greater capacity of Large Volumes to significantly augment the gap with siblings reared in intensive (conventional) modality.

Skeletal Anomaly Monitoring in Rainbow Trout (Oncorhynchus mykiss, Walbaum 1792) Reared under Different Conditions

The incidence of skeletal anomalies could be used as an indicator of the “quality” of rearing conditions as these anomalies are thought to result from the inability of homeostatic mechanisms to compensate for environmentally-induced stress and/or altered genetic factors. Identification of rearing conditions that lower the rate of anomalies can be an important step toward profitable aquaculture as malformed market-size fish have to be discarded, thus reducing fish farmers’ profits. In this study, the occurrence of skeletal anomalies in adult rainbow trout grown under intensive and organic conditions was monitored. As organic aquaculture animal production is in its early stages, organic broodstock is not available in sufficient quantities. Non-organic juveniles could, therefore, be used for on-growing purposes in organic aquaculture production cycle. Thus, the adult fish analysed in this study experienced intensive conditions during juvenile rearing. Significant differences in the pattern of anomalies were detected between organically and intensively-ongrown specimens, although the occurrence of severe, commercially important anomalies, affecting 2–12.5% of individuals, was comparable in the two systems. Thus, organic aquaculture needs to be improved in order to significantly reduce the incidence of severe anomalies in rainbow trout.

Gonadal disorder in the thinlip grey mullet (Liza ramada, Risso 1827) as a biomarker of environmental stress in surface waters.

The aim of this study was to evaluate the use of gonadal alterations in the thinlip grey mullet (Liza ramada) as a biological indicator in assessing aquatic ecosystems health, with particular emphasis to river ecosystems exposed to sewage discharges. For this purpose, the reproductive status and the presence of gonadal alterations were studied in 206 mullets collected from two sites on the low course of the Tiber River, downstream of a large urban sewage treatment plant and in the estuarine area, and from an uncontaminated pond considered as reference site. Intersex and irregularly shaped gonads were observed in 20.8% of the mullets from the most polluted site, and intersex gonads in 10.3% of those from the estuarine area. No alterations were detected in the fish from the reference site, which also showed distinct stages of gonadal development. Conversely, unclear stages of testicular and ovary development were observed in the fish from the two polluted river sites. The results of this study suggest that L. ramada may represent a sentinel species in environmental risk assessment and support the use of gonadal alterations of this species as a bioindicator for extensive monitoring of pollution in lower stretches of rivers and estuarine areas.