Comparative evaluation of the effects of different activating media and temperatures on European eel (Anguilla anguilla) sperm motility assessed by computer assisted sperm analysis.

The European eel is a critically endangered teleost fish with very poor success rate for captive breeding and artificial reproduction. Therefore, to support its conservation, new strategies are needed to ensure fertilization. Objective analysis of sperm motility may be critical as it potentially represents one of the most important reproductive quality parameters. Spermatozoa acquire motility once in contact with hyperosmotic solutions as saltwater, yet the exact mechanisms and the role of temperature are still to be clarified. The main aim of the study was to assess the effects of 3 activating media (artificial sea water, tank water and commercial Actifish®) at 4 and 20 °C on sperm motility, by means of computer assisted sperm analysis. Secondary aim was to test 2 different concentrations of Actifish® mimicking sea water pH/osmolality, at 4 °C. The results suggested how both temperature and activating media have effects on spermatozoa motility and kinematics, with temperature mainly acting upon interaction with the media type. The samples activated with tank water at 20 °C showed the poorest motility outcomes (mean 38.1%), while the ones activated with Actifish® diluted 1:4 and artificial sea water, at 4 °C, the highest (means 51.8 and 51.5% respectively). Additionally, diluting Actifish® to reach same pH and osmolality of seawater led to worse motility outcomes, suggesting that composition may be the critical factor for activation rather than osmolality itself.

Effects of Environmental Enrichment on the Behavior of Octopus vulgaris in a Recirculating Aquaculture System.

Octopus vulgaris is a commercially valuable species. It is overexploited in the natural environment and is considered to be an innovative species for aquaculture. However, large-scale farming is generally designed only based on economic requirements, disregarding any form of enrichment that induces the natural behavior of aquatic species. Although many studies have shown the influence of environmental enrichment on terrestrial vertebrates, fish, and cephalopod mollusks, information on the effect of environmental enrichment on the body patterns of O. vulgaris is limited. Therefore, in this study, we assessed how different environmental conditions (Basic vs. Enriched) affect sub-adults of O. vulgaris kept in recirculation systems, through qualitative-quantitative studies of the main body patterns and their potential application in the commercial production of this species. The results indicated that octopuses kept in the enriched environment showed several body patterns and gained a significantly higher weight than those kept in the basic environment. The body patterns displayed by the individuals kept in the basic environment were similar to those exhibited under situations of hostility and inter/intra-specific conflict. Hence, the environment of octopuses needs to be enriched, especially for the large-scale production of this species.

Influence of age and seasonality on boar seminal plasma steroids quantification: A preliminary study.

Background and Aim: Seasonal changes, especially temperature and photoperiod, are well-known determining factors of swine reproductive capacity, but the underlying mechanisms remain unknown. This study aimed to investigate the effect of age and seasonal variations on boar seminal plasma steroids (dehydroepiandrosterone [DHEA], cortisol [CORT], and testosterone [TEST]) over 1 year. Materials and Methods: Four commercial hybrid adult boars (Large White × Duroc), aged between 12 and 44 months, were repeatedly evaluated at the Department of Veterinary Medical Sciences of the University of Bologna. Daily temperature and light hours relating to the collection date were considered for each observation within the four astronomical seasons: Winter, spring, summer, and autumn. Hormones were quantified using radioimmunoassay. The association between seasonal factors and hormone concentrations was evaluated using linear regression models. Univariate models were estimated for each hormone to assess the influence of the independent variables; two multivariate models were assessed to evaluate the effect of temperature and daylight hours, including boar and season factors. Results: Age significantly affected all analyzed hormones (CORT p < 0.0001; DHEA p < 0.0001; and TEST p < 0.0001). The highest average levels were found for each hormone during summertime, suggesting a positive correlation between steroid concentrations with temperature and light hours. Conclusion: The results of this study support the hypothesis that the increase in external temperature and light hours is somehow associated with higher levels of steroid concentrations in the seminal plasma of in-housed boars. These findings may help further investigate seasonal fluctuations in reproductive outcomes, which are well-known for porcine species.

Evaluation of reproductive performances of the common octopus (Octopus vulgaris) reared in water recirculation systems and fed different diets.

The reproductive performance of Octopus vulgaris broodstocks fed two different diets (mixed fish [F group, BW 1,048.14 g] or mixed crustaceans [C group, BW 998.44 g]) was analyzed using an experimental recirculating aquaculture system consisting of a tank equipped with spawning and incubation chambers. A total of 8 females (F1-4; C1-4), and 8 males (M1-M8) were selected. DI of the C group females was significantly (p < 0.05) higher (3.0 ± 0.29%) than the F group (2.16 ± 0.67%). SGR in C group was significantly higher (1.43 ± 0.12%) than the F group (1.18 ± 0.25%). Egg clusters, number of clusters, number of clusters/kg BW, and total length were more favorable in the C group than the F group. The number of clusters/kg BW of C females was 2.5 times higher than that of F females (78.1 ± 6.5 vs 31.1 ± 13.3). The total eggs number, number of eggs/cm, number of eggs/kg BW in the C group were significantly (p < 0.05) higher compared with the F group; the number of eggs/kg BW and paralarvae/kg BW were 5 times higher in the C group (115,928 ± 12,513 C vs 22,109 ± 7912 F and 114,953 ± 12,591 vs 20,729 ± 7104, respectively). Hatching rate of the C group was significantly (p < 0.05) higher compared to the F group.

Multifactorial Causes of Chronic Mortality in Juvenile Sturgeon (Huso huso).

This investigation focused on an episode of chronic mortality observed in juvenile Huso huso sturgeons. The examined subjects underwent pathological, microbiological, molecular, and chemical investigations. Grossly severe body shape deformities, epaxial muscle softening, and multifocal ulcerative dermatitis were the main observed findings. The more constant histopathologic findings were moderate to severe rarefaction and disorganization of the lymphohematopoietic lymphoid tissues, myofiber degeneration, atrophy and interstitial edema of skeletal epaxial muscles, and degeneration and atrophy of the gangliar neurons close to the myofibers. Chemical investigations showed a lower selenium concentration in affected animals, suggesting nutritional myopathy. Other manifestations were nephrocalcinosis and splenic vessel wall hyalinosis. Septicemia due to bacteria such as Aeromonas veronii, Shewanella putrefaciens, Citrobacter freundii, Chryseobacterium sp., and pigmented hyphae were found. No major sturgeon viral pathogens were detected by classical methods. Next-generation sequencing (NGS) analysis confirmed the absence of viral pathogens, with the exception of herpesvirus, at the order level; also, the presence of Aeromonas veronii and Shewanella putrefaciens was confirmed at the family level by the metagenomic classification of NGS data. In the absence of a primary yet undetected biological cause, it is supposed that environmental stressors, including nutritional imbalances, may have led to immune system impairment, facilitating the entry of opportunistic bacteria and mycotic hyphae.