Are different parasite guilds of Pagrus pagrus equally suitable sources of information on host zoogeography?

Metazoan parasite assemblages of Pagrus pagrus inhabiting the southwestern Atlantic were analysed with the aim of identifying the existence of different stocks and to comparatively assess the value of different parasite guilds as indicators of zoogeographical regions. A total of 186 fish was examined. Samples were obtained from three Brazilian and one Argentine localities, distributed in three different biogeographic districts of the Argentine Zoogeographical Province. Pagrus pagrus harboured 26 metazoan parasite species distributed in three guilds, ectoparasites (10 species), long-lived larval endoparasites and short-lived gastrointestinal endoparasites (eight species each). Prevalence and abundance values of the former two guilds allowed analysing them comparatively to assess their value as biological indicators of both host population structure and zoogeography. Results of analyses on long-lived parasites evidenced the existence of three stocks, one in the regions of Rio de Janeiro and Sao Paulo, other in southern Brazil (Rio Grande do Sul) and a third in northern Argentina (Mar del Plata), responding to the differential environmental conditions characteristic of three zoogeographical ecoregions. Ectoparasite assemblages exhibited significant differences between all pairs of samples, including those considered as a single stock according to data on persistent parasites. Assemblages of long-lived larval parasites are considered as better indicators for stock assessment purposes than ectoparasites, whose population parameters were variable temporally and heterogeneous at small spatial scales. The distributional variability of persistent parasites of P. pagrus along large scales provides valuable information to help defining robust biogeographical patterns, applicable to stock identification and fishery management of this species.

Unravelling growth trajectories from complicated otoliths - the case of Brazilian codling Urophycis brasiliensis.

Uncertainty regarding the age determination of the Brazilian codling Urophycis brasiliensis has hampered its stock assessment. Transverse sections of otoliths displayed up to seven (in males) and 12 (in females) alternate opaque and translucent bands that could not be conclusively validated as annuli, resulting in unrealistically high ages of first maturity (A50 ) (A50male = 4·5 years and A50female = 6 years). Therefore, growth was described by the von Bertalanffy (VB) model using an alternative approach that combined microstructure data (daily growth increments) and a fixed asymptotic total length (L∞ ). This approach was supported by applying it to two other co-occurring species, the whitemouth croaker Micropogonias furnieri and the king weakfish Macrodon atricauda, for which daily and annual ring formation has previously been validated. The sensitivity to realistic errors associated with the choice of the L∞ and the daily increment readings was shown to be low. The results show that U. brasiliensis has a fast growth rate (Kmale = 1·19 year-1 , Kfemale = 0·71 year-1 ) and early maturation (A50male = 1·1-1·5 years, A50female  = 1·6-1·8 years); typical life-history traits for a sub-tropical coastal gadiform. This novel study offers an alternative approach for age and growth reconstruction for species with complex patterns of opaque and translucent bands provided that daily growth increments in the yearlings can be counted and L∞ reliably estimated.

Density-dependent changes in the feeding behaviour of Macrodon atricauda of southern Brazil.

Long-term density-dependent changes in the population dynamics of the king weakfish Macrodon atricauda of southern Brazil between 1976 and 2013 may be related to a change in diet and an increase in feeding intensity. The importance of the small crustacean, Artemesia longinaris, increased in the diet of adults, whereas the importance of teleosts decreased and the frequency of full stomachs increased. Macrodon atricauda currently benefits from a high availability of A. longinaris, which results in a higher energy intake per individual, which, in turn, induces faster body growth and an earlier onset of sexual maturation.

[Studies regarding the chronicization potential of viral hepatitis in children]. / Cercetari privind potentialul de cronicizare a hepatitei virale la copii.

Out of 205 children, former patients with viral hepatitis, investigated after the end of the follow-up period by clinical and laboratory examinations, 9 (4.4%) presented mild or moderate pathological alterations. At the second control, carried out after an another interval de 1-1½ years, the pathological alterations were refound only in 2 of the former patients, suggesting that all the others presented lasting forms of acute viral hepatitis evolving towards healing. The presence of AgHBs and the alteration of proteinogramme in the acute phase of VH can serve as criteria of unfavourable prognosis of the disease evolution and impose a preferential follow-up of this category of patients.