Distribution and human health risk assessment of PAHs in four fish species from a SW Atlantic estuary.

The aim of this study is to assess-for the first time-the concentration of the 16 polycyclic aromatic hydrocarbons (PAHs) in the muscle tissues of four fish species (Micropogonias furnieri, Cynoscion guatucupa, Ramnogaster arcuata, and Mustelus schmitti) from Bahía Blanca estuary, Argentina and to evaluate their sources, distribution, and the human health risks implicated. Considering the four species under study, mean total PAH concentrations showed the following decreasing accumulation trend: M. schmitti, R. arcuata, C. guatucupa, and M. furnieri. Low molecular weight PAHs, such as naphthalene and phenanthrene, were generally predominant, displaying properties of PAH mixtures generated from petrogenic pollution. Of the four fish species analyzed, M. furnieri was the only one that did not raise any human consumption warning. In the case of the other species, exceeding values were found above the safety human consumption guidelines. Nevertheless, the screening criteria for carcinogenic PAHs proposed by the USEPA indicated a good quality status for these fish species.

Relationship between ecomorphology and trophic segregation in four closely related sympatric fish species (Teleostei, Sciaenidae).

This study explores the relationship between ecomorphology and trophic segregation in four closely related sympatric fish species (Teleostei, Sciaenidae) that are known to differ in their trophic habits. Only adult specimens were analyzed: 103 Cynoscion guatucupa, 77 Pogonias cromis, 61 Micropogonias furnieri, and 48 Menticirrhus americanus. The four species presented divergent ecomorphological traits related to swimming agility, prey spotting and capture, and the potential size of prey they were able to swallow. Results suggest that these sciaenid species can partition the food resources, even though they completely overlap in space. Differences in their ecomorphological traits appear to correlate closely with the diet and consequently could explain the trophic differentiation observed. Arguably, these ecomorphological differences play a significant role in the coexistence of the adults of these sympatric fish species.

Histological remarks of the uterus of sympterygia acuta (Garman, 1877) and sympterygia bonapartii (Müller & Henle, 1841) (chondrichthyes; rajidae) / Características histológicas del útero de sympterygia acuta (Garman, 1877) y sympterygia bonapartii (Müller & Henle, 1841) (chondrichthyes; rajidae)

Chondrichthyes constitute a conserve and vulnerable clade of increasing importance. However, there is scarce knowledge about the morphological aspects of the reproduction, so that only one work exists about the structure of the gravid uterus of an oviparous species. The work presented here describes the morphological, histological and histochemical remarks of the uterus of two Rajids of the Sympterygia genus along the life cycle. Both species presented paired uteri that lead independently to a common urogenital sinus. The uteri of immature females are filiform, translucent and unspecialized tubes. When sexual development starts, all the genital system displays a transitional and progressive change. In all studied females, independently of the maturing stage, the same four layers were present all over the uterus: a mucosa, which comprises the lining epithelium and lamina propria, a submucosa, a muscular and a serosa. The major changes in the structure of the uterus along the life cycle occur in the mucosa. The uteri of mature, gravid and non-gravid, females presents three distinguishable areas, cranial, medial and caudal, that vary both in the structure and histochemistry of the mucosa and in the thickness of the muscular layer. The results presented here are discussed in a physiological, adaptive and phylogenetic context.

Los condrictios constituyen un clado sumamente conservado y vulnerable a la explotación, que ha cobrado una importancia creciente en los últimos años. Sin embargo, existe poca información sobre los aspectos morfológicos relacionados con la reproducción; tanto así, que la estructura del útero en hembras grávidas sólo ha sido estudiada en profundidad en una especie ovípara. El presente trabajo describe las características morfológicas, histológicas e histoquímicas del útero de dos especies de Rájidos del género Sympterygia a lo largo del ciclo de vida. Ambas especies presentan úteros pares que desembocan independientemente en un seno urogenital común. El útero de las hembras inmaduras es filiforme, translúcido y poco especializado. Cuando se inicia el desarrollo sexual, todo el sistema genital exhibe un cambio direccional y progresivo. En todas las hembras estudiadas, independientemente del grado de madurez, se encontraron las mismas cuatro túnicas a lo largo del útero: una mucosa, compuesta por un epitelio de revestimiento y un corion, una submucosa, una muscular y una serosa. Los cambios mayores en la estructura del útero a lo largo del ciclo de vida ocurren a nivel de la mucosa. En el útero de hembras maduras, grávidas o no grávidas, se pueden reconocer tres regiones claramente diferenciables, craneal, media y caudal, que varían tanto en la estructura como en la afinidad histoquímica de la mucosa, así como en el grosor de la túnica muscular. Los resultados del presente trabajo se discuten en un contexto fisiológico, filogenético y adaptativo.