Eye morphology of Guiana dolphins (Sotalia guianensis) and Clymene dolphins (Stenella clymene).

Recent studies showed that vision and hearing in dolphins are mechanisms for perception of the environment, and transmission of information among individuals. Considering that Guiana dolphins (Sotalia guianensis) are distributed in costal regions, and Clymene dolphins (Stenella clymene) are found in oceanic environments, the objective of this study was to compare the morphology of the eyes of these two species, assessing the differences in eye structures in both environments. Five specimens of Sotalia guianensis and four specimens of Stenella clymene were analyzed. All the specimens were found stranded in the northeastern coast of Brazil. Samples were fixated in 10% formaldehyde, dissected, photographed, processed, and analyzed by optical microscopy. The inferior palpebral region of the two species showed a granular layer, subcutaneous lymphoid tissue, and innervation. Morphometric values of the eyelid structures and eye bulb were greater in S. clymene. The cornea showed four layers in S. clymene: anterior epithelium, anterior lamina, stroma, and posterior lamina. The sclera of S. guianensis showed more melanocytes and presence of mechanoreceptors next to the Harderian gland. It is possible to suggest that the geographical distribution of these cetaceans determine their eye morphology, which is an adaptation to the intrinsic characteristics of the aquatic environment.

Causes of mortality of seabirds stranded at the Northeastern coast of Brazil / Causas de mortalidade de aves marinhas encalhadas na costa do Nordeste do Brasil

The aim of this work was to determine the main species of stranded seabirds at the Northeastern coast of Brazil in addition to the most frequent causes of stranding and mortality. The study was conducted in a monitored area for three years (2012-2014), from the coastline of south Alagoas through north coast of Bahia encompassing 254km of coast. The seabirds found alive during the monitoring were sent to rehabilitation, clinically examined and the carcasses were removed, necropsied and histopathologically analyzed. A total of 1.347 seabirds were found stranded. Of these, 378 were found alive and sent to rehabilitation. From the 969 dead seabirds 806 were unsuitable for necropsy, being only 163 submitted to necropsy and histopathological analysis. Calonectris borealis, Puffinus gravis and Puffinus puffinus were the main seabirds stranded in the studied area. Most stranding occurred from March to June with an increase during April and May for the most species of seabirds. The main clinical signs of stranded seabirds consisted of inappetence, apathy, low body score, hypothermia, flying or movement difficulty and prolonged recumbency. Natural causes followed by infectious diseases and anthropogenic environmental factors were the main causes of death of seabirds stranded on the Northeastern coast of Brazil.(AU)

O objetivo deste trabalho foi determinar as principais espécies de aves marinhas encalhadas na costa do Nordeste do Brasil, bem como as mais frequentes causas de encalhe e mortalidade. O estudo foi desenvolvido em área monitorada durante três anos (2012-2014), entre o litoral sul de Alagoas e o litoral norte da Bahia, perfazendo um total de 254km de extensão da costa. As aves encontradas vivas foram encaminhadas para reabilitação e examinadas clinicamente; as carcaças foram removidas, necropsiadas e os órgãos foram analisados por meio da histopatologia. Um total de 1.347 aves foi encontrado, encalhadas. Dessas, 378 estavam vivas e foram encaminhadas para a reabilitação. Das 969 aves marinhas mortas, 806 estavam impróprias para realização de necropsia, sendo apenas 163 submetidas à necropsia e análise histopatológica. Calonectris borealis, Puffinus gravis e Puffinus puffinus foram as principais espécies encontradas na área estudada. A maioria dos encalhes para grande parte das aves marinhas ocorreram de março a junho, com um aumento durante abril e maio. Os principais sinais clínicos das aves marinhas consistiram em inapetência, apatia, baixo escore corporal, hipotermia, dificuldade de voo ou movimento e decúbito prolongado. Causas naturais, seguidas de doenças infecciosas e fatores antropogênicos, foram as principais causas de mortes de aves marinhas encalhadas na costa do Nordeste do Brasil.(AU)

Morphology of mucosa-associated lymphoid tissue in odontocetes.

This study describes the mucosa-associated lymphoid tissue (MALT) in odontocetes from the Brazilian coast and freshwater systems. Seven species were evaluated and tissue samples were analyzed by light, scanning and transmission electron microscopy, and immunohistochemistry. Laryngeal tonsil was a palpable oval mass located in the larynx, composed of a lymphoepithelial complex. Dense collections of lymphocytes were found in the skin of male fetus and calf. Clusters of lymphoid tissue were found in the uterine cervix of a reproductively active juvenile female and along the pulmonary artery of an adult female. Lymphoid tissues associated with the gastrointestinal tract were characterized by diffusely arranged or organized lymphocytes. The anal tonsil was composed of an aggregate of lymphoid tissue occurring exclusively in the anal canal, being composed of squamous epithelium branches. MALT was present in different tissues and organic systems of cetaceans, providing constant protection against mucosal pathogens present in their environment.

Reproductive morphology of female Guiana dolphins (Sotalia guianensis).

The reproductive morphology of cetaceans is poorly studied and, despite the large number of strandings, reports on this subject are scarce due to access to carcasses mostly in an advanced state of decomposition. The present study aimed to describe histological characteristics of the female genital tract of Sotalia guianensis, in order to assist in future studies on the reproductive biology of these animals. Females of different ages, from stranding events on beaches in northeastern Brazil, were used. Fragments of all organs were collected and processed for light and scanning electron microscopy. Histological analyses showed that these structures were similar to those found in terrestrial mammals, with some peculiarities, such as the presence of differentiated cells in the vulvar subepidermal layer, not described in the literature on cetaceans. Reproductive studies with a morphological description of the female genital organs are extremely important, since they would enable a better understanding of the species reproductive physiology and assist in the development of new strategies for the species conservation.

Morphology of the eyeball from the Humpback whale (Megaptera novaeangliae).

Aquatic mammals underwent morphological and physiological adaptations due to the transition from terrestrial to aquatic environment. One of the morphological changes regards their vision since cetaceans' eyes are able to withstand mechanical, chemical, osmotic, and optical water conditions. Due to insufficient information about these animals, especially regarding their sense organs, this study aimed to describe the morphology of the Humpback whale (Megaptera novaeangliae) eyeball. Three newborn females, stranded dead on the coast of Sergipe and Bahia, Brazil, were used. Samples were fixed in a 10% formalin solution, dissected, photographed, collected, and evaluated through light and electron microscopy techniques. The Humpback whale sclera was thick and had an irregular surface with mechanoreceptors in its lamina propria. Lens was dense, transparent, and ellipsoidal, consisting of three layers, and the vascularized choroid contains melanocytes, mechanoreceptors, and a fibrous tapetum lucidum. The Humpback whale eyeball is similar to other cetaceans and suggests an adaptation to diving and migration, contributing to the perception of differences in temperature, pressure, and lighting.