Trophic Relationships and Habitat Preferences of Delphinids from the Southeastern Brazilian Coast Determined by Carbon and Nitrogen Stable Isotope Composition

To investigate the foraging habitats of delphinids in southeastern Brazil, we analyzed stable carbon (δ13C) and nitrogen (δ15N) isotopes in muscle samples of the following 10 delphinid species: Sotalia guianensis, Stenella frontalis, Tursiops truncatus, Steno bredanensis, Pseudorca crassidens, Delphinus sp., Lagenodelphis hosei, Stenella attenuata, Stenella longirostris and Grampus griseus. We also compared the δ13C and δ15N values among four populations of S. guianensis. Variation in carbon isotope results from coast to ocean indicated that there was a significant decrease in δ13C values from estuarine dolphins to oceanic species. S. guianensis from Guanabara Bay had the highest mean δ13C value, while oceanic species showed significantly lower δ13C values. The highest δ15N values were observed for P. crassidens and T. truncatus, suggesting that these species occupy the highest trophic position among the delphinids studied here. The oceanic species S. attenuata, G. griseus and L. hosei had the lowest δ15N values. Stable isotope analysis showed that the three populations of S. guianensis in coastal bays had different δ13C values, but similar δ15N results. Guiana dolphins from Sepetiba and Ilha Grande bays had different foraging habitat, with specimens from Ilha Grande showing more negative δ13C values. This study provides further information on the feeding ecology of delphinids occurring in southeastern Brazil, with evidence of distinctive foraging habitats and the occupation of different ecological niches by these species in the study area.Peer reviewe

Molecular identification and microscopic characterization of poxvirus in a Guiana dolphin and a common bottlenose dolphin, Brazil

The poxviruses identified in cetaceans are associated with characteristic tattoo or ring skin lesions. However, little is known regarding the prevalence and progression of these lesions and the molecular characterization of cetacean poxviruses in the Southern Hemisphere. This manuscript describes the progression of poxvirus-like skin lesions in 5 free-ranging Guiana dolphins Sotalia guianensis. Additionally, 151 skin samples from 113 free-ranging cetaceans from Brazil, including 4 animals with tattoo skin lesions, were selected for poxvirus testing. Poxviral DNA polymerase gene PCR amplification was used to detect the virus in β-actin-positive samples (145/151). DNA topoisomerase I gene PCR was then used in Cetaceanpoxvirus (CePV)-positive cases (n = 2), which were further evaluated by histopathology and electron microscopy. Based on photo-identification, adult Guiana dolphins presented regressing or healed poxvirus-like lesions (2/2), while juveniles presented persistent (2/3) or healed and progressive lesions (1/3). CePV DNA was amplified in a common bottlenose dolphin Tursiops truncatus and in a Guiana dolphin. Intracytoplasmic inclusion bodies and viral particles consistent with poxvirus were identified by histology and electron microscopy, respectively. CePV-specific amino acid motifs were identified through phylogenetic analysis. Our findings corroborate previous studies that suggest the placement of poxviruses from cetaceans within the novel CePV genus. This is the first molecular identification of poxvirus in South American odontocetes

Scanning-based chromatic dispersion estimation in mode-multiplexed optical systems

Mode-multiplexed coherent optical systems emerge as an alternative to overcome the capacity limits of current optical communication systems. As in single-mode systems, mode-multiplexed transmission experiences accumulated chromatic dispersion that must be estimated and compensated for by digital signal processing. Although scanning-based methods are widely used to estimate chromatic dispersion in single-mode optical systems, their performance in mode-multiplexed systems has not been evaluated. In this paper, we study three scanning-based chromatic dispersion estimation techniques in the scope of mode-multiplexed optical systems. The results indicate that the algorithms loose accuracy for high levels of crosstalk and ASE noise. However, we show that the estimation criterion based on the delay-tap sampling method can be properly modified to significantly improve the estimation performance even in the worst scenario of crosstalk evaluateCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão tem2017/25537-8; 2015/24341-7; 2015/ 24517-821st International conference on transparent optical networks (ICTON

Morphology of the Guiana dolphin (Sotalia guianensis) off southeastern Brazil: growth and geographic variation

The objective of this study was to analyze the morphology of Guiana dolphin (Sotalia guianensis) to evaluate the existence of geographical variation along southeastern Brazil. Body length and 39 cranial variables were measured of specimens stranded or accidentally captured to consider ontogenetic and geographic variations. The areas studied were Espírito Santo (ES; 18°30’S-20°40’S), northern Rio de Janeiro (NRJ; 21°35’S-22°25’S), southern Rio de Janeiro (SRJ; 23°00’S-23°07’S) and São Paulo (SP; 23°30’S-25°30’S). Body length at age zero predicted by a non-linear Gompertz model for the Guiana dolphin was 148.3cm for area ES, 108.97cm for area NRJ, 98.4cm for area SRJ and 90.9cm for area SP. Asymptotic values were reached at about six years of age for total body length and cranial variations. These results indicate that Guiana dolphins reach adult size and sexual maturity simultaneously at six to seven years of age, when specimens cease to grow. The growth pattern for body and skull size indicated that there is variation between geographic areas. Guiana dolphins found in São Paulo are smaller than those analyzed in northern Rio de Janeiro and Espírito Santo, which implies a different growth rate. A canonical discriminant analysis of the cranial metric characters indicated significant differences between the four geographic areas. Differences between areas NRJ, SRJ and SP were responsible for 54% (axis 1) and 34% (axis 2) of the variation, respectively. The third axis depicted a difference between the area ES and the others. A partial overlap between geographic areas was observed in the projection of the species on the canonical axes, suggesting parapatry. Geographic variation recorded in this study is likely to be related to environmental adaptations. One of the areas that could play a role in the distribution of Guiana dolphin in the surveyed area is the central coast of Rio de Janeiro, which is characterized by the absence of river discharges, a narrowing of the continental shelf and upwelling influence that might be limiting the species occurrence in this area

Perspectives on carbon footprint of agricultural land-use in Brazil

Brazil is one of the main producers in the agricultural and forestry sector worldwide, with production systems based on high consumption of inputs that contribute to high levels of greenhouse gas (GHG) emissions. This paper presents an analysis of the scenario of national GHG emissions and carbon footprints in the major production systems of agriculture, including livestock production and forestry, and the potential for soil carbon storage as a mitigation strategy under these systems. The main sources of national GHG emissions are beef cattle due to enteric fermentation and the management of agricultural soils through the use of nitrogen fertilizers. The increasing adoption of low-carbon agriculture has led to a reduction in the carbon footprint through no-till technologies, agrosilvopastoral systems, N2 fixation, and tree plantations. These technologies deserve to be increasingly disseminated to generate economic opportunities leading to financial gains from the commercialization of carbon credits and payment for environmental services

Comparative histopathologic and viral immunohistochemical studies on CeMV infection among Western Mediterranean, Northeast-Central, and Southwestern Atlantic cetaceans

Cetacean morbillivirus (CeMV) is a major natural cause of morbidity and mortality in cetaceans worldwide and results in epidemic and endemic fatalities. The pathogenesis of CeMV has not been fully elucidated, and questions remain regarding tissue tropism and the mechanisms of immunosuppression. We compared the histopathologic and viral immunohistochemical features in molecularly confirmed CeMV-infected Guiana dolphins (Sotalia guianensis) from the Southwestern Atlantic (Brazil) and striped dolphins (Stenella coeruleoalba) and bottlenose dolphins (Tursiops truncatus) from the Northeast-Central Atlantic (Canary Islands, Spain) and the Western Mediterranean Sea (Italy). Major emphasis was placed on the central nervous system (CNS), including neuroanatomical distribution of lesions, and the lymphoid system and lung were also examined. Eleven Guiana dolphins, 13 striped dolphins, and 3 bottlenose dolphins were selected by defined criteria. CeMV infections showed a remarkable neurotropism in striped dolphins and bottlenose dolphins, while this was a rare feature in CeMV-infected Guiana dolphins. Neuroanatomical distribution of lesions in dolphins stranded in the Canary Islands revealed a consistent involvement of the cerebrum, thalamus, and cerebellum, followed by caudal brainstem and spinal cord. In most cases, Guiana dolphins had more severe lung lesions. The lymphoid system involved in all three species, with consistent lymphoid depletion. Multinucleate giant cells/syncytia and characteristic viral inclusion bodies were variably observed in these organs. Overall, there was widespread lymphohistiocytic, epithelial, and neuronal/neuroglial viral antigen immunolabeling with some individual, host species, and CeMV strain differences. Preexisting and opportunistic infections were common, particularly endoparasitism, followed by bacterial, fungal, and viral infections. These results contribute to understanding CeMV infections in susceptible cetacean hosts in relation to factors such as CeMV strains and geographic locations, thereby establishing the basis for future neuro- and immunopathological comparative investigations

Survey of selected viral agents (herpesvirus, adenovirus and hepatitis E virus) in liver and lung samples of cetaceans, Brazil

Abstract Hepatic and pulmonary lesions are common in cetaceans, despite their poorly understood viral etiology. Herpesviruses (HV), adenoviruses (AdV) and hepatitis E virus (HEV) are emerging agents in cetaceans, associated with liver and/or pulmonary damage in mammals. We isolated and molecularly tested DNA for HV and AdV (n = 218 individuals; 187 liver and 108 lung samples) and RNA for HEV (n = 147 animals; 147 liver samples) from six cetacean families. All animals stranded or were bycaught in Brazil between 2001 and 2021. Positive-animals were analyzed by histopathology. Statistical analyses assessed if the prevalence of viral infection could be associated with the variables: species, family, habitat, region, sex, and age group. All samples were negative for AdV and HEV. Overall, 8.7% (19/218) of the cetaceans were HV-positive (4.8% [9/187] liver and 11.1% [12/108] lung), without HV-associated lesions. HV-prevalence was statistically significant higher in Pontoporiidae (19.2%, 10/52) when compared to Delphinidae (4.1%, 5/121), and in southeastern (17.1%, 13/76)—the most industrialized Brazilian region—when compared to the northeastern region (2.4%, 3/126). This study broadens the herpesvirus host range in cetaceans, including its description in pygmy sperm whales (Kogia breviceps) and humpback whales (Megaptera novaeangliae). Further studies must elucidate herpesvirus drivers in cetaceans