Riparian areas are recognized for their buffering capacity regarding phosphorus and nitrogen from agricultural and urban runoff. However, their role in attenuating nutrient loads of rivers receiving point source nutrient inputs (e.g., from wastewater treatment plants, WWTPs) is still little understood. Here, we investigated whether ammonium (NH4-N), nitrate (NO3-N), and soluble reactive phosphorus (SRP) retention were influenced by the riparian land use in three Brazilian rivers receiving WWTP effluents. We hypothesized that nutrient attenuation would be potentially influenced by the hydrological connectivity between the main channel and riparian areas with native vegetation. We estimated retention from longitudinal patterns of dilution-corrected nutrient concentrations below the WWTPs. We assessed nutrient retention during periods with high (i.e., the wet) and low connectivity (i.e., the dry season). Relationships between non-conservative (nutrients) and conservative (chloride) solutes in both seasons were used to identify potential changes in the river chemistry due to the hydrological connectivity with the riparian areas. We also evaluated the relationship between net uptake velocities (Vf-net) and the accumulated percent native vegetation cover in the 100-m buffer using linear regressions, comparing the response for each nutrient between seasons with Analysis of Covariance. Slopes of regressions between nutrients and chloride significantly differed between seasons for NO3-N and SRP but not for NH4-N. The relationships between Vf-net and accumulated native vegetation in the riparian buffer presented steeper slopes for SRP in the wet than in the dry season. No significant relationships between NO3-N Vf-net and native vegetation cover were observed in either season. In contrast, increases in Vf-net with increasing vegetation cover were observed for NH4-N in the dry season. In periods with expected higher connectivity, NO3-N and SRP concentrations tended to be lower relative to chloride concentrations, with a potential effect of native vegetation in the riparian area on SRP retention. Our results suggest that seasonal connectivity between nutrient-rich river water and riparian areas is likely to induce changes in the predominant nutrient transformation processes, thereby favoring either nutrient retention or export in such rivers.
O divertículo vitelínico é um remanescente do pedúnculo vitelínico que se encontra na maioria das aves, e é mais desenvolvido nas mais jovens. É formado por um tecido linfóide, permanece até aos 21 meses de idade e sua localização não é precisa na literatura existente. O objetivo deste trabalho foi descrever a localização precisa e o tamanho do pedúnculo e divertículo vitelínicos em aves de corte. Foram coletadas vísceras celomáticas de 19 frangos de corte de 21 dias de idade, alimentados com ração comercial. O pedúnculo apresentou tamanho médio de 1,23±1,20 cm e o divertículo vitelínico 2,23±1,82 cm, localizando-se na região distal do jejuno.
Pesq. Vet. Bras. 32(Supl.1):1-3, dezembro 2012 1 RESUMO.-[Descrição anátomo-radiográfica do esqueleto axial do cachorro-do-mato (Cerdocyon thous).] O objetivo deste trabalho foi descrever o esqueleto axial de um carnívoro selvagem brasileiro, o cachorro-do-mato (Cerdocyon thous). Cinco animais foram previamente descongelados para exames radiográficos e posteriormente submetidos a dissecação óssea e maceração química. Os animais apresentavam sete vértebras cervicais e, à partir da terceira, eram mais curtas e largas e o processo espinhoso mais evidente a partir da quinta vértebra cervical. Há treze vér-tebras torácicas e o processo espinhoso das vértebras lombares, que são sete, diminui partir da quinta vértebra. O sacro é constituído por duas vértebras fundidas e há 20 ou 21 vértebras caudais. Pode-se concluir que o esqueleto axial do cachorro-do-mato se assemelha ao do cão doméstico. The aim of this study was to describe the axial skeleton of a wild Brazilian carnivorous, the crab-eating fox (Cerdocyon thous). Five specimens of crab-eating fox were previously unfrozen for radiographic exams and their bones went through dissection and chemical maceration. This animal presents seven cervical vertebrae, and from the third on, they become shorter and wider than the other ones e the spinous process was makeable from the fifth cervical vertebrae on. There are thirteen thoracic vertebrae and the spinous process of the lumbar vertebrae, which are seven, decreases from the fifth on. The sacrum is formed by two vertebrae and there are twenty or twenty one caudal vertebrae. It can be concluded that the crab-eating fox axial skeleton is similar to that of the domestic dog.
Rivers and streams provide many ecosystem services, including provision of food, water purification, and nutrient abatement. Ecosystem functioning, the set of processes that regulate the fluxes of energy and matter, is the backbone of ecosystem services. A myriad of human impacts affects the functioning of running waters. To reduce these impacts, strategies for conservation and recovery of riparian vegetation, as well as direct interventions for stream restoration, have been carried out. However, these actions have been more limited in sub/tropical than in temperate regions. Based on case studies from southeastern Brazil and comparisons with their temperate counterparts, we illustrate and discuss how restoration of riparian canopy cover and stream reconfiguration through the addition of wood can influence two key ecosystem processes: nutrient retention and metabolism. Our findings indicate that the distinctive environmental features of the sub/tropical climate strongly shape the effect of stream restoration on ecosystem functioning. However, as in the temperate climate, effects are rarely monitored for a long time after the restoration, indicating the need for their longer-term assessment. Understanding how restoration evolves over time to impact the functioning of sub/tropical streams is fundamental for the management and conservation of these strategic water bodies and the relevant ecosystem services they provide.
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