Introduction We investigated the incidence of, outcome from and possible risk factors for readmission to the surgical intensive care unit (ICU) at
Resource pulsing is a widespread phenomenon, but its effects on ecosystem dynamics are often difficult to predict. Hydrological pulsing, in particular, is known to influence the structure and dynamics of fluvial and coastal ecosystems, but little information is available about its effects on trophic connectivity between wetlands and estuaries. We investigated the hypothesis that hydrologic pulsing drives 1-way trophic subsidies (e.g. suspended organic matter and freshwater fish) from wetland to estuary. Our study system is a coastal lagoon with an ephemeral mouth that, when closed, stores freshwater as a sustained flood pulse that is subsequently released when a connection with the sea is reestablished. We monitored isotopic composition of consumers and food sources over the course of an entire flood pulse to infer trophic linkages and spatial subsidies. Before the flood peak (April and May), freshwater and estuarine zones were largely dependent on local primary production sources (seston and C 3 plants vs. C 4 plants and microphytobenthos, respectively), essentially functioning as disconnected compartments. A sustained pulse of freshwater inflow (June to August) induced greater habitat connectivity and a net flow of biomass and energy from the freshwater zone into the estuarine zone. The opening of the lagoon outlet channel abruptly terminated the flood pulse and reduced freshwater subsidies to estuarine consumers, and both zones returned to dependence on autochthonous production. Our findings contribute to current concerns that artificial opening of sandbars in coastal lagoons alters natural ecological dynamics with significant effects on biodiversity and ecosystem processes.
Pseudis minuta is abundant in a variety of aquatic environments of the Pampa domain. Therefore, it can be considered a good model for testing hypotheses on environmental heterogeneity and the influence of climate on the activity of anurans. In this study, we examined the spatial distribution pattern of P. minuta in terms of microhabitats and the influence of abiotic factors on seasonal fluctuations in the abundance of this species. Samples were collected monthly from April 2008 to May 2009 in wetlands and coastal dunes in the Lagoa do Peixe National Park. A total of 112 specimens of P. minuta were collected, of which 45 were found in the wetland area and 67 in the dune area. The species showed seasonal fluctuation in abundance, and it was most abundant in months with higher temperatures (spring-summer). Pseudis minuta was mainly associated with aquatic vegetation, an expected pattern in terms of their morphological adaptations to this environment. Among the abiotic parameters analyzed, only the monthly mean temperature showed a significant correlation (p < 0.05; r = 0.67) with the abundance of P. minuta. We concluded that P. minuta is a generalist species with respect to microhabitat use and also that fluctuation in its population abundance is mainly associated with seasonal variation in temperature.Keywords: abundance, anuran, coastal plain, Lagoa do Peixe, spatiotemporal distribution.Padrão de atividade e uso de micro-habitat de Pseudis minuta Günther, 1858 (Anura, Hylidae) no Parque Nacional da Lagoa do Peixe, uma reserva da biosfera na região subtropical do Brasil ResumoPseudis minuta é uma espécie abundante em diferentes tipos de ambientes aquáticos do domínio Pampa. Por essa razão, essa espécie pode ser considerada um bom modelo para testar hipóteses relacionadas à heterogeneidade ambiental e à influência do clima sobre padrões de atividade em anuros. Neste trabalho, foi avaliado o padrão de distribuição espacial de P. minuta em termos de micro-habitats, além de se avaliar a influência de fatores abióticos nas flutuações sazonais da abundância dessa espécie. Coletas foram realizadas mensalmente, entre abril de 2008 e maio de 2009, em áreas úmidas e de cordões de dunas costeiras no Parque Nacional de Lagoa do Peixe. Um total de 112 indivíduos de P. minuta foi coletado, sendo 45 em áreas de banhado e 67 em área de dunas. A espécie apresentou flutuação sazonal na abundância, sendo mais abundantes em meses com temperaturas mais elevadas (primavera-verão). Pseudis minuta esteve associada principalmente à vegetação aquática, um padrão esperado em função de suas adaptações morfológicas a esse meio. Entre os parâmetros abióticos analisados, somente a temperatura média mensal apresentou correlação significativa (p < 0.05; r = 0,67) com a abundância de P. minuta. Foi possível concluir que P. minuta é uma espécie generalista com relação ao uso do habitat e que as flutuações na sua abundância populacional estão principalmente associadas à variação sazonal da temperatura.Palavras-chave: abundância, anuro, planí...
Despite increasing efforts in recent years to catalog the fish diversity of Amazonian rivers, many regions are still under-sampled, and sandy beach environments are particularly poorly understood. The present study focused on a 300 km stretch of the Acre river, in the southwestern Amazon basin, where we sampled 30 sandy beaches separated by a mean interval of 10 km. We collected 15,329 fish representing 80 species, 26 families, and nine orders. The Characiformes were the most abundant order, providing 88.24% of the individuals collected, followed by the Siluriformes, with 10.03%, while the Siluriformes had the highest species richness, with 37 species (45.0%), followed by the Characiformes, with 30 (37.5%). The most abundant species were the characiforms Knodus orteguasae and Creagruto barrigai. Reliable data on a region’s biota is fundamental for the evaluation of patterns of biodiversity, and the occurrence and management of threatened species. As fish are directly affected by pollutants and the degradation of aquatic environments, further research in areas that are still poorly sampled will be essential for the elaboration of effective conservation strategies.
ResumoAlimentação de Hoplias aff. malabaricus (Bloch, 1794) e Oligosarcus robustus Menezes, 1969 em uma lagoa sob influência estuarina, Pelotas, RS. O objetivo do presente trabalho foi o de estudar a dieta de Hoplias aff. malabaricus e Oligosarcus robustos na Lagoa Pequena, com o intuito de avaliar a importância de organismos estuarinos na alimentação dessas espécies. Foram identificados 12 itens alimentares, sendo peixes o recurso mais frequente na dieta de ambas as espécies. Peixes eurialinos como a tainha Mugil platanus e o peixe-rei Odontesthes argentinensis foram itens comuns na dieta das duas espécies, caracterizando um comportamento oportunista por incluir na sua alimentação não apenas peixes de água doce, mas também peixes oriundos do ambiente estuarino adjacente, integrando as cadeias alimentares estuarinas e de água doce. Unitermos: dieta, peixe, carnívoro, estuário, Lagoa Pequena AbstractFeeding of Hoplias aff. malabaricus (Bloch, 1794) and Oligosarcus robustus Menezes, 1969 in a lagoon under estuarine influence, Pelotas, RS. The objective of the present paper was to study the diets of Hoplias aff. malabaricus and Oligosarcus robust in "Pequena Lagoon" and evaluate the importance of estuarine organisms in the feeding of freshwater fish. A total of twelve food categories were identified and it was established that the fish resource was the most frequent in the diet of both species. Euryhaline fish such as Mugil platanus mullets and Odontesthes argentinensis silversides were common items in the diets of these two species, which included not only freshwater fish but also euryhaline fish from the adjacent estuarine zone, integrating both resources in the food chain.
ResumoAlimentação de Cyphocharax voga (Hensel, 1869) (Characiformes, Curimatidae) no Arroio Corrientes, Pelotas, Rio Grande do Sul, Brasil. A espécie Cyphocharax voga, ocorre desde a bacia hidrográ¿ ca do Rio Paraguai, baixo Paraná, até os sistemas hidrográ¿ cos costeiros da América do Sul. O Arroio Corrientes limita os municípios de Turuçu e Pelotas, sendo um ambiente pouco estudado quanto à sua biota. Este trabalho teve como objetivo estudar a alimentação de C. voga para um melhor conhecimento de sua dieta no local. Foram coletados 32 indivíduos entre dezembro e março no ano de 2005, acondicionados em caixa com gelo e levados até o laboratório. A dieta foi analisada pelos métodos de freqüência de ocorrência e freqüência relativa, sendo que para machos e fêmeas foi registrado soma, media e desvio padrão, aplicando o teste t de Student e o teste qui-quadrado Ȥ 2 para os itens ingeridos. Foi identi¿ cado um total de 18 categorias alimentares, sendo que, algas ¿ lamentosas e sedimento tiveram ocorrência em 100% dos animais. A predominância destes itens, juntamente com microorganismos associados à alimentação, faz com que a espécie seja considerada iliófaga neste ambiente. Não foi houve diferença na alimentação entre machos e fêmeas pelo teste qui-quadrado Ȥ 2 .Unitermos: recurso alimentar, biru, Curimatidae
The present paper describes the length-weight relationship of 18 fish species from the Siluriformes order in a subtropical basin, southern Brazil. U.S.
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