Influência do tamanho corporal, hora do dia, tipo de incubação e tempo na excreção de nutrientes de duas espécies de peixe e duas espécies de camarão em rios de Mata Atlântica

• Ano de defesa: 2016
• Autor(a) principal: Cunha, Priscila de Oliveira
• Orientador(a): Zandonà, Eugenia
• Banca de defesa: Dias, André Tavares Corrêa , Buchas, Rosana Mazzoni , Albrecht, Miriam Pilz , Rosado, Bruno Henrique Pimentel
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade do Estado do Rio de Janeiro
• Programa de Pós-Graduação: Programa de Pós-Graduação em Ecologia e Evolução
• Departamento: Centro Biomédico::Instituto de Biologia Roberto Alcantara Gomes
• País: BR
• Palavras-chave em Português: Ciclagem de nutrientes; Alometria; Nitrogênio; Fósforo; Metodologia; Ecologia aquática - Brasil; Peixes - Excreção; Camarão - Excreção; Ecossistemas aquáticos - Mata Atlântica; Impacto ambiental
• Palavras-chave em Inglês: Nutrient cycling; Allometry; Nitrogen; Phosphorus; Methodology
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA::ECOLOGIA DE ECOSSISTEMAS
• Link de acesso: http://www.bdtd.uerj.br/handle/1/5896

Aquatic consumers can affect their ecosystems in many ways. One of them is by excreting nutrients, especially nitrogen and phosphorus, the limiting nutrients in the majority of aquatic ecosystems. In many cases, nutrient excretion by consumers represents an important source of nutrients to the system, and because of that it has been studied in the past years. To better understand the roles of consumers in nutrient cycling it is necessary to estimate excretion rates. However, little is known about how different methodologies can affect the experiments results. The liberation of nutrients by consumers can be influenced by a series of factors, such as body size, life habits and diet. Consumers are considered homeostatic, which means they do not change their own body compositions with changes in their diets. In this way, individuals with poor nutrient diets retain more nutrients compared to individuals with rich diets. Consumer excretion can also vary throughout the day, due to their feeding habits, because fasting reduces excretion rates. Fish and shrimp of different species have different body stoichiometry and diet, and therefore, different excretion rates. To better understand how aquatic consumers affect their ecosystem through excretion, we must investigate which factors, from physiology and life habits and experimental methodology used, can affect the nutrient excretion rates. This study has verified differences between species and investigated the influence of body size, time of day, type of incubation (normal and with stress reduction) and time of incubation, on the NH4 and PO4 excretion rates of the fishes Bryconamericus microcephalus and Characidium japuhybense, and the shrimps Potimirim brasiliana and Macrobrachium olfersi. We found an allometric relation between body size and nutrient excretion, with smaller individuals excreting proportionately more nutrients than bigger individuals. Time of day influenced NH4 excretion, with animals excreting more during the period of day in which they feed. The attempt to minimize stress during incubation was not successful, and the time of incubation affected excretion rates, which had more variance and excretion peaks during the first 15 minutes.