Seasonal variability of periphyton nutrient status and biomass on artificial and natural substrates in a tropical mesotrophic reservoir

Abstract

Aim: Study aimed at evaluating the periphytic community seasonal variation, nutrient status and biomass on artificial and natural (Nymphaea spp., Utricularia foliosa Linnaeus) substrates at a shallow mesotrophic reservoir (Ninféias Reservoir) located in the Parque Estadual das Fontes do Ipiranga, São Paulo, southeast Brazil; Methods: Samplings for physical, chemical and biological characteristics was performed in winter (August-2006), spring (October-2006), summer (January-2007) and autumn (April-2007). Periphyton was collected growing on artificial (microscope glass slides, 28 days colonization) and natural substrate (Nymphaea spp. and Utricularia foliosa). Periphyton attributes studied were: chlorophyll a, dry mass, ash free dry mass, and N and P content; Results: During the study period was recorded the highest values of water transparency and DO in the winter, PO 4 -P and free CO 2 in the spring, temperature and phytoplankton biomass in summer and autumn of DIN. The highest biomass values were recorded in winter and autumn. Periphyton P and N content varied seasonally on the substrates. Nymphaea spp. had the highest periphyton P content in summer, while U. foliosa and artificial substrate presented in the spring. Higher periphyton N content in Nymphaea spp., U foliosa and artificial substrate was recorded in the spring, winter and autumn, respectively. Periphyton and water ratio N: P molar indicated P-limitation, except the water in the spring (N-limitation). Conclusion: Periphyton N and P content and biomass variation was controlled by the seasonal scale. However, the microhabitat type seems to influence the periphyton nutrient status, especially in low nutrient availability in the environment.Keywords: biomass, natural and artificial substrates, nutrient status, periphyton.Resumo: Objetivo: Estudo avaliou a variação sazonal do estado nutricional e biomassa da comunidade perifítica em substrato artificial e natural (Nymphaea spp. e Utricularia foliosa Linnaeus) em reservatório mesotrófico raso (Reservatório das Ninféias, Parque Estadual das Fontes do Ipiranga, São Paulo, Brasil); Métodos: A amostragem das variáveis físicas, químicas e biológicas foi realizada no inverno (agosto-2006), primavera (outubro-2006), verão (janeiro-2007) e outono (abril-2007). O perifíton foi coletado de substrato artificial (lâminas de vidro, 28 dias de colonização) e do pecíolo de macrófitas aquáticas U. foliosa e Nymphaea spp.). Os atributos estudados do perifíton foram: clorofila a, massa seca, massa seca livre de cinzas e conteúdo de N e P; Resultados: No período de estudo foram registrados os maiores valores de transparência da água e OD no inverno, de P-PO 4 e CO 2 livre na primavera, temperatura e biomassa fitoplanctônica no verão e de NID no outono. Os maiores valores de biomassa foram registrados no inverno e no outono. O conteúdo de P e N do perifíton variou sazonalmente em todos os substratos. O maior conteúdo de P foi observado em Nymphaea spp. no verão, em U. foliosa e substrato artificial na primavera. O...

You are what, where, and when you eat: seasonal and ontogenetic changes in a tropical tadpole’s diet

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