Substrate influence and temporal changes on periphytic biomass accrual and metabolism in a tropical humic lagoon |
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Authors: | Rafael D Guariento Adriano Caliman Francisco A Esteves Reinaldo L Bozelli Alex Enrich-Prast Vinicius F Farjalla |
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Institution: | a Laboratório de Limnologia, Universidade Federal do Rio de Janeiro-UFRJ, Av. Brigadeiro Trompowski s/n, Prédio CCS, Bloco A, sub-solo, sala A0-008-Ilha do Fundão, CXPostal (P.O. Box) 68020, CEP 21941-590 Rio de Janeiro, RJ, Brazil b Núcleo em Ecologia e Desenvolvimentos Sócio-Ambiental de Macaé, Av. Rotary Club s/n, São Jose do Barreto, Macaé, CxP. 119331, Agência Correio de Macaé, Brazil c Laboratório de Biogeoquímica (UFRJ), Av. Brigadeiro Trompowski s/n, Prédio CCS, Bloco A, sala A2-102 Ilha do Fundão, CXPostal (P.O. Box) 68020, CEP (ZipCode) 21941-590 Rio de Janeiro, RJ, Brazil |
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Abstract: | We performed a field experiment in a tropical humic coastal lagoon to evaluate periphyton biomass accrual and metabolism on three different substrates (1) plastic ribbons, (2) green and (3) senescent leaves of the emergent macrophyte Typha domingensis) over 30 days. The contribution of autotrophic biomass decreased as total biomass increased over the time. Mean periphytic ash free dry weight ranged from 0.8 to 5.6 mg cm−2, but periphyton chlorophyll a concentrations presented shorter amplitudes, which oscillated from 0.12 to 0.44 μg cm−2 throughout the experiment. Periphyton metabolism was overall heterotrophic on all substrates, especially on senescent leaves. Our data show that substrate type influenced both biomass accrual and periphyton net productivity and respiration rates throughout periphyton development and highlighted the dominance of heterotrophic metabolism. The periphyton respiration may be subsidized by both water- and substrate-derived allochthonous energy pathways, shedding light on the role of periphytic assemblages to the carbon cycling, as a source of CO2 to the system. |
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Keywords: | Periphyton Heterotrophy Humic lakes Typha domingensis Carbon cycle |
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