Effects of nitrogen and phosphorus availabilities on growth, pigment, and protein contents in Hypnea cervicornis J. Agar
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Effects of nitrogen and phosphorus availabilities on growth, pigment, and protein contents in Hypnea cervicornis J. Agardh (Gigartinales, Rhodophyta) Ana Lívia N. L. Ribeiro & Kenner E. Tesima & Jonatas M. C. Souza & Nair S. Yokoya
Received: 13 April 2012 / Revised and accepted: 29 October 2012 / Published online: 14 November 2012 # Springer Science+Business Media Dordrecht 2012
Abstract The selection of seaweed species for their use as biofilters should be based on the knowledge of their nutrient requirements and tolerance to wide variations of nutrient concentrations. Therefore, tolerance and the physiological capabilities of Hypnea cervicornis J. Agardh (Gigartinales, Rhodophyta) to growth under nitrate, ammonium, and phosphate variations and to assimilate them into soluble proteins and photosynthetic pigments were evaluated in laboratory conditions. Treatments were composed of sterilized seawater enriched with 25 % von Stosch solution (without nitrogen and phosphorus), and nitrate or ammonium and phosphate were added in combination of 100:1 and 10:1 nitrogen/phosphorus (N/P). Nitrate concentrations varied from 0 to 500 μM, and ammonium concentrations varied from 0 to 50 μM. Growth rates of H. cervicornis increased linearly with addition of ammonium, but with nitrate addition, growth varied following a saturation kinetic, and the highest growth rate (14.45 % d−1) was observed in 200 μM of N/P ratio of 10:1. An excess of nutrients was accumulated as proteins and phycobiliproteins (mainly as allophycocyanin and phycoerythrin) at higher phosphate availability (N/P ratio of 10:1), and H. cervicornis tolerated the highest ammonium and nitrate concentrations (50 and 500 μM, respectively). These physiological responses suggest that this species could be used as biofilter for nutrient removal in eutrophicated seawater and could be cultivated in integrated multitrophic aquaculture systems. Keywords Ammonium . Hypnea . Nitrate . Nitrogen storage . Pigments . Phosphate . Proteins A. L. N. L. Ribeiro : K. E. Tesima : J. M. C. Souza : N. S. Yokoya (*) Núcleo de Pesquisa em Ficologia, Instituto de Botânica, Secretaria do Estado do Meio Ambiente, P.O. Box 68041, 04045-972, São Paulo, SP, Brazil e-mail: [email protected]
Introduction There is growing concern on the environmental impacts and eutrophication caused by marine aquaculture and by other human activities as discharge of effluents into seawater. Seaweeds are efficient in the uptake of nitrate, ammonium, and phosphate from seawater, and the assimilation of these nutrients into nitrogenous compounds (e.g., amino acids, proteins, pigments) stimulates seaweed growth (Lobban and Harrison 1997). Therefore, seaweeds could be used as biofilters to remediate the eutrophication, and their cultivation has an essential role in the integrated multi-trophic aquaculture systems (Neori 2008; Buschmann et al. 2008; Bolton et al. 2009). There are some reports on the role of seaweeds as biofilters for nutrient removal in integrated cultivation, mainly with species of the genera Ulva an
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