title: Influence of the interaction between phosphate and arsenate on periphyton's growth and its nutrient uptake capacity.
abstract: Periphyton communities grown in microcosms were studied under the exposure to different arsenate (As) and phosphate (P) regimes with the aim of revealing the effect of chronic exposure to As on periphyton physiological and structural characteristics. Also, we aimed to study periphyton changes on sensitivity to As, exposed to different P and As regimes. As affected structural and functional parameters of periphyton communities starved of P, inhibiting algal growth, photosynthetic capacity, changing community composition and reducing the ability of the community to retain P. The effects of As on these parameters were only detected in P starved communities, showing that chronic exposure to As led to changes in the photosynthetic apparatus under the conditions of P-limitation, but not when P-availability was higher. This fact reveals a lower toxicity and/or a higher adaptation of the P-amended community. Intracellular As contents were higher in communities starved of P. However, As tolerance was only induced by the combination of As and P but not by As or P alone indicating that tolerance induction may be an ATP-dependent mechanism. This study reveals that chronic exposure of natural communities to environmentally realistic As concentrations will damage periphyton communities affecting key ecosystem processes, as P uptake, leading to changes in stream ecosystems, as these organisms play a key role in nutrient cycling through nutrient uptake and transfer to higher trophic levels.
authors.affiliation: Consejo de Investigaciones Científicas y Técnicas (CONICET), Argentina; Departamento de Ciencias Básicas, Universidad Nacional de Luján, Argentina. Electronic address: Carolina.rodriguez.castro@gmail.com.
authors.forename: Ma Carolina
authors.initials: MC
authors.lastname: Rodriguez Castro
authors.affiliation: Inst. Ecologia Aquàtica and Dep. Ciències Ambientals, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain.
authors.forename: Gemma
authors.initials: G
authors.lastname: Urrea
authors.affiliation: Inst. Ecologia Aquàtica and Dep. Ciències Ambientals, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain.
authors.forename: Helena
authors.initials: H
authors.lastname: Guasch
mesh_terms: D059001:Aquatic Organisms / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D001149:Arsenates / Q000633:toxicity*; D058086:Microalgae; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D010758:Phosphorus / Q000032:analysis / Q000378:metabolism; D010933:Plankton; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D001149:Arsenates; D010710:Phosphates; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D009584:Nitrogen; C025657:arsenic acid
keywords: Arsenic; Biofilm; Ecotoxicology; Phosphate; Stream