SUMMARY: Continuous and short-term disturbances are produced on intertidal Brachidontes rodriguezii mussel beds by the sewage outfall of Mar del Plata, SW Atlantic. The effects on the associated polychaetes living on and between mussels were investigated, in both the spatial and short-term temporal scales. Multivariate methods show that the polychaete fauna was influenced by tidal level, total amount of sediment accumulated between mussels, distance from the sewage outfall, organic carbon of interstitial sediments, and sewage volume before and after the summer season. Environmental variables in the water column fitted with a spatial and temporal organic gradient. Capitella 'capitata' sp. showed typical opportunistic behaviour in relation to organic enrichment, as did Neanthes succinea, both being numerically dominant near the sewage discharge. Cirratulus sp., Caulleriella alata, and Boccardia polybranchia were common at intermediate distances from the outfall. Syllis prolixa, S. gracilis, and Protoariciella uncinata reached their highest abundance at intermediate stations and were characteristic of the control site. Close to the outfall mussel density and dominance is low, and opportunist polychaetes successfully colonize organically enriched interstitial sediments. At intermediate distances from the outfall sediments retained by mussels reach their maximum values, and density of polychaetes is also high. The control station is characterized by monolayered mussel beds and very low diversity of polychaetes. Opportunistic polychaetes increase in response to shortterm increases of sewage discharge during the summer season (November-March).Keywords: polychaetes, intertidal, mussel beds, organic pollution, sewage, spatial and before-after summer season distribution, SW Atlantic. RESUMEN: PERTURBACIONES DEBIDAS A EFLUENTES DOMÉSTICOS EN POLIQUETOS ASOCIADOS A BANCOS DE BIVALVOS DEBRACHIDONTES RODRIGUEZII EN MAR DEL PLATA (ATLÁNTICO SUDOCCIDENTAL). -Perturbaciones contínuas y de corto período de tiempo debidas a efluentes domésticos afectan a los bancos de los bivalvos Brachidontes rodriguezii en Mar del Plata, Atlántico sudoccidental. Se investigaron sus efectos sobre los poliquetos que viven asociados dentro y sobre los bancos, tanto en la escala espacial como la temporal (corto plazo). Métodos multivariados mostraron que los poliquetos estuvieron relacionados al nivel de marea, al total de sedimentos acumulados entre los bivalvos, a la distancia al efluente, al carbono orgá-nico total de los sedimentos y al volumen de descarga antes y después del verano. Las variables ambientales de la columna de agua estuvieron en concordancia con un gradiente de enriquecimiento orgánico espacial y temporal. Capitella 'capitata' sp. mostró el típico comportamiento oportunista en relación al enriquecimiento orgánico, al igual que Neanthes succinea, siendo ambas especies numéricamente dominantes cerca del efluente. Cirratulus sp., Caulleriella alata y Boccardia polybranchia fueron comunes a distancias intermedias del efluente. Syllis...

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The production of onion waste derived mainly from bulbs affected by fungal diseases, during onion classification and storage presents an important agro-environmental issue in onion production regions. Composting is an environmentally friendly strategy to recycle agricultural waste and produce organic fertilizers. Modifications of the microbial community in soil can affect the ability of pathogen propagules to survive, germinate and infect plant roots. Hence, the main objective of this work was to exploring the mechanisms involved on the presence of three soil-borne phytopathogenic fungi during the composting process of onion waste under the hypothesis if that the resulting compost effectively prevents or minimizes the dispersion of phytopathogenic fungi. To this end, three composting piles of 60 tonnes each were built by layering onion waste affected by phytopathogenic fungi and cow dung at 1:1 ratio. Temperature, moisture, pH, electrical conductivity (EC) and Aspergillus niger, Penicillium sp. and Fusarium sp. growth were monitored for 100 days. During the first 28 days of composting, the presence of phytopathogenic fungi increased significantly showing thereafter a downward trend. Final estimations of fungal populations densities indicated a predominance of A. niger and an effective reduction in the abundance of Fusarium sp. This pilot-scale work demonstrates the feasibility of composting onion waste contaminated with phytopathogenic fungi and highlights the positive environmental impact associated with this practice. Therefore, the composting of onion waste and cow dung is a feasible and sustainable procedure to recycle onion waste and to promote circular economy in onion production regions.