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Nutrient dynamics in Mediterranean temporary streams: A case study in Pardiela catchment (Degebe River, Portugal) |
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| Authors: | Ana Isabel Lilleb Manuela Morais Pedro Guilherme Rita Fonseca Antnio Serafim Ramiro Neves |
| Institution: | aIMAR – Institute of Marine Research, Department of Zoology, University of Coimbra, 3004-517 Coimbra, Portugal bCESAM – Centre for Environment and Marine Studies, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal cWater Laboratory, Environment and Ecology Center, University of Évora, Rua da Barba Rala, 1, P.I.T.E., 7005-345 Évora, Portugal dDepartment of Geosciences, University of Évora Apartado 94, 7002-554 Évora, Portugal eCREMINER, Faculty of Sciences, University of Lisbon, Campo Grande, 1794-016 Lisbon, Portugal fMARETEC – Marine Environment & Technology Center, Instituto Superior Tecnico, 1049-001 Lisboa, Portugal |
| Abstract: | Most of the streams in the Mediterranean region are temporary, following predictable seasonal of flooding and drying, with a transition from lotic conditions to shallow lentic conditions. The goal of our study was to assess the nitrogen and phosphorus dynamics in channel-bed processes of temporary streams between floods. Results show that, during winter, temperatures ranged between 9.5 and 11.2 °C and oxygen concentration ranged from 8.0 to 9.5 mg L?1, whereas, during summer, temperatures varied between 21.2 and 26.8 °C and oxygen between 1.2 and 5.3 mg L?1, with oxygen depletion in the pools during the night. The nitrate concentrations were far more abundant during winter (February), while ammonium concentration increased after stream fragmentation into pools (especially in July when oxygen depletion conditions favoured ammonification). Results on sediment profiles showed that the most active sediment layers for NH4-N are the top 2–3 cm, corresponding to the sediment depositional sites of the stream. Phosphate concentrations had larger variability, yet concentrations decreased from winter to spring and increased again in summer, when the shallow water pools were formed. Sediment profiles at the sediment depositional sites showed that PO4-P was more dynamic in the first 6 cm. In Mediterranean temporary streams, nutrient dynamics vary seasonally, as the system transits from lotic conditions to shallow lentic conditions, evidencing the regeneration of nutrients from organic and inorganic matter during the flow cessation period. |
| Keywords: | Temporary streams Nitrogen Phosphorus Sediment profiles Mediterranean |
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