Sedimentation of phosphorus fractions and temporal variation in the C:P ratio in La Concepción reservoir, southern Spain

Abstract

The settling flux and content of organic carbon (C), organic matter, and different phosphorus (P) fractions were measured fortnightly during a 6-month stratified period (from early April to early November) with sediment traps located at five different depths in La Concepcion, a mesotrophic and P-limited reservoir in southern Spain. Characterisation of P fractions in the collected material was performed by a sequential extraction procedure. Sedimentation rates exhibited a distinct seasonal pattern, that allowed us to differentiate three periods: (1) a biogenic sedimentation period (BS), in which the sedimentation rates and total suspended matter concentration were lowest and the result of material of autochthonous origin; (2) a calcium carbonate precipitation period (CCP), in which there were high calcium concentrations in the settling seston; and (3) a rainfall period (R), in which the highest sedimentation rates occurred. Organic C, organic matter, and organic P content were highest *Author for correspondence. M00079

The importance of sedimenting organic matter, relative to oxygen and temperature, in structuring lake profundal macroinvertebrate assemblages

“…Therefore, C:P and N:P are generally positively related to body size, which is consistent with the pattern observed in this study. The relationships between chironomid body stoichiometry and trophic preference also correspond with previously reported alteration of SOM C:N:P stoichiometry during the sedimentation process; deeper basins provide nitrogen-poor but phosphorus-rich sedimenting organic material (Gálvez et al, 1991;Andersen & Jensen, 1992;Garcia-Ruiz et al, 2001). Even though our SOM data lacked vertical monitoring and within-lake data did not support this pattern, the chironomid data suggest that profundal taxa with differing ecological niches differently assimilate the key macroelements, either due to differences in feeding habits (Johnson, 1987;Goedkoop et al, 1998), to selective feeding or to varying stoichiometric requirements relative to the available food.…”

“…Moreover, many studies have reported a pronounced enrichment of phosphorus (P) of seston during sedimentation (Gálvez et al, 1991;GarciaRuiz et al, 2001;Hudson & Taylor, 2005). This phenomenon is not only mainly a result of relatively slow decrease of phosphorus content compared to carbon (C) and nitrogen (N) (Gálvez et al, 1991) but also due to physico-chemical or bacterial P incorporation into the descending SOM (Garcia-Ruiz et al, 2001;Bloesch, 2004). Such alteration of SOM during the sedimentation process with depth might significantly contribute to the quantitative and qualitative variation in food resources for the profundal fauna both within and among lakes.…”

Adsorption-Release Characteristics of Phosphorus and the Community of Phosphorus Accumulating Organisms of Sediments in a Shallow Lake

“…During the rainy season, PP mainly forms BP, which settles to the lake's bottom to form sediments; during the rainy period (especially the storm rain phase), PP was primarily deposited as apatite P (P that can extract HCl). PP was also deposited faster from organisms in the lesser rain phase [44]. The Sanshiliujiao Lake area is along the southeast coast and has a rainy climate; thus, MP may be the primary P deposited in the lake.…”

“…During the rainy season (especially the heavy rain period), it is deposited primarily in apatite P (phosphorus that can extract HCl). Moreover, it deposits more quickly from organisms during the stage of less rain [44]. During the rainy season, PP mainly forms BP, which settles to the lake's bottom to form sediments; during the rainy period (especially the storm rain phase), PP was primarily deposited as apatite P (P that can extract HCl).…”

Estado trófico y características morfométricas como factores reguladores de las tasas de sedimentación en embalses mediterráneos

“…El valor medio de la tasa de sedimentación en los seis embalses estudiados osciló entre 6.6 y 66.6 g DW m -2 d -1 registrados en los embalses de Quentar y Alhama, respectivamente (Tabla 3). Estos valores se encuentran dentro del rango medido en otros embalses del sur de España como en La Concepción (García-Ruiz et al, 2001) y Charco-Redondo (García-Ruiz et al, 1993). Sin embargo, son valores significativamente más elevados, y variables estacionalmente, que la mayoría de los lagos citados en la bibliografía (Tartari y Biasci, 1997).…”