Effect of temperature on nutrient cycling of a stream shredder associated to their elemental relationships with detritus

CALAPEZ, RAQUEL; DÍAZ VILLANUEVA, VERÓNICA; ALBARIÑO, RICARDO; CANHOTO, CRISTINA

Huelva, España

Congreso; VI Congreso Iberico de Limnologia; 2008

Metabolic rates increase with temperature, regulating the rates at which material resources are taken up from the environment, used for biological structure and function, and excreted back into the environment. In this regard, global warming may affect stoichiometric relationships and nutrient cycling by accelerating those biological rates that face strong elemental imbalances in nature. We hypothesized that metabolic rates will increase as result of a higher temperature, leading to changes in the elemental relationships of feces and in their own bodies. Also we aimed to test if  the response to temperature is constant on different food resources. With this purpose, the stream shredder Sericostoma vittatum was exposed to feed on three different single leaf species: Alnus glutinosa, Quercus robur and Eucalyptus globulus, at 15º and 20º C for 10 days. We measured larval consumption, egestion, excretion and respiration rates at each temperature X diet treatments, and analysed P and N content in food resource, consumer body, feces and soluble wastes to estimate and compare C:N:P ratios. Consumer stoichiometry was strict in larvae among resources but not between temperatures. Although larvae kept at 20º C had a lower C:N body ratio, net gaining of N was negatively affected by temperature reducing the ability of larvae to retain it in their bodies. While C:P ratios of animals were unaffected both by temperature and diet, P retention was also reduced at 20ºC. In particular, larvae fed on Q. robur had a net loss of P. Results indicate that temperature my alter the quantity and quality of the end-products of detritus feeders (i.e. feces and nutrient release) and may result in deleterious internal imbalances at the organism level.