Effect of increased atmospheric CO₂ on the performance of an aquatic detritivore through changes in water temperature and litter quality

Abstract

Cold water woodland streams, where terrestrially derived organic matter fuels aquatic food webs, can be affected by increases in atmospheric CO 2 concentrations, as these are predicted to lead to increases in water temperature and decreases in organic matter quality. In fact, elevated CO 2 (580 ppm) decreased the initial phosphorus concentration of birch litter by 30% compared with litter grown under ambient conditions (380 ppm). Here, we first assessed the effect of differences in litter quality on mass loss, microbial colonization and conditioned litter quality after submersion in a mountain stream for 2 weeks. Leaching did not change the relative differences between litter types, while fungal biomass was two fold higher in elevated litter. We then offered this litter (conditioned ambient and elevated) to a stream detritivore that was kept at 10 and 15 1C to assess the individual and interactive effects of increased temperature and decreased litter quality on invertebrate performance. When given a choice, the detritivore preferred elevated litter, but only at 10 1C. When fed litter types singularly, there was no effect of litter quality on consumption rates; however, the effect of temperature depended on individual size and time of collection. Growth rates were higher in individuals fed ambient litter at 10 1C when compared with individuals fed elevated litter at 15 1C. Mortality did not differ between litter types, but was higher at 15 1C than at 10 1C. Increases in temperature led to alterations in the individual body elemental composition and interacted with litter type. The performance of the detritivore was therefore more affected by increases in temperature than by small decreases in litter quality. However, it seems conceivable that in a future global warming scenario the simultaneous increases in water temperature and decreases in litter quality might affect detritivores performance more than predicted from the effects of both factors considered individually.

Increased temperature causes different carbon and nitrogen processing patterns in two common intertidal foraminifera (<i>Ammonia tepida</i> and <i>Haynesina germanica</i>)

“…Accordingly, increased DIC-13 C content within the SSW at elevated temperatures suggests higher respiratory activities (Table 1). Elevated temperatures have been reported to increase respiration and food consumption in aquatic herbivores, detritivores and foraminifera (Bradshaw, 1961;Carr and Bruno, 2013), to lower grazing rates with simultaneously increased oxygen consumption (Ferreira et al, 2010) or to raise respiration to cover the costs of maintenance of protein metabolism levels (Whiteley and Faulkner, 2005). In general, DIC-13 C values in this experiment were very high compared to foraminiferal 13 C. It cannot be excluded that the foraminiferal cultures contained bacteria.…”

Elevated atmospheric CO2 interacts with drought and competition to produce complex results in plant quality and subsequent microbial aquatic decomposition

“…The concentration of structural carbohydrates (cellulose, hemicellulose, among others), which is higher in A. capillaris, could be another reason, as was reported by Picon-Cochard et al (2004), who found that grasses have a higher content of structural carbohydrates than forbs. In the same direction but for P, Ferreira et al (2010) and Ferreira and Chauvet (2011) observed that although alder leaves grown at elevated CO 2 had reduced P concentration, they decomposed faster than control leaves. Similarly, in terrestrial ecosystems, changes in plant composition induced by elevated CO 2 have been shown to have no effects on litter decomposition (Norby et al 2001).…”

Comparison of three shredders response to acute stress induced by eucalyptus leaf leachates and copper: single and combined exposure at two distinct temperatures

“…Temperature has a major influence in biological and ecological processes: it may be a stressor by itself (Ferreira et al, 2010;McFeeters and Frost, 2011;Wojewodzic et al, 2011), it may modify the toxicity of chemicals (Prato et al, 2009;Lapointe et al, 2011;Vieira and Guilhermino, 2012), and may change abiotic conditions (e.g. water eutrophication and oxygen depletion) .…”

“…Considering the ability of temperature to influence chemicals' toxicity (Boeckman and Bidwell, 2006;Prato et al, 2009), tests were performed at 10 and 20 xC. These are common temperatures in colder and warmer seasons, respectively, in the streams where the invertebrates were collected (Canhoto and Laranjeira, 2007;Ferreira et al, 2010). A. desmarestii, E. meridionalis and S. festiva were selected for this study because they play a key role in leaves decomposition in low-order streams where they occur, are abundant and easily maintained in the laboratory.…”