Effects of increasing temperature and, CO2 on quality of litter, shredders, and microorganisms in Amazonian aquatic systems

Abstract

Climate change may affect the chemical composition of riparian leaf litter and, aquatic organisms and, consequently, leaf breakdown. We evaluated the effects of different scenarios combining increased temperature and carbon dioxide (CO2) on leaf detritus of Hevea spruceana (Benth) Müll. and decomposers (insect shredders and microorganisms). We hypothesized that simulated climate change (warming and elevated CO2) would: i) decrease leaf-litter quality, ii) decrease survival and leaf breakdown by shredders, and iii) increase microbial leaf breakdown and fungal biomass. We performed the experiment in four microcosm chambers that simulated air temperature and CO2 changes in relation to a real-time control tracking current conditions in Manaus, Amazonas, Brazil. The experiment lasted seven days. During the experiment mean air temperature and CO2 concentration ranged from 26.96 ± 0.98ºC and 537.86 ± 18.36 ppmv in the control to 31.75 ± 0.50ºC and 1636.96 ± 17.99 ppmv in the extreme chamber, respectively. However, phosphorus concentration in the leaf litter decreased with warming and elevated CO2. Leaf quality (percentage of carbon, nitrogen, phosphorus, cellulose and lignin) was not influenced by soil flooding. Fungal biomass and microbial leaf breakdown were positively influenced by temperature and CO2 increase and reached their highest values in the intermediate condition. Both total and shredder leaf breakdown, and shredder survival rate were similar among all climatic conditions. Thus, low leaf-litter quality due to climate change and higher leaf breakdown under intermediate conditions may indicate an increase of riparian metabolism due to temperature and CO2 increase, highlighting the risk (e.g., decreased productivity) of global warming for tropical streams.

Effects of elevated atmospheric CO2 concentration and temperature on litter decomposition in streams: A meta‐analysis

“…The primary studies used in the present meta‐analysis were geographically limited and most studies that addressed the effects of elevated [CO 2 ] were conducted in temperate regions (mainly Europe; but see Martins, Melo, et al, ; Martins, Rezende, et al, for studies conducted in the neotropics) and used fast‐decomposing litter types. Studies are required in other parts of the world, such as tropical regions where slow‐decomposing litter types are common and litter decomposition is mainly carried out by microbes.…”

Survival of silver diamine fluoride among patients treated in community dental clinics: a naturalistic study

“…Dental caries, the most common disease of childhood and most prevalent health condition worldwide, persists despite concerted clinical and public health efforts to eliminate it over the last half-century [ 1 , 2 ]. Untreated caries contributes to health problems including pain, poor quality of life, and psychosocial suffering, as well as societal burdens that include reduced productivity at work and school [ 1 , 3 , 4 ]. Preventing dental caries through oral health education, home hygiene, the avoidance of fermentable carbohydrates, consumption of fluoridated water, and access to and utilization of routine dental screenings, examinations, and care is essential in reducing disease incidence and burden, meeting population-level oral health goals, and addressing patient concerns [ 1 , 4 ].…”

Leaf litter quality drives the feeding by invertebrate shredders in tropical streams

“…The experiments were performed in the microcosms of the (Martins, Melo, et al, 2017;Martins, Rezende, et al, 2017). Larvae were kept in containers in an experimental room with continuous aeration at a temperature of 20°C and with a light/dark ratio of 12/12 hr throughout the experiment.…”

“…Leaf litter processing by Phylloicus larvae can also be negativity influenced by environmental conditions, as increase of temperature (Martins, Melo, Gonçalves, Campos, & Hamada, 2017;Martins, Rezende, et al, 2017;Navarro et al, 2013). Nevertheless, all these mentioned studies just refer to single populations, using leaf litter and larvae just from the same place in their design.…”