Editorial: Microbial Role in the Carbon Cycle in Tropical Inland Aquatic Ecosystems

Microorganisms have been recognized as central to nutrient mineralization and recycling in aquatic ecosystems since Lindeman's groundbreaking work on the trophic-dynamic aspect of ecology (Lindeman, 1942). Since the seventies, the development of new analytical technologies led to important conceptual perspectives, such as the microbial loop and the microbial food web (as summarized elsewhere, e.g., Cotner and Biddanda, 2002; Weisse, 2004), which have been important to understanding connections between microbially-mediated allochthonous and autochthonous organic matter decomposition and carbon dioxide (CO 2) concentrations and fluxes to the atmosphere (e.g., Cole et al., 2007; Berggren et al., 2012; Fonte et al., 2013). Currently, one of the main foci of microbial ecologists is to open the " microbial playbill " so that we can better understand who is doing " what " and " when " in ecosystem " plays " (Logue et al., 2015). It is well-documented how seasonal variation of temperature, light incidence, and precipitation affects microbial metabolism (e.g., Simon and Rosenstock, 1992; Berggren et al., 2010) in high latitude ecosystems. Considering that temperature and light incidence are less variable and remain high year-round in the tropics (Lewis, 1996), one could expect differences in metabolic processes among the latitudinal regions (Farjalla et al., 2009) and consequent effects on microbial respiration and carbon emissions (essentially CO 2 and methane) to the atmosphere. On the one hand, more intense metabolic processes are expected in lower latitudes. On the other hand, regional (e.g., flood pulse) or local (e.g., landscape characteristics) environmental conditions could be more relevant regulators of microbial metabolism than global factors (e.g., temperature, etc.). For instance, small rather than large planktonic organisms predominate at the base of microbial food webs of tropical aquatic ecosystems (i.e., pico-vs. nano-plankton) in comparison to temperate lakes, which typically means a higher flow of carbon through the microbes in the tropics than in temperate regions (Roland et al., 2010; Sarmento, 2012). Yet, certainly several new microbial ecology fundamentals will arise from asking questions that remain poorly understood, such as: (1) Does the current knowledge derived mostly from temperate ecosystems hold for tropical ecosystems? and (2) Can tropical ecosystems be good models to predict the changes in microbial metabolism and carbon cycling in temperate aquatic systems in light of climate warming scenarios? The aim of this research topic—Microbial role in the carbon cycle in tropical inland aquatic ecosystems—was to provide a selection of studies that look at the wide …