Supplement 1. Data from the 83 South American lakes sampled.

<h2>File List</h2><blockquote> <p><a href="South_American_Lakes_data.txt">South_American_Lakes_data.txt</a> -- data file </p> </blockquote><h2>Description</h2><blockquote> <p>The "South American Lakes data file" contains data on 83 shallow lakes sampled in South America between November 2004 and March 2006. The following data is presented: X coordinate (Decimal degrees); Y coordinate (Decimal degrees); name (Name of the lake. Not all lakes have a name and some lakes are referred to by multiple names); climate zone (The lakes were grouped in five different categories based on the prevailing climate characteristics following the Köppen climate system (1936) digitized by Leemans and Cramer (1991): tropicali, tropical, subtropical, maritime temperate and tundra zone. The Köppen classification is based on monthly rainfall and temperature. Tropicali is an isothermal subzone in the tropics, which has a smaller annual temperature range than the tropical zone, source:<br> <a href="http://www.fao.org/WAICENT/FAOINFO/SUSTDEV/EIdirect/climate/EIsp0002.htm">http://www.fao.org/WAICENT/FAOINFO/SUSTDEV/EIdirect/climate/EIsp0002.htm</a>); average air temperature in warmest month (Celcius, source: M. New, D. Lister, M. Hulme, and I. Makin. 2002. A high-resolution data set of surface climate over global land areas. Climate Research 21. The complete paper can be freely downloaded via:<br> <a href="http://www.cru.uea.ac.uk/cru/data/tmc.htm">http://www.cru.uea.ac.uk/cru/data/tmc.htm</a>); average air temperature in coldest month (Celcius, source: M. New, D. Lister, M. Hulme, and I. Makin. 2002: A high-resolution data set of surface climate over global land areas. Climate Research 21. The complete paper can be freely downloaded via:<br> <a href="http://www.cru.uea.ac.uk/cru/data/tmc.htm">http://www.cru.uea.ac.uk/cru/data/tmc.htm</a>); soil type (Source: SOTERLAC "Soil and terrain database for Latin America and the Caribbean ", FAO: Land and Water Digital Media Series #5, scale: 1:5 million scale. Type of top soil and descriptions of the different types can be found at:<br> <a href="http://www.fao.org/AG/agl/agll/key2soil.stm">http://www.fao.org/AG/agl/agll/key2soil.stm</a>); lake area (m², determined using landsat Orthorectified Landsat Thematic Mapper Mosaics of the year 2000. If image was cloudy images of 1990 were used. In rare cases when image deviated much from area observed in the field, all waypoints measured in the field were plotted on top of the image and a "best matching" polygon was drawn around it, of which the area was determined); average depth (Meter, the average depth of the lake was determined using depth measurements from 20 random points and 20 points along transects perpendicular to the longest axis of the lake); altitude (Meter above sea level, based on DEM from gtopo30, converted to an Arcview grid using the procedure published on herpnet.org GTOPT_DEM); conductivity (µS/cm); Total nitrogen (mg/L); Total phosphorus (mg/L); chlorophyll <i>a</i> (µg/L)</p> -- TABLE: Please see in attached file. -- </blockquote

Data_Sheet_1_Widespread dominance of methane ebullition over diffusion in freshwater aquaculture ponds.docx

An ever-increasing demand for protein-rich food sources combined with dwindling wild fish stocks has caused the aquaculture sector to boom in the last two decades. Although fishponds are potentially strong emitters of the greenhouse gas methane (CH4), little is known about the magnitude, pathways, and drivers of these emissions. We measured diffusive CH4 emissions at the margin and in the center of 52 freshwater fishponds in Brazil. In a subset of ponds (n = 31) we additionally quantified ebullitive CH4 fluxes and sampled water and sediment for biogeochemical analyses. Sediments (n = 20) were incubated to quantify potential CH4 production. Ebullitive CH4 emissions ranged between 0 and 477 mg m−2 d−1 and contributed substantially (median 85%) to total CH4 emissions, surpassing diffusive emissions in 81% of ponds. Diffusive CH4 emissions were higher in the center (median 11.4 mg CH4 m−2 d−1) than at the margin (median 6.1 mg CH4 m−2 d−1) in 90% of ponds. Sediment CH4 production ranged between 0 and 3.17 mg CH4 g C−1 d−1. We found no relation between sediment CH4 production and in situ emissions. Our findings suggest that dominance of CH4 ebullition over diffusion is widespread across aquaculture ponds. Management practices to minimize the carbon footprint of aquaculture production should focus on reducing sediment accumulation and CH4 ebullition.</p