Ecosystem metabolism of freshwater ecosystems has been studied for several decades, with theory and synthesis largely derived from temperate streams and rivers in North America and Europe. Advances in sensor technology and modeling have opened a wider range of streams to be included to test theories beyond temperate streams. In this paper, we review and synthesize ecosystem metabolism data from tropical streams and rivers to determine to what extent the constraints of metabolism measured in temperate streams are similar in tropical streams. We compiled 202 measurements of gross primary productivity (GPP) and ecosystem respiration (ER) from 83 tropical streams spanning 22.2°S to 18.4°N. Overall, tropical streams were heterotrophic (ER > GPP), with GPP ranging from 0.01 to 11.7 g O2m−2d−1and ER ranging from −0.2 to −42.1 g O2m−2d−1, similar on average to rates reviewed from temperate streams, but with higher maximum ER in tropical streams. Gross primary productivity increased with watershed area; a result also observed in temperate streams. ER decreased with elevated phosphorus and higher annual rainfall. We constructed a structural equation model that explained greater variation of ER (74%) than GPP (26%), and reflects similar drivers, such as land‐use and watershed area, as in temperate streams. We conclude that tropical stream ecosystem metabolism has similar drivers as temperate streams, and a warmer and wetter climate and human use of tropical lands will influence metabolic rates in streams.
River metabolism and, thus, carbon cycling are governed by gross primary production and ecosystem respiration. Traditionally river metabolism is derived from diel dissolved oxygen concentrations, which cannot resolve diel changes in ecosystem respiration. Here, we compare river metabolism derived from oxygen concentrations with estimates from stable oxygen isotope signatures (δ18O2) from 14 sites in rivers across three biomes using Bayesian inverse modeling. We find isotopically derived ecosystem respiration was greater in the day than night for all rivers (maximum change of 113 g O2 m−2 d−1, minimum of 1 g O2 m−2 d−1). Temperature (20 °C) normalized rates of ecosystem respiration and gross primary production were 1.1 to 87 and 1.5 to 22-fold higher when derived from oxygen isotope data compared to concentration data. Through accounting for diel variation in ecosystem respiration, our isotopically-derived rates suggest that ecosystem respiration and microbial carbon cycling in rivers is more rapid than predicted by traditional methods.
more » « less- Award ID(s):
- 1442562
- NSF-PAR ID:
- 10379334
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Communications Earth & Environment
- Volume:
- 3
- Issue:
- 1
- ISSN:
- 2662-4435
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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