Effects of seasonality, trophic state and landscape properties on CO2 saturation in low-latitude lakes and reservoirs

Pedro Ciarlini Junger; Fabíola da Costa Catombé Dantas; Regina Lucia Guimarães Nobre; Sarian Kosten; Eduardo Martins Venticinque; Fernando de Carvalho Araújo; Hugo Sarmento; Ronaldo Angelini; Iagê Terra; Andrievisk Gaudêncio; Ng Haig They; Vanessa Becker; Camila Rodrigues Cabral; Letícia Quesado; Luciana Silva Carneiro; Adriano Caliman; André Megali Amado

doi:10.1016/j.scitotenv.2019.01.273

Effects of seasonality, trophic state and landscape properties on CO₂ saturation in low-latitude lakes and reservoirs

Sci Total Environ. 2019 May 10:664:283-295. doi: 10.1016/j.scitotenv.2019.01.273. Epub 2019 Jan 24.

Authors

Pedro Ciarlini Junger¹, Fabíola da Costa Catombé Dantas², Regina Lucia Guimarães Nobre², Sarian Kosten³, Eduardo Martins Venticinque⁴, Fernando de Carvalho Araújo⁴, Hugo Sarmento⁵, Ronaldo Angelini⁶, Iagê Terra², Andrievisk Gaudêncio⁷, Ng Haig They⁸, Vanessa Becker⁶, Camila Rodrigues Cabral², Letícia Quesado², Luciana Silva Carneiro⁴, Adriano Caliman⁴, André Megali Amado⁹

Affiliations

¹ Departamento de Oceanografia e Limnologia, Universidade Federal do Rio Grande do Norte, Natal, RN 59014-002, Brazil; Departamento de Hidrobiologia, Universidade Federal de São Carlos, São Carlos, SP 13565-905, Brazil.
² Programa de Pós-Graduação em Ecologia, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil.
³ Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525AF Nijmegen, the Netherlands.
⁴ Departamento de Ecologia, Universidade Federal do Rio Grande do Norte, Natal, RN 59078-900, Brazil.
⁵ Departamento de Hidrobiologia, Universidade Federal de São Carlos, São Carlos, SP 13565-905, Brazil.
⁶ Departamento de Engenharia Civil, Universidade Federal do Rio Grande do Norte, Natal, RN 59078-970, Brazil.
⁷ Departamento de Oceanografia e Limnologia, Universidade Federal do Rio Grande do Norte, Natal, RN 59014-002, Brazil; Programa de Pós-Graduação em Engenharia Sanitária e Ambiental, Universidade Federal do Rio Grande do Norte, Natal, RN 59078-970, Brazil.
⁸ Departamento de Oceanografia e Limnologia, Universidade Federal do Rio Grande do Norte, Natal, RN 59014-002, Brazil; Centro de Estudos Costeiros, Limnológicos e Marinhos (CECLIMAR), Departamento Interdisciplinar, Universidade Federal do Rio Grande do Sul, RS 96625-000, Brazil.
⁹ Departamento de Oceanografia e Limnologia, Universidade Federal do Rio Grande do Norte, Natal, RN 59014-002, Brazil; Departamento de Biologia, Universidade Federal de Juiz de Fora, Juiz de Fora, MG 36036-900, Brazil. Electronic address: andre.amado@ufjf.edu.br.

PMID: 30743122
DOI: 10.1016/j.scitotenv.2019.01.273

Abstract

The role of tropical lakes and reservoirs in the global carbon cycle has received increasing attention in the past decade, but our understanding of its variability is still limited. The metabolism of tropical systems may differ profoundly from temperate systems due to the higher temperatures and wider variations in precipitation. Here, we investigated the spatial and temporal patterns of the variability in the partial pressure of carbon dioxide (pCO₂) and its drivers in a set of 102 low-latitude lakes and reservoirs that encompass wide gradients of precipitation, productivity and landscape properties (lake area, perimeter-to-area ratio, catchment size, catchment area-to-lake area ratio, and types of catchment land use). We used multiple regressions and structural equation modeling (SEM) to determine the direct and indirect effects of the main in-lake variables and landscape properties on the water pCO₂ variance. We found that these systems were mostly supersaturated with CO₂ (92% spatially and 72% seasonally) regardless of their trophic status and landscape properties. The pCO₂ values (9-40,020 μatm) were within the range found in tropical ecosystems, and higher (p < 0.005) than pCO₂ values recorded from high-latitude ecosystems. Water volume had a negative effect on the trophic state (r = -0.63), which mediated a positive indirect effect on pCO₂ (r = 0.4), representing an important negative feedback in the context of climate change-driven reduction in precipitation. Our results demonstrated that precipitation drives the pCO₂ seasonal variability, with significantly higher pCO₂ during the rainy season (F = 16.67; p < 0.001), due to two potential main mechanisms: (1) phytoplankton dilution and (2) increasing inputs of terrestrial CO₂ from the catchment. We conclude that at low latitudes, precipitation is a major climatic driver of pCO₂ variability by influencing volume variations and linking lentic ecosystems to their catchments.

Keywords: Carbon cycle; Ecosystem metabolism; Eutrophication; Land-water coupling; Precipitation; Shallow lakes.