Temperature sensitivity of oxygen demand varies as a function of organic matter source

Abstract

Dissolved oxygen (DO) impairment within coastal waters is widespread and rising temperatures may exacerbate low DO levels by enhancing organic matter (OM) degradation. Here, the temperature sensitivity of OM degradation was investigated as DO decay rates determined during standard five-day biochemical oxygen demand (BOD) measurements conducted under different incubation temperatures. Sampling was conducted in the Waccamaw River watershed, South Carolina, a blackwater river with extensive forested wetland that also receives drainage from stormwater detention ponds associated with coastal development, thus providing different sources of contrasting OM composition. Temperature sensitivities were measured as Q10 temperature coefficients, which define how DO decay rates change with 10 degrees of warming. The average Q10 value for the wetland sites (2.14 ± 0.41) was significantly greater (p < 0.05) than those measured in either the River (1.49 ± 0.36) or stormwater ponds (1.41 ± 0.21). Furthermore, using Intergovernmental Panel on Climate Change intermediate-to-very high temperature estimates for 2100 of +2.7 – 4.4°C, average predicted increases in DO decay rates for wetlands (~22-39%) are more than double the River (~11-18%) and stormwater pond rates (~9-16%). Our findings for inland, coastal waters agree with previous results for soils, suggesting that temperature sensitivities are variable across sites and increase with more complex, lower quality OM. Future modeling scenarios of DO utilization must therefore consider the influence of OM heterogeneity and the temperature sensitivity response of OM degradation across sources and region to better predict how climate change may impact oxygen impairment in aquatic ecosystems.

The Changing Biological Carbon Pump of the South Atlantic Ocean

“…The elevated C:N observed at 40°S could then also result from a changing balance between water masses from the north and the south. Organic matter (OM)with higher C:N requires more oxygen for its remineralization, thereby accelerating the consumption of dissolved oxygen (Matsumoto et al, 2020;Szewczyk et al, 2023). Climate change is expected to cause significant stoichiometric shifts in plankton biomass, with warmer temperatures and rising CO 2 levels promoting higher C:P and N:P ratios (Ayo et al, 2017;DeVries, 2018;DeVries et al, 2017;Toseland et al, 2013;van de Waal et al, 2010;Yvon-Durocher et al, 2017) which may result in increased oxygen consumption during remineralization and thus higher AOU (DeVries, 2018).…”

Fish Growth Performance in RAS Pond Using Hydrocyclone Mechanical Filter

“…The lower DO value will increase the temperature in the pond and make the pond more acidic (Hapsari et al, 2020). High water temperature is negatively correlated with low dissolved oxygen in intensive ponds (Szewczyk et al, 2023). The temperature sensitivity of organic matter (OM) degradation, which affects dissolved oxygen levels, increases with rising temperatures (Carbajal-Hernández & Sánchez-Fernández, 2016).…”

Impact of the Citrus Industry on the Water Quality of the Filobobos River in Veracruz, Mexico

“…The influence of water temperature on dissolved oxygen (DO) levels, particularly in polluted conditions, has been extensively documented [30]. Elevated temperatures can exacerbate low DO levels by accelerating the decomposition of organic matter, thereby inducing alterations in ecological and environmental conditions, such as heightened eutrophication through increased nutrient discharge into sediments [31]. Furthermore, when dissolved oxygen levels plummet, fish and other aquatic organisms struggle to survive.…”