Carbon Fixation Trends in Eleven of the World’s Largest Lakes: 2003–2018

Abstract

Large freshwater lakes provide immense value to the surrounding populations, yet there is limited understanding of how these lakes will respond to climate change and other factors. This study uses satellite remote sensing to estimate annual, lake-wide primary production in 11 of the world’s largest lakes from 2003–2018. These lakes include the five Laurentian Great Lakes, the three African Great Lakes, Lake Baikal, and Great Bear and Great Slave Lakes. Mean annual production in these lakes ranged from under 200 mgC/m2/day to over 1100 mgC/m2/day, and the lakes were placed into one of three distinct groups (oligotrophic, mesotrophic, or eutrophic) based on their level of production. The analysis revealed only three lakes with significant production trends over the study period, with increases in Great Bear Lake (24% increase over the study period) and Great Slave Lake (27%) and a decline in Lake Tanganyika (−16%). These changes appear to be related to climate change, including increasing temperatures and solar radiation and decreasing wind speeds. This study is the first to use consistent methodology to study primary production in the world’s largest lakes, allowing for these novel between-lake comparisons and assessment of inter-annual trends.

A review of carbon monitoring in wet carbon systems using remote sensing

“…Several recent works have used a mechanistic carbon fixation model adapted for use in the Laurentian Great Lakes [396,397] to estimate carbon fixation in the world's large lakes [402]. Additionally, a simple depth integrated model approach (DIM) was refined to estimate growing season carbon fixation of ∼80 000 freshwater lakes [403].…”

“…However, several recent works have estimated global scale freshwater carbon fixation for satellite observable lakes [402,403]. These works also examined carbon fixation on multiple temporal scales ranging from a single year growing season snapshot for ∼80 000 lakes [403] to a 15 year time-series for the world's eleven largest lakes [402]. The latter work revealed significant changes in carbon fixation for several lakes, likely in response to changes in climate.…”

“…Still, global-scale estimates remain elusive due to the lack of readily available remote sensing products appropriate for optically and spatially complex inland lakes. However, several recent works have estimated global scale freshwater carbon fixation for satellite observable lakes [402,403]. These works also examined carbon fixation on multiple temporal scales ranging from a single year growing season snapshot for ∼80 000 lakes [403] to a 15 year time-series for the world's eleven largest lakes [402].…”

Arctic-Boreal Lake Phenology Shows a Relationship between Earlier Lake Ice-Out and Later Green-Up

“…One barrier towards achieving this goal is the lack of spatially distributed observations of lake phenology, which studies have attempted to solve by using satellites to track lake ice-out and productivity. However, most past attempts at mapping trends in lake dynamics have relied on coarse temporal or spatial resolution satellites [19,20]. This is unfortunate, because the majority of lakes are small (<1 km) [1,2] and phenological shifts can happen over short timeframes.…”

The genetic population structure of Lake Tanganyika’sLatesspecies flock, an endemic radiation of pelagic top predators

“…During the last few decades, harvest records from Lake Tanganyika's fishery have indicated a general decline in population sizes (Kimirei et al 2008;Van der Knaap 2013;Van der Knaap et al 2014;van Zwieten et al 2002). This decline has resulted from a combination of an increase in the number of fishermen and vessels on Lake Tanganyika, changes in fishing practices (e.g., the use of beach seining, which targets fish in their in-shore nursery habitats) (Kimirei et al 2008;Petit & Shipton 2012;Van der Knaap 2013; Van der Knaap et al 2014;van Zwieten et al 2002), and warming lake surface temperatures (Cohen et al 2016;O'Reilly et al 2003;Sayers et al 2020). Decreases in fish abundance are likely also linked to reduced productivity in the lake caused by stronger water column stratification due to climate change (O'Reilly et al 2003;Verburg et al 2003).…”