Ecosystem Effects of a Tropical Cyclone on a Network of Lakes in Northeastern North America

Abstract

Here we document the regional effects of Tropical Cyclone Irene on thermal structure and ecosystem metabolism in nine lakes and reservoirs in northeastern North America using a network of high-frequency, in situ, automated sensors. Thermal stability declined within hours in all systems following passage of Irene, and the magnitude of change was related to the volume of water falling on the lake and catchment relative to lake volume. Across systems, temperature change predicted the change in primary production, but changes in mixed-layer thickness did not affect metabolism. Instead, respiration became a driver of ecosystem metabolism that was decoupled from in-lake primary production, likely due to addition of terrestrially derived carbon. Regionally, energetic disturbance of thermal structure was shorter-lived than disturbance from inflows of terrestrial materials. Given predicted regional increases in intense rain events with climate change, the magnitude and longevity of ecological impacts of these storms will be greater in systems with large catchments relative to lake volume, particularly when significant material is available for transport from the catchment. This case illustrates the power of automated sensor networks and associated human networks in assessing both system response and the characteristics that mediate physical and ecological responses to extreme events.

Intra- and inter-annual variability in metabolism in an oligotrophic lake

“…These advances have enabled new discoveries about the role of lakes in the global C cycle (e.g., Solomon et al 2013), controls on metabolism (Hoellein et al 2013), and spatial variability of metabolism within lakes (Van de Bogert et al 2012). Furthermore, these rapidly-developing techniques have facilitated investigation of the variability of metabolism at finely-resolved spatial (Klug et al 2012; Van de Bogert et al 2012) and temporal (Hanson et al 2008;Solomon et al 2013) scales.…”

“…To date, most lake metabolism studies using these techniques have focused on temporal variation based on measurements made in the epilimnion and restricted to one year time periods (e.g., Carignan et al 2000;Sadro et al 2011;Klug et al 2012;Solomon et al 2013;Morales-Pineda et al 2014), in part because the deployment of high-frequency sensors is a recent phenomenon (Weathers et al 2013). In the few studies when metabolism was estimated across multiple years in lakes, rivers, or estuaries, metabolic rates were linked to anthropogenic nutrient loading (Uehlinger 2006) and climatic variation (Roberts et al 2007;Staehr and Sand-Jensen 2007;Einola et al 2011;Laas et al 2012;Caffrey et al 2014;Roley et al 2014).…”

“…For example, at the daily scale, photosynthetically-active radiation (PAR) is one of the primary controls on GPP and NEP, as phytoplankton respond to the diel cycle of fluctuating PAR over 24 h (Hanson et al 2006;Langman et al 2010;Silsbe et al 2015), whereas temperature is a primary control on R (Yvon-Durocher et al 2012). Seasonal variability in metabolism could be driven by changes in temperature or light (Hanson et al 2006;Langman et al 2010;Laas et al 2012), plankton abundance and succession (e.g., phytoplankton blooms, the zooplankton clear water phase), as well as by storms (Jennings et al 2012;Klug et al 2012;Staehr et al 2012). For example, Klug et al (2012) detected a decoupling of GPP and R in seven lakes in northeastern North America during and after Hurricane Irene in 2011, likely due to increased physical mixing and nutrient and organic matter entering the lakes from their catchments.…”

“…Seasonal variability in metabolism could be driven by changes in temperature or light (Hanson et al 2006;Langman et al 2010;Laas et al 2012), plankton abundance and succession (e.g., phytoplankton blooms, the zooplankton clear water phase), as well as by storms (Jennings et al 2012;Klug et al 2012;Staehr et al 2012). For example, Klug et al (2012) detected a decoupling of GPP and R in seven lakes in northeastern North America during and after Hurricane Irene in 2011, likely due to increased physical mixing and nutrient and organic matter entering the lakes from their catchments. At the inter-annual scale, variation in metabolic rates could be due to broader changes in climate or the catchment that alter subsidies of nutrients or organic matter.…”

“…At the inter-annual scale, variation in metabolic rates could be due to broader changes in climate or the catchment that alter subsidies of nutrients or organic matter. For example, if nutrient loads to a lake increase, the lake may exhibit increased GPP (Wetzel 2001), or, if the frequency and intensity of storms increase, GPP and R may become increasingly decoupled (e.g., Klug et al 2012).…”