The influence of landscape position on lake chemical responses to drought in northern Wisconsin

Abstract

Climatic shifts to drier conditions during drought alter the hydrologic pathways of water and solute flow to aquatic ecosystems. We examined differences in drought-induced trends in the semiconservative cations, Ca+Mg, in seven northern Wisconsin lakes. These spanned the range of hydrologic settings in the region, including hydraulically mounded, groundwater flowthrough, and groundwater-discharge lakes. Parallel increases in concentration across the seven lakes during drought were attributable to evapoconcentration. However, we observed divergent trends for mass, which better reflects altered solute flux by accounting for changes in lake volume. Ca+Mg mass increased in three groundwater-dominated lakes as precipitation inputs were low and groundwater discharging from longer flowpaths became proportionately more important. In contrast, decreases in Ca+Mg mass for two precipitation-dominated lakes reflected diminished inputs of solute-rich groundwater. Landscape position, defined by the spatial position of a lake within a hydrologic flow system, accounted for the divergence in chemical responses to drought.

Paleolimnological evidence of the effects on lakes of energy and mass transfer from climate and humans

“…Similarly, comparison of historical changes in net water balance (as fossil-reconstructed salinity) among lakes of the northern Great Plains reveals that both the magnitude and the direction of limnological response to common climate forcing vary among sites because of the differential importance of groundwater m flux among regions and variable topographic position of lakes relative to local groundwater sources (Fritz et al 2000;Laird et al 2003;Fritz 2008). Unlike similar limnological conclusions based on whole-lake mass balances (Webster et al 1996;Pham et al 2008), sedimentary studies reveal that differences in lake response to climate may persist for centuries or may suddenly become coherent after long intervals of asynchrony. Taken together, these studies demonstrate that climatically induced changes in m influx alter spatial synchrony among lakes (Pham et al 2008(Pham et al , 2009) and suggest that evaluation of lake response to climatic variability should r Fig.…”

Controls of δ13C‐DIC in lakes: Geochemistry, lake metabolism, and morphometry

“…However, we were able to create a more complete budget for three lakes (Trout, Allequash, and Big Musky Lakes), in which this input can be well estimated. Inputs of water from the watershed were calculated based on estimates of water residence times for these lakes and precipitation and evaporation values for the region (Michaels 1995;Webster et al 1996). To estimate the alkalinity of the inflowing water, we assumed a steady-state alkalinity in the lake, and acid deposition that is balanced by internal alkalinity generation.…”

Freshwater bacterioplankton richness in oligotrophic lakes depends on nutrient availability rather than on species–area relationships

“…Further, recognising lakes as integral components of a region, lake ecologists have begun to implement a basic tenet of landscape ecology, namely that the spatial position of an ecosystem within a landscape influences the properties of that very system. In doing so, Kratz and colleagues (Kratz et al, 1991(Kratz et al, , 1997Webster et al, 1996;Soranno et al, 1999;Magnuson and Kratz, 2000;Riera et al, 2000) developed the concept of lake landscape position. One of the metrics used so far to define a lake's position in a landscape is lake chain number (LCN), which measures lake landscape position with respect to lakes connected along a linear chain through primarily surface-flow systems (Soranno et al, 1999).…”