The waterscape continuum concept: Rethinking boundaries in ecosystems

Abstract

Continuity and discontinuity are fundamental concepts of ecosystem science.In reality, both continuities and discontinuities can exist; lentic and lotic systems can expand and contract as can soil/rock moisture and groundwater systems. Surface water, soil moisture, rock moisture, and groundwater, represent hydrological domains that are interconnected. Under a state of expansion each domain may be characterized by spatial continuity; for instance, a river may be entirely flow connected. However, under a state of contraction, discontinuities may appear, and the river may become fragmented. The rate of expansion and contraction in each domain, that is land-, lentic-, and lotic-scapes, is a function of topography, geology, climate, and biota. In an effort to reconcile older, and sometimes incongruous, concepts of continuity and discontinuity we present a view of water-connected ecosystems, such as riverscapes and catchments that are nested upon and within the uppermost layer of Earth. This layer is the key interface between the lithosphere, atmosphere, hydrosphere, and biosphere, and is known as the critical zone (CZ). We present the waterscape continuum and define it as the spatially and temporally dynamic water upon and within the CZ. To guide ecosystem research (across the land-, lentic-, and lotic-scapes), we introduce the waterscape continuum template (WCT).We propose the waterscape continuum and the WCT can enhance our understanding of ecosystem processes and mechanisms.

A New Approach for Assessing Groundwater Recharge by Combining GRACE and Baseflow With Case Studies in Karst Areas of Southwest China

“…Although the cross‐correlation analysis indicates no time lag between RE GRACE /RE OBS and precipitation in both basins (Figure 7), the mean seasonal cycles in Figures 5d and 5f show that RE GRACE (GWSC GRACE ) lags behind RE OBS (GWSC OBS ) or precipitation by 1 month in XRB, but no time lag was found in WRB (Figures 5 and 7). The reason might be that GRACE detects a larger extent of deep non‐karst aquifers in the XRB than WRB (O'Sullivan et al., 2022). The deep non‐karst aquifers have lower permeability than shallow karst aquifers monitored by observation wells, leading to longer response time of RE to precipitation in the XRB.…”

No effects of macroconsumer exclusion on macroinvertebrate functional composition in Brazilian karst streams along a gradient of riparian forest loss

“…Our findings showed that manipulating the presence of macroconsumers did not induce effects on the abundance of the FFG benthic invertebrates along the forest cover gradient in this biologically diverse tropical region. Given these results, we emphasize the need for studies that describe the trophic relationships among macroconsumers and the FFG of aquatic insects and other macroinvertebrates where riparian‐buffer sizes differ, especially in karst regions where hydrologically complex boundaries can alter expected ecosystem connectivity (O'Sullivan et al., 2022). There is also a need for baseline studies and extended periods of time for observations during different seasons and years.…”

Water temperature at the time of the catch‐and‐release event is a better predictor of survival in Atlantic salmon (Salmo salar) than acute water temperature changes before and after

“…Salmon caught‐and‐released in the summer may encounter not only warmer water temperatures at the time of the catch‐and‐release event but also greater variability in the magnitude and duration of water temperatures before and after the catch‐and‐release event. This variability depends on the level of primary (i.e., air temperature and solar radiation) and secondary (i.e., river characteristics, geomorphology, and land use) sources of thermal energy driving river‐specific thermal conditions (O'Sullivan et al, 2022, 2023).…”

“…This variability depends on the level of primary (i.e., air temperature and solar radiation) and secondary (i.e., river characteristics, geomorphology, and land use) sources of thermal energy driving riverspecific thermal conditions (O'Sullivan et al, 2022(O'Sullivan et al, , 2023.…”