How Does Climate Change Affect Emergent Properties of Aquatic Ecosystems?

Abstract

Emergent properties of ecosystems are community attributes, such as structure and function, that arise from connections and interactions (e.g., predator-prey, competition) among populations, species, or assemblages that, when viewed together, provide a holistic representation that is more than the sum of its individual parts. Climate change is altering emergent properties of aquatic ecosystems through component responses, a combination of shifts in species range, phenology, distribution, and productivity, which lead to novel ecosystems that have no historical analog. The reshuffling, restructuring, and rewiring of aquatic ecosystems due to climate impacts are of high concern for natural resource management and conservation as these changes can lead to species extinctions and reductions in ecosystem services. Overall, we found that substantial progress has been made to advance our understanding of how climate change is affecting emergent properties of aquatic ecosystems. However, responses are incredibly complex, and high uncertainty remains for how systems will reorganize and function over the coming decades. This cross-system perspective summarizes the state of knowledge of climate-driven emergent properties in aquatic habitats with case studies that highlight mechanisms of change, observed or anticipated outcomes, as well as insights into confounding non-climate effects, research tools, and management approaches to advance the field.

Climate tracking by freshwater fishes suggests that fish diversity in temperate lakes may be increasingly threatened by climate warming

“…Due to a paucity of sampling data, climate‐driven shifts of freshwater fish distributions in Ontario remain comparatively understudied (Alofs et al, 2014; Heino et al, 2009; Staudinger et al, 2021). Although climate velocity as a benchmark for climate vulnerability has been extensively used to analyse range shifts for a variety of marine and terrestrial species within a continuous environment for dispersal (Burrows et al, 2011; Pinsky et al, 2013), its usage has not yet been evaluated for species in inherently fragmented habitats such as lakes where passive dispersal may be much more difficult (Hodgson et al, 2012; Tonn & Magnuson, 1982).…”

“…For example, northward range expansions of predator fishes may limit similar northward expansions of smaller‐bodied prey fish (Biswas et al, 2017). Moreover, the resulting novel interactions and voracious predation may extirpate native fishes from northern lakes (Cazelles et al, 2019; Staudinger et al, 2021; Van Zuiden et al, 2016). Other factors to dispersal success include life histories, diets and body traits (Angert et al, 2011; Mims et al, 2010; Whitney et al, 2017), with generalist, longer‐living and larger‐bodied species more likely to expand ranges (Alofs et al, 2014; Comte & Olden, 2018).…”

Ecological and social strategies for managing fisheries using the Resist‐Accept‐Direct (RAD) framework

“…Aquatic systems can transform via many mechanisms, but climate change often exacerbates the impacts of other stressors. When these factors interact, aquatic systems can respond in a nonlinear fashion through feedback loops, synergies, threshold effects, and time lag responses, often with uncertain and unpredictable outcomes (Liu et al, 2007; Staudinger et al, 2021). So‐called “regime shifts,” have been documented in both marine and freshwater systems.…”

A Resist‐Accept‐Direct (RAD) future for Salmon in Maine and California: Salmon at the southern edge

“…It should be noted that the term “management” implies dominance over the species and ecosystems and Indigenous systems would classify actions more as stewardship (see, e.g., Shultz et al, 2022). For salmon at the southern edge of their range, the RAD approach provided a framework to review management options to address both historical stressors and climate in a systematic way (Lynch et al, 2021; Staudinger et al, 2021; Thompson et al, 2021). Here, we consider the relevance of RAD for sustaining Atlantic and Pacific salmon, their habitats, and connections to people at the southern edges of their range.…”