Does dispersal capacity matter for freshwater biodiversity under climate change?

Abstract

Summary Freshwater ecosystems appear to be sensitive to even minor climatic shifts, and the dendritic nature of rivers as well as patchy distribution of habitats within the terrestrial landscape could limit the ability of species to track suitable climate conditions. Although the importance of dispersal is recognised in theory, there is great uncertainty when quantifying the capacity of species to shift their distributions in response to climate change. The influence of dispersal capacity on species’ vulnerability to climate change was assessed, using the modelled projections of 527 freshwater species in New South Wales (NSW), Australia. Species’ future ranges were calculated by iteratively identifying colonisation of accessible habitats and loss of suitable habitats within network models. The accessibility of new habitats was based on a given dispersal mode (aquatic, semi‐terrestrial and aerial). The relative impact of dispersal parameters on projected range were evaluated alongside other known sources of uncertainty (climate and emissions scenarios, modelling algorithm and biological group), analysed collectively in a generalised additive mixed‐model, and spatially to locate regions of NSW where projections are associated with the most uncertainty. Our simulations (1.4 million scenario combinations) suggest at least a third of species will lose more than half their range under climate change. Nevertheless, we emphasise the broad uncertainty that any average encapsulates. Dispersal capacity only had a minor impact on projected range shifts relative to other modelling assumptions but the network‐pathways and maps of uncertainty have value for conservation planning at large scales. Projected range losses initially decreased rapidly as dispersal rates increased but the benefits are reduced above 2–3 km year−1. Taxa restricted to dispersal within the stream network (aquatic) were more vulnerable to climate change than taxa with semi‐terrestrial or aerial dispersal and maps of variation due to dispersal mode and rate indicate where habitat connectivity would be most beneficial. This study demonstrates the breadth of uncertainties that challenge plans for improving ecosystem adaptation under climate change and highlights where in the landscape those differences were consistent. We emphasise the need for freshwater conservation studies to be ecologically representative, to focus on broad‐scale connectivity for taxa that can move between catchments, and an accessible network of refugia for taxa with more limited dispersal.

DISPERSE – A trait database to assess the dispersal potential of aquatic macroinvertebrates

“…Recent trait-based approaches have integrated dispersal into SDMs, and DISPERSE could increase model accuracy (Cooper & Soberón, 2018; Willis et al, 2015). Including dispersal in SDMs is especially relevant to assessments of biodiversity loss and species vulnerability to climate change (Bush & Hoskins, 2017; Markovic et al, 2014; Willis et al, 2015). DISPERSE could also advance understanding of eco-evolutionary relationships and biogeographical phenomena.…”

Fish dispersal in flowing waters: A synthesis of movement‐ and genetic‐based studies

“…Broadening the spatial and taxonomic scope of dispersal studies thus undeniably represents urgent issues in the freshwater realm. More importantly, understanding the ecological and evolutionary mechanisms underlying dispersal will be paramount in determining whether, and if so how, species will respond to rapid environmental change (Bush & Hoskins, ; Urban, Zarnetske, & Skelly, ). The identification of the environmental and biological determinants of dispersal (Comte & Olden, ; Radinger & Wolter, ) holds considerable promise to map and predict the movements of individuals and gene flow in riverine fishes (Radinger, Kail, & Wolter, ).…”

Synthesizing the role of epigenetics in the response and adaptation of species to climate change in freshwater ecosystems

“…In a climate change context, extreme climatic events, the exacerbation of existing pollution and alien species invasion, rising of (water) temperatures, greater variability in precipitation patterns and higher levels of salinity have been set forward as the most important threats to freshwater biodiversity and ecosystems (Bush & Hoskins, 2017;Cañedo-Arg€ uelles et al, 2013;Carpenter et al, 2011;Jackson et al, 2016;Markovic, Carrizo, K€ archer, Walz, & David, 2017;Woodward et al, 2010Woodward et al, , 2016. Focusing mostly on temperature and salt stress, several studies explored the role of epigenetic mechanisms in the short-term responses of different species using various techniques and examining different epigenetic mechanisms, as synthesized in Table 2.…”