Abstract
A climatic shift from temperate to arid conditions is predicted for Northwest Africa. Water temperature, salinity, and river intermittency are likely to increase, which may impact freshwater communities, ecosystem functioning, and related ecosystem services. Quantitative data and information on the impact of climate change on insect communities (e.g., richness, taxonomic and trait composition) are still scarce for Northwest Africa. In this study, we extracted information on freshwater insect occurrence and environmental variables in Northwest Africa from the results of a literature search to study potential consequences of changing climatic conditions for these communities. Our data set covered 96 families in 165 sites in Morocco and Algeria. We quantified the impact of several explanatoryvariables (climate, altitude, water temperature, conductivity, intermittency, flow, aridity, dams, and land cover) on richness, taxonomic and functional trait composition using negative binomial regression models and constrained ordination. Family richness in arid sites was on average 37 % lower than in temperate sites in association with flow, river regulation, cropland extent, conductivity, altitude, and water temperature. With 36 % of the studied temperate sites predicted to turn arid by the end of the century, a loss of insect families can be predicted for Northwest Africa, mainly affecting species adapted to temperate environments. Resistance and resilience traits such as small body size, aerial dispersal, and air breathing promote survival in arid climates. Future research should report insect occurrences on species level to allow for better predictions on climate change effects.
Highlights
Northwest Africa is characterized by the temperate Mediterranean and arid Saharan climate and is subject to droughts (Schilling et al, 2012; Waha et al, 2017)
In total there were 165 sites covering a wide range of environmental conditions (Table 1). 91 sites were located in arid climate and 74 in temperate climate, of which 27 (36%) are predicted to shift towards arid climate by 2071–2,100 (Figure 1)
With family richness being on average 37% lower in arid than in temperate sites, our model suggests that intermittent flow and increasing conductivity will play major roles in the loss of richness
Summary
Northwest Africa is characterized by the temperate Mediterranean and arid Saharan climate and is subject to droughts (Schilling et al, 2012; Waha et al, 2017). Arid climate is predicted to extend northwards covering increasing parts of the Maghreb until the mid- and late-21st century (Born et al, 2008; Beck et al, 2018). This will likely lead to increased salinity levels and flow intermittency in rivers (Williams, 1999) potentially affecting biodiversity and dependent human livelihoods (Arthington et al, 2010; Berger et al, 2018) through changes in the supply of ecosystem goods and services. Water abstraction (Dewson et al, 2007), flow modification (Martínez et al, 2013) and additional human-induced forms of secondary salinisation (CañedoArgüelles et al, 2013) related to human land use in the river catchment may exacerbate salinity levels and flow intermittency.
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