Communities at the extreme: Aquatic food webs in desert landscapes

Abstract

Studying food webs across contrasting abiotic conditions is an important tool in understanding how environmental variability impacts community structure and ecosystem dynamics. The study of extreme environments provides insight into community‐wide level responses to environmental pressures with relevance to the future management of aquatic ecosystems. In the western Lake Eyre Basin of arid Australia, there are two characteristic and contrasting aquatic habitats: springs and rivers. Permanent isolated Great Artesian Basin springs represent hydrologically persistent environments in an arid desert landscape. In contrast, hydrologically variable river waterholes are ephemeral in space and time. We comprehensively sampled aquatic assemblages in contrasting ecosystem types to assess patterns in community composition and to quantify food web attributes with stable isotopes. Springs and rivers were found to have markedly different invertebrate communities, with rivers dominated by more dispersive species and springs associated with species that show high local endemism. Qualitative assessment of basal resources shows autochthonous carbon appears to be a key basal resource in both types of habitat, although the particular sources differed between habitats. Food‐web variables such as trophic length, trophic breadth, and community isotopic niche size were relatively similar in the two habitat types. The basis for the similarity in food‐web structure despite differences in community composition appears to be broader isotopic niches for predatory invertebrates and fish in springs as compared with rivers. In contrast to published theory, our findings suggest that the food webs of the hydrologically variable river sites may show less dietary generalization and more compact food‐web modules than in springs.

A call for collaboration: linking local and non-local rangeland communities to build resilience

“…For example, the Rotary Club of Longreach welcomes guest speakers on a wide range of topics. Non-local scientists conducting long-term ecological studies into bird migratory patterns (Bino et al 2020), resource web interactions (Moran et al 2019) and smallmammal ecology (Dickman and Robin 2014) would be welcomed as guest speakers to share their experiences, skills and expertise with Rotary, other local community service clubs, Landcare groups, RAPAD and DCQ. Their knowledge would also be welcomed into local school classrooms (both physically and virtually) to inspire local youth through examples of science within their own region, potentially providing educational benefits to future generations (Schweisfurth et al 2018).…”