DrGalen Holt

I am a quantitative community ecologist working primarily in rivers and other aquatic systems. I study biodiversity maintenance and how species respond to a changing climate, pairing ecological theory with fieldwork, and I turn that understanding into models that inform fundamental ecological knowledge and guide water management. I have led modelling teams in several national water programs, and the open-source tools we build, HydroBOT and eFlowEval, are used to assess water management, climate adaptation, and inform methodological improvements across the Basin.

My background is in theoretical community ecology, where I use mathematical theory and simulation models to understand how variation in the environment across space and time interacts with species' life histories to shape diversity and community structure. My current theoretical work extends this to a changing climate, asking how the ways organisms move and grow across a varied landscape determine population trajectories and distributions.

I connect this theory to real communities through field and laboratory studies, which both sharpen the theory and reveal the processes that maintain diversity and shape climate responses in particular systems. My current empirical work follows a caddisfly community, its competitive interactions, and an emergent disease. Earlier work ranged from aquatic insects to desert annual plants to fish, showing how species' life history shapes coexistence and community dynamics.

The issues facing water management parallel those in my theoretical and empirical research: how do the species' responses and their interactions scale up to whole-of-system outcomes, and how do management actions alter those outcomes? Addressing these issues requires good models of how species respond to their environment and to each other, and the ability to scale those models across varied conditions and compare scenarios. Leading the modelling teams in the Flow-MER and MD-WERP programs, I developed open-source models and used them to assess ecological condition across the Murray-Darling Basin, support climate-adaptation planning, and improve how uncertainty and model assumptions are handled in Basin decision making.

Highlights

• I have developed theoretical and modelling work across NSF and ARC-funded projects in the US and Australia, as well as multiple programs of work focusing on models for improved water management in the Murray-Darling Basin.
• In two recent ARC Discovery projects, I developed analytical and simulation models to connect empirical caddisfly ecology to coexistence and aedt theory.
• My work in the EWKR (Environmental Water Knowledge and Research) project developed new techniques for estimating trophic relationships and new models that assessed how environmental watering scenarios might have different impacts through the food web.
• My work in the Flow-MER (Monitoring, Evaluation, and Research) program developed the eFlowEval modelling tool, enabling wetland-scale process based ecological modelling across the full Murray-Darling Basin for a suite of ecological groups.
• In the MD-WERP (Water and Environmental Research Program), I led the team developing HydroBOT, a modelling tool to assess, synthesise, and report ecological consequences of flows across the Murray-Darling Basin and through time.
• These tools have been used in national-scale programs in partnership with the MDBA and CEWH to improve our understanding of water management, assess the impact of past actions and potential climate adaptations, and interrogate and improve modelling methods.