Survival strategies of aquatic invertebrates as a response to drying in intermittent rivers — ASN Events

Survival strategies of aquatic invertebrates as a response to drying in intermittent rivers (#91)

Sylvia Hay 1 , Kim Jenkins 1 , Patrick Driver 2 , Richard Kingsford 1
  1. University of New South Wales, Sydney, NSW, Australia
  2. NSW Office of Water, Orange, NSW, Australia

Intermittent rivers, or rivers that periodically cease to flow, are the prevalent river type in Australia and occur across many climatic regions. It was long assumed that intermittent rivers had low biodiversity value; however intermittent rivers support a diverse range of taxa, with aquatic invertebrates pivotal in the 'boom and bust' ecology of these systems. During dry periods, aquatic invertebrates may survive in pools, become dormant or disperse as winged adults. Resilience mechanisms, or those that involve recolonisation rather than resistance in-situ, are believed to be the dominant strategy for post-drought recovery by invertebrate communities.

We know little however about the survival strategies that aquatic invertebrates use under different environmental conditions, such as different climatic regions or differing lengths of dry period. We investigated dominant physiological and behavioural strategies to survive drying, and contrasted these across different climate types or biomes. The prevalence of persistence in pools, aestivation in dry sediment and aerial dispersal as refugial strategies were quantified.

Dominant survival strategies used by invertebrate communities differed between climate types, with refugial pools supporting diverse invertebrate communities in temperate creeks, and dormancy in dry sediments dominant in the semi-arid region. Invertebrate communities exhibited taxonomic and functional redundancy in the survival mechanisms utilised. Invertebrates recolonising by aerial means were comprised of a distinct group of taxa found rarely using alternative mechanisms. These findings challenge the theory that resilience mechanisms are dominant in promoting recovery of aquatic invertebrate communities after drying.

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