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Refilling temporary ponds has timing‐dependent effects on Hyla gratiosa performance

Pintar, Matthew R., Resetarits, William J., Jr.
Freshwater biology 2018 v.63 no.12 pp. 1550-1559
Hyla, amphibians, aquatic animals, compensatory growth, drying, freshwater, habitats, larvae, larval development, metamorphosis, ponds
Disturbances and variation in abiotic habitat conditions greatly affect populations and communities. The multitude of processes that occur in natural systems offers the possibility that the trajectories of ephemeral habitats and the effects of disturbances can be slowed or reversed. Hydroperiod is a defining characteristic in freshwater systems, with temporary ponds supporting distinct communities of organisms with plastic developmental trajectories and complex lifecycles that allow them to cope with the vagaries of pond duration. Despite work on the effects of pond drying on aquatic animals, little consideration has been given to filling, which can extend the duration of small, drying ponds. Our goal was to assess how increasing the volume of small ponds affects the developmental trajectories of larval amphibians living in these habitats. We conducted a field mesocosm experiment to assess how filling of ponds early, midway and late in the larval period affected the survival and development of the barking treefrog, Hyla gratiosa. We hypothesised that filling early in the larval stage would provide the most benefits, producing more and larger metamorphs than filling later in development. We found that through various effects on survival, metamorphosis, habitat quality and competition, increasing volume early in development produced more and larger metamorphs with faster growth rates than any other treatment, whereas filling late in development produced few, small, slow growing metamorphs. Our results provide support for the role of stressors in initiating metamorphosis and also show that increased pond volumes early in larval development can provide benefits to Hyla populations in terms of compensatory growth, but filling late in development has little benefit.