Invasive crayfish does not influence spawning microhabitat selection of brown frogs

Area of Science:

• Ecology
• Amphibian Biology
• Invasive Species Research

Background:

• Amphibian microhabitat selection is crucial for breeding success and can be influenced by environmental factors and predators.
• Invasive alien species pose significant threats to amphibians, yet their impact on amphibian breeding microhabitat choice is understudied.
• The invasive red swamp crayfish (Procambarus clarkii) is a known predator of amphibian larvae, including brown frogs.

Purpose of the Study:

• To quantitatively characterize the microhabitats selected for egg clutch deposition by Rana dalmatina and Rana latastei.
• To investigate whether the position and aggregation of egg clutches differ in breeding sites with and without the invasive Procambarus clarkii.

Main Methods:

• Field surveys were conducted in Northern Italy during spring 2017 at 15 brown frog breeding sites.
• Microhabitat features (clutch position, depth, aggregation) and the presence/abundance of Procambarus clarkii were assessed at each site.
• Statistical analyses were performed to compare microhabitat characteristics between frog species and between invaded and non-invaded sites.

Main Results:

• Significant differences were found in microhabitat selection between Rana latastei and Rana dalmatina.
• Rana latastei clutches were more aggregated and located in deeper water, while Rana dalmatina clutches were more spaced out and in shallower areas.
• No significant differences in spawning microhabitat features were observed between sites with and without Procambarus clarkii for either frog species.

Conclusions:

• Brown frogs exhibit species-specific microhabitat preferences for egg-laying.
• The presence of the invasive red swamp crayfish did not alter the spawning microhabitat selection of these brown frog species.
• Further research is needed to determine if other behavioral adaptations occur in response to this invasive predator.