Influence of the Aquarium Volume on Egg-Laying of the Alpine Newt (Ichthyosaura alpestris)

Characteristics of reproduction habitat can influence egg-laying in amphibians. Egg-laying variables are studied in experiments focused on reproduction. However, the potential influence of the facility where the animals are housed during experiments is unknown. Therefore, I performed an experiment with a caudate species widely used in behavioural experiments – the Alpine newt (Ichthyosaura alpestris). Sixty-four females were captured in the Czech Republic and divided into two groups after controlled mating. Females from the first group were reared individually in small tanks (volume of 6 dm-3), females from the other – in large tanks (volume of 20 dm-3) and differences in egg-laying variables (the overall number of laid eggs, duration of the egg-laying period and the rate of egg-laying) between these groups were compared. The proportion of females that laid at least one egg (63%) did not differ between the groups. The average number of laid eggs per female was 77 (range 3-176), the mean duration of the egg-laying period (from first to last laid egg) was 15.35 days (range 3-34) and the mean rate of egg-laying was 4.73 eggs laid per day (range 0.40 – 12.40). The volume of tank did not influence these variables; however, the body length of the female (SVL), but not weight, was positively associated with the total number of laid eggs and the rate of egg-laying. We can conclude that an aquarium volume of 6 dm-3 of water is sufficient for individual housing of Alpine newt females and it does not represent any limitation in their reproduction outcomes.