Salinity tolerance in early-developmental stages in Pelobates fuscus (Laurenti, 1768) and Pelobates syriacus (Boettger, 1889) (Anura: Pelobatidae)

TitleSalinity tolerance in early-developmental stages in Pelobates fuscus (Laurenti, 1768) and Pelobates syriacus (Boettger, 1889) (Anura: Pelobatidae)
Publication TypeConference Poster
2014
AuthorsStănescu F, Székely D, Székely P, Cogălniceanu D
Conference detailsInternational Zoological Congress of "Grigore Antipa" Museum, 19-22 November 2014, Bucharest, Romania
Conference date11/2014
embryo, larvae, salinity, spadefoots, survival, tolerance

We tested the survival thresholds under different salinity conditions in earlydevelopmental stages of two syntopic species of spadefoots (genus Pelobates) from the Black Sea coast, Romania. Water salinity of breeding and potential breeding ponds ranges from 0.5 to over 10 ‰ in the study area. We used an experimental design with three salinity treatments (moderate – 3 ‰, high – 6‰ and extreme – 9 ‰ NaCl), and a control (dechlorinated tap water – 0.3 ‰ NaCl). Portions of freshly deposited egg clutches were collected from the natural habitats and randomly introduced in five to nine replicates per treatment. The experiment lasted until all embryos achieved Gosner stage 25. We expressed survival as the percentage of living larvae from the initial number of eggs in each replicate.

No embryos survived in the extreme salinity treatment. Both species showed similar tolerance thresholds under moderate salinity conditions, which is in accordance with our observations in natural breeding ponds. We found differences between the species’ survival in the high salinity treatment (W=15, p<0.01), with a significant lower survival in P. fuscus embryos. P. syriacus seems to cope better with high osmotic stress in early-development stages (mean survival±SD: 43.8±17.2) compared to P. fuscus (mean survival±SD: 3.2±2.2). We suggest that the increased salinity tolerance of P. syriacus explains its higher abundance in the coastal areas.

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