Assessing waterbird habitat use in coastal evaporative systems using stable isotopes (δ 13C, δ 15N and δD) as environmental tracers

• Published in: Estuarine, coastal and shelf science coastal and shelf science, 2011-04, Vol.92 (2), p.217-222
• Main Authors: Ramírez, Francisco, Abdennadher, Aida, Sanpera, Carola, Jover, Lluís, Wassenaar, Leonard I., Hobson, Keith A.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Brackish water ecosystems; carbon isotopes; deuterium; Fundamental and applied biological sciences. Psychology; habitat selection; nitrogen isotopes; salinity gradients; saltworks of Thyna; Sfax; Synecology; Tunisia
• ISSN: 0272-7714; 1096-0015
• DOI: 10.1016/j.ecss.2010.12.035

Isotopic patterns of biota across salinity gradients in man-made evaporative systems could assist in determining the use of these habitats by animals. Here we report δ 13C, δ 15N and δD measurements of a euryhaline fish, the Mediterranean toothcarp ( Aphanius fasciatus), inhabiting a range of salinities in the Thyna saltworks near Sfax (Tunisia). The contribution of these salinity niches to egg formation of two typically piscivorous bird species breeding in the area and feeding within saltworks, Little Tern ( Sternula albifrons) and Little Egret ( Egretta garzetta), was inferred trough a triple-isotope (δ 13C, δ 15N and δD) Bayesian mixing model. Isotopic trends for fish δ 15N and δD across the salinity gradient followed the equations: δ 15N = e (1.1 + 47.68/Salinity) and δD = −175.74 + Salinity + Salinity 2; whereas fish δ 13C increased as salinity rose (δ 13C = −10.83 + 0.02·Salinity), after a sudden drop in fish isotopic values for salinities >60 (Practical Salinity Scale) (average fish δ 13C for salinities