title: Surviving in a semi-marine habitat: Dietary salt exposure and salt secretion of a New Zealand intertidal skink.
abstract: Species that inhabit marine and intertidal ecosystems face osmoregulatory challenges, risking dehydration and increased ion concentrations in the body. Lizards need to either tolerate or regulate these increased ion concentrations. In this study, we aim to understand how Suter's skink (Oligosoma suteri), an intertidal skink restricted to shoreline habitats, is able to cope with the physiological stress of living in an extreme salt environment. We determined the diet, prey species' salt content, and nasal and cloacal salt excretion on Rangitoto and Motutapu Islands in northern New Zealand, where the skinks have contrasting access to terrestrial invertebrates. Analysis of stable isotopes suggests inter- and intra-population variability in Suter's skink diets. Intertidal invertebrates under washed up seaweed appear to compose a major part of the diet of the Rangitoto population, while the Motutapu population showed evidence for a mixed diet of terrestrial and intertidal invertebrates. Sodium content of prey species decreased with an increasing distance from the seawater. Field secretion of cations through nasal glands consisted primarily of Na(+), which is consistent with other marine and intertidal species. Sodium was also the primary cation in urine. In contrast, fecal cations consisted primarily of K(+). This first study into the salt secretion of an intertidal skink species provides evidence of Suter's skink's plasticity in secreting excess ions through nasal salt glands. This likely enables it to deal with the challenges of living in a semi-marine habitat.
authors.affiliation: Resource Ecology Group, Wageningen University, Droevendaalsesteeg 3A, 6708 PB Wageningen, The Netherlands. Electronic address: j.janssen88@gmail.com.
authors.forename: Jordi
authors.initials: J
authors.lastname: Janssen
authors.affiliation: Institute for Applied Ecology New Zealand, Auckland University of Technology, Auckland 1142, New Zealand.
authors.forename: David R
authors.initials: DR
authors.lastname: Towns
authors.affiliation: School of Applied Sciences, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland 1142, New Zealand.
authors.forename: Mark
authors.initials: M
authors.lastname: Duxbury
authors.affiliation: Resource Ecology Group, Wageningen University, Droevendaalsesteeg 3A, 6708 PB Wageningen, The Netherlands.
authors.forename: Ignas M A
authors.initials: IM
authors.lastname: Heitkönig
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000378:metabolism; D004032:Diet; D017753:Ecosystem; D005843:Geography; D008116:Lizards / Q000502:physiology*; D009520:New Zealand; D009587:Nitrogen Isotopes / Q000378:metabolism; D064587:Osmoregulation / Q000502:physiology*; D011188:Potassium / Q000378:metabolism; D012623:Seawater; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000008:administration & dosage / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D012965:Sodium Chloride; D012964:Sodium; D011188:Potassium
keywords: Invertebrates; Physiology; Plasticity; Potassium; Regulation; Salt; Sodium; Stable isotopes; Stress; Suter's skink