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Klink, S; Giesemann, P; Gebauer, G: Picky carnivorous plants? Investigating preferences for preys’ trophic levels – a stable isotope natural abundance approach with two terrestrial and two aquatic Lentibulariaceae tested in Central Europe, Annals of Botany, in press (2019), doi:10.1093/aob/mcz022
Abstract:

Background and Aims

Stable isotope two-source linear mixing models are frequently used to calculate the nutrient-uptake efficiency of carnivorous plants from pooled prey. This study aimed to separate prey into three trophic levels as pooled prey limits statements about the contribution of a specific trophic level to carnivorous plants’ nutrition. The utilization of phytoplankton as autotrophic reference was applied for aquatic plants as the lack of suitable reference plants impedes their efficiency calculation.

Methods

Terrestrial (Pinguicula) and aquatic (Utricularia) carnivorous plants alongside autotrophic references and potential prey from six sites in Germany and Austria were analysed for their stable isotope natural abundances (δ15N, δ13C). A two-source linear mixing model was applied to calculate the nutrient-uptake efficiency of carnivorous plants from pooled prey. Prey preferences were determined using a Bayesian inference isotope mixing model.

Key Results

Phytophagous prey represented the main contribution to Pinguicula’s nutrition (~ 55 %), while higher trophic levels contributed to a smaller amount (diverse ~ 27 %, zoophagous ~ 17 %). Apart from around 48 % nitrogen a small proportion of carbon (~ 9 %) from prey was recovered in plant’s tissue. Aquatic Utricularia australis received 29 % and U. minor 21 % nitrogen from zooplankton when applying phytoplankton as autotrophic reference.

Conclusions

The separation of prey animals into trophic levels revealed a major nutritional contribution of lower trophic level prey (phytophagous) for temperate Pinguicula species. Naturally, prey of higher trophic levels (diverse, zoophagous) are rarer resulting in a smaller chance of being captured. Phytoplankton represents an adequate autotrophic reference for aquatic systems to estimate the contribution of zooplankton-derived nitrogen to carnivorous plant’s tissue. The autonomous firing of Utricularia bladders results in the additional capture of phytoplankton, demanding new aquatic references to determine the nutritional importance of phytoplankton for aquatic carnivorous plants.

Letzte Änderung 18.03.2019