BayCEER Workshop 2016

Feeding with fondness? Obtaining a higher precision in nitrogen gain estimates among carnivorous Pinguicula species by considering the trophic level of their prey

P 6.9 in Paving the way for research: Databases, instruments, networks
& Open Session

Introduction:

Carnivorous plants evolved a special habit to obtain essential nutrients that allows them to most often inhabit moist and nutrient-limited habitats: the trapping of animals [1]. While many tropical carnivorous plants of different genera have been studied, there is a significant knowledge gap about the success of alpine Pinguicula species to gain nutrients from prey.

Material and Methods:

Pinguicula vulgaris and P. alpina were sampled in the Austrian Alps to calculate nutrient gain effectiveness according to the two-source linear mixing model. Fully autotrophic reference plants and potential prey animals were collected nearby the carnivorous plants. Prey animals were graded corresponding to their trophic level. Stable isotopes (δ¹³C, δ¹⁵N) of plants and animals were analysed with EA-IRMS. 

Results:

Nutrient gain effectivity was estimated for P. vulgaris (*24% / 54%) and P. alpina (*3% / 31%) by comparing their δ¹⁵N-values with autotrophic plants and potential prey animals. Stepwise enrichment per trophic level of about 3‰ in δ¹⁵N as expected was confirmed (r² = 0.72: photo-autotrophic, carnivorous plants, herbivorous, zoophagous). Using this approach a clearer resolution of the prey derived nutrient gain of a carnivorous plant was achieved.

Interestingly, the reference plant Tofieldia calyculata revealed a higher enrichment in δ¹⁵N compared to the other reference plants
(W = 50, p = 0.003) resulting in consequences for the efficiency calculation (*). Tofieldia calyculata, a member of one typical plant association of temperate Pinguicula species [2], should be analysed for the reasons of the unexpected enrichment in δ¹⁵N. 

Conclusions:

 Carnivorous plants play an important role in many biotic interactions and ecosystem functioning. The calculation of nutrient gain efficiencies and influences of different trophic levels of temperate montane species aims to complement knowledge about nutrient flows in carnivorous species and their importance for our ecological understanding.      

 

Keywords: Pinguicula vulgaris, Pinguicula alpina, Trophic levels, stable isotopes (δ13C, δ15N), two-source lineare mixing model