Herein, meal size can play an important role and critically affect the detection of trophic interactions (Greenstone, Payton, Weber, & Simmons, 2014). Biological, methodological and environmental factors affect prey DNA detection success, and for a meaningful interpretation of field‐derived molecular trophic data, it is indispensable to understand how these factors influence postfeeding prey detection over time (e.g., King, Read, Traugott, & Symondson, 2008 Pompanon et al., 2012 Traugott, Kamenova, Ruess, Seeber, & Plantegenest, 2013). Molecular methods are widely used to investigate trophic interactions, and the methodology itself has become almost as diverse as the ecosystems and interactions investigated (Symondson & Harwood, 2014). The less reliable prey DNA detection of small meals or meal shares in faeces signifies the importance of large numbers of dietary samples to obtain reliable trophic data. In pellets, molecular methods reliably identified the meal consumed the previous day, which was not possible via morphological analysis or when examining individual faeces. Furthermore, large meals were detectable for a significantly longer time span with a detection limit at ~76 hr and a 50% detection probability at ~32 hr postfeeding. Molecular analysis of faeces revealed that both large meal size and share had a significantly positive effect on prey DNA detection rate postfeeding. Samples were examined for prey DNA and fish hard parts. Faeces and pellets were sampled twice a day after the feed of large (350–540 g), medium (190–345 g) and small (15–170 g) fish meals contributing either a large (>79%) or small (<38%) share to the daily consumption.
Jaal 1986 torretn trial#
Here, we present a feeding trial on abundant piscivorous birds, Great Cormorants ( Phalacrocorax carbo), to assess meal size effects on postfeeding prey DNA detection success. Moreover, different noninvasively obtained sample types remain to be compared in such experiments. The effect of meal size, however, has not yet been explicitly considered for vertebrate consumers. To facilitate the interpretation of field‐derived data, feeding trials, investigating the impacts of biological, methodological and environmental factors on prey DNA detection, have been conducted. Molecular methods allow noninvasive assessment of vertebrate predator–prey systems at high taxonomic resolution by examining dietary samples such as faeces and pellets.
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