Greenland glacier retreat: Exploring arctic arthropod food webs in a glacier foreland area near Nuuk in West Greenland

Activity: Talk or presentation typesLecture and oral contribution

See relations at Aarhus University

Eigil Vestergaard Gravesen - Lecturer

Paul Henning Krogh - Other

Jamin Dreyer - Other

Arthropod food webs were explored in a glacier foreland area in Kobbefjord, near Nuuk in West Greenland during the summer of 2015 and 2016 using a combination of wet and dry pitfall traps. Arthropod predators and their potential arthropod prey were identified to family or species level. Specimens representing each arthropod species will be barcoded. Arthropod predators sampled individually in dry pitfall traps were analyzed for DNA gut content using a technique with predesigned primers targeting potential prey animals.
All surface-active arthropods were sampled with traditional “wet” pitfall traps during the summer of 2015 and 2016. Potential prey animals for the arthropod predators are collembolans, mites, flies and aphids. Structural Equation Modelling (SEM) integrating biotic and abiotic parameters indicates both bottom-up and top-down food chains in the glacier foreland area. Spiders were found in bottom-up food chains with a very significant, positive relationship with the numbers of mites. The relationships between potential food animals and the harvestman, Mitopus morio, and the ground beetle, Nebria rufescens, revealed (in some instances) negative relationships, indicating top-down relations between the prey animals and these two arthropod predator species.
Live arthropod predators (spiders, ground beetle and harvestmen) sampled in dry pitfall traps during the summer of 2015 have been analyzed for DNA gut content using 18S markers for Collembola, Diptera and aphids. Preliminary results from these analyses shows that Collembola was a common prey item, and spider consumption of Collembola increased in direct relationship to their abundance in each habitat type - which was either gravel, bare ground or vegetated patches.
In relation to the aphid Thecabius populimonilis – the aphid DNA was only detected in beetles and harvestmen from bare ground patches where aphid abundance was very low and there were no vascular plants (Salix herbacea) for them to feed on while no aphid DNA was found in the beetles or harvestmen from the vegetated patches where all potential prey animal densities were relatively high compared to the bare ground patches where the densities of all potential prey animals were low. An explanation for this could be that aphids are “easier” prey for the predators in the open, bare ground patches compared to the other potential prey animals.
20 Aug 201725 Aug 2017

Event (Conference)

Title30th European Congress of Arachnology
CountryUnited Kingdom
Degree of recognitionInternational event


ID: 114710160