Circle of life

Carcasses are a ubiquitous but temporary food source for many vertebrate and invertebrate species (“scavengers”). Besides being a valuable food source for many species, carcasses are nutrient reservoirs, including scarce trace elements, meaning that the process of carcass decomposition has potentially far-reaching effects on the nutrient cycle, which is one of the main driving factors of ecosystem functioning. However, it remains unclear how the nutrients that are stored in carcasses are redistributed over the landscape during and after the decomposition process.

We offer various options to investigate the importance of carcasses and scavengers in nature, with special attention to the nutrient cycle.

These options include:

(1) Examining the nutrient fluxes during the decomposition process.

We experimentally investigate how scavengers affect the nutrient fluxes during the decomposition process by systematically excluding different subsets of scavengers from carcasses. We periodically take samples beneath the carcasses to measure the (i) nutrient fluxes in the soil, (ii) the nutrient uptake by plants, and (iii) the effect on mesofauna (mites and springtails). We offer students the possibility to contribute to this ongoing experiment by focussing on one or more of these aspects.

(2) Examining the long-term effects of carcass decomposition on soil nutrients.

Svalbard comprises a relatively simple ecosystem, with reindeer as the only large herbivore species and a scavenger community consisting of arctic fox, glaucous gull and polar bear, and the vast majority of reindeer mortality in winter (causing minor decomposition due to arthropods). Soil samples have been collected on historic carcass locations (from 2003 onwards), allowing us to investigate how and to what extend reindeer carcasses modulate soil nutrients on the long term.

(3) Examining the nutrient redistribution after a mass death due to a lightning strike.

In 2016, lighting had killed nearly an entire herd of >320 wild tundra reindeer in Norway. These carcasses decomposed at the site. As the carcasses were not uniformly distributed over the site, soil samples were taken using a grid covering the study site. Repeated sampling allows us to investigate how the nutrients are redistributed over the study site.

It is possible for the student to assist in fieldwork for all the mentioned options. The exact possibilities can be discussed in more detail.

Contact and supervision:

Henk Siepel;

Elke Wenting;