Breeding Westland petrels as providers of detrital carbon and nitrogen for soil arthropods: a stable isotope study

ISSN： 0303-6758

Source： Journal of the Royal Society of New Zealand, Vol.43, Iss.1, 2013-03, pp. : 58-65

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Abstract

Seabirds deposit large quantities of marine detritus on land, but little is known of the soil arthropods processing this material. Burrow-nesting seabirds concentrate their activities within their burrows, so we tested the hypothesis that burrow arthropod fauna is more marine-like in its isotopic enrichment (¹³C/¹²C, ¹⁵N/¹⁴N; expressed as δ¹³C and δ¹⁵N) than the arthropods on the adjacent forest floor. Results from a Westland petrel (Procellaria westlandica) colony on the South Island of New Zealand did not support the hypothesis. Instead, δ¹⁵N was universally marine (13-22‰). While δ¹³C separated into two clusters, the distribution was not according to arthropod provenance. Most taxa had a terrestrial δ¹³C; only two taxa (a leiodid beetle and the mesostigmatic mite Ayersacarus woodi) incorporated marine C. The leiodid beetle occurs both in burrows and on the forest floor; beetles from both habitats had a marine δ¹³C. Ayersacarus woodi is found only in burrows. We conclude that, in this system, marine and terrestrial detrital C is processed separately, and that marine detrital C enters the terrestrial ecosystem through a very few arthropod taxa.