Authors: Takashi F Haraguchi Masao Uchida Yasuyuki Shibata Ichiro Tayasu
Publish Date: 2012/09/11
Volume: 171, Issue: 4, Pages: 935-944
Abstract
Prey subsidies originating from detritus add nutrients and energy to arboreal communities Measurement of this subsidy is required in the understanding of how food web dynamics respond to changes in surrounding environments Shrub spiders are one of the key predators involved in food web coupling We evaluate the effects of potential changes in prey availabilities during secondary succession on the contribution of subsidy from detrital food webs to shrub spiders and how different spider feeding guilds used the subsidy of prey from detrital food webs We measured the relative importance of the subsidy for the spider feeding guilds using the ratios of stable isotopes of C δ13C and N δ15N and C isotope discrimination Δ14C Diet age was calculated from Δ14C values because old diet ages of spiders indicate that the spiders consume prey from detrital food sources Dominant aerial prey Diptera had a distinctively old diet age compared with arboreal prey which indicates that aerial prey were subsidized from detrital food webs Sitandwait spiders tended to have an older diet age than active hunting spiders which indicates that sitandwait spiders depended more on subsidies Diet age varied only slightly for spiders in stands of different ages indicating that rates at which spiders use grazing and detrital prey are probably determined more by foraging strategies and not by stand age A dominance of sitandwait predators will lead to higher detrital subsidy inputs in shrub habitats This study highlights the effect of shrub spider community structure feeding guild composition on the volume of the subsidy received from the detrital food webWe thank Mr Hajime Yamagata for facilitating our work at the OFR Members of the Community Dynamics and Insect Ecology Laboratories in the Forestry and Forest Products Research Institute particularly Dr Takenari Inoue provided us with site information We are also grateful for assistance from Drs Shoji Naoe CER Naoto F Ishikawa CER and Zin’ichi Karube NIES This study was financially supported by the Global Environment Research Fund F–073 the Research Institute for Sustainable Humanosphere the Japan Society for the Promotion of Science JSPS no 19681002 22370011 23657021 and a GrantinAid for JSPS Fellows no 22–978
Keywords: