Association of spiders and lichen on Robben Island, South Africa: a case report

Aeshita Mukherjee,L.G Underhill,Ansie Dippenaar-Schoeman,Burkhard Wilske,Rene A Navarro

doi:10.11609/jott.o2295.815-9

Abstract

The present study is a first record of spider occurrence on Robben Island, South Africa. Some habitats were rich in lichens. As we know, lichens enhance wildlife habitat in less direct ways. The objective of the study was to examine the potential importance of lichens in enriching spider diversity and abundance. A total of 260 spiders (170 from lichens and 90 from bush) were collected following the visual search method over one year. Seasonal trends in overall species richness and abundance indicated that the relative density of spiders was greater in lichens than in bushes. The result suggests that habitat structure, such as branch size and epiphytic lichen abundance, can be an explanation for the greater number of spiders in lichen-rich patches of the island.

Highlights

With the exception of caribou, whose dependence on lichen is well documented, references to lichens in literature on wildlife are few (Richardson & Young 1977; Lawrey 1986; Blewitt & Cooper-Driver 1990)
It is known that the phytophagous fauna increases with a plant’s structural complexity (Strong et al 1984), and a distinct positive association exists between beetle diversity and plant composition (Southwood et al 1979)
Most studies on spiders showed that there is a positive association between species richness of orb builders and plant canopy complexity (Stratton et al 1979; Hatley & MacMohan 1980; Greenstone 1984)

Summary

Introduction

With the exception of caribou, whose dependence on lichen is well documented, references to lichens in literature on wildlife are few (Richardson & Young 1977; Lawrey 1986; Blewitt & Cooper-Driver 1990). Common Greenshield, and other lichens do cover or give shelter to tiny animals, such as water bears, mites, springtails, spiders, insects, and lizards. Several species of invertebrates live on and among lichens, using them for concealment, shelter or food. Many lichen species contain bitter compounds that may discourage feeding by invertebrates, very little is known about the nutritional quality of lichens (Lawrey 1986; Blewitt & Cooper-Driver 1990)

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Conclusion