Only golfers and other idle souls have the wherewithal to spend the latter half of a cloudy day on the green by MacRitchie Reservoir, where men in loud orange vests labour by the banks to remove bog moss before returning to base in a municipal bathtub of a boat. A skimpy path runs between the singular holes and a shallow basin that supports an alien menagerie: cichlids from Africa, Central and South America, Malayan cyprinids, North American terrapins and freshwater clams that run riot in artificial lakes, though few venture into the streams that have survived a century of unsustainable croppings. Parts of this track, which skirts with visible menace the terrain of a distant club, are bisected by a low wall of fountain grass, an ornamental herb with invasive potential but whose habitus offers a refuge for orbweavers, which occupy nearly every gap between the stalks and many other, smaller, planes of existence in a hedge of brown and purple blades.
The dominant spider on this well-brushed fringe appears to be Argiope catenulata, one of five local members of a genus that spins vertical traps, to which they add the finishing touch of dense zigzags made from aciniform silk, a tough, non-sticky fibre also used to wrap eggcases and struggling insects. This species, which has been recorded from swampy fields in open country, is distinguished by a broad, oval opistosoma marked by an irregular, tapering, dorsal stripe that overlays three bands of variable colour – a chained or catenulate combination said to meld with the silvery patterns of the animal's snare. In habit, though not in choice of habitat, Argiope catenulata deviates little from its kin, which variously occupy mangroves, scrubland and forest margins. The females, which hang head down on hubs marred by unruly gusts, blundering dragonflies or difficult prey, respond to disturbance by arching their bodies and, if pressed, shaking the web with arresting vigour, using their bulky abdomens as counterweights for a rhythm that may help to throw off the senses of wasps and warblers. Harassed further, the spider may slip to the other side of the web or drop into the undergrowth, where she will sit out the disruption to her routine before pulling herself back up to face a parlour of tiny mates and return the blow of pressures that refuse to let up on this shore of exposed and endangered waters.
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