An Evaluation of The Habitat Characteristics of Pools Used by Platypuses (Ornithorhynchus Anatinus) in the Upper Macquarie River System, New South Wales.

Abstract

The study conducted during 1993 assessed the habitat characteristics of 36 pools along the upper Macquarie River system. A range of biophysical parameters were assessed at each site, including: pool morphology; riparian floristics and habitat structure; benthic substrate composition; and physicochemical properties. The results of a complementary observation program indicated that 19 of the pools were being used by platypuses. Statistical analyses were carried out to identify significant platypus-habitat relationships. Platypuses were most often associated with long pools with consolidated, angled banks; slow flowing waters; mean depths of one to two metres; low level sand accumulation; abundant native vegetation with overhanging foliage; many instream logs; and, abundant aquatic vegetation. Of these characteristics pool length, pool depth and overhanging foliage were most strongly associated with pool use. Platypuses were sighted using pools ranging from apparently ideal to seemingly unsuitable, based on the habitat analysis, but were most often associated with high integrity areas of the river system. The results illustrate that while habitat usage appears to reflect remarkable adaptiveness, there is a clear preference for pools that have been less disturbed by human activities.

Field biology of the platypus (Ornithorhynchus anatinus): historical and current perspectives

“…These are normally dug into earth which is consolidated by the roots of riparian vegetation. The presence of riparian vegetation overhanging river banks has been identi¢ed in all three studies as an important habitat requirement of the platypus (Rohweder 1992;Bryant 1993;Woon 1995;Ellem et al 1998). This is probably due to the shelter provided for individuals foraging in the stream near the bank and permitting safe access to burrow entrances.…”

“…A number of workers have used visual observations to assess presence or absence of the species in an area. The numbers of individuals observed at one time can be used as a measure of broad categories of abundance, such as rare',`common' or`abundant' (Grant 1992b;Rohweder 1992;Bryant 1993;Woon 1995). However, observations and netting together show that lack of observation may not necessarily indicate absence of the species from an area because platypuses have been captured at locations where local people have indicated that the species is absent (T. R. Grant, unpublished data).…”

“…Semon 1899;Kershaw 1912;Burrell 1927;Fleay 1944). Such descriptions also include many of the characteristics distinguished by a number of recent ¢eld investigations aimed at elucidating the ¢ne detail of the biophysical parameters which constitute suitable habitat requirements of the species (Rohweder 1992;Bryant 1993;Woon 1995;Ellem et al 1998). These studies have used a number of statistical analyses to match a wide range of physical features and water quality parameters to the observed presence or absence of platypuses in a number of streams in New South Wales.…”

“…Higher invertebrate productivity is usually associated with areas where logs, roots and vegetation provide a range of habitats for di¡erent invertebrates and where a cobbled or gravel substrate provides ¢xed habitat, rather than shifting substrates, such as sand (Hynes 1970;Marchant et al 1984). The complexity of benthic habitats (Rohweder 1992), and the presence of aquatic vegetation (Bryant 1993;Woon 1995), have both been shown to be indicators of the occurrence of platypuses. Platypuses feed both in pools and ri¥es and the identi¢cation of sequences of these being associated with the presence of the species is related to their higher productivity, with ri¥es normally being more productive than pools (Hynes 1970).…”

“…Although the important stream and riparian zone characteristics identi¢ed by the studies of Rohweder (1992), Bryant (1993), andWoon (1995), occur most often in areas with the least human disturbance, platypuses can be found in a wide range of habitats, both pristine and degraded, showing the remarkable adaptiveness of the species. As discussed earlier in this review, small populations have been identi¢ed in severely disturbed streams around Melbourne (Serena 1994) and the species is still occasionally reported close to the Sydney metropolitan area (Grant 1998).…”