The productivity of the macroinvertebrate prey of the platypus in the upper Shoalhaven River, New South Wales

Abstract

The platypus (Ornithorhynchus anatinus) feeds almost exclusively on benthic macroinvertebrates, yet no attempt has been made to link its energy demands with the productivity of its benthic macroinvertebrate prey. In the upper Shoalhaven River, New South Wales, we estimated macroinvertebrate production (in 2009 and 2011) from benthic samples and recorded platypus diet (2009 only) from cheek pouch samples. Ephemeroptera, Trichoptera and Chironomidae were the most numerous of six major groups in both the cheek pouches and the benthic samples. Three other groups (Odonata, Coleoptera, Sphaeriidae) were much less abundant in the benthos, but Odonata were common in the cheek pouches. In both years the Ephemeroptera, Trichoptera and Chironomidae had levels of production that were an order of magnitude higher than those of the three other groups. Rank correlation indicated that the most productive taxa were those most likely to occur in the cheek pouches. Total macroinvertebrate production for the six groups varied from 7.8gDWm–2year–1 in 2009 to 13.1gDWm–2year–1 in 2011. Previous estimates of field metabolic demand of the platypus enabled calculation of the number that could be supported by a given level of production. The observed levels of production were sufficient to support 13–27 platypuses in 2009 and 22–45 in 2011 along a 1.5-km reach of the river. Despite considerable landscape change, productive foraging habitat persists in the upper Shoalhaven River.

A diverse suite of pharmaceuticals contaminates stream and riparian food webs

“…4 ), both of which occur in the study catchment 35 – 37 . We estimate, based on platypus energetics 38 , that a platypus consuming invertebrates from Brushy Creek would consume a total of 1154 µg kg −1 day −1 of pharmaceuticals spanning 67 compounds from 22 therapeutic drug classes. Platypus would thus consume about one-half of an average human daily dose of antidepressants by eating aquatic invertebrate prey from this stream (Fig.…”

“…Our estimates of the dietary intake of pharmaceuticals by platypus are based on a study of the macroinvertebrate prey of the platypus in the Shoalhaven River, New South Wales, Australia 38 . Energetic requirements of platypus have been estimated at 684 53 and 341 kJ kg day − 1 22 .…”

Optimal survey designs for environmental DNA sampling

“…yabbies, shrimp), vertebrates (e.g. fish, frogs) and a wide range of invertebrates (Marchant & Grant, 2015;McLachlan-Troup, Dickman, & Grant, 2010).…”

Life history and dynamics of a platypus (Ornithorhynchus anatinus) population: four decades of mark-recapture surveys

“…However, robust estimates of population size remain elusive 21 . Variation in population estimates could be due to choice of survey technique, sampling season 1 23 , habitat availability 74 75 or unexplained variability in capture rates 76 77 78 .…”

“…Also, distribution and numbers of platypuses in peri-urban streams around Melbourne were affected by the area of non-absorbent surfaces in their catchments and subsequent high run-off during rain events 83 . Floods can also reduce short term availability of macroinvertebrate prey although medium to high flow increase this productivity 75 .…”