Demographics, pollination syndrome and conservation status of Macrozamia platyrhachis (Zamiaceae), a geographically restricted Queensland cycad

To assess the International Union for Conservation of Nature (IUCN) status of Macrozamia platyrhachis F.M.Bailey, we surveyed this central Queensland cycad for its population abundance and health and its pollinator type and pollination syndrome (thermogenesis and volatile emissions). Plants are locally abundant within the 11 discrete populations surveyed, with an estimated population of 611 315 adult plants. Plants are highly restricted to a small area of occupancy, seed dispersal is nearly non-existent and extreme fires appear to have destroyed almost all seeds and seedlings and decimated the pollinators. Of known Macrozamia pollinators, only the thrips, Cycadothrips chadwicki Mound, were found on cones, and these were found in very low numbers. The pollination syndrome for this cycad appears to be unique, based on two cone traits. For one, thermogenesis peaks in early evening, a contrast with daytime peaks of other Cycadothrips-pollinated Macrozamia, but matches that of the Tranes weevil-pollinated Macrozamia machinii. In addition, cone volatiles include both previously unreported compounds as well as those reported exclusively on either Cycadothrips- or Tranes-pollinated species. Based on its small, fragmented area of occupancy, projected population declines and the unique pollination syndrome, we recommend that M. platyrhachis retain its current status as 'Endangered'. Habitat management plans should stipulate that controlled burns be avoided during cycad coning season and that wildfires be controlled to minimise damage to seedlings and pollinators.

Age-based demographics of the pearl perch Glaucosoma scapulare (Ramsay, 1881)

Summary: This research represents the first age-based demographic assessment of pearl perch, Glaucosoma scapulare (Ramsay, 1881), a highly valued species endemic to coastal waters off central eastern Australia. The study was conducted across the species' distribution that encompasses two state jurisdictions (Queensland in the north and New South Wales in the south) using data collected approximately 10 years apart in each state. Estimates of age were made by counting annuli (validated using marginal increment ratios) in sectioned sagittal otoliths. The maximum estimated age was 19 years. Pearl perch attained approx. 12 cm fork length (FL) after one year, 21 cm FL after 2 years and 29 cm FL after 3 years. Fish from the southern end of the species' distribution grew significantly more slowly than those from the northern part of its range. Commercial landings in the north were characterized by greater proportions of larger (>40 cm FL) and older (>6 years) fish than those in the south, with landings mainly of fish between 3 and 6 years of age. The observed variations in age-based demographics of pearl perch highlight the need for a better understanding of patterns of movement and reproduction in developing a model of population dynamics and life-history for this important species. There is a clear need for further, concurrent, age-based studies on pearl perch in the northern and southern parts of its distribution to support the conclusions of the present study based on data collected a decade apart. © 2013 Blackwell Verlag GmbH.