An integrated study of the temporal and spatial variation in the supply of propagules, recruitment and assemblages of intertidal macroalgae on a wave-exposed rocky coast, Victoria, Australia

Recruitment is known to influence distributions and abundances of benthic marine organisms. It is therefore important to document patterns of variability in recruitment and how these relate to patterns in established assemblages. This study provides an integrated assessment of the temporal and spatial variation in supply and recruitment of propagules and established populations of several macroalgae. Propagules in water samples from two stages of the incoming tide, recruitment to artificial substrata and percentage cover of species established on the shore were recorded every 2 months from December 1994 to October 1995, in two zones of an intertidal, wave-exposed rocky shore. Variability in recruitment was measured at three spatial scales: 10s cm, 100s cm and 100s m. Availability and recruitment of most taxa were greatest between April and August, although many species had available propagules and recruited throughout the year. Temporal variation in the established assemblages was, however, more species-specific. Differences in established assemblages between zones were reflected in differences in availability and recruitment of propagules between zones. Recruitment could not be predicted directly from supply of propagules, but the two processes were linked. For most species, the greatest variation in recruitment occurred at the smallest spatial scale of 10s cm, although there was also considerable large-scale (between site) variation in recruitment of several species. Results indicate that while pre-and post-settlement mortality are likely to influence macroalgal distribution and abundance, the temporal and spatial variability in supply and recruitment of propagules can explain much of the patchiness in macroalgal assemblages.

Effects of human activities on rocky shores of the Surf Coast Shire: scientific basis for management at the regional level

The Surf Coast Shire in regional Victoria contains some of the most spectacular coastline in Australia, running from Point Impossible in the east to just west of the resort town of Lorne. The Surf Coast Shire council is committed to ecologically sustainable tourism based on its coastal assets, including the important intertidal environments. The challenge for the Shire is to protect and enhance the biodiversity of its intertidal areas whilst allowing for their sustainable use as a critical component of the local economy. In order to do this the Council needed to identify the conservation values of intertidal areas within the shire and assess the impacts that current human use has on these values. The impacts of shellfish collecting on rocky shores were identified as an issue of particular concern. We have conducted a research project with the Shire to provide a scientific basis for management decisions. The principal aims of this project were to: (1) determine the patterns of human use of intertidal habitats; (2) measure the impacts of human usage on biological communities and species populations; and (3) to identify intertidal sites of regional conservation significance for the Surf Coast Shire. Surveys of human usage identified reef walking, looking in rock pools and fossicking as major uses of rocky shores within the Surf Coast. This poster reports the effects of this usage on gastropod populations of rocky shores within the Surf Coast Shire. A small proportion of visitors collected intertidal organisms. Shores were categorized as high or low use based on total numbers of people observed at each shore over the first year of the project. Mean size and catch per unit effort were compared for several gastropod species between high use and low use shores. The results presented here show that the populations of some gastropod species are of smaller mean size and less abundant on high use shores than on low use shores. There was also a noticeable difference in degree of effect detected between sandstone and mudstone shores. The implications of these results are briefly discussed in terms of management options available to the Shire.

Cholinesterase response in native birds exposed to fenitrothion during locust control operations in Eastern Australia

Huge aggregations of flightless locust nymphs pose a serious threat to agriculture when they reach plague proportions but provide a very visible and nutritious resource for native birds. Locust outbreaks occur in spring and summer months in semiarid regions of Australia. Fenitrothion, an organophosphate pesticide, is sprayed aerially to control locust plagues. To evaluate fenitrothion exposure in birds attending locust outbreaks, we measured total plasma cholinesterase (ChE), butrylcholinesterase (BChE), and acetylcholinesterase (AChE) activities in four avian species captured pre- and postfenitrothion application and ChE reactivation in birds caught postspray only. Eleven of 21 plasma samples from four species had ChE activity below the diagnostic threshold (two standard deviations below the mean ChE activity of prespray samples). Granivorous zebra finches (Taeniopygia guttata) and insectivorous white-winged trillers (Lalage sueurii) had significantly lower mean plasma total ChE, BChE, and AChE activity postspray, while other insectivores, white-browed (Artamus superciliosus) and masked woodswallows (Artamus personatus), did not. Cholinesterase was reactivated in 19 of the 73 plasma samples and in one of three brain samples. We conclude that native bird species are exposed to fenitrothion during locust control operations. This exposure could have detrimental impacts, as both locust outbreaks and avian reproductive events are stimulated by heavy summer rainfall, leading to co-occurrence of locust control and avian breeding activities.

Modelling of birds and locust-control operations in Eastern Australia

Locust outbreaks provide an abundant, but unpredictable food source for many native species in Australia. For economic reasons, locust control is unavoidable and can affect a considerable area in Eastern Australia. Depending on the pesticide applied, locust control operations may affect birds in treated areas, either directly through intoxication of the predator, or indirectly, through elimination of its prey. As a preliminary step in identifying the potential impact of these operations on native species, the co-occurrence of birds and locust control operations was assessed using GIS mapping techniques. Data from the Birds of Australia New Atlas provided information about species' distribution between latitudes 17 and 37 degree S, and longitudes 136 and 152 degree E. Of the 834 species present in this region, 292 were chosen on the basis of their geographical distribution and occurrence west of the Great Dividing Range. Sightings for each species were mapped using reporting rates and number of observations per half-degree grid cells. Birds were categorised by habitat, distribution, movement and feeding habits and those species reported to consume Orthopterans were noted. APLC locust survey (1987–2000) and spraying data (1977–2002) were analysed and overlapped with soil and vegetation maps obtained from Geoscience Australia and Environment Australia to find significant hotspots for locust occurrence. These maps were then overlayed with bird distributions to identify the species most likely to be in areas of locust presence and spraying operations.

Metaphoric use of the mountain symbol in painting

This paper consists of two parts. The focus of Part I is the symbol of the mountain and its metaphoric use in art history and in the mythology of many cultures. Part II links an examination of twentieth century contemporary artists and relevant issues, the mythology and historical references covered in Part I and the paintings that make up the body of the thesis. The study is concerned with the role of the symbol and the form of its interpretation in the expression of ideas and images that are relevant to it. These themes have been developed in order to place the paintings in a context of continuity and establish iconographic links with the past. One particular site has been chosen through which to examine the symbolic associations between the mountain and the metaphoric quest. The metaphor of pilgrimage to the site and of searching for a lost unity is implicit in this process. The realisation reached at the summit confirms the significance of this journey. Each painting is discussed and linked with the themes that are relevant to it, linking the research recorded in Part I with the execution of the paintings, aiming at a synthesis of theory and practice.