The dispersion and initial transport of Cryptosporidium oocysts from fecal pats were investigated during artificial rainfall events on intact soil blocks (1,500 by 900 by 300 mm). Rainfall events of 55 mm h ؊1 for 30 min and 25 mm h ؊1 for 180 min were applied to soil plots with artificial fecal pats seeded with approximately 10 7 oocysts. The soil plots were divided in two, with one side devoid of vegetation and the other left with natural vegetation cover. Each combination of event intensity and duration, vegetation status, and degree of slope (5°a nd 10°) was evaluated twice. Generally, a fivefold increase (P < 0.05) in runoff volume was generated on bare soil compared to vegetated soil, and significantly more infiltration, although highly variable, occurred through the vegetated soil blocks (P < 0.05). Runoff volume, event conditions (intensity and duration), vegetation status, degree of slope, and their interactions significantly affected the load of oocysts in the runoff. Surface runoff transported from 10 0.2 oocysts from vegetated loam soil (25-mm h ؊1 , 180-min event on 10°slope) to up to 10 4.5 oocysts from unvegetated soil (55-mm h ؊1 , 30-min event on 10°slope) over a 1-m distance. Surface soil samples downhill of the fecal pat contained significantly higher concentrations of oocysts on devegetated blocks than on vegetated blocks. Based on these results, there is a need to account for surface soil vegetation coverage as well as slope and rainfall runoff in future assessments of Cryptosporidium transport and when managing pathogen loads from stock grazing near streams within drinking water watersheds.

Mesh netting of beaches along the more populous sections of the NSW coast for the protection of swimmers and surfers against shark attack has been carried out since 1937 in Sydney and since 1949 in Newcastle and Wollongong. Data for the catches of sharks by taxonomic groups are presented for the period from 1950 to 1990. Although there were large year-to-year fluctuations, neither catch nor catch per unit effort showed any discernible trend for the period up to 1972. In 1973, the catches of all taxonomic groups increased substantially following changes to the specifications of nets and their deployment. Since 1974, there has been a continuing decline in both the numbers of sharks caught and the catch per unit effort. Although Carcharhinus spp. (whalers) and Carcharodon carcharias (white pointer sharks) have shown an almost unbroken decline since the commencement of meshing, Sphyrna spp. (hammerheads) and Squatina australis (angel sharks) have shown large fluctuations over the entire study period, particularly in the period following the upgrading of netting effectiveness (post-1973). Substantial changes have occurred in the size compositions of a number of the taxonomic groups between the first and second 20-year periods of the meshing programme. High proportions of S. Australis and Carcharias taurus (grey nurse sharks) were females. There were major differences in the species compositions of catches between the three major meshing areas and between the pre- and post- 1973 periods. Data on the catches of nontarget species for the Newcastle region for the period from 1965-66 to 1980-81 indicated significant increases in the catches of rays and jewfish in the post-1973 period. Post-1973 changes in the catches of dolphins, turtles and tunas were not statistically significant.

The spatial and temporal variability of potentially harmful phytoplankton was examined in the oyster-growing estuaries of New South Wales. Forty-five taxa from 31 estuaries were identified from 2005 to 2009. Harmful species richness was latitudinally graded for rivers, with increasing number of taxa southward. There were significant differences (within an estuary) in harmful species abundance and richness for 11 of 21 estuaries tested. Where differences were observed, these were predominately due to species belonging to the Pseudo-nitzschia delicatissima group, Dinophysis acuminata, Dictyocha octonaria and Prorocentrum cordatum with a consistent upstream versus downstream pattern emerging. Temporal (seasonal or interannual) patterns in harmful phytoplankton within and among estuaries were highly variable. Examination of harmful phytoplankton in relation to recognised estuary disturbance measures revealed species abundance correlated to estuary modification levels and flushing time, with modified, slow flushing estuaries having higher abundance. Harmful species richness correlated with bioregion, estuary modification levels and estuary class, with southern, unmodified lakes demonstrating greater species density. Predicting how these risk taxa and risk zones may change with further estuary disturbance and projected climate warming will require more focused, smaller scale studies aimed at a deeper understanding of species-specific ecology and bloom mechanisms. Coupled with this consideration, there is an imperative for further taxonomic, ecological and toxicological investigations into poorly understood taxa (e.g. Pseudo-nitzschia).

The dispersion and transport of Cryptosporidium parvum oocysts, Escherichia coli and PRD1 bacteriophage seeded into artificial bovine faecal pats was studied during simulated rainfall events. Experimental soil plots were divided in two, one sub-plot with bare soil and the other with natural vegetation. Simulated rainfall events of 55 mm.h(-1) for 30 min were then applied to the soil plots. Each experimental treatment was performed in duplicate and consisted of three sequential artificial rainfall events ('Runs'): a control run (no faecal pats); a fresh faecal pat run (fresh faecal pats); and an aged faecal pat run (one week aged faecal pats). Transportation efficiency increased with decreasing size of the microorganism studied; Cryptosporidium oocysts were the least mobile followed by E. coli and then PRD1 phage. Rainfall events mobilised 0.5 to 0.9% of the Cryptosporidium oocysts, 1.3-1.4% of E. coli bacteria, and 0.03-0.6% of PRD1 bacteriophages from the fresh faecal pats and transported them a distance of 10 m across the bare soil sub-plots. Subsequent rainfall events applied to aged faecal pats only mobilised 0.01-0.06% of the original Cryptosporidium oocyst load, between 0.04 and 15% of the E. coli load and 0.0006-0.06% of PRD1 bacteriophages, respectively.

Aims: To generate field-relevant inactivation rates for Cryptosporidium oocysts in soil that may serve as parameter values in models to predict the terrestrial fate and transport of oocysts in catchments. Methods and Results: The inactivation of Cryptosporidium oocysts in closed soil microcosms over time was monitored using fluorescence in situ hybridization (FISH) as an estimate of oocyst 'viability'. Inactivation rates for Cryptosporidium in two soils were determined under a range of temperature, moisture and biotic status regimes. Temperature and soil type emerged as significantly influential factors (P < 0AE05) for Cryptosporidium inactivation. In particular, temperatures as high as 35°C may result in enhanced inactivation. Conclusions: When modelling the fate of Cryptosporidium oocysts in catchment soils, the use of inactivation rates that are appropriate for the specific catchment climate and soil types is essential. FISH was considered cost-effective and appropriate for determining oocyst inactivation rates in soil. Significance and Impact of the Study: Previous models for predicting the fate of pathogens in catchments have either made nonvalidated assumptions regarding inactivation of Cryptosporidium in the terrestrial environment or have not considered it at all. Field-relevant inactivation data are presented, with significant implications for the management of catchments in warm temperate and tropical environments.