Hornsby, Australia
Hornsby, Australia

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Coad P.,Hornsby Shire Council | Cathers B.,University of New South Wales | Ball J.E.,University of Technology, Sydney | Kadluczka R.,Manly Hydraulics Laboratory
Environmental Modelling and Software | Year: 2014

Algae proliferate when favourable biological, chemical and physical conditions are present. Algal blooms within the Hawkesbury River, NSW, are a regular feature of seasonal cycles and develop in response to non-periodic disturbances. To improve the understanding of processes that lead to algal blooms, an autonomous buoy has been deployed (since 2002) which has generated a high resolution, temporal data set. Parameters monitored at 15min intervals include Chlorophyll-a, temperature (water and air), salinity and photosynthetically available radiation. This data set is used to configure an Artificial Neural Network (ANN) to predict (one, three and seven days in advance) the mean, 10th and 90th percentile, daily Chlorophyll-a concentrations. The prediction accuracy of the ANNs progressively decreased from one to seven days in advance. Incorporating predictive models coupled with near real time data sourced from automated, telemetered monitoring buoys enables environmental managers to implement proactive algal bloom management strategies. © 2014.


Rubio A.,Hornsby Shire Council | Frances J.,Port Stephens Fisheries Institute | Coad P.,Hornsby Shire Council | Stubbs J.,Broken Bay Oysters Association | Guise K.,Hornsby Shire Council
Journal of Shellfish Research | Year: 2013

Since the 1970s, significant QX disease outbreaks have taken place in Sydney rock oyster (Saccostrea glomerata)producing estuaries in New South Wales, Australia, devastating production. Despite research efforts, there are still many gaps in our knowledge of QX disease (causative agent: Marteilia sydneyi). A better understanding of the timing and triggers of the QX infection would allow the management of oyster farms to be tailored to address the high-risk period. This study examined the extent and variability of the QX window of infection across multiple years (2005/2006 to 2008/2009) in the Hawkesbury River and characterized environmental conditions prior to, during, and after the infection window during these years. The window of QX infection onset across the years was found to be highly variable, with start times occurring between November and February, whereas the infection termination time was more defined, occurring within the first week in April, except in 2006/2007, which ceased during the last week of April. The termination of the infection window occurred during a significant decrease in water temperature (at a rate of 3.7°C/mo), with no infection occurring at water temperatures less than 21.5°C Environmental conditions were more variable at the onset of the infection window, when water temperatures showed high levels of variability among years as a result of cool freshwater inputs from rainfall events, which occur commonly at this time of year. These freshwater inputs also resulted in significant decreases in salinity levels (to at least ∼10 ppt), which may be an additional factor influencing QX disease outbreaks. Previous QX work suggested an infection period of 19 days; here, longer infection periods were observed and lasted between 8 wk and 18 wk, depending on the year.


Daniell K.A.,Australian National University | White I.,Australian National University | Ferrand N.,IRSTEA | Ribarova I.S.,University of Architecture, Civil Engineering and Geodesy | And 8 more authors.
Ecology and Society | Year: 2010

Broad-scale, multi-governance level, participatory water management processes intended to aid collective decision making and learning are rarely initiated, designed, implemented, and managed by one person. These processes mostly emerge from some form of collective planning and organization activities because of the stakes, time, and budgets involved in their implementation. Despite the potential importance of these collective processes for managing complex water-related social-ecological systems, little research focusing on the project teams that design and organize participatory water management processes has ever been undertaken. We have begun to fill this gap by introducing and outlining the concept of a co-engineering process and examining how it impacts the processes and outcomes of participatory water management. We used a hybrid form of intervention research in two broad-scale, multi-governance level, participatory water management processes in Australia and Bulgaria to build insights into these coengineering processes. We examined how divergent objectives and conflict in the project teams were negotiated, and the impacts of this co-engineering on the participatory water management processes. These investigations showed: (1) that language barriers may aid, rather than hinder, the process of stakeholder appropriation, collective learning and skills transferal related to the design and implementation of participatory water management processes; and (2) that diversity in co-engineering groups, if managed positively through collaborative work and integrative negotiations, can present opportunities and not just challenges for achieving a range of desired outcomes for participatory water management processes. A number of areas for future research on co-engineering participatory water management processes are also highlighted. © 2010 by the author(s).


Wilkie E.M.,Macquarie University | Bishop M.J.,Macquarie University | O'Connor W.A.,Port Stephens Fisheries Institute | McPherson R.G.,Hornsby Shire Council
Marine and Freshwater Research | Year: 2013

Marine diseases represent a significant threat to wild organisms and the ecosystem services they support, yet studies often consider only disease impacts to aquaculture. In eastern Australia, the Sydney rock oyster (Saccostrea glomerata) aquaculture industry is increasingly affected by outbreaks of QX disease caused by parasitic Marteilia sydneyi. The present study considered impacts of M. sydneyi infection on the structure of wild-oyster populations that are dominated by S. glomerata, but that may also include the non-native Pacific oyster, Crassostrea gigas. In the Hawkesbury River Estuary, where cultured S. glomerata has experienced up to 98% QX-induced mortality, we found that disease prevalence was comparatively low among wild S. glomerata, peaking at 14%, and annual infections did not cause seasonal patterns of mortality. Furthermore, C. gigas, a competitor of S. glomerata that is not susceptible to QX disease, was not consistently more abundant at sites with than without the parasite. Overall, our results indicated that relative to cultured counterparts, wild S. glomerata in the Hawkesbury River Estuary is minimally affected by QX disease. Nevertheless, our study showed that diseases of aquaculture stocks have the capacity to infect wild populations, and that longer-term assessment of wild populations at risk is essential. © CSIRO 2013.


Knights D.,Equatica | Beharrell D.,Hornsby Shire Council | Wright I.,University of Western Sydney
WSUD 2012 - 7th International Conference on Water Sensitive Urban Design: Building the Water Sensitive Community, Final Program and Abstract Book | Year: 2012

A study was undertaken to assess the relationship between Effective Imperviousness (EI) and stream health using Hornsby Council's existing extensive monitoring data. The 15 year data set ranges from bushland reference streams with an EI of zero, to heavily urbanised streams with very high EI. The data set also includes both water quality and biological parameters. EI was, in general, a reasonable predictor of the rapid deterioration of stream health as EI increased from 0 to 5%. However it was observed that selective streams in Hornsby Local Government Area (LGA) had a relatively high level of stream resilience which was correlated to the increase in distance from the last significant directly connected stormwater input. It is often suggested that stream health recovers downstream in waterways due to the in-stream processes of 'disconnection' attenuating frequent flows through in-stream infiltration. However, field investigations have shown that the streams investigated were unlikely to be attenuating frequent flows. This study found that some streams which are likely to have high frequent flow disturbance also have high stream health demonstrating a level of stream resilience. The paper postulates as to the reasons for this observation.


Paul-Pont I.,University of Sydney | Evans O.,University of Sydney | Dhand N.K.,University of Sydney | Rubio A.,Hornsby Shire Council | And 2 more authors.
Aquaculture | Year: 2014

Mortality of farmed triploid Pacific oysters (Crassostrea gigas) associated with Ostreid herpesvirus-1 (OsHV-1) was first recorded in Australia in the Georges River/Botany Bay estuary (New South Wales) in late 2010. Two years later, the first sign of possible inter-estuarine spread was observed when commercial triploid Pacific oysters in the Hawkesbury River estuary, located 50. km north of Botany Bay, were affected by mass mortality. The aim of this study was to describe the epidemiological features of the Hawkesbury outbreak via a formal investigation which was conducted in real time and comprised: an assessment of stock levels, past oyster acquisitions and a trace forward investigation to identify stock at greatest risk due to transfers of oysters; passive surveillance of the spread of mortalities in the estuary; active surveillance using PCR to identify the distribution of OsHV-1 infection on farms in the estuary and mortality estimates to identify age and size classes affected; identification of the time of first infection using data from sentinel oysters; and assessment of environmental risk factors. Mortalities were recorded in all age classes but were greater in spat and juveniles than in adults. The incubation period for mass mortality was <. 4. days, however subclinical OsHV-1 infection was detected three months prior to the first signs of mortality in the index case site (first location affected), which suggests that low viral loads of OsHV-1 are insufficient to induce the disease. While inefficient oyster-to-oyster transmission occurred at two locations, a synchronous infection arising from a common environmental source was required to explain the mass mortalities at the index case site (Mullet Creek). Estuarine hydrodynamics then assisted rapid dispersal of viral particles throughout the estuary. Seawater temperatures were consistently above 24. °C during the month preceding mass mortalities with variations (±. 3. °C) being observed over a few days during this period; however this did not necessarily lead to mortality events when the virus was present. There was no evidence of prior movement of potentially infected oysters or farming equipment into the Hawkesbury River estuary to explain the outbreak. © 2013 Elsevier B.V.


Daniell K.A.,Australian National University | Manez Costa M.A.,Climate Service Center | Ferrand N.,IRSTEA | Kingsborough A.B.,University of Oxford | And 2 more authors.
Regional Environmental Change | Year: 2011

Progress towards climate change aware regional sustainable development is affected by actions at multiple spatial scales and governance levels and equally impacts actions at these scales. Many authors and policy practitioners consider therefore that decisions over policy, mitigation strategies and capacity for adaptation to climate change require construction and coordination over multiple levels of governance to arrive at acceptable local, regional and global management strategies. However, how such processes of coordination and decision-aiding can occur and be maintained and improved over time is a major challenge in need of investigation. We take on this challenge by proposing research-supported methods of aiding multi-level decision-making processes in this context. Four example regionally focussed multi-level case studies from diverse socio-political contexts are outlined-estuarine management in Australia's Lower Hawkesbury, flood and drought management in Bulgaria's Upper Iskar Basin, climate policy integration in Spain's Comunidad Valenciana and food security in Bangladesh's Faridpur District-from which insights are drawn. Our discussion focuses on exploring these insights including: (1) the possible advantages of informal research-supported processes and specifically those that provide individual arenas of participation for different levels of stakeholders; (2) the complexity of organisation processes required for aiding multi-level decision-making processes; and (3) to what extent progress towards integrated regional policies for climate change aware sustainable development can be achieved through research-supported processes. We finish with a speculative section that provides ideas and directions for future research. © 2010 Springer-Verlag.

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