A Predictive Monitoring Program (PMP) has been developed to protect sensitive marine environments from the impacts of construction. The primary goal of the program is to predict the environmental impacts of key pollutant-generating processes in order to trigger intervention before a measurable impact occurs. To do this, a PMP directs compliance monitoring primarily towards pollutant-generating activities, using model-derived pollutant trigger values that incorporate construction and hydrodynamic processes and known habitat tolerances. Non-compliance with these trigger values instigates immediate pre-defined management responses. To maximise protection, compliance monitoring of discharge activities is undertaken during the pre-discharge phase to allow intervention prior to discharge. For dredging activities, compliance monitoring is undertaken at the post-mixing boundary of the plume. Routine habitat condition monitoring is employed in a supporting role to validate the efficacy of the program for protecting key habitats.

　

The generic concept of the PMP has been implemented for two case studies to mitigate the impacts of sediment-laden water discharge and cutter-suction dredging in marine national parks. Increased sediment suspension was identified as the key pollutant generated by each construction process. Accordingly, programs were specifically developed to protect fringing coral reef and mangrove habitats from the impacts of light attenuation and sedimentation. Results indicated that the PMP was highly successful in protecting sediment-intolerant coral communities in the Great Barrier Reef Marine Park. This was largely due to the rapid and repetitive intervention that the program triggered. Intervention in the dredging process to protect mangrove communities in Charles Darwin National Park was not required.

　

　

The success of the PMP can be attributed to the incorporation of important emerging philosophies in impact management within marine systems. Principal among these is the recognition that monitoring and management programs must integrate knowledge of construction processes and ecological requirements (Bach et al., 1997; Clarke & Wilbur, 2000). The PMP achieved this by integrating knowledge of habitat tolerances with hydrodynamic modelling of specific construction processes to produce pollutant trigger values that considered mixing and dispersion dynamics as well as environmental requirements. In the instance of the case study on dredging, trigger values were set at relatively high levels in consideration of substantial capacity for dispersion and the substantial sediment tolerance displayed by mangrove communities. As a result, dredge activities proceeded with a minimal requirement for intervention. In contrast, discharge of sediment-laden water in close proximity to fringing coral reef communities require substantial intervention because trigger values took into account limited dispersion characteristics and low sediment tolerances of key biota.

　

　

It was also recognized that management responses to unsustainable pollutant generation would need to be very rapid if highly sensitive habitats were to be protected. While the need for rapid response has been highlighted (Gray and Jensen, 1993; Bach et al., 1997), methods to achieve this have not proved to be as rapid as may be required. In addressing the impacts of substantial dredge works on eelgrass communities, Bach et al. (1997) implemented a feedback monitoring system that utilised physiological indicators of eelgrass condition as the trigger for management response. However, the use of biota as the trigger mechanism resulted in inherent delays in management response, due to the time required for stress to manifest itself. For eelgrass, this was expressed as an approximate two-week delay (Bach et al., 1997). The PMP addressed this problem by focusing compliance monitoring on actual pollutant-generating processes, allowing non-compliance with trigger immediate intervention. In the case of wastewater discharge adjacent to coral reefs, lag-times did not exceed one hour. This rapid response was regarded as a key element in the success of the program.

　

　

The necessity to examine biological condition is well recognized (Thomas, 1993) and is usually incorporated within an impact monitoring program (i.e., Bach et al., 1997). In such cases, the detection of measurable environmental harm is used to trigger a management response. Although not used to trigger intervention, biological monitoring remained an integral component of the PMP, being used to validate trigger values, management responses and the effectiveness of the program for protecting key habitats. Specifically, biological assessment of coral communities, when integrated with water quality monitoring, proved useful to delineate construction impacts from natural variability. Given that dredging works did not trigger management responses, assessment of mangrove communities was used to validate the relatively high trigger values adopted by this program (Table 3).

　

Biological monitoring also plays a substantial role in the determination of habitat tolerances. While the tolerance of coral and mangrove communities to sedimentation is relatively well understood, the need for substantial baseline and other assessments may be required to adapt this approach to other habitat types. Such baseline studies may also prove useful to delineate the natural variability in condition that may exist in many habitats. It should be recognized that habitat condition assessment may be expensive. The PMP addressed this limitation by confining condition assessment to designated key habitats only.

　

　

1. Each case study would have benefited from more intensive baseline data collection to allow accurate determination of natural variability of pollutants and key habitat condition. This would enable construction monitoring to be more targeted and efficient and would have increased the cost-effectiveness of both programs. Therefore rigorous baseline studies are recommended.

2. The effectiveness of the PMP would be enhanced by incorporation of trigger values and pre-defined management responses within development approvals prior to the commencement of construction.

3. The case studies clearly identified that the generic PMP concept can successfully be implemented to protect sensitive environments from construction related impacts. A PMP needs to be designed according to specific environmental settings and proposed construction activities.

　

　

The PMP philosophy has been developed to incorporate a preventative approach to environmental management. The two case studies presented indicate that the implementation of a PMP has been successful in mitigating construction related impacts in sensitive marine environments. Furthermore, it is suggested that PMPs are sufficiently flexible to be implemented for a variety of construction processes and over a range of habitats. Advances in modeling technology will allow improved consideration of pollutant-generating processes, near-field mixing and far-field pollutant behavior (Fryar, et al., 2002). This is likely to substantially improve the performance of the PMP. The project team intends to continue the refinement of the PMP as a tool to protect sensitive marine environments.

　

　

The authors would like to thank the Great Barrier Reef Marine Park Authority and the Northern Territory Department of Infrastructure, Planning and Environment for whom the programs were designed and implemented. The authors are grateful for the contributions of Andrew Chin (Great Barrier Reef Marine Park Authority, Townsville), Peter Ridd (James Cook University, Townsville), Ross Jones (The University of Queensland, Brisbane) and Bill Venables (CSIRO, Brisbane) during the course of these works. Our appreciation goes to the staff and students of all scientific institutions who provided logistical and technical support.

　

Bach, H.K. K. Jensen and J.E. Lyngby. 1997. Management of marine construction works using ecological monitoring. Estuarine Coastal and Shelf Science. 44(Supp A):3-14.

Botev, I. and R. Fryar. 2002. Application of 3D models in the coastal environment. Australian Journal of Water Resources. 6(1):1-9.

Clarke, D.J. and D.H. Wilbur. 2000. Assessment of potential impacts of dredging operations due to sediment resuspension. DOER Technical Notes Collection (EDRC TN-DOER-E9), US Army Engineering Research and Development Centre, Vicksburg MS. Available from US Army Corps of Engineers DOER Technical Notes via the Internet (http://www.wes.army.mil/el/dots/doer).

Clarke, P.J. and P.J. Myerscough. 1993. The intertidal distribution of the grey mangrove (Avicennia marina) in southeastern Australia: The effects of physical conditions, interspecific competition, and predation on propagule establishment and survival. Australian Journal of Ecology. 18:307-315.

Craik, W. 1996. The Great Barrier Reef Marine Park, Australia: A model for regional management. Natural Areas Journal. 16(4):344-353.

　

Elander, P. and T. Hammar. 1998. The remediation of Lake Jarnsjon: Project Implementation. Ambio. 27(5):393-398.

Ellison, J.C. 1998 Impacts of sediment burial on mangroves. Marine Pollution Bulletin. 37:420-426.

Fairweather, P.G. 1990. Ecological changes due to our use of the coast: research needs versus effort. Proceedings of the Ecological Society of Australia. 16:71-77.

Frusher, S.D., F.L. Giddins and T.J. Smith III. 1994. Distribution and abundance of grapsid crabs (Grapsidae) in a mangrove estuary: effects of sediment characteristics, salinity tolerances, and osmoregulatory ability. Estuaries. 17:647-54.

　

Fryar, R.M., I.B. Botev and B.L. Regan. 2002. Using three dimensional models to Manage Outfalls and Minimise Environmental Impacts - Modelling Moreton Bay and The Brisbane River. Managing Water to Protect the Coastal Zone, AWA 2002 Weekend Regional Conference, Mooloolaba, QLD, 8-10 November 2002.

Gray. J.S. and K. Jensen. 1993. Feedback monitoring: A new way of protecting the environment. Trends in Ecology and Evolution. 8:267-305.

Healy. T., A. Mehta, H. Rodriguez and F. Tian. 1999. Bypassing of dredged littoral muddy sediments using a thin layer dispersal technique. Journal of Coastal Research. 15(4):1119-1131.

Hodgson, G. 1989. The effects of sedimentation on Indo-Pacific reef corals. PhD Thesis. University of Hawaii.

Jones, R.J., J.K. Oliver and R. Berkelmans. 1997. The recurrent bleaching of corals at Magnetic Island (Australia) relative to air and seawater temperature. Marine Ecology Progress Series. 158:289-292.

Jrgensen, P.V. and K. Edelvang. 2000. CASI data utilized for mapping suspended matter concentrations in sediment plumes and verification of 2-D hydrodynamic modelling. International Journal of Remote Sensing. 21(11):2247-2258.

　

Lawing, W.D. and R.C. Hanumara. 1989. Use of log-linear modelling to assess environmental changes. Environmental Monitoring and Assessment. 11(2):115-126.

Loya, Y. 1976. Effects of water turbidity and sedimentation on the community structure of Puerto Rican reefs. Bulletin of Marine Science. 26:450-466.

　

Marques, J.C., P. Maranhao and M.A. Pardal. 1993. Human impact assessment on the subtidal macrobenthic community structure in the Mondego Estuary (Western Portugal). Estuarine Coastal and Shelf Science. 37(4):403-419.

　

Nichols, M., R.J. Diaz and L.C. Schaffner. 1990. Effects of hopper dredging and sediment dispersion, Chesapeake Bay. Environmental Geology and Water Science. 15(1):31-43.

Rogers, C.S. 1990. Responses of coral reefs and reef organisms to sedimentation. Marine Ecology Progress Series. 62:185-202.

Perry, C.T. 1996. The rapid response of reef sediments to changes in community composition: Implications for time averaging and sediment accumulation. Journal of Sediment Research. 66:459-467.

Puckette, T.P. 1998. Evaluation of dredge material plumes - Physical monitoring techniques. DOER Technical Notes Collection (TN DOER-E5) US Army Engineer Research and Development Centre, Vicksburg MS. Available from US Army Corps of Engineers DOER Technical Notes via the Internet (http://www.wes.army.mil/el/dots/doer).

　

Quigley, M.P. and J.A. Hall. 1999. Recovery of macrobenthic communities after maintenance dredging in the Blyth Estuary, north-east England. Aquatic Conservation. 9(1):63-73.

Ridd, P.V., A. Orpin, P. Marshall and J. Oliver. Natural variability in turbidity close to coral reefs. Submitted to Estuarine Coastal and Shelf Science 2000.

　

Ruffin, K.K. 1998. The persistence of anthropogenic turbidity plumes in a shallow waste estuary. Estuarine Coastal and Shelf Science. 47(5):579-592.

Stafford-Smith, M.G., U.L Kaly and J.H. Choat. 1994. Reactive Monitoring (short term responses) of coral species. In: Benson L.J., P.M. Goldsworthy, I.R. Butler and J.K. Oliver (eds) Townsville Port Authority Capital Dredging Works. 1993: Environmental Monitoring Program. Townsville Port Authority, No.1 The Strand, Townsville Qld 4810.

　

Thomas, J.D. 1993. Biological monitoring and tropical biodiversity in marine environments: a critique with recommendations, and comments on the use of amphipods as bioindicators. Journal of Natural History. 27:795-806.

　

Wolanski, E. and R. Gibbs. 1992. Resuspension and clearing of dredge spoils after dredging, Cleveland Bay, Australia. Water Environment Research. 64(7):910-914.