Managing nutrients to limit coastal algal blooms

The increased occurrence of coastal algal blooms is a worldwide phenomenon linked to nutrient-enrichment of coastal waters. This is also a concern in Queensland where blooms have increased in incidence, duration and intensity (e.g. toxic Lyngbya blooms in Moreton Bay). Such blooms have negative impacts on aquatic communities and pose a significant threat to human health, biodiversity, water quality, marine megafauna, and the recreational and commercial values of coastal waterways.

Nutrients of concern that contribute to increased algal growth include phosphorus, iron, nitrogen and organic matter (dissolved organic carbon). Land-based development and management activities that disturb soils and sediments, or alter the natural hydrological regime (including groundwater levels and composition and surface-water run-off), can mobilise and transport increased loads of nutrients into coastal waters.

Policies

The following documents contain specific policy provisions to better manage development and activities that mobilise and transport nutrients of concern to waters where they exacerbate coastal algal blooms: 

These policies outline requirements to identify nutrient hazardous areas & ensure urban development in these areas is located, designed, constructed & operated to avoid the mobilisation and release of nutrients of concern for coastal algal blooms. 

Policy implementation guidelines

The coastal algal bloom (CAB) implementation guideline Implementing Policies and Plans for Managing Nutrients of Concerns for Coastal Algal Blooms in Queensland (PDF, 2.3M)*, provides direction for State and local governments, industry, consultants, land and natural resource managers and the community on how to implement these policies into planning and development assessment. The document also provides direction for incorporating algal bloom nutrient management initiatives into non-regulatory frameworks and activities.

Technical guidelines

Coastal algal bloom nutrients of concern technical guidelines (CAB technical guidelines) are currently being developed to provide further support on sampling, assessment and management of nutrients of concern for coastal algal blooms. They will include methods for developing hazard maps, best-practice water and groundwater management for nutrients of concern (particularly iron and organic matter) and model development conditions.

Nutrient hazardous areas

Nutrient hazardous areas are defined in the SPP Healthy Waters as land areas containing appreciable levels of nutrients of concern (particularly nitrogen, phosphorus, iron and organic matter), that may contribute to the increased occurrence, frequency or intensity of coastal algal blooms.  In nutrient hazardous areas:

See the CAB implementation guideline for further information.

Criteria for identifying and mapping nutrient hazardous areas

Nutrient hazardous areas are restricted to catchments that flow to the Queensland coastline and local government areas listed in Appendix 1 of the CAB implementation guideline. These areas are shown on the following maps:

Within these areas, the following criteria are used to identify nutrient hazardous areas:

In addition to these mapped areas, nutrient hazardous areas can also include the following:

Hazard maps

Hazard maps are decision-support tools for the spatial identification of nutrient hazardous areas.  Further information on hazard maps, the different scales and their application is provided in the CAB implementation guideline.  The methodology for producing coarse-scale and detailed-scale hazard maps, and developing ‘temporary nutrient hazardous area overlays’, is currently being finalised.

Coarse-scale hazard maps are currently available for the following areas:

Detailed-scale hazard maps (~ 1:50 000 scale) are currently being developed for the following areas:

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Last updated 6 July 2011

Harmful algal blooms