We describe the pressures, values and conceptual models for ecosystems in the Northern Marine Region.

To do this, we implement the first three of five steps of the GBR Cumulative Impact Guidelines (Dunstan et al. 2019):  1) understanding pressures; 2) understanding values; and 3) the description of conceptual models of ecosystems. These first three steps provide a systematic hazard assessment for the Northern Marine Region, adding a consistent spatial component to earlier hazard assessments. Progressing from this hazard assessment to a cumulative impact assessment requires the subsequent or final two steps of the GBR Cumulative Impact Guidelines: 4) dose-response curves and 5) quantitative assessment. Parks Australia has recently described a set of ecosystem complexes we spatially mapped in the Northern Marine Region using a number of different data layers generated from previous NESP work to provide the values (Step 1). The data on pressures (Step 2) was also obtained from previous work completed by the NESP Marine Biodiversity Hub. Finally (Step 3), a workshop was held in Darwin in September 2019 to describe the conceptual models for each ecosystem complex, namely the ecosystem components and the pressures that are acting on each component. This analysis is designed to identify which ecosystem components should be examined in the future to assess the significance of cumulative impacts (ie through a formal risk assessment). The outputs from this first stage have identified the key natural values in the ecosystem complexes that may be at risk of unsustainable impacts. These outputs will also be useful in identifying potential indicators for the ecosystem complexes described by Parks Australia