The ecological benefits of highly protected marine parks accumulate over time. Recovery of biomass, age structure, predator populations and ecosystem processes often occurs over decades rather than years, particularly for long-lived species and ecosystems subject to historical depletion (Lester et al. 2009; Edgar et al. 2014; Sala & Giakoumi 2018). Consequently, the effectiveness of marine parks depends not only on the extent and level of protection provided, but also on the durability and stability of that protection.

Protected Area Downgrading, Downsizing and Degazettement (PADDD) refers to the weakening, reduction or removal of legal protections from existing protected areas. Because many conservation benefits accrue gradually through long-term protection, PADDD has the potential to interrupt ecological recovery and erode gains achieved through decades of management. Australia has been identified as a global hotspot for PADDD, reflecting the frequency and scale with which marine protected area boundaries and protection levels have been revised over time (Kuempel et al. 2023). The 2018 review of Commonwealth marine parks resulted in substantial reductions in highly protected no-take zones across several marine park networks, illustrating how conservation gains can be vulnerable to policy change.

Long-term protection is particularly important in marine systems because many ecological processes operate over large spatial and temporal scales. Population recovery, rebuilding of predator communities, restoration of trophic interactions and adaptation to climate change all depend on management certainty over extended periods. Scientific evidence supporting highly protected marine parks is founded largely on studies of reserves that have remained protected for many years or decades (Edgar et al. 2014). Maintaining durable protection therefore increases the likelihood that marine parks achieve their intended biodiversity, fisheries and climate resilience outcomes.

Australia's Commonwealth marine park network represents one of the largest marine conservation systems in the world. Ensuring that highly protected areas remain protected through time is an important component of effective marine conservation and helps ensure that long-term ecological recovery is not undermined by short-term policy change. Durable protection provides the foundation upon which the biodiversity, fisheries and climate resilience benefits of marine parks can accumulate and persist.