The current Special Edition includes 27 articles derived from a session on GBR water quality at the Conference on the Challenges in Environmental Science and Engineering held in Cairns, Australia in 2010. The GBR is one of the world’s best known and most complex natural systems, including key coastal, check details coral reef and seagrass ecosystems and supporting important human uses such as tourism and fisheries (GBRMPA, 2009). Even though well-managed, the GBR is under pressure from climate change, continued declining water quality from catchment runoff, loss of coastal habitats from coastal development and fishing (ibid.). On the landward side of the

GBRWHA, numerous rivers continue to discharge pollutants derived from agricultural, urban, mining and industrial activity Daporinad on the catchments, and many inshore coral reefs and seagrass meadows show signs of declining health in response to

this. Brodie et al. (2012a) provides a detailed review and analysis of the water quality issues addressed in this Special Issue and the appropriateness and success of the management responses. This keynote paper summarises the current understanding of the catchment sources of pollutants (i.e., suspended sediment from erosion in cattle grazing areas; nitrate from fertiliser application on crop lands; herbicides from various land uses) and the transport and effects of these pollutants in the receiving marine environment. Research across the catchment to reef continuum has been on-going for many years and the Australian and Queensland Governments Oxymatrine responded to the concerns of marine pollution from catchment runoff with a plan to address this issue in 2003 (Reef Plan; updated 2009). However, active management and monitoring of its effectiveness across the catchment to reef

continuum has only recently begun with incentive-based voluntary management initiatives in 2007 (Reef Rescue) and a State regulatory approach in 2009 (the Reef Protection Package) and the Reef Plan Paddock to Reef Integrated Monitoring, Modelling and Reporting Programme (fully implemented in 2008; described in Carroll et al., 2012). The papers in this Special Issue cover aspects across the whole catchment to reef continuum, including studies at the scale of paddocks, sub-catchments, catchments, freshwater systems, rivers, the GBR coastal zone and inshore GBR ecosystems. We summarise the content below grouped into sources, loads, transport, fate and consequences of land-based pollution. Land use (and land management) changes are seen as the primary factors responsible for changes in sediment and nutrient delivery to receiving water bodies.