Quick questions on Human-induced stress on ecosystems: HSC Geography

Nitrogen and phosphorus from fertilisers and animal waste drive algal blooms in rivers, lakes, and coastal waters. The Great Barrier Reef catchments deliver around 14 Mt of sediment, 50,000 t of nitrogen, and 4,200 t of phosphorus annually to reef waters. Sugarcane and beef are the dominant sources. The Reef 2050 Plan includes targets for 60 percent reduction in nitrogen and 25 percent reduction in sediment.

Mine tailings, smelter emissions, refinery discharges. Acid mine drainage from old mines (Mount Lyell, Captains Flat) continues decades after closure. PFAS contamination from defence sites and firefighting foam affects groundwater across 90-plus Australian sites.

Around 130,000 t of plastic enters Australian waters each year. Microplastics are now ubiquitous in marine ecosystems and have been found in fish, seabirds, turtles, and human blood.

PM2.5 (fine particulate matter) from wood-fire heating, vehicle emissions, and bushfires causes around 1,700 premature deaths per year in Sydney (UNSW study 2022). Black Summer smoke produced PM2.5 levels 26 times above hazardous thresholds in Canberra for weeks.

Light pollution affects 80 percent of the world's population. Sea turtle hatchlings disoriented by beach lighting. Noise pollution affects whale communication and reef fish behaviour.

Most Australian fisheries are now managed within sustainable limits, but historical overfishing has lasting impacts. Orange roughy off Tasmania collapsed in the 1990s and is only slowly recovering. School shark in southern Australian waters remains overfished. Tropical reef fish populations on the inshore Great Barrier Reef have declined from fishing pressure.

Native forest logging has been declining as states phase out: Victoria ended native forest logging in 2024, Western Australia in 2024, Queensland by 2025. NSW transitions remain contested. Tasmania continues with native forestry under managed plans.

Bushmeat hunting is not a major issue in Australia (no legal hunting of native mammals). Crocodile and kangaroo harvest are managed under quotas.

Around 3,000 naturalised introduced plant species in Australia. Major weeds include lantana (4 million ha), prickly pear (still controlled by Cactoblastis moth), Mimosa pigra (NT wetlands), buffel grass (changing fire regimes across central Australia), and gamba grass (NT, drives fierce woodland fires).

Yellow crazy ants on Christmas Island and Lord Howe Island. European honey bees outcompete native bees. Asian honey bees and Varroa mite (incursion in NSW 2022) threaten the apiculture industry.

Phytophthora cinnamomi (water mould affecting WA jarrah). Chytrid fungus (frog declines). Myrtle rust (Myrtaceae plant family). Avian influenza variants spreading.