Hobart, Tasmania, Australia
The Tasmanian marine environment is characterised by a diverse range of habitats and assemblages shaped by the large gradient in wave exposure, depth and light, and distinct biogeographic regions. Water temperatures are relatively mild for a temperate zone, oceanic waters ranging from 11-18 oC through the year. Subtidal rocky reefs hold the greatest biomass and diversity of larger plants and animals, and support major coastal fisheries such as rock lobster and abalone. Shallow wave-exposed reefs are dominated by large kelps, which are replaced by diverse sessile invertebrate communities (including colourful sponge gardens) in deeper areas. The many sheltered embayments formed by a highly convoluted coastline include extensive seagrass beds dominated by four different plant genera (Posidonia, Zostera, Amphibolis and Halophila), while sheltered reefs possess starkly different shallow water seaweed communities from adjacent exposed coasts. Southeastern Tasmania, in particular, provides home for a number of endemic species, including a fish family of 14 species that is largely endemic to the region – the handfishes (Brachionichthyidae).
The Maria Island Marine Reserve, on Tasmania’s east coast, has been one of the best studied Marine Protected Areas (MPAs) in the world, with an ongoing reef monitoring program that commenced with declaration of the MPA in 1991 (part of the University of Tasmania Long-term Temperate Reef Monitoring Program). Despite what could be considered low fishing pressure around Tasmania by global standards, the long-term study of the Maria reserve has shown considerable ecological change through time, diverging from reference sites outside the reserve boundaries. Lobsters have grown to enormous sizes, and along with recovering fish populations, have depressed invertebrate populations and resisted influx of warm-water range shifting species.
The terrestrial wildlife and landscapes of the spectacular Maria Island National park, which abuts the marine reserve, make this both a World Heritage Area and a scenic laboratory where a huge range of habitat types can be studied above and below water. The range of geological strata within 5 km of the former convict settlement of Darlington include sandstone, dolerite, limestone, granite, and mudstone. Underwater caves, seagrass meadows, kelp forests, sponge gardens, red algal beds, and sand plains occur interspersed around the coast.