Turtles and tortoises have a history dating back 220 million years, predating crocodiles and snakes. Among Australian turtles, the Mary River turtle boasts one of the most ancient lineages, with its nearest living ancestor existing approximately 50 to 60 million years ago. The Mary River itself represents a dynamic river system. The majority of its water flow takes place during the Southern Hemisphere's summer and early autumn, leading to notable fluctuations in river levels. In contrast, the flow remains relatively consistent during the winter months.

The primary habitat of the Mary River turtle consists of riffle zones and pools within the river. It predominantly searches for food within these riffle zones, requiring the presence of accessible rocks and logs for sunbathing. Additionally, it seeks out open sandy sites along the riverbank to serve as nesting spots and nocturnal resting places. These specific habitats must offer a secure environment, free from potential predators.

The Mary River turtle possesses dual methods of respiration. When it emerges to the surface, it employs its lungs for breathing. However, nestled within its tail lies a profound cavity adorned with gill-like structures, enabling it to extract oxygen from the water. This adaptation grants the turtle the ability to remain submerged for extended durations, earning it the moniker of a 'bum-breather.' A noteworthy instance involves a hatchling documented to have stayed underwater for 2.5 days under optimal temperature and oxygen conditions.

Distinguishing itself, the Mary River turtle features notably elongated hind legs. These lengthy limbs serve a crucial purpose – facilitating the excavation of nesting chambers to a depth of about 13 to 15 centimeters. This depth is vital in shielding the developing embryos from the harsh surface temperatures. At this depth, conditions are conducive to embryo development, and the soil retains moisture for an extended period, both vital elements for ensuring successful incubation amid the scorching and arid Australian summers. The intensification of heat and drought due to climate change exacerbates the challenges posed by the summer conditions.

Four decades in the past, Mary River turtles were marketed as affordable pets, commonly known as "penny turtles," just in time for the Christmas season. These turtles took their first steps into the world with impeccable timing. It requires approximately two decades for a Mary River turtle to mature and become capable of reproducing. The act of laying eggs exposes female freshwater turtles, including the Mary River Turtle, to predators such as cats, dogs, and foxes. The eggs are also sought after by monitor lizards, commonly referred to as goannas. As a result of these predation pressures, the population of this species was rapidly declining even before it gained recognition and was scientifically identified as a distinct species.

The Mary River serves as the exclusive home to the Mary River cod (Maccullochella mariensis), a type of temperate perch that is indigenous to the coastal segment of the river system. Within Australia, the Mary River cod ranks among the most critically endangered fish species.

Additionally, the Mary River remains a vital and prominent habitat for the Queensland lungfish (Neoceratodus forsteri). This particular lungfish species is one of the six existing members of the ancient air-breathing lungfish lineage that thrived during the Devonian period, spanning approximately 413 to 365 million years ago. Notably, the Queensland lungfish stands out as the most evolutionarily distinct among these species.

A decade ago, the Australian government rejected the Queensland government's Traʋeston Crossing dam project. This decision averted the potential extinction of the Mary River turtle and the Mary River cod, while also preventing further endangerment of the Queensland lungfish.

Queensland Conservation played a pivotal role in rallying community opposition against this disastrous proposal. The project would have submerged a significant portion of Queensland's most productive agricultural lands, impacting the long-term food security of Brisbane. Ironically, the lack of water security in Brisbane had initially prompted the Traʋeston Crossing dam idea.

Currently, volunteers from Queensland's Tiaro and District Landcare are actively engaged in monitoring the nesting sites of the Mary River turtle. They take measures to safeguard the eggs by placing protective covers over each nest, effectively deterring foxes, wild dogs, and monitor lizards from disturbing and consuming the eggs.

As our climate warms, there is a growing risk that summer storms may not occur. This poses a danger to the developing eggs due to prolonged hot and dry conditions. To counteract this, volunteers step in to water the nests and prevent the eggs from drying out.

The Mary River catchment group plays a crucial role in safeguarding the well-being of Australia's most unique freshwater turtle. Their efforts are focused on maintaining the health of the river system, aiming to improve the chances of survival for the endangered Mary River turtle.