TOWARDS the end of 2011, near to 1000 turtle and 170 dugong deaths were reported along the Queensland coast. Less than half that number were recorded during the same period in the previous year.
This increase may be directly attributed to the loss of seagrass meadows. In Cape York seagrass meadows are generally healthy and support a rich and diverse aquatic life, due to relatively good water quality.
Land useage, including mining, cattle grazing and tree clearing for roads and houses can cause erosion that displaces and deposits sediment, Initially into rivers, and ulitmately onto the seagrass meadows and adjacent reefs. In order to protect Cape York’s valuable aquatic resources, including fish species, prawns, turtles and dugongs, it is crucial to consider the enviornmental impacts of human activities and take action to prevent erosion.
Local scientists and the Yuku-Baja-Muliku Rangers assessed the health of intertidal seagrass meadows at Walsh Bay, near Archer Point, south of Cooktown, in April, July and October of 2014. Interest in the condition of local seagrass meadows was high, after reports of major seagrass losses elsewhere in Queensland.
The Archer Point seagrass meadows have been monitored quarterly since 2002, as part of the Seagrass-Watch Program, allowing recorded changes to be compared with previous years’ data. In general the seagrass at Archer Point appeared to be healthy and intact. However, mats of algae, which can limit the seagrass growth growing over and around the meadows, were recorded.
It is suspected that the increased algae is a result of unusually nutrient rich currents flowing north from flooded areas, or to be the result of increases in water temperature.
Information collected from temperature dataloggers and sediment and seagrass nutrient samples collected for the Department of Employment, Economic Development and Innovation (DEEDI) and the Commonwealth Reef Rescue Program, are to be released shortly. This data may aid in the understanding increased algal growth.
Further monitoring was undertaken in September 2014 with the Hopevale Youth and Pelican Project team, on seagrass meadows near the mouth of the Starke River. Seagrass in the Starke area appeared to be healthy and diverse, with extnesive coverage of seven species recorded in the one bay.
Reports of healthy seagrass coverage in Princess Charlotte Bay bodes well for resident turtles and dugongs. Seagrass meadows cover extensive areas of of the seas adjacent to eastern Cape York, particularly in the large protected bays to the north of Cape Flattery.
Seagrass meadows are vital to the health of the turtle and dugong populations of Far North Queensland, as floods and cyclones have wiped out many seagrass meadows to the south of the region. DEEDI Seagrass -Watch program manager, Len McKenzie reported that extensive losses of seagrass meadows had been observed between Cairns and Townsville after cyclone Yasi in early 2011.
“Up to ninety eight percent of the seagrass has been lost in some areas,” Mr McKenzie said.
“These seagrass meadows could take anywhere from two to five years to recover and may be slowed by compounding issues such as poor water quality.”
The massive floods in southern Queensland have taken a toll, with major seagrass declines reported near Rockhampton and Gladstone. The depleted conditions of the beds is detrimental for turtles and dugongs that depend on seagrass as a main food source, and for the prawns, juvenile fish and other organisms, that inhabit the seagrass meadows.
Pic of guy measuring turtle with kids
PHOTO: Dr Ian Bell with locals undertaking research.