Patchiness in the Fly River plume in Torres strait

Oceanographic studies were carried out from August 1994 to March 1995 on th e intrusion of the Fly River plume in Torres Strait. Measurements at offsho re coral reefs revealed an event of decreased salinity (approximate to 24) while salinity of the water over the reefs fluctuated between 30-34 the res t of the time. Modelling suggests that this event resulted from the reversa l of longshore currents advecting old river plume water back past the river mouth. There the new river water mixed with the old river plume water gene rating a patch of low-salinity water. While such events may be infrequent, they have the potential to leave a terrestrial signature on offshore coral reefs, in terms of (1) an input of terrigenous sediment and (2) the possibl e incorporation of riverine particulate metal into the food chain. The impa ct during an intrusion event may be significant. In the long term the river ine material is diluted in calcareous sediment produced throughout the year by bio-erosion of coral reefs. (C) 1999 Elsevier Science B.V. All rights r eserved.