During our ReefClean Chilli Beach Clean-up in the Kutini-Payamu National Park in Cape York last month, we came across a drift card that indicated that it was from a Great Barrier Reef Marine Mark Authority (GBRMPA) and James Cook University (JCU) research project.
Minutes after we posted it on social media, followers indicated that it might be related to drift cards designed by Mr Walker and Dr Collins from JCU, and that it was possible the drift card was released 30-40 years ago.
Well, thanks to our friends at James Cook University and GBRMPA doing some digging around, we now have the answers! This card pictured was indeed likely released in the early 80’s as part of a joint project to measure water movements on the Queensland Continental Shelf.
In the 80’s, the currents of the GBR were not well known. Most information available back then had been derived from ships navigation records and weren’t very reliable. Building knowledge of surface water movement was important for several factors, including shipping and navigation, transportation of the larvae of reef dwelling organisms, as well as pollutants such as oil (and plastic!).
After a pilot study in 1980, GBRMPA funded a series of regular releases along the Barrier Reef over the course of 12 months. Close to 100,000 cards were released from aircraft at 13 stations between the Torres Strait and the Capricorn Channel. The cards were double-sealed in polythene and designed to travel in an upright position, supported by a small float. Most (95%) of the card remained submerged so as to mainly be affected by surface water movements as opposed to wind.
Each card was stamped with an identification number and members of the public who found them were encouraged to send them back to JCU/GBRMPA with the details of recovery. By comparing the time and position of drift card release and recovery, the direction of drift was determined, and in instances where the card was found soon after beaching, a minimum drift speed could be calculated.
From studies such as this, we now know that for most of the year Southeast Trade Winds generate a northwestward surface flow along the GBR. During the course of the study in 1981, the longest distance travelled by a card (straight line) was 920 km / 480 nautical miles from near Townsville (18°S) to the Olive River (12°S), which is just North of Chilli Beach!
Of course, we are very aware of the effect of ocean currents on the distribution of plastics around the world. Although most (<90%) of the debris washing up on the shores of Cape York is foreign, the litter from Australia also just ends up on someone else’s shores. This serves as a reminder that all of our oceans are interconnected and marine debris is everybody’s problem.
Below is a section taken from one the papers by Walker, T and Collins, J…
“The continued success of this project will depend upon the good-will of the beach-combing public finding and returning these cards to the James Cook University. It is hoped that the novelty of returning them will not flag as all cards are important in revealing a part of the drift pattern with time.”
Thankfully the novelty hadn’t worn off for the Tangaroa Blue team at Chilli Beach!
We’d like to extend a MASSIVE THANK YOU to the team Research Online team at JCU and GBRMPA for doing some digging for us. If you’d like to read more about the studies by Dr Collins and Mr Walker, please see the links below
- Walker, T. and J.D. Collins, J.D., (1985) Surface circulation in the Central Region of the Great Barrier Reef lagoon.p. 23-28 In: C. Gabrie and M. Harmelin (assoc. eds.). Proceedings of The Fifth International Coral Reef Congress. Tahiti, 27 May -1 June 1985. Vol. 6: Miscellaneous Paper (B).
- Walker, T and Collins, J. Great Barrier Reef surface drift studied. Australian Fisheries 41(12): 7-9, Dec, 1982. https://nla.gov.au/nla.obj-748686730/view?partId=nla.obj-748710050#page/n8/mode/1up
- Collins, J and Walker, TA. Cards to measure Reef currents. Reeflections ISSN 0314-6510 (7): 3, Jun 1981.http://hdl.handle.net/11017/3295
- Walker, T and Collins, J. Surface currents of the central Great Barrier Reef studied. Australian fisheries ISSN 0004-9115 39(12):8-9, Dec 1980. https://nla.gov.au/nla.obj-747771822/view?partId=nla.obj-747819444#page/n9/mode/1up