The Influence of Industrialization and Urbanization on Dugong Mortality in Queensland, Australia Dugongs (Dugong dugon)

Amanda MacNeill 1; Michael Belanger 1; Dr. Carin Wittnich 1,2

(1) Oceanographic Environmental Research Society, 12 Burton Avenue, Barrie, Ontario L4N 2R2, Canada

(2) Department of Zoology, University of Toronto, Toronto, Ontario, M5S 1A8, Canada

Increased industrialization and urbanization are key factors in the accumulation of various pollutants in oceans. This can result in the death of coastal seagrass beds, the primary sustenance of the dugong, leaving less food for them to feed upon, and potentially affecting their mortality rates.  As pollutants can enter waterways indirectly via rainfall run-off, in addition to direct sources like industrial effluent, the question of whether rainfall could be used as a predictor of dugong mortality was investigated. 

This study focused on comparing dugong mortalities versus rainfall in Queensland, Australia over the period of 1996-2004 using data obtained from the Australian Government Bureau of Meteorology and the Queensland Government Environmental Protection Agency. 

During 1996-1998 and 2003-2004, both inclusive, mean annual rainfalls were 520.9 ± 48.1mm and 499.4 ± 17.7mm (mean annual rainfall between 1996 and 2004, inclusive, was 530.230 ± 103.470mm).  Dugong mortalities had a mean value of 34 ± 2.6 and 37.5 ± 0.7 over the years of 1996-1998 and 2003-2004, respectively.  In 2000, rainfall peaked at 727.3mm, with a concurrent rise in dugong mortality to a total of 83.  Data pertaining to annual mortality were correlated with annual rainfall using linear regression analysis, and showed a strong direct correlation and statistical significance (R=0.702, P=0.035).  

This data shows that increased rainfall mediates increased dugong mortality by transporting pollutants to the waterways.  This may prove useful in forecasting when dugongs may experience highest mortality rates, and should stimulate interest in years where rainfall is expected to be high, allowing for assistance programs to help dugongs survive during these times or for institutes to promote training programs for the public to assist in dugong death prevention.  Furthermore, measures should be taken to lessen the impact of industrialization/urbanization and its accompanying stressors.

Presented as an oral presentation at the inaugeral EchoHealth One 2006 Conference