Is the East Australian Current causing a marine ecological hot-spot and an important fisheries near Fraser Island, Australia?

Abstract

The distributions of chlorophyll-a (Chl-a) blooms near the Fraser Island continental shelf along the east coast of Australia were analysed for the period 2002–2012. The blooms were found to exhibit two distinct quasi-climatological patterns. The first pattern was a broad near-coast mid-shelf distribution that prevailed from about March to July each year. The second pattern was established due to re-occurring outer-shelf Chl-a blooms southeast of Fraser Island from about August to February. The outer-shelf Chl-a bloom concentration maxima appeared to be higher than those associated with the near coast pattern. Both distributions were found to be characterised by significant year-to-year variability in the number of total blooms, the length of blooms and the Chl-a bloom concentration maxima. The physical cause of the outer-shelf Chl-a concentration maxima was of particular interest, since this location overlaps with a region previously identified as a key eastern Australian marine ecological site and important fisheries. In this analysis, we found that the area also overlaps with a hot-spot in EAC-generated bottom layer stress, which appears to be the main driver of the “Southeast Fraser Island Upwelling System”.