So what exactly is the impact of flood water on on these two unique environments? Well, based on previous flooding events in the region, it is anticipated that there will be substantial impacts on seagrass meadows and inshore and fringing coral reefs. Those species that are reliant on seagrass as their primary food source, particularly green turtles and dugongs, are likely to be affected in those areas exposed to significant flooding. Previous flooding (Cyclone Yasi, 2011) saw a dramatic spike in the mortality of both species in the GBR. There is likely to be a time-lag of weeks to many months before, very sadly, we start to see these animals starving and dying.

In addition, floodwaters (literally) 'muddy the waters'.  “In years with much monsoonal rainfall, large fresh water flood plumes carrying sediment, nutrients, other pollutants and debris from the mainland enter the coastal zone and may reach out to the outer reefs of the Great Barrier Reef

threatening vulnerable corals”…"Flood plumes can have a number of effects on coral reefs. Large scale flooding can carry land-based pollutants such as insecticides, fertilisers and herbicides out to the reef. Fresh water can kill corals at shallow depths where mixing is low, and sediment in the water blocks light which the coral needs to survive." - Australian Institute of Marine Science

Previous flooding has also seen chlorophyll plumes (phytoplankton responding to the extra nutrients in water) flowing across the continental shelf and into to the Coral Sea. Of this current flood, researchers have stated that the run-off is flowing as far as outer-shelf reefs 60 kilometres from the Queensland coast.

All this, on a reef system already weakened by increasing sea temperature, pollution and Crown of Thorns Starfish.. leaving it more susceptible to stress from flood plumes.

Is all of the above definite? We won’t know for sure the full effect of the current flood situation, but past inundations indicate that it’s not just humans that have a long recovery ahead.  With so many of the world's coral reefs degraded and/or dying, we can only hope that the flood debris does not linger too long nor damage too much, of the single largest reef system in the world.

(PS: On the upside… the monsoon brought with it some high cloud cover over and an influx of cooler water, which will provide a cooling effect and is likely to help mitigate the threat of any mass bleaching from thermal stress. Thank goodness for silver linings..)