Reef Report for Friday, April 8, 2016
Soil Conservation, an extremely important part of effectively protecting the Great Barrier Reef
In most coastal communities worldwide folks have a pretty clear understanding of the connection between urban and agricultural runoff and its impact on the ocean. Everywhere you go you can see stencils on suburban street drains that remind us of this connection.
That even extends to agricultural chemical use, as the agricultural industry worldwide is under pressure to reduce the runoff of fertilizers, herbicides, and pesticides into waterways, and the scientific evidence is piling up on the impact these chemicals have on ecosystems if they leave the farm in runoff.
The scale and impact of soil erosion on the Great Barrier Reef is only now being more understood, and the size of the problem and challenges to solving it are significant.
During heavy rainfalls many of the rivers in Queensland run brown or red with suspended soil particles, the color depending on the soil type in the river catchment. Some erosion is natural, but grazing, agricultural, and construction practices have increased the amount of soil erosion significantly in the past 100 years.
The soil as it washes in to the ocean alongside the Great Barrier Reef has a number of effects. Erosion is connected with increased survival of Crown of Thorns starfish, which eat coral. Silt blankets coral and seagrasses, and puts them under stress by reducing the amount of food they can make through photosynthesis.
This soil is also lost to the land it came from, reducing the fertility and productivity of the land, not to mention the soils ability to store carbon.
Queensland has large expanses of sodic soils, which are very fragile and highly erodible once disturbed. These soils are not very fertile, and with a bit of disturbance from construction, overgrazing, land clearing or plowing become highly erodible.
Preventing soil loss is a lot easier and less expensive than fixing large scale erosion problems. One of the challenges that Australia faces in itís plan to protect the Great Barrier Reef is to meet the stated targets for the reduction of soil and silt in the runoff that flows in from adjacent lands. This will be a case of fixing, and will cost millions and millions of dollars, probably far beyond whatís currently budgeted. In some marginal lands the cost of fixing the problems caused by land clearing, grazing, agriculture, and construction will far outweigh any profits ever made by the economic activities that increased erosion from itís natural rate, with the fix paid by the government, not the enterprise involved.
'A line of dump trucks from Perth to Sydney and back again': How sediment is killing the Great Barrier Reef
Queensland land clearing is undermining Australiaís environmental progress
Eyes down: how setting our sights on soil could help save the climate
Federal Environment Minister Greg Hunt launches investigation into Gulf Country land-clearing claims
The weekly reef report is written by Joel Groberg of DiveTheReef.com,
who compiles them from the many conversations he has with dive staff in the area, as well as† many other local sources in the dive
Index of all reef reports.