Reef Report for Tuesday, April 1, 2008
Rain, Runoff, and Oceans
What ends up on your lawn, street, and local farms ends up in our Oceans
Rain is a pretty amazing event to folks like me, who grew up in a very dry region of Southern California. Rain falling in great quantities is even more amazing, and after moving here to Far North Queensland I have learned first hand about rainfall.
For March of 2008 our rain gauge recorded 763mm (2 Ĺ feet) of rainfall.
Locally thatís not even newsworthy, as the small town of Tully recorded 1131mm (almost 4 feet!) of rainfall over the same time period.
That much rainfall does cause flooding, but in the far north of Queensland weíve managed to avoid serious damage. The highway was closed for a day or two, and people largely go about their business, just with an umbrella and damp shoes.
Dive conditions are affected by rain, as flooding rivers carry silt into the ocean and can push it out onto the reef, reducing visibility from our usual 15-25 meters to less than 10 meters.
More important than the impact on visibility is the impact of runoff from agricultural and urban areas on the Great Barrier Reef, and in fact on ocean ecosystems all over the world.
Just google "Urban Runoff." or "Agricultural Runoff" and browse through the thousands of results. In some areas these two forms of pollution are the major sources of pollutants in nearby marine ecosystems.
One website we ran across (for a city in California) put it in words in a simple and understandable slogan: "The ocean starts at your front door." How true is that?; anything that you spray on your lawn, pour down the storm drain, and that your car drips onto the street ends up in the ocean. Anything washed off of construction sites and farmlands ends up in the ocean.
At first glance the amount of drainage off your driveway and yard does not seem like much, but think about the total area of gardens, farms, streets, parking lots and other areas in your home region and it starts to add up to a significant amount of area, runoff, and pollution to local waterways.
Here along the Great Barrier Reef the big concerns are over chemicals that act as fertilizers for algal growth. (mainly chemicals and materials that contain Nitrogen, Phosphorus and Potassium). Algae compete with coral for space and light on the reef, and anything favoring their growth can be at the expense of coral growth.
Itís also been found that certain agricultural chemicals, especially herbicides, can be very toxic to the early life stages of corals. While the impact of these chemicals on the Great Barrier Reef has yet to be measured, Scientists are very concerned over the issue, and the Queensland government is working with farmers to use these chemicals in smaller quantities, and in ways that reduce the chances of them washing into the ocean.
So if the ocean starts in your front yard what should you do? For a start, reduce the use of toxic chemicals in your home. Anything that ends up going down the sink, the toilet, or washing off your garden ends up in the ocean. Why not choose household cleaners that are less toxic, garden organically, and reduce the amount of herbicides and fertilizer you put on your lawn? Doing so saves the ocean, saves you money, and likely is healthier for your and your family.
Queensland Rainfall Map, from The Bureau of Meteorology
Runoff Threat to the Reef, from The Age
Fertilizer runoff impacts waterways in the USA., from Scientific American
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.