Estuaries are among some of the world’s most productive environments. They sustain organisms in many of their life stages, serve as migration routes and form havens for a multitude of species. Estuaries are also highly sought-after places for humans to settle. Unfortunately, this increasing concentration of people is upsetting the natural balance of estuary ecosystems and threatening their integrity.
Whilst estuaries are traditionally rich in nutrients, they are not capable of dealing with the increase of nutrients and pollutants brought about by human development. Whenever there is human activity, there is a potential source of pollutants. Estuary pollution is generally divided into either point of source pollution or non-point source pollution. Point of source pollution describes pollution that comes from a discernible source, such as industrial discharge or waste water treatment plants. Normally there is a pipeline, channel or obvious discharge point. Non-point source pollution, on the other hand, comes from a variety of sources and don’t have a singular discharge point. Examples include runoff from urban areas into storm water systems, agricultural runoff, fertilizers, phosphates in washing powder and/or faulty or leaking septic tanks. The nutrients work their way down the landscape and over time collect within the estuary. This build-up of nutrients and pollutants are exasperated in estuaries when their mouth stays closed for long periods of time.
This build-up of nutrients can cause eutrophication. Eutrophication is a problem within estuaries as it can cause excessive algal blooms with consequent algal overload. Under certain conditions these blooms may die, decompose and produce an offensive sewage-like smell. Algae are vital to the ecosystem and to many lifeforms in it, but when it becomes excessive it can be a big ecological and socio-economic problem.
In the Great Brak River Estuary, when we see and smell vast areas covered in algae, there are often calls for water to be released from the dam in efforts to flush away the problem. These efforts will never bear fruit as it does not address the causation of growth, neither does it limit emissions of nutrients and pollutants at their source. Nor does it address the fact that the million cubic litres of water allocated for release, by the dam for environmental purposes, is not enough to provide the scouring effects needed to scour the estuary bed of the built-up algae spores.
If we are to better understand the algae growth within Great Brak River we would be wise to address our own inputs as we could be very well exasperating the situation by literally feeding a growing beast, whilst simultaneously expecting it to go away.
