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The Port River Estuary and Climate Change
As a biology class, we recently got the opportunity to visit the Port River Estuary: an interconnected system of tidal creeks and channels that open up into the Gulf St Vincent in South Australia. The estuary consists of brackish water; water that has a higher salinity level than fresh water, yet less than ocean water.The Port River estuary is a biologically diverse aquatic ecosystem, supporting extensive mangrove stands, saltmarshes and sea grass beds. This provides varied habitats for many species of birds, fish, crustaceans, other marine invertebrates, dolphins and seals- thus making the estuary an important natural asset. This environment supports a diverse array of wildlife, however, it is also home to a number of large industries, including coal handling facilities, cement works, electricity generating plants, salt harvesting, boat building facilities, sewage treatment plants, chemical plants and waste management sites.
The banks of the estuary are largely industrialised and have some of Adelaide’s wharves bulk cargo and container handling facilities, although there are some remnant mangroves. One of its main attractions other than transport is the Port River dolphins, which are the only wild dolphins in the world that live within a city.
The Port River Estuary is a vital part of the natural vegetation. It is an extremely important part of our local environment, allowing us to understand the impact of climate change within our own community.
Importance:
The Port River estuary environment is an essential feeding, breeding and nursing area for many commercially important fish and crustacean species. These include King George Whiting and Blue Swimmer Crab. A wide range of industries within the area, including important fisheries contribute approximately $100 million per annum to our State economy. However, these fisheries are threatened by pollution. If the pollution levels continue to increase, detrimental environmental effects will occur. The most pressing would be that the wild life and fish will die out in unstable conditions. Therefore these fisheries would stop working, as a result costing the state millions and having drastic effects on the environment.
Where Have The Mangroves Gone?
The Port River Estuary used to be a mangrove territory. However, the majority of them were removed for industrial development, for boat ramps, housing to name a few. Elevated nutrient levels from sewage, industry and storm water discharges often cause the growth of large drifts of algae, such as Ulva. Ulva prevents the establishment of young mangroves and chokes established trees by smothering and eventually killing their aerial roots. Trampling of mangrove seedlings and aerial roots by recreational fishers looking for bait in the mud is also a problem and has caused the mangroves to die out. Thus the majority of the mangroves have disappeared and only a small section remains in the area.
Factors affecting the river: Resulting in pollution
The mangroves in the Port river estuary have been severely altered by coastal development. As a result there is increased sedimentation associated with coastal strip development such as, contamination of marine sediment by heavy metals from factory work, as well as sewage discharge.
The water quality and ecology of the Port River Estuary have been affected historically by Adelaide’s industrial and urban development. Dredging has created deep channels for shipping, and extensive areas of vegetation, including saltmarshes, mangroves and seagrass, have been removed. Wastewater treatments and Penrice Soda outfall discharge large amounts of chemicals and nutrients into the estuary. The estuary is also used by power stations for cooling purposes, adding thermal pollution to the estuary. Additional pollution is due to building and maintenance of ships and slipways around the estuary. Storm water flow into the estuary is often contaminated by organic waste such as animal faeces, leaf litter and lawn clippings, industrial runoff, rubber, oil, lead, copper and zinc from motor vehicles. This alters water movement and salinity, and increased pollution in the estuary. Nearing part of the Port River is one of Adelaide's active landfill sites, which causes toxins and rubbish to be blown from the deposit site, into the river, infects the wildlife. Furthermore, the toxins and chemicals washed down our drains every day reach their final destination at the Port River, before being drifted out to sea. As a result of all this the temperature of the water and salinity levels are increasing and could result in grave circumstance on the natural ecosystems.
The natural ecosystems that are vital to the environment are being damaged, namely the dolphin population and fishery. The wild Dolphin population in the estuary is declining due to viruses from the unnaturally high temperature levels in the waters. This temperature increase is not only due to the waste expelled from the surrounding factories, but also the devastating result of climate change.
My reflection:
The Port River Estuary is an extremely important part of our environment, and allows us to understand the impact of climate change on a local level. We have been polluting the Port River estuary for many years and, even if we could prevent all pollutants from entering the estuary, it would still take time to recover. Nutrients and metals stored in the sediments and the historical loss of seagrass and mangroves will continue to impact on the estuary’s water quality.
Whilst on the cruise, I found that it was a shocking experience to see the stark contrast between the natural mangrove reserve on one side of the river, to the hugely industrial factories on the other. It was a true representation of struggling nature juxtaposed against the iron fisted man-made economy. People forget that the industrial areas are there. They forget that those factories spewing out pollution and chemicals are what keeps a city running. People also forget that the simple things that we take for granted such as electricity, hot water, sewerage, rubbish disposal and the food that we eat- essentially all the things that create the blissful comfort of human life possible also damage the world and contribute to climate change.
Therefore change is needed. It appeared on the cruise that the people in charge of the area are trying their best to preserve the important natural reserve but fail to realize that what they do elsewhere will effect it. We have been polluting the Port River estuary for many years and, even if we could prevent all pollutants from entering the estuary, it would still take time to recover. Nutrients and metals stored in the sediments and the historical loss of seagrass and mangroves will continue to impact on the estuary’s water quality.
However, I believe that things can be done to help protect the environment. It would be beneficial to keep industrial rubbish producers away from rivers, as it is the rivers who provide all humans, animals and plants with food. If this is polluted, then it is most likely all life will be affected, showing the necessity of this problem. Restoration of the mangroves is also needed, to restore balance to the natural ecosystems.
