Australia has long been known as a land of contrasts. This has never been demonstrated better than in
recent years. Throughout 2018 we
have been inundated with unusually disastrous
or cataclysmic natural events, drought, storm and fire that exceed cyclic expectations.
We learn about these shattering news events from a land-based perspective however little perspective is provided as to the effects on our coastal waters in the aftermath other than the occasional aerial footage. There is no easily available information to holistically
explain what happens in the ocean and yet the
effects of almost everything that happens on the land has a large impact on the health of the
ocean. We can infer that major events may have massive impacts.
Storms
Extreme weather can be devastating. Each drop of rain is an
explosion hitting earth. Raindrops pummel and scour the land during any storm but even more so during extreme events. The
aftermath sees trees down, crops ruined, debris across flooded roads, severe erosion, animals and plants in
shock or dead.
Waterways and drains become clogged thoroughfares for debris, sediments, and poisonous chemicals, dragged downward by gravity until the
water can go no further. All of those watery passengers can be classed as
natural debris or non-natural pollution.
Any keen snorkeler, diver or surfer can tell you that the water is much
cleaner and clearer during times of drought and that storms following a drought
make it much harder to know what is in the water. In fact shark experts
pointedly advise against swimming near murky stormwater outlets, streams or
rivers following bad weather as opportunistic sharks will be looking for quick
snacks in stormwaters.
Drought
Plants hold the land together with their roots, when removed the dirt
particles shift and move easily with wind and water causing severe erosion. Storms
can pull riparian vegetation away to cause erosion however drought is also the
cause of erosion as plants to die of thirst and lose their grip on the
soil.
Fire
Thunderstorms bring not only the threat of flooding but also lightning strike and fire. When a fire devastates the land, as it has around
Australia this past year, plants die, cinders and smoke are lifted into the air and deposited surfaces everywhere i.e. forests, paddocks, buildings, roads, roofs. The wind and rain eventually wash those deposited chemicals and particles into the nearest river, stream or drain. Affected waterways carry a higher concentration
of contaminants from the catchment in disaster run-off. The waterway becomes a poisonous highway straight down into the ocean, poisoning and smothering inhabitants.
Land changes
What is the ripple effect from fierce disasters like
drought, storms and forest fires and how do they affect the health of our ocean
territory (200 nautical miles surrounding Australia). Perhaps an equally telling question is what
happens to us if our ocean is unwell, corals die, fish numbers drop, turtle and
iconic species are lost or ecosystems fail?
The easiest example relates to the erosion of sediments carried
downstream. The bigger the storm, the greater the pollutant load down the
rivers and creeks.
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| "Moreton Bay Seagrasses" brochure by UTC |
Seagrasses, which are true plants and prolific food
factories can be smothered by dirt particles. Without light they cannot
photosynthesize and die. Without seagrasses whole ecosystems can collapse and a whole range of animals including commercially important fish species are badly affected. Corals suffer also.
Australia is unique. Unlike the northern hemisphere, this island continent is built on a low nutrient system. That means less of one kind of thing but lots of smaller numbers of many
different living things to form a viable web of life. Owing to the fragile
nature of our ecosystems we now know that Australia has one of the highest
extinction rates[i].
Population
Where people are the land is changed by how they use it,
farms, towns, industry and even tourism. The number of people living in this
breakable landscape has been growing astronomically, as it has across the
world. in 1950[ii]
the population was 8.2 million people and it increased more than 25% by 1960.
Between 1950 and 2017 the numbers are staggering, increasing to 24.7 million
increasing more than 200%[iii].
The more of us there are the greater the land changes the
greater the impact on the health of our seas and ultimately our own. Are we
trying to understand how to find a sustainable balance?
REFERENCES:
[i] https://www.abc.net.au/news/2015-08-19/fact-check-does-australia-have-one-of-the-highest-extinction/6691026
[ii] https://www.populationpyramid.net/australia/1950/
[iii] https://tradingeconomics.com/australia/population
www.ausmepa.org.au
