The Sydneysiders Who Live Below…

Growing up near Sydney – Narrabeen to be exact – I (the writer of this post) often spent my weekends enjoying inner-city adventures, hopping on and off ferries along Circular Quay and Manly, being mesmerised by the features of Darling Harbour, begging my Dad to take me to Taronga Zoo (I really love that place!) and generally spending quite a lot of time near, on and sometimes even in the waters of Sydney Harbour.

Of course, I knew this huge expanse of water had living creatures in it, just like any body of unpolluted water. I attended plenty of school excursions to the local aquariums, the Australian Museum and other places that were meant to educate me on these things; however, despite this, I never realised just how full of amazing life Sydney Harbour really is, until now, and I certainly didn’t realise it has been named as one of the world’s most biologically diverse harbours!

Back in 2013 (yes, old news, but new to me), five Australian Museum scientists analysed the vast collection of species, which had been gathered from in and around Sydney Harbour over the last 150 years. These collections include genera of worms, molluscs, echinoderms (star fish, sea cucumber, sea urchins etc.), crustaceans and fish. Out of these genera alone, it was found that there were over 3000 species. Three thousand! That means that there are 3000 different types of worms, molluscs, echinoderms, crustaceans and fish, all with their own little groups, swimming, crawling, eating, sleeping, mating – and whatever else sea creatures do – right below our feet, whenever we set off on a cruise along the Harbour.

Besides discovering there were many more species than anyone imagined, the scientists also found that the waters of Sydney Harbour actually contained higher numbers (two to three times higher) of polychaete, mollusc and crustacean species than the surrounding estuaries. This is thought to be occurring because Sydney Harbour has more diversity in habitats and a more significant tidal flushing than the nearby Hawkesbury River, Botany Bay and Port Hacking estuaries.

Another interesting thing about these findings is that they don’t even include the full range of Sydney Harbour’s genera. Nor did the research expand into all areas of the Harbour, with the upper Middle Harbour being unanalysed, as well as some of the deeper Harbour troughs. This means there may be thousands of other related wildlife types under that very famous sparkling vista, including (but certainly not limited to) corals, sponges, ascidians (sea squirts) and mammals. With all these amazing and very important species right under our rudders, we don’t know how Mother Nature managed to fit the water in!

At Sensational Sydney Cruises, we love our gorgeous waterway, so we endeavour to use environmentally friendly practices whenever we take our passengers out on the water. You can do your part to help too, by not littering, not pouring pollutants, household cleaners and other chemicals down drains and by having a continuous awareness of the fragility of our Harbour’s Eco-system. If you come across a species that you think may be rare or unusual while enjoying the Harbour, you can photograph it (but don’t try to catch it) and report it to the Australian Museum. We feel blessed to live and work on such an amazing harbour!