Museum collections show us how diversely biodiverse Gamay (Botany Bay) really is

Savvy travellers will tell you that the best seat to sit in when you fly into Sydney is the window seat on the left-hand side of the plane. Why? To get the best views of the city and all her gorgeous waterways below, of course. Or was it the right-hand side?

Either way, while you’re cruising at semi-high altitudes, an entire weird and wonderful world exists below you (not Sydney itself, I mean underwater).

Gamay (or Kamay), also known as Botany Bay, is one of the most heavily modified estuaries in the world. The Gamay catchment, including the Cooks River and Georges River, houses Australia’s largest urbanised city, largest international airport, and international shipping port.

Throughout its industrial history Gamay has been subject to mass dredging of the seafloor, modifications to natural foreshores, and widespread pollution.

Despite the doom and gloom, Gamay still boasts many different ecosystems, such as endangered seagrass beds, rich mangroves and saltmarshes, sandy beaches and subtidal soft sediments, and rocky shores, and there is great potential to host a wide range of species.

The issue is, however, there is yet to be any study that documents this biodiversity. The Gamay catchment spans approximately 1,165km and species sampling across habitats would likely be a monumental task. So how can we find out what species reside in the bay? Luckily, the Australian Museum hosts a wide catalogue of specimens collected from Gamay, spanning back to 1860.

The museum has an electronic database that essentially catalogues all the specimens currently held along with key information, such as the collection location, habitat type and year. This enables research scientists to simply enter the longitude and latitude and compile a list of all specimens collected in that area, and method was used to help us understand the biodiversity of Sydney Harbour back in 2013.

Using the database we found an astonishing 10,985 records from Gamay. From these records, there were 429 distinct species of polychaetes, 580 crustaceans, 802 molluscs, 76 echinoderms, and 272 fishes. At least 57 species from these taxa were first discovered in the bay, though these numbers are likely to be higher as some records have only been identified to family or genus.

Given that each record lists the location it was collected, we can also map the distribution of species across the bay, so we can assess what habitat types may be under-sampled, or even help us identify specific areas of the bay that boast high species richness and require more robust monitoring or management.

Being a major international port, Gamay is always under threat from invasion risk. Records from 2013 show us that the European fan worm, Sabella spallanzanii, was identified from a wharf at Kurnell, likely unintentionally introduced through ballast water. Other invasive species have also been identified such as the Yellowfin goby, Acanthogobius flavimanus, European green crab, Carcinus maenas, and Mosquito Fish, Gambusia holbrooki. The invasion risk is always present, and many invasive species may still be flying under the radar.

This study shows us just how important museum collections are, not only for understanding what lives in the bay, but also helping us understand how both invasion risk and climate change can drive faunal changes. For example, the distribution of a species is likely to spread – or simply just change – as coastal temperatures continue to rise.

Knowing what has historically lived in the bay and what suddenly appears is crucial in understanding how climate change can impact coastal ecosystems.

Undoubtedly, the biodiversity we see is likely an underestimation as this study solely relies on material deposited at the museum. For example, common species from ecological studies in Gamay are absent from the database and even though they are clearly observed in Gamay, they are not included in our study. By highlighting the value of museum collections, we are hoping that this study encourages researchers to deposit their specimens. Not only are they permanently digitised but can then be referred to a physical specimen and aid further studies on the species.

Recently, a sea urchin species thought to be the invasive Tripneustes gratilla along the east coast turned out to be Tripneustes australiae, an endemic species recorded in Gamay back in 1978. A feat that may not have been possible without the AM collections. Taxonomic revisions and biodiversity studies like this show us how valuable museum collections are. There are still countless ways the museum collections can be utilised and hopefully this study encourages people to think about how museums can aid their research.

Sarah Whitehead, Honours Candidate, The University of Sydney in association with the Marine Invertebrates team, Australian Museum Research Institute

Dr. Pat Hutchings, Senior Fellow, Marine Invertebrates, Australian Museum Research Institute

Acknowledgments:

Maria Byrne, Emily McLaren, Shane Ahyong, Amanda Hay, Winston Ponder, Catherine Samways, Sally Reader, Talia Stelling-Wood, Helen Stoddart, Alison Miller, Ian Loch, Robert Dooley, Pauline Ross, and Tim Glasby.