It's our favourite time of year again... cuttlefish season! Once a year, just metres from the shore at Stony Point an iridescent mass of over 200,000 majestic and highly intelligent Australian giant cuttlefish (Sepia apama) congregate to mate and then die. Discovered by divers in the late 1990's, this location is the only place in the world cuttlefish are known to aggregate in such large numbers. This unique gathering every May-August is linked to the optimal rocky reef habitat which provides suitable crevices and caves which protect their eggs.
|Cuttlefish congregate to breed from May-August each year 📸: Catherine Larkin|
AusOcean in partnership with Whyalla Secondary College deployed a research buoy (Rig) built by students as part of AusOcean's school program Network Blue. The purpose of this rig is to monitor the cuttlefish by collecting video data and environmental data such as sea surface temperature (SST), salinity (concentration of dissolved salt) and dissolved oxygen (the amount of oxygen that is present in water). The aim of this project is to collect continuous long-term data which may help researchers understand why cuttlefish numbers can fluctuate so dramatically each year. In particular, water temperature and salinity may play a key role in influencing population numbers.
|Floating Rig at Stony Point 📸: Catherine Larkin|
The Rig is equipped with network communications which sends the data in real-time to the cloud, where it stored and shared. Students login to AusOcean's data store where they can view, export and analyse the data. Students can also watch the underwater live stream to view the weird and whacky behaviour of cuttlefish whilst they mate, fight and impressively change colour.
Like all of AusOcean's technology, this set-up utilises low-cost hardware and open source software. On the surface sits the Rig which is connected to two concrete mooring blocks. The camera cable in conduit runs down the mooring line and 20m across the seafloor. Garden pavers with hose clamps are used to secure the conduit to the seafloor and the camera is attached to a steel bar with a PVC pipe saddle clamp.
|AusOcean's low-cost underwater camera deployed at Stony Point|
📸: Trek Hopton
Cuttlefish hanging out on paver
📸: Trek Hopton
The live stream is available most days during daylight hours on the AusOcean YouTube channel. The cuttlefish aggregation is truly one the world's most exciting marine spectacles. Braving the chilly waters is a worthwhile endeavour to get up close and personal with these mystifying creatures.