Some Like It Hot

I decided to take a few months off from journal posts as we plodded through the depths of the winter weather doldrums, and hence fewer opportunities for the amazing citizen scientists supporting our Marine Biodiversity of Southern Sydney Harbour project to get into the water and photograph plants and animals. In personal news, my wife and I welcomed our first child into the world at the end of September, and so available time has gotten precious indeed!

I just thought I'd kick start my monthly musings with a post about what to expect in Sydney Harbour early in 2025, prior to me restarting the "Observations of the Month" journal posts that coincide with increased photo submissions on iNaturalist in the austral summer. It would appear that large pockets of the NSW coastline are likely to experience marine heatwave conditions this summer, which is defined as an extended period of unusually warm water in a region, and here we are referring to SE Australia. As might be expected, prolonged temperature increases facilitate the incursion and successful recruitment of plants and animals from the tropics, as well as the gradual decline or displacement of some temperate species. These marine heatwaves have now become so common place, and are of great concern, that our primary state monitoring agency, NSW DPIRD, developed a Marine Heatwave Response Plan in 2023/2024, complete with warning, assessment, response, and communications. Moreover, this recently published scientific paper in the journal Oceanography provides a comprehensive picture of these responses across our countries marine estate. Suffice to say, as you dip back into Southern Sydney Harbour this summer, eyes peeled and cameras armed to capture records of anything unusual or exceedingly rare. Much like the Bluespine Unicornfish or Naso unicornis that I photographed in Parsley Bay at the end of summer in 2022, there will be plenty of tropical fish species taking a one-way trip down to Sydney Harbour in early 2025.

This journal post was written by project leader and iNaturalist member, Dr Joseph DiBattista.