Port Noarlunga, South Australia's Journal

Yesterday the Port Noarlunga project shot past another milestone: 1500 observations! The most recent batch was a set of photographs I took back in 2015 when I was just a very occasional visitor to the reef. On closer inspection of the images, I found a couple of nice surprises... one was a St Vincent's nudibranch crawling onto a Euryspongia sp. sponge, and the other was a Dusky morwong with what looks like a Western cleaner clingfish attached to its flank... probably providing the service it's named after.

In terms of exploration effort, you'll see some more data points have been added for the reef's southern section, and there are more to come. The southern section of reef is rewarding to explore, particularly for a snorkeler, as it is generally shallower than the northern section (as one might expect, being nearer to the mouth of a river). If the depth profile has changed in recent times, it would be worth investigating flooding events to cast possibilities about the timing of major silt-dumps.

The main frontiers as I see ahead for exploration and discovery on the reef now would appear to be nocturnal (many otherwise rarely seen crustaceans, molluscs and echinoderms become active at night).. and sightings from the deeper, darker grottos of reef wall. The reef's boulderous structure creates a multitude of shaded areas of various size, many of which would require a diver to access, and ideally, nice bright video lights (given than the northern section of reef can b 7m+ to seabed).

Our species count has gradually increased to 274, with sponges and alga being the least resolved groups. Another great thrill of the week past was the observation of a sub-adult Western blue groper (possibly two similar aged individuals, or one individual observed twice) on the outer wall of the reef, south of the jetty. As you're probably well aware, these are slow-growing, site-attached fish that are protected by "no take" status in both SA gulfs to aid their recovery.

Thanks to everyone for their contributions to their project, including all the taxonomic discussions as we try to make sense of the less studied (in recent times at least) groups of organisms.

The Port Noarlunga project is charging ahead, and just today leaped past our 300 species milestone. The leap followed a substantial extension of the boundary of the "Onkaparinga river estuary"... one of the two "Places" that combine to form the total project area. The extension captured for the first time, observations made from beyond Port Noarlunga proper, including the wetlands, banks and oxbows of the river, all the way up to Old Noarlunga. Taxa include fishes, birds and marine invertebrates.

Anyone would be forgiven for thinking at a glance that the boundary extension was a case of boundary creep gone mad, but the decision to extend upstream was carefully considered. Firstly, I sought local knowledge about the extent of saltwater infiltration upstream, and was told that the salt water reached as far as Old Noarlunga. I tested this by making several visits, where I observed barnacles, mussels and sea snails living in the intertidal zone, and tasted the water and determined that it was indeed closer to sea water than fresh. I then referred to a recently-acquired book entitled "Port Noarlunga - An endearing coastal town 1840-1998" by Lisa Martella, which states that "the Onkaparinga estuary extends 10.5 kms inland from the sea at Port Noarlunga to a deep pool or oxbow lagoon adjacent to Old Noarlunga township."

Meanwhile, the recent spell of hot weather is making night snorkeling ever more appealing, though explorers need to be mindful of Jimbles (box jellyfish) which feed at night near the water's surface, typically over sandy bottom. Dropping onto the reef from the jetty is a good strategy for avoiding these, or entering the water from the jetty's midway stairs. The seaward end set of stairs that was lost in a storm in late 2018 is due for replacement in February 2020.

Personal highlights among recent observations and identifications include @cobaltducks records of various birds upstream, a delightful encounter with a Western blue groper on the northern outer wall of the reef (still awaiting uploading), and a nocturnal sighting of a Cobbler wobbegong made on the inshore limestone shelfing reef. Special thanks also go to @marinejanine for digging through her archives and adding a few more invertebrates to our ever-growing catalog of local life.