Marine Biodiversity of Southern Sydney Harbour's Journal

The results are in!!! I am excited to announce that we have now completed our environmental DNA (or eDNA) seawater sampling at Parsley Bay (Vaucluse) and Camp Cove (Watsons Bay) for the Marine Biodiversity of Southern Sydney Harbour project. This represents 13 months of sampling at both sites. As mentioned previously, eDNA can be thought of as genetic “breadcrumbs” left behind in the environment that can identify every living thing, from microbes to mammals. This was all thanks to DNA sequencing provided by our friends at Wilderlab in New Zealand (https://www.wilderlab.co.nz/). Feel free to look through the "explore" tab on their webpage to view our sampling data populated on their map. Also feel free to view all the amazing flora and fauna that were detected at each of these locations.

Based on the “Wheels of Life” you see here constructed for Parsley Bay and Camp Cove, we detected 133 and 150 species of fish (with approximately 77% faunal overlap), respectively, with a number of cryptic species detections as well as detections of commercially important species. Almost all the usual fishy suspects were well represented (bream, goatfish, kelpfish, leatherjackets, longtoms, morwong, mullet, snapper, whiting, wrasses), with some of the more interesting detections including at least seven species of weedfish (Heteroclinus sp. and Cristiceps sp.), seahorses (genus (Hippocampus), at least two species of pipefish, a butterflyfish (Chaetodon flavirostris sp.), moray eels, at least six species of ray (including an eagle ray), a blind shark, and even mahi-mahi. We also detected 43 mollusc taxa at each site (including chitons, clams, cowries, limpets, mussels, nudibranchs, oysters, periwinkles, sea hares, turbans, warreners, and whelks); 31 and 23 worm taxa, respectively; 41 and 47 crustacean taxa (including amphipods, barnacles, lots and lots of copepods, crabs, and shrimps), respectively; 7 and 16 sponge taxa, respectively; 33 and 42 cnidarian taxa (including anemones, hydroids, hydromedusa, hydrozoans, snowflake corals, and jellyfish, including jellyfish blubber!), respectively; 6 bryozoan taxa at each site ; and 73 and 77 algal taxa (including brown algae, green algae, oyster theifs, kelp, seaweed, and sea rubber), respectively. These detections were in addition to hundreds of species of rotifers, fungi, insects, plants, diatoms, ciliates, bacteria, birds (ducks, gulls, shags, and teals), common dolphins (Delphinus delphis), New Zealand fur seals, humpback whales, two types of starfish (Astropecten sp., Parvulastra sp.), two types of sea urchin (Centrostephanus sp., Heliocidaris erythrogramma), three types of ascidian (Microcosmus sp., Pyura sp., and Styela sp.), two species of skink (Eastern Water Skink and Gully Skink, likely lounging on the adjacent shoreline), and unidentified penguins! These data will be used in a scientific publication under preparation, with your valuable iNaturalist observations used to ground truth our detections and put them into context. Thank you so much for your continued contributions.

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

We are forging ahead with the monthly photo submission competition with renewed support from Blue World, and so I'd like to congratulate user eschlogl for his Photo Observation of the Month of August of a White's Seahorse (Hippocampus whitei) from Parsley Bay. Erik’s amazing photo truly highlights the yellow to brown body colouration on this seahorse, the numerous pale flecks, and its ability to camouflage from predators. Typical of other seahorses, the female will transfer her eggs into the abdominal pouch of the male, where he will fertilize them, provide physical protection to the embryos, aerate them, and provide initial-stage nourishment.

The observation of this species is extremely timely in the conversation about threatened species and habitat restoration in Sydney Harbour, particularly with some of the upscaled restoration efforts being led by Project Restore based out of the Sydney Institute of Marine Science. Pollution, urban development (including the installation of boat moorings and anchors), and illegal trade are major sources of the decline of seahorses, though illegal trade is less of a concern in Australia. Indeed, the motivation behind the Seahorse Hotels we now see at select locations around NSW harbours was that severe storms, about 10 years ago, reduced the population in NSW by 90%. These storms shift huge volumes of sand, smothering the soft corals, sponges and seagrass that they associate with. More recently, in 2022, a one-in-100-year flood event nearly wiped out an already rapidly declining White's Seahorse population in Port Stephens. Based on this, any pollution spilling into the Harbour would be a threat to seahorses and the marine habitat that they depend on. All the more reason to protect the inner harbour ecosystem that hosts these endangered sea creatures in Parsley Bay from further construction and infrastructure projects.

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