Coral Reef Ecosystem Health Study in Emily Bay and Slaughter Bay 2022

During April the visiting team of Marine Scientists have been snorkelling in Emily and Slaughter Bay as well as Cemetery Bay, conducting a study of the reef health. They have collected water samples and surveyed the reefs with underwater cameras and remotely operated vehicles (ROVS). They have monitored and observed the effects of coral bleaching from a recent years and the coral health and or disease and algal cover as indicators of the health of the corals in Emily and Slaughter Bay.

This research will provide an important record of the health of the unique coral reef ecosystem on Norfolk Island and the diversity of marine life in the Norfolk Marine Park. The research team shared some of the early result of this important project with the community at the public presentation on 21 April 2022. The public talk included information on reef health, coral disease, water quality and the importance of sea urchins and sea cucumbers on reef health.

Bill Leggat and Troy Gaston are from University of New Castle. Bill spoke about the studies of water quality, the water flow and lagoon outlets, the increase in nitrogen in the lagoon since the recent heavy rain and the swamp water had flushed into Emily Bay. He also compared the data between the bays and to previous visits. Bill also show images of the red algae growth on the coral and the green sea grapes. This is concern as it is spreading very quickly and normally will kill the coral or plants which it covers.

Jane Williamson, from Macquarie University spoke about the importance of sea urchins “wanna” and sea cucumbers. These sea creatures keep the coral lagoon healthy, they filter the sand, and they also will consume the unwanted algae. Jane spoke about their importance and the value every creature in the lagoon as they play their part of supporting the coral reef.

Tracy Ainsworth from University of NSW spoke about the coral and marine environment. Her study has been surveying the amount of coral and types of coral and which ones are more vulnerable and others that have been less effected by the recent year’s environmental stresses. She has also gathered information from the plates which were put in the lagoons on concrete blocks. It was sad to see the Kingston lagoons are did not grow as many young corals as Cemetery Bay, also it was surprising that the data from the surveys showed that there has been a decrease of corals in Slaughter Bay. Charlotte Page from University of NSW has also been busy surveying the reef and we thank her from her excellent data gathering.

Jim Castle, Norfolk Island Marine Park Team spoke at the presentation, which was held in a tent at Emily Bay in the public picnic area. PJ Wilson also spoke about Norfolk Island water quality and new policies regarding sewerage systems which are being introduced to preserve underground water quality and the effects on the Norfolk Island water ways and the Kingston swamp and lagoons.

Questions from the public at the meeting showed concern about the swamp water entering Emily Bay, and questions why the swamp had been blocked off and maybe the possible build up in the swamp is worse on the lagoon than a slow and steady flow. These questions do not have easy answers, it must be better not to have any polluted water or water flow high in nitrogen entering the fragile lagoon. I am sure there will be more studies comparing our lagoon with other lagoons which have also had similar issues and hopefully find a way to reduce the red algae on the reef.

I have met Bill and Trace and their team during their previous visits to Norfolk Island, and this is their 5^th time they have spent time here studying and surveying the Kingston lagoon and reefs. They have said that Norfolk Island has some of the best coral they have seen, we compare to outer areas of the Great Barrier Reef. It is not common to have such high-quality coral reefs on the shoreline, normally they have to travel my boat to access areas with ecosystems like our lagoons.

As marine scientists they teach and as well as study coral and marine areas. They have taught me that the infected corals, sometimes can be seen with black or white bands where it is being overgrown or the tissues dies, and the skeleton of the coral is exposed. It is interesting to read that some diseases can be seasonable and hopefully the coral bleaching is only temporary. Bleaching can break down the corals and turns white and seen in pinks and blues. When there are changes in the environment, the coral can become stressed and vulnerable to diseases and infections.

Bill and Trace have taught me about the coral and what to look for if the coral is under stress, such as bleaching, algae, diseases. Since the recent drought and global warming events, the coral in our lagoon had coral bleaching in 2020 and since then there has continued to be signs of stress. This summer some areas were once again turning white, and this was outer layers of the coral dying and exposing the under layer of the coral skeleton. These events spread quickly in some of the corals in Emily and Slaughter Bay and the corals appeared to die and a algae (red algae) took over these areas of the reef. Bill explained the high levels of nitrogen in the lagoon promoted the growth of the algae.

The health of the coral is the focus of their study, and the reef structure and the general health and comparing different areas of the coastal zones. When there are changes in the environment, the coral can become stressed and vulnerable to diseases and infections. It will be interesting to read the results of their monitoring and the comparison to previous years and future years.

Trace, Bill, their family and research team have now returned home to NSW and plan to return later in the year. They have asked local snorkelers to photograph some of the reef areas and they hope to set up a Facebook page to post images of these coral reef areas. I will always be keen to be a citizen scientist.

Thank you to the Marine Scientist team, Bill, Jane and Trace and locals Jim and PJ for organising the presentation. Thank you to the local members of the community who attended and shared their support, knowledge and questions.

Betty Matthews
April 2022