Newsletter

The next meeting is the April General Meeting which will be held at the Conservation Centre, 120 Wakefield Street on Wednesday 18^th commencing at 7.30pm.

Ms. Pat Harbison will speak at 7.30pm. Her talk is titled "Gulf waters - detecting the threats". She will discuss monitoring methods used to detect threats to seagrass habitats in both the Spencer and St Vincent Gulfs.

Follow-Up On Two Previous Articles

Two Dives In Two Weeks

Environmental Considerations of Artificial Reefs

The Fishes Of Australia’s South Coast

The Hobart

KESAB Clean Up Australia Day

The AGM will be held on the 16^th May.

Under our Constitution I need to publish the names of persons wishing to stand for Committee positions in the May Newsletter.

Present Committee members can nominate themselves but other club members have to be nominated by another club member.

All positions are declared vacant at the AGM so please consider being nominated yourself, or nominating someone else for one.

Please e-mail me your nominations ( with the person’s consent) before the 25th April (ANZAC Day). or give me a written or verbal nomination at the April General Meeting.

In my article "More Early Naturalists (1800 – 1900s) I wrote about the naturalist Francois Peron who had sailed with Nicholas Baudin in 1800-4. The article metioned Peron working with a Le Sueur who was in fact Charles Lesueur. Lesueur was apparently an artist on the expedition by Baudin.

In my article "Tasmania’s Low-light Creatures" in our November Newsletter I wrote about Chevalier d’Entrecasteaux. I suggested that the Recherche Archipelago in WA was named after d’Entrecasteaux’s frigate "Recherche". I can now confirm this to have been the case. My source of information is the July-Sept 1992 issue of "Australian Geographic". The article "A Hundred Islands in a Lonely Sea" by Howard Whelan provided me with the details. D’Entrecasteaux searched for Count La Perouse with two ships – the Recherche and the Esperance. He named the many islands L’Archipel de la Recherche. He also landed on Observatory Island in the Archipelago. This island is on the edge of Esperance Bay, close to Esperance itself, so it seems that Esperance is named after d’Entrecasteaux’s other ship. My ‘low-light creatures’ article also mentioned d’Entrecasteaux’s second in command, Huon d’Kermandec. The "Australian Geographic" gives the spelling as d’Kermadec, with Kermadec Island and Kermadec Rocks occurring in the Archipelago. There is a photo of the island on page 48 with a caption saying that the island has swell-swept flanks and foreboding caves. It is a 1km long and 79m high granite dome that is a breeding ground for Australian sea lions.

Whilst on the subject of my ‘low-light creatures’ article, Philip Hall recently donated several magazines and reports to our Society library. Some of them were either already in our library or a file for them already existed. Some, however, were new to the library and have now been recorded as new entries. One of the magazines was "40degrees South – Tasmania & Beyond" No.5 December 1996. A Weedy Seadragon features on page 75 as part of an article titled "40degree Parks". A sub-heading for the article is "Creatures from the deep". On page 76 this part of the article goes on to discuss Ninepin Point Marine Reserve and Bathurst Channel, both of which were discussed in my article last November.

Not that there is anything strange about me having two dives in two weeks, but two ‘Society’ dives in that time, now that is unusual! The last time that I had dived with another Society member was last August. The last time that I dived with more than one member was last May. The last boat dive that I did was two years earlier than that.

On 25^th February Geoff Prince took several members out in his brother’s boat for a dive at the Aldinga Drop-off. I hadn’t dived there for almost 12 years. It was a good day to do it again with flat seas and fair viz. The day’s maximum was 33 degrees but it was slightly overcast. Four members (Geoff, David, Chris and myself) plus my buddy Peter went with Geoff’s brother Roger and Megan. We managed to anchor right on the edge of the drop-off. I couldn’t wait to get in the water and I was the first to get wet. Peter followed me down the anchor line to the edge of the drop-off. The sight was awesome with peaks, crevices, ledges, crevasses and sheer walls. I kept easing my way down the drop-off but there was always another ledge to go. Finally I reached the bottom at about 18m. I hadn’t been that deep in years. The fish life was incredible. I remember seeing Blue Devils, Black-banded Sea Perch and a large male Blue-throated Wrasse. Then there were the invertebrates such as a large cray, a large gorgonian fan and a large black cowry. Yes, much of the marine life down there was of a large size, although the two cuttlefish that we saw were just an average size. We saw a fair bit of David diving solo with his camera. We also saw another group of three divers swimming through the area. When David indicated that he was returning to the boat. Peter and I decided to do likewise. Our dive time was just under the one hour mark. By the time we managed to get back into the boat, Chris and Geoff had returned from their dive. Geoff just climbed straight into the boat complete with tank and weights. We were soon on our way back to the O’Sullivan Beach boat ramp whilst raving about the dive.

The second dive was the KESAB Clean-up at Port Noarlunga on 4^th March. I dived with Tony who was busy video filming. (Actually, we did two short dives together so perhaps this report should be re-titled "Three dives in 8 days".) I should mention that despite delays with Tony’s camera preparation we still managed to enter the water on time at 10am. We had soon filled our rubbish bag with debris tossed off of the jetty during maintenance work. We had even started to stockpile bolts around the jetty so we exited at the steps and Tony returned his camera to his car. In the meantime Alex brought me some more bags to gather more rubbish. When Tony returned we jumped into the water again and proceeded to retrieve our stockpiles of bolts. We found the fish to be very friendly. Perhaps they appreciated our efforts. With our last empty bag we swam back along the jetty gathering more rubbish. The bag was soon almost too heavy to swim with, even with two of us dragging it along, but we somehow managed to get it back to the first set of steps. Geoff Prince was doing his bit on the day whilst diving with students and a few other divers also offered to help. Alex did all of the coordinating on dry land and had other volunteers helping out. She also took plenty of photos and saw that everyone gt a bottle of Mount Lofty Natural Spring Water for their efforts.

Assistant D.O. 2000-1

Whilst the creation of artificial reefs for fish attraction or productivity is often lauded as a way of creating enriched marine environments, there are a number of important factors to consider before supporting or rejecting proposals to create artificial reefs.

Whilst some research suggests artificial reefs enhance production, others contradict this claim. Artificial reefs do tend to significantly increase the biomass of benthic invertebrates. However the increase in productivity is typically a specific mix of species particularly suited to life on the particular artificial substrate i.e. the species mix is unique to the artificial structure.

Generally speaking, research has shown that larger artificial reefs are characterised by higher biomass densities, composed of larger but fewer individuals, thus being recommended for fisheries applications. Smaller reefs, tend to produce greater fish densities, and are generally believed to be preferential for recruitment purposes.

Also to consider is that either aggregating marine species or enhancing species production (of a certain species mix) in an area, may impact on the surrounding natural systems e.g. spillover of predatory species from the artificial reef onto nearby natural reefs. These types of impacts remain largely unknown and largely unquestioned in the process of creating artificial reefs.

Artificial reefs may provide shelter for juveniles, critical for settlement and decreasing predation. The aim of constructing an artificial reef then, is to create areas of nutrient availability, water flow and light penetration so as to set up a process of ecological succession that will, in time, lead to a diverse and extensive marine ecosystem.

Reef occupants change habitat requirements with age, suggesting that the primary purpose of reef deployment, be it for fishing, diving or tourism activities, significantly influences reef design. The effectiveness of artificial reefs in increasing productivity also appears to depend on reef design, specifically whether the configuration and siting of the reef meets the requirements of individual target species and age groups. Limited information exists however regarding the relative benefits of different reef designs with respect to productivity.

Many inherent characteristics of artificial reefs are incompatible with the aims of environmentally sound management of marine areas. Dumping derelict vessels or prefabricated units into the sea introduces large amounts of foreign material, and the presence of rust and corrosion on these materials can inhibit sustainable colonisation by framework building organisms. Once installed on the seabed, structures are difficult to remove, such that the area is unlikely to return to a natural state for a significant period of time. Pollution from inappropriate or incomplete cleaning of the vessel prior to sinking is a significant threat to the marine environment. The sinking of vessels for disposal purposes or the breakup of sunken wrecks due to improper planing are also important issues.

With the alteration of species abundance and diversity, reef simulation has been found to alter ecology, thus potentially introducing new predators and competitors. Aggregation of individuals in one area may lead to depletion elsewhere with a concentrating of fish, allowing them to be more readily caught by fishers, thus possibly depleting stocks of desirable species. Fisheries management practices must therefore be enforced at artificial reef sites to prevent general over-fishing and the removal of juveniles.

The presence of an artificial reef may also become a barrier to fish migration. Whilst it is unlikely that vessels would cause a significant physical barrier, the enhanced and protected environments that artificial reefs provide may alter fish migration patterns. Fish populations may linger at artificial reefs due to the increased productivity, food supply, feeding efficiency, or shelter from predation, possibly changing migration behaviour. This may then have significant local and far-reaching impacts on species occurrence and abundance.

Whilst there is widespread deployment of artificial reefs, there remains much uncertainty as to both the actual benefits of artificial reefs and the ecological mechanisms through which such benefits might be produced. The long-term implications of artificial reefs and their ability to preserve marine wildlife remain unclear, with many believing they actually threaten the long-term sustainability of fish populations, serving to relocate fish from less suitable habitats to new ones. These concentrated populations would then be more vulnerable and accessible to fishing pressures. Artificial reefs in Australia however, are generally created for tourism purposes rather than to increase fish stocks. With increasing interest in artificial reefs, further research is necessary to better understand the exact dynamics of artificial reef environments and the potential impacts on marine ecosystems.

* Jessica Norty is a science graduate from the University of NSW, and currently assisting MCCNNSW. Jessica's article highlights the key points from her review of available literature about artificial reefs and their contribution to marine systems.

Environment Australia 1999. "Artificial Reefs - A Fact Sheet." Ocean Protection and International Section, Marine Group.

Pickering, H. and Whitmarsh, D. 1996. "Artificial reefs and fisheries exploitation: a review of the ‘attraction versus production’ debate: the influence of design and its significance for policy." Fisheries Research 31: 39-59

Branden, K., Pollard, D.A. and Reimers, H.A. 1994. "A review of Recent Artificial Reef Developments in Australia." Bull. Mar. Sci. 55 (2/3): 992-994

Pollard, D.A. 1989. "Artificial Habitats for Fisheries Enhancement in the Australian Region." Marine Fisheries Review 51(4): 23-25

I enjoyed reading David Muirhead’s article about this book in our July 2000 Newsletter. I hadn’t heard of slickheads, crustheads or cubeheads but some of the other fish names I had. Names such as Ribaldo, Whiptail and Thetis Fish had surfaced at times. I am more familiar with names such as Whitenose Pig Fish, Goblinfish and Elephant Fish. At the end of the article David mentioned that the book had been "achieved locally by dedicated naturalists on a tight budget". Yes, the book was printed (published) in 1994 but we had awaited its release for about eleven years. Actually, the book was first envisaged thirteen years earlier, in 1981. That was the year that the SA Museum received a grant to enable it to carry out a survey of fish in SA’s marine waters. Information gathered during the survey was used in the preparation of the book. Fish collecting for the survey was mostly carried out by commercial fishing operations and shallow water beach nettings. Divers, however, were required to collect fish from inshore areas and around rocky reefs. A group of professional divers with the relevant expertise was approached to assist this part of the survey. The divers were members of the Marine Life Society Of SA (which was called M.A.R.I.A. at the time). The group made two trips to Yorke Peninsula in 1981. One of the trips was to Wardang Island and the other was to southern Yorke Peninsula. Our divers collected more than 200 fish of over 40 species on the two trips. The book had been due out in 1984 but late in 1993 we were still waiting for it. It finally appeared early in 1994 as reported in our April ‘94 Newsletter (No.199). Details of the SA Museum fish survey and our participation were published in our 1985 Journal. A follow-up report about the survey was published in our June 1995 Newsletter (No.212 - the front cover incorrectly said No.112). That report said that the book contained a magnificent photo of a boarfish by David Muirhead.

Late last year the destroyer HMAS Hobart was gifted to SA for sinking off Wirrina as an artificial reef for scuba divers. She is tied up at Port Adelaide at present. It is hoped that the ship will be scuttled later this year. Much work, however, needs to be done to prepare the Hobart for sinking. Volunteers are urgently needed to do the necessary work.

A registration form is available for volunteers to offer their services. Groups of volunteers are expected to spend a full day working on the ship a couple of times per month. It has been suggested that BBQ meals would be provided to the workers.

If you can, please give some thought to volunteering your services to help get the Hobart down as soon as possible. Registration forms are available from Steve or Philip. If you wish to find out more about the Hobart try this web site: http://users.senet.com.au/~pearcey/hobart

The turn out for this event, held at Port Noarlunga, was disappointingly few, especially divers – but with only 2 weeks notice to organise, publicity was virtually impossible. I could not dive because I was the on-site supervisor.

It was a pleasant surprise that two young students from Woodforde College turned up, participating in the day as part of some community service they have to fulfil for the International Baccalaureate certificate. In two hours, they recovered two very full bags of rubbish and had a positive attitude toward the clean up.

Tony Isaacson and Steve Reynolds dived together and recovered a fair amount of the industrial crap that had been dropped whilst re-planking the jetty. It was extremely hard work, as even with BCDs fully inflated they still had to swim hard to rise to the surface with heavy metal objects such as large pieces of cable, enormous nuts and bolts and large metal rods. Geoff, our illustrious diving officer, was instructing a group of student divers, but nonetheless managed to also recover some of the heavy industrial rubbish.

Patsy Mendham from the Southern Regional Environment Group, and an acquaintance of some of us MLSSA folk, also turned up with a friend. Patsy kindly provided some ties for the bags in which were blow-away objects, as there was a strong wind that day.

I managed to secure a small amount of sponsorship for the day in the form of a box of spring water, kindly provided by Mount Lofty Springs. The water went down well with everyone as the day heated up, especially post-dive.

There are slides of all these folk and the large pile of rubbish they collected ready to go on the MLSSA website, so at last we can have something under "What we do".

It was very disappointing that not more casual divers that just turned up for a dive did not wish to participate when I approached them. However, to counteract that there was another dive club that stayed all day and covered the entire length of the jetty. The Onkaparinga Council kindly collected the rubbish the next day.

According to the other dive club, there was not too much rubbish left under the jetty itself and another disappointment is that we did not get to cover the reef. However, next year we shall prepare much earlier and publicise like mad. Apparently there used to be a very active local politician for that area, who used to get hundreds of people involved – perhaps next year we can try approaching a prominent local figure to help us.

Despite the small turn out, I was glad just to get these few dedicated folk and I hope those MLSSA members that were not at Port Noarlunga were cleaning up in their local area.