Reef watcher

Issue 1, number 2, July 1997

Australia's Southern Temperate Reefs

The following article is adapted from the Marine and Coastal Community Network's factsheet "The Forgotten Fringe: Our Temperate Reefs". Reef Watch also acknowledges the work of Dr Karen Edyvane, SARDI, and Dr Anthony Cheshire, Dept. Botany, University of Adelaide in informing this article

Temperate and coral reefs - some distinctions
Reefs are well known by divers to attract and support a staggering variety of marine organisms.

Australia possesses a great number of reef systems found in many areas around the continent. Undoubtedly, the best known of these is the spectacular Great Barrier Reef in the warm, tropical waters off the coast of Queensland in the country's north.

Much less is known about reefs of the cooler southern, or 'temperate' regions. They are found where naturally occuring rocky seabeds allow the attachment and growth of a spectacular range of algaes and invertebrate organisms. In contrast to coral reefs there are few 'reef building' organisms in temperate areas - the exception being coralline algaes which produce a calcium crust on the reef surface.

Until recently, relatively little was known about the ecology of temperate reefs and marine environments. Historically, most of the research and even concern for Australia's marine life has been devoted to the warmer tropical areas. Indeed, tropical reefs support a greater variety of fish species, but interestingly, it is the temperate southern reefs which support a greater diversity of algaes (seaweeds) and invertebrate animals. In addition, many of the species found on temperate Australian reefs are 'endemic' or unique, existing nowhere else on earth.

This incredible uniqueness endows our southern waters with a special ecological and conservation significance. Consider these facts: 85% of the 600 temperate fish species, 95% of the species of molluscs, 90% of the 110 species of echinoderms (sea stars and sea urchins) are endemic to temperate Australia. A huge range of ascidians, or sea squirts, are also found with 189 species recorded. Many of these species are reef dwellers at some stage of their life cycle. In the tropics, where many species tend to disperse more widely, only 13% of fish species, 10% of molluscs and 13% of echinoderms are endemic.

In addition, the 1100 species of temperate red algae so far described represent 25% of the world's total, with 75% of them being endemic to southern Australia. Australian waters also contain some of the world's most diverse seagrass meadows with the greatest diversity (22 different species) and endemism found in the temperate southern regions. Incredibly, species of seaweeds in temperate Australian waters outnumber species of corals in the entire Great Barrier Reef!

Unique conditions, unique reefs

Just as temperature, soil and rainfall will determine the range of lifeforms found on land, so too the great variations between different temperate reefs are the result of the range of environmental conditions and processes found in different marine areas. In particular, nutrient levels, currents, water temperature, wave action, depth and bottom type will influence the range of organisms found in a given site. It is no coincidence that the particular range of environmental conditions found off southern Australia is mirrored by the unique nature of the reefs of the region. Some of the factors which contribute to this are listed below.

Isolation

Australia has the longest south-facing coastline of all the great landmasses of the southern hemisphere, particularly when compared with South America and Africa, which are 'V' shaped in comparison. Added to this, Australia is geologically isolated, having separated from Antarctica many millions of years ago. Over time, an abundance of habitats have formed ranging at the coast from sheltered bays, beaches and estuaries to exposed rocky cliffs and headlands. Below the ocean surface extensive seagrass meadows and intricate rocky reefs have formed on the continental shelves.

Currents and Nutrients

Another dimension is added to this isolation by the influence of currents flowing from the north to the south down both the eastern and western coasts, bringing warm, generally nutrient poor water from the tropics. It is thought that these currents prevent the migration of our temperate marine organisms away from Australian waters and also prevent the invasion of organisms from other temperate regions, thus further isolating the marine ecosystems of the southern coast.

Significantly, there are few additional sources of nutrients, due mainly to the lack of major rivers (except for the Murray) discharging off the southern coast. Overall, the nutrient levels of Australia's temperate seas are relatively low.

Understanding changes over time

It is widely known, but not fully understood, that all ecological systems change over time. Reefs are no exception to this and can be influenced by naturally occuring events such as storms or even, for example, an outbreak of sea urchins or star fish. Changes may also occur between seasons or other natural cycles.

Variation between different reef systems are relatively well known and are attributed to the wide range of conditions described above. However, changes to individual reefs are not fully understood and quickly reveal gaps in our scientific knowledge. In many cases it is not known whether certain changes may be the result of natural processes or a response to stress from human activities.

By monitoring changes over time, Reef Watch will contribute to our understanding of 'reef dynamics' and assist us in recognising when an ecosystem may be suffering stress. These changes are likely to be reflected in the presence, absence or abundance of species thought to be indicative of reef status and health. Information gathered by Reef Watch participants will act as an important indicator of the need for further scientific research.

Reef Watch Program News

The Kit

Reef Watch is continuing to progress steadily towards getting divers in the water monitoring reefs. After much time, research and thought, artwork for the Kit has now been completed and is off to the printers. Over the month of August, weather permitting, the kit will be trialled to enable any practical issues to be sorted out before we mass produce them. This is a very important stage which will ensure the kit is fully prepared and proof tested.

To accompany the Kit a program manual is being produced containing all the information divers will need to successfully monitor South Australia's reefs.

Assuming all goes well, especially the weather, divers should be able to celebrate the onset of Spring by getting back in the water with their Reef Watch Kit.

Community Information Evenings

Up to this stage, community groups present on the Steering Committee have ensured community input into the development of Reef Watch. To maximise community involvement we plan to hold community information evenings, here at the Conservation Council. They could be held bi-monthly, two weeks after the release of each newsletter, on the second Wednesday of the month.

Some great benefits could come from these meetings:

meet with all those involved in Reef Watch;
assist with training in the use of the Kit;
enable people to have input into the running and further development of the project;
invite speakers to expand our understanding of reefs and the marine environment.

In addition you could also:

plan and organise reef monitoring dive expeditions;
perhaps even form a Reef Watch dive club.

The dates for the next three meetings are:
August 13
October 8
December 10

Time: 7 pm - 8pm
Address: 120 Wakefield St, Adelaide, enter at rear of the building
Hope to see you there!

Database and Internet

The computer which will hold the database of information gathered by divers has been purchased and will be set up at the Conservation Council, 120 Wakefield St, Adelaide. Access to this computer by the public can easily be arranged. Thanks to the generous support of CoastNet (DEST, Canberra) we have also purchased a modem enabling Internet access. Work on the Reef Watch home page has commenced and will soon make the project accessible to a world audience through the World Wide Web.

Reef Watcher Subscriptions

Please note that your subscription to Reef Watcher is vital in enabling us to continue providing a good quality newsletter. If you wish to receive the newsletter but have not paid your subscription, please send it soon.

Funding

Applications to Coastcare for the next round of project funding are due on July 25. Coastcare has been a very important contributor of funds so far.

From Your Slate

First, a warm word of thanks for the very encouraging, positive feedback following the first newsletter. Don't forget, your contributions will help to make this a varied and interesting newsletter. For inclusion in the September issue, please ensure any letters or articles are in by August 20. In this edition, From Your Slate looks at the current issue of artificial reefs. What is clear is that each article shows the need for caution in making decisions.

Artificial Reefs - some views ...

Recently, there has been a parliamentary inquiry into the development of a network of artificial reefs off the South Australian coast. The Environment, Resources and Development Committee will put its recommendations to State Parliament sometime this year.

To ensure an outcome which has the best interests of the marine environment at heart, it is very important that we have a balanced and informed debate which considers all sides of the argument. The following are the views of two organisations having input into the debate. We would welcome your views for inclusion in further issues of Reef Watcher.

SARDI Aquatic Sciences

"The position of SARDI Aquatic Sciences on artificial reefs has recently been publicised in conjunction with a parliamentary enquiry. As our position is apparently in conflict with those expressed by recreational divers, some explanation seems warranted.

When artificial reefs are proposed for fisheries purposes, the reason generally follows the line that increased habitat will increase fish production and therefore improve fishing success - either recreational or commercial. The question whether these reefs actually increase production (ie add biomass to the existing stocks) or whether they simply aggregate existing populations is one of the most frequently asked throughout the world. From the volume of international literature available on the subject, based on many different ecosystems, little evidence is available to suggest production is increased.

It appears likely therefore that artificial reefs aggregate existing fish populations. Because their location is well known by recreational anglers, artificial reefs are heavily fished. As a consequence, fish stocks are vulnerable to over-exploitation. On this basis, and strictly from a fisheries management perspective, more artificial reefs are not supported.

This line of reasoning does not preclude support for reefs constructed as recreational diving sites. In fact there are good reasons for separating the two uses, having personally been diving on the Glenelg dredge recently when a fishing boat anchor was thrown onto the aft deck."

David McGlennon
Fisheries Scientist
SARDI Aquatic Sciences

Scuba Divers Federation

Mark Durnell, Secretary, SDF

SDF have long considered the establishment of artificial reefs, in various forms, as important for the economic benefits in regard to Dive Tourism, but also re-establish badly dedraded reef systems throughout the gulfs.

With the move to increased development along our coasts the natural reefs are deteriorating to the point that they may not recover. Fish stocks throughout the gulf are declining. Seagrass are receding and reef systems such as Aldinga Reef can only be described as dying.

Artificial reefs play an important role by creating alternative ecosystems that can lower the pressures being experienced on our natural reefs. The gulfs of SA are composed of mainly sand and mud with isolated reef outcrops. These isolated reefs are very important as they are the only areas providing shelter and spawning grounds for a majority of marine species. By introducing artificial reefs we can provide a corridor for fish species to move from area to area and provide additional ecosystems to encourage the reintroduction of such species as blue groper, sharks and barracouta which are not seen locally any more. The disappearance of these predator species should be seen as an indicator of health of our gulfs.

By placing artificial reefs further off shore we may be able to limit the impact of stormwater and pollutants on the existing system by providing a larger area for the local species to expand into.

SDF has been actively pursuing the acquisition and sinking of the derelict tugboat R.T.TANCRED for some time. This vessel and others like her would be a considerable draw for interstate divers. Our gulfs are ideal places to foster and promote Dive Tourism as we have an easily acessible coastline and shallow water, allowing extended dive times.

Artificial reefs can be constructed at minimal capital cost but the ongoing benefits will continue for many years to come. As has been demonstrated overseas steel hulled vessels have an economic life of seventy years plus and concrete structures are expected to last several hundred years. It has been stated that concrete is not suitable for construction as it does not promote growth. This is because the pH of concrete is not the same as sea water but this can be varied at the time of construction or allowed to weather in the rain for six months.

We view the establishment of artificial reefs as important and would encourage the formation of a dedicated group with Government support and input to coordinate any future reef developments. We understand that some agencies view artificial reefs as aggregation devices but overseas experience proves the opposite.

From Our Slate

Some thoughts from the editor

A dive club recently asked me for my views on artificial reefs and I realised I didn't know as much about them as I probably should have. So here are some thoughts after a little more reading and thinking.

The Environment, Resources and Development Committee has been asked by parliament to report on the establishment of artificial reefs as a means of "increasing habitat for enhancing population of any desired marine organism (especially commercial/recreational fish and crustacea species) and any other benefits which might accrue ..." Before we dive in head first, it's worth considering some of the impacts as well as benefits of artificial reefs.

Artificial reefs clearly attract fish and as well as divers may also attract large numbers of fishers. Unregulated fishing may place considerable pressure on some already depleted fish species. A question worth asking is whether there are sufficient resources within fisheries compliance units in SA to adequately enforce any necessary controls. Fisheries compliance staff already seem to have their hands full. Only if regulations for fishing on artificial reefs can be adequately enforced, will it reduce the very real potential for overfishing of these sites.

It is important to recognise too that although large numbers of fish may be present at a reef site, many of those species may require entirely different habitats such as sheltered estuaries, mangroves and seagrass beds for breeding and nursery areas. In the Adelaide area there has already been widespread habitat modification causing loss of seagrasses and mangrove areas since European settlement. So for many species, creating artificial reefs will not necessarily increase their populations. If this is the goal of the Environment, Resources and Development Committee, it should, as a parallel measure, be looking to restore the condition of breeding and nursery habitats.

In an article in the Advertiser, May 17, 1997, the suggestion (a little sensationalist perhaps!) was that new artificial reefs could be "formed by all kinds of heavy items, from sunken ships to washing machines." Whether you agree or disagree with artificial reefs, the prospect of dumping rubbish such as old washing machines or tyres at sea is obviously a situation we should avoid. If artificial reefs are to become a feature of the seascape, it is imperative that they be constructed of materials which do not add to marine pollution.

The strong positions put by SARDI and SDF indicate that this important debate will continue for some time. As part of the ongoing discussion it may be wise to consider any impacts on adjoining areas of the construction of artificial reefs. It may be that concentrating fish in relatively small areas will produce unforseen changes in other areas and possibly even in fish behaviour. It appears likely that further study specific to South Australia is necessary. Reef Watch has arisen because caution has not been a strong feature of environmental decision making in the past. We must ensure we are cautious in our decisions with respect to this issue.

Opportunities for public submissions to the report have now closed but the relevant Ministers will consider the ER&DC report and state their positions to Parliament later this year. There may then be another opportunity for public comment. In the meantime, we welcome your views.

Hot off the press

Divers, snorkellers, beachcombers, fossickers and fisherfolk will be delighted by a fascinating new book devoted entirely to the marine life of temperate Australia. Entitled Australian Marine Life: the plants and animals of temperate waters , author and marine scientist Dr Graham Edgar has provided a rare opportunity for those of us in the temperate south of the continent to learn more about the staggering array of spectacular marine life inhabiting our coasts, estuaries, reefs, inshore and offshore areas.

With more than 500 pages containing over 1300 beautiful photographs this book provides useful information on the habitats and distributions of 1200 common species of marine plants and animals.

It is a particularly valuable book for divers intending to participate in Reef Watch. Edgar explains the sometimes very subtle differences in appearance between closely related species and the full-colour photographs will assist in identifying the reef species we are surveying.

Copies can be purchased from the Conservation Centre bookshop for the recommended retail price of $69.00. Highly recommended!!

Seagrass monitoring workshop

The issue of seagrass loss remain high on the Environment Protection Authority's agenda. A workshop held on June 16, and attended by Reef Watch, stimulated some mch needed discussion on the subject of monitoring and assessment of seagrass. Eleven presentations provided by an insight into the current status of research, management and potential methods of monitoring. Interestingly, many of these issues affecting seagrasses also pose threats to reefs, especially sewage and other polluting discharges, and a lack of political will, coordinated management and knowledge.

The potential for community groups to contribute to monitoring and assessment was also discussed. It is certainly early days as yet, but there is a potential for a seagrass – orientated program similar to Reef Watch to develop in the future. Should this eventuate, it will again be likely that divers will play an important role. A national seagrass monitoring meeting is to be held in Canberra later this year.

Have your say!!

Primary Industries (Fisheries) have recently released a discussion paper on the management and development of recreational fishing in South Australia.

As the paper states, recreational fishing is one of the most popular pastimes in the state, and "..any expansion of receational fishing effort may place increased pressure on fish stocks and other fisheries resources, may of which are fully exploited. Now is the time to identify and tackle the important issues of access, allocation, protection and enhancement of our fisheries resources.."

The public are invited to have input into proposals for the future management of recreational fishing. You have until August 29 to make a submission. Copies of the discussion paper are available by calling 8226 2322.

Public input into such processes for the management of the marine environment is extremely important; the management of fish stocks is of particular importance to the futre health of our reefs. So, have a say!!

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