A study of "pioneer" algae growth in Slaughter Bay, Norfolk Island.

To examine the rate of growth of new marine organisms (if any) on rubber car tyres in the fringing coral reef in Slaughter Bay, Norfolk Island.

On the 30/4/98, I placed three tires in their positions one being in deeper open waters (location A.) The other in open middle height waters (location B.) and the other in shallow enclosed water (location C.) They all had fishes swimming in and around the tyres. The types of fish were ‘Apogon Norfolkensis’ and another ‘Chromis fumea’ and ‘Neoglyphidodon polyacanthsis.’ This way I can record down different results and show differences and likenesses.

After 4 weeks on 28\5\98 I took photos of Locn A, B, C recording down that Locn A. (e,g the deepest location) had grown its first layer of pioneer algae being called ‘Enthomorthra Chathrata’ and two sea urchins ‘Tripneustes gratilla’ attached.

Locn B. had also the same pioneer algae attached with also two of the same family of urchins ‘tripneustes gratilla’ attached.

Locn C. (in shallow waters) had the same pioneer algae attached but was missing the urchins, though in the distance of around 30 centimeters two ‘Tripneustes gratilla’ lay beside the tire.

This showed me that the first pioneer algae the ‘Enthomorthra Chathrata’ is the first to take over a new habitat; and that ‘Tripneustes gratilla’ is the first urchin to claim a new habitat. Other urchin species ‘heliocidaris tuberculata’ and the ‘diadema savignyi’ (common name "Brown urchins"), may need some more time to become attached.

In the colder parts of the year, two weeks later, 6/6/ 98 I placed location D. next to location B. The reason for placing a new tire into Slaughter Bay was to see if there is any difference in the speed which the ‘Enthomorthra Chathrata’ (algae) will grow, and if the ‘ Tripneustes gratilla’ (urchin) will become attached. The of the drop in water temperature is around 3 degrees from when I first put in Locn A, B, C.

After 4 weeks, on the 4/7/98, I will be taking photos of Locn A, B, C and Locn D. to compare any difference or similarities, between A,B,C and D.

After this two weeks later on the 18/7/98, I will be placing yet another tyre in Slaughter Bay and I will be taking photos to yet again to see if there is any difference in growth speed, with A,B,C and D.

Commentary:

METHOD:

I then went down to Ball Bay to collect a number of basalt rocks that would fill all the rims of all the tyres.

On the 30\4\98 with the help of Peter Langley, Jack Margues and my Dad, Mike Andrew I filled the insides of my tyres with the Basalt rocks and we swam along the water and placed them in their positions in Slaughter Bay. The tyres had no problem sinking with all the weight of the rocks. The paint was effective for about 3 weeks till the algae ‘ enthomorthra chathrata’ covered the writing completely.

Four weeks later on the 28\5\98 I bought a disposable camera and I took 3 or 4 pictures of each of my locations, A, B and C.

I placed the pictures in a photo album with marked dates, and descriptions.

On the 6\6\ 98 I picked up another large tyre and bought another disposable camera and went down to Ball Bay and picked a few good basalt rocks to hold my tyre (location D.) down.

With the help of Peter Langley and my Dad we swam out carrying location D, and placed it firmly next to location B.

I then took another set of pictures of the progress of location A, B, C and took a picture of location D. to show the difference.

On the 4\7\98 four weeks later I will be taking photos of location A, B, C including D. to see if there is any difference in growth as the temperature has dropped, and also see if there is any different marine organisms that has formed onto the tires.

On the 18\7\98 I will be getting another tyre, getting more basalt rocks to hold the tire in the

Water, and with the help of Peter Langley and my dad I will be placing location E. next to location A. and will be taking photos.

Above water shots have been taken to show a better look at the whole bay. The exact markings of the tyres are also shown, rock pools, barren spots, populated areas.

I noticed that ‘schooling’ fish like these areas as well even larger fish. They both don’t sleep in the area for they are too large but they enjoy the area. The tyres have brought in more growth for the areas that they are in, being that the areas that were once bare have started producing and are still producing

The fish (Apogon norfolkensis and Chromis Fumea) have not only found it a great dining area but also a home and a safe place.

The main data I have collected are

• photos of each location,
• water temperature,
• air temperature,
• sea depths.
• names of marine organisms.

The photos are in order of date inside photo albums.

I can look back into May when I first took pictures and then look at the recent pictures taken in June & July and look at the difference in growth which is very surprising. Despite changes in temperature, and general sea conditions, there is no marked difference in the rate of growth on the tyres. The deciding factor appears to be depth and isolation from competing coral outcrop or rocks.

From my observations I can now confidently determine if and when the reef and lagoon becomes damaged. Up until now, if a chemical spill such as oil or other pollutant were to kill a section of the coral, it’s effects were not immediately obvious, as the coral appears the same for some time. However, the presence of ‘lime green’ algae (which grows rapidly), and the urchin species mentioned above would sound an alarm that something serious has occurred. Neither the algae, nor the urchins are pests, it is simply that their presence in such numbers, in isolation indicate something wrong. I also now know to look for schooling fish in the areas affected.

I do not know if my ‘test’ would work on the Barrier Reef but would love the opportunity to find out.

Most old descendants of Norfolk island are quite concerned about the conservation of all the things that are precious and rare that grow and breed on the island, it is very important to take care of those things.

It is already against the rules to have dogs on the beaches and bays, jet skis cannot come into the reef area in case of damage; if there was any problem with endangered marine species and we needed the community to know about it, the Norfolk Island newspaper is where to place it to let the community know about it.