Fisheries Research and Development Corporation Australia - Hope Island

Restoration Project

Fisheries Research and Development Corporation Australia - Hope Island

Restoration Objective:

At Hope Island, preliminary short term trial clearings of urchin from barrens resulted in little recovery of macroalgal vegetation. It was postulated that limpets may be an additional herbivore controlling vegetation so this experiment was conducted to determine if urchins were the principal herbivore at Hope Island.

Site Selection Criteria:

Sites were selected that were urchin barrens, but had previously had kelp beds.

Cause Of Decline:

Overgrazing by sea urchins is thought to have led to the decline of Macrocystis populations in Tasmania.

Key Reasons For Decline:

Overgrazing

Scientific Paper

FRDC Grant 93/221. A pilot program to maximise tasmania's sea urchin (Heliocidaris erythrogramma) resource.

J.C. Sanderson, M. Rossignol, W. James
https://eprints.utas.edu.au/1...1/JCSUrchFRDCChpt0_1_2_3.pdf

Organisation:

Fisheries Research and Development Corporation Australia

Site Observations:

Observation Date

1st May 1994 – 1st May 1996

Action Summary:

Four treatments were used; 1) no urchins; 2) no urchins, abalone and limpets; 3) no abalone or limpets; 4) control. These were done in quadruplicate for 16 squares (10 m x 7.5m) divided by 50cm high netting. There were two blocks of four squares each on each side of the island with randomly allocated treatments. Ten Macrocystis plants were introduced to each of the squares. Juvenile plants (0.2-1.0m high) were obtained from Dodges Ferry, kept moist under hessian sacks and within 24 hours of harvest, replanted at Hope Island in June 1994. Individual plants were attached to bricks using rubber bands over the haptera at the base of the plant.

Lessons Learned:

Lack of propagule supply was likely the main cause for minimal revegetation.

Project Outcomes:

Two years post-transplantation, an area that was regularly cleared of urchins outside treatment areas still did not have significant vegetation coverage. It is likely that the lack of vegetation was due to a lack of algal spores.

Key Reasons For Decline:

Overgrazing

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Kelp Cover

0.0000
%
0.0000
%

Observation Date

15th Jun 1994 – 15th May 1996

Action Summary:

Four treatments were used; 1) no urchins; 2) no urchins, abalone and limpets; 3) no abalone or limpets; 4) control. These were done in quadruplicate for 16 squares (10 m x 7.5m) divided by 50cm high netting. There were two blocks of four squares each on each side of the island with randomly allocated treatments. Ten Macrocystis plants were introduced to each of the squares. Juvenile plants (0.2-1.0m high) were obtained from Dodges Ferry, kept moist under hessian sacks and within 24 hours of harvest, replanted at Hope Island in June 1994. Individual plants were attached to bricks using rubber bands over the haptera at the base of the plant.

Lessons Learned:

Clearing limpets had little effect on revegetation.

Project Outcomes:

At Hope Island, there was significantly higher survival in squares that had been cleared of urchins. At both sites, the most marked change was observed the year after the transplants were initiated. The plants that had been placed into the sites released spores resulting in many new plants in the following year.

Key Reasons For Decline:

Overgrazing

Area of Restoration (Ha)

0

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Adult Kelp Density

25.4000
/ m2
10.0000
/ m2
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