Restoration Project

Wonkwang University - Gwanmaedo-ri

Restoration Objective:

Restoration of Silvetia siliquosa is highly desirable due to its high ecological and economic importance in Korea. The aim of this study was to develop a suitable and cost-effective restoration method to increase or maintain S. siliquosa population under severe overharvesting stress.

Site Selection Criteria:

Sites were selected where S. siliquosa populations were still present.

Cause Of Decline:

The brown alga Silvetia siliquosa is one of the most ecologically and economically important algal species in Korea. Previously, S. siliquosa was widely distributed, however it has experienced a continuous decline from the mid-1990s onward and is now only found on offshore islands. The causes of the sudden decrease in S. siliquosa populations are not clear, but one possible cause is over-harvesting due to its high market price (approximately 10 dollars kg-1 wet weight).

Key Reasons For Decline:

Harvest

Scientific Paper

Growth, reproduction and recruitment of Silvetia siliquosa (Fucales, Phaeophyceae) transplants using polyethylene rope and natural rock methods

X. Gao, H.G. Choi, S.K. Park, J.R. Lee, J.H. Kim, Z.M. Hu, K.W. Nam, , Algae, Vol. 32.https://doi.org/10.4490/algae.2017.32.12.6

Organisation:

Wonkwang University

Site Observations:

Observation Date

10th May 2014 – 1st Nov 2014

Action Summary:

Natural rock pieces with S. siliquosa thalli were obtained by cutting the intertidal rocks. Cut stones with healthy 4–6 cm long thalli were selected. Each stone had more than 9 transplants and a surface area between 160 and 200cm2. The stones were fixed to the natural rocks at study sites using underwater epoxy cement (mixed cement powder and seawater at a ratio of 3:1) after removing all organisms inhabiting the rock surfaces by using a steel brush. Four replicate stones were established at each study site with a total of 69–72 transplants.

Lessons Learned:

Transplantation using polyethylene ropes is more effective than using natural rocks to restore S. siliquosa.

Project Outcomes:

Silvetia siliquosa transplants survived at rates of over 90 and 40% after two and six months except for stone transplants at Yeongsando (6% survival). Rope transplants showed significantly higher survivorship at Yeongsando, but stone transplants survived better at Gwanmaedo than at Yeongsando. Survivorship was higher (9–40%) for rope transplants compared to stone transplants.

Key Reasons For Decline:

Harvest

Area of Restoration (In Square Metres)

0.1

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Percent Survival

40
%
100
%
Transplant Info:
Adherence Method:Epoxy
Life Stage:Juveniles
Costings:
Cost Currency:USD

Observation Date

10th May 2014 – 1st Nov 2014

Action Summary:

Thalli of S. siliquosa were collected from natural populations. Healthy thalli of sizes 4-9 cm were selected, inserted in some strings (1.2–1.5 m in length and 3 mm in diameter) at 5 cm intervals, and fixed with instantaneous adhesive glue. The following day, the strings with thalli were fixed on the polyethylene ropes (14mm in diameter) with plastic cable ties. Next, these ropes were fixed into the rocks with anchor pines at 25–30cm intervals, and 90–95 transplants were established at each study site.

Lessons Learned:

Transplantation using polyethylene ropes is more effective than using natural rocks to restore S. siliquosa.

Project Outcomes:

Silvetia siliquosa transplants survived at rates of over 90 and 40% after two and six months except for stone transplants at Yeongsando (6% survival). Rope transplants showed significantly higher survivorship at Yeongsando, but stone transplants survived better at Gwanmaedo than at Yeongsando. Survivorship was higher (9–40%) for rope transplants compared to stone transplants.

Key Reasons For Decline:

Harvest

Area of Restoration (In Square Metres)

4.5

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Percent Survival

46.4516129
%
100
%
Transplant Info:
Adherence Method:Line
Life Stage:Juveniles
Costings:
Cost Currency:USD