Restoration Project

Chiba University - Akane Island

Restoration Objective:

The aim of the present study was to determine whether large sporophytes originating from Nabeta Bay would turn into small sporophytes with short stipes when transplanted to Nakagi Bay.

Cause Of Decline:

Ecklonia cava is a large perennial kelp and forms a dense forest along the coast from central to southern Japan. The kelp forest plays an important role as nursery and breeding space for commercial fish, shellfish and other animals, and has high productivity. Recently, it has been reported that marine plant communities, including kelp forests, have disappeared or diminished along the Japanese coast. As an extreme example, 180 ha of E. cava forest disappeared in Tosa Bay, resulting in a collapse of the abalone fishery.

Key Reasons For Decline:

Multiple

Scientific Paper

Growth and survival rates of large-type sporophytes of Ecklonia cava transplanted to a growth environment with small-type sporophytes

Y. Serisawa, M. Aoki, T. Hirata, A. Bellgrove, Tsuchiya Kurashima, Y. Yokohama, , Journal of applied phycology, Vol. 15.https://doi.org/10.1023/A:1025183100958

Organisation:

Chiba University

Site Observations:

Observation Date

15th Nov 1995 – 15th Nov 1997

Action Summary:

Healthy juvenile sporophytes (< 1 year old) of Ecklonia cava with stipes <5cm long were collected from Tei in Tosa Bay in June 1995. Twenty-five sporophytes were attached individually to artificial slates (9 cm × 9 cm, 0.4 cm thick, composed of asbestos and cement) at the holdfast, using instant gel-type adhesive (Aron Alpha GEL-10) and kept in an indoor tank with flowing seawater (20°C, in darkness) for 1 day to confirm complete attachment. The slates with sporophytes were temporarily fixed for 5 months to concrete reefs, which were settled in advance at the sea bottom (9 m depth) close to the experimental site in Nabeta Bay, using water-resistant epoxy resin adhesive.

Lessons Learned:

Not focused on restoration

Project Outcomes:

Five Tei sporophytes and seven Nabeta sporophytes survived to the end of the study. The stipe length was consistently longer in Nabeta sporophytes than in Tei sporophytes after the second month of observation. After 2 years, the stipe of Nabeta sporophytes became longer and thicker than that of Tei sporophytes, reaching 25.6 ± 2.5cm in length.

Nature of Disturbance:

Some plates were detached from the experimental reefs by strong stormy waves during the winter of the first year.

Key Reasons For Decline:

Multiple

Scientific Paper:

Y. Serisawa, Aruga Yokohama, J. Tanaka, , Phycological Research, Vol. 50.https://doi.org/10.1046/j.1440-1835.2002.00274.x

Area of Restoration (In Square Metres)

2.4

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Adult Kelp Count

713
Costings:
Cost Currency:USD

Observation Date

15th Dec 1996 – 15th Dec 1998

Action Summary:

10 large juvenile Ecklonia cava sporophytes with stipes >5cm were collected via SCUBA at 5-10m depth in December 1995 from Nabeta Bay. These were blotted dry and attached to artificial slates (10 x 10cm and 0.4cm thick, made of asbestos and cement) using a jelly-type instant adhesive. Prior to transplantation artificial reefs were settled on the sandy bottom at 9m depth in Nakagi Bay. Four concrete blocks (50 × 60 × 54 cm) were fixed in a straight line with stainless steel tubes (5 cm diameter). Five slates with sporophytes were attached to each artificial reef (2 blocks with Nakagi sporophytes and 2 with Nabeta sporophytes) using water-resistant epoxy resin adhesive.

Lessons Learned:

Not focused on restoration.

Project Outcomes:

The survival rate of the Nabeta sporophytes was 100% until June in 1996, about 70% in 1997 and 20– 30% in 1998.

Key Reasons For Decline:

Multiple

Area of Restoration (In Square Metres)

1.8

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Percent Survival

25
%
100
%
Costings:
Cost Currency:USD