Restoration Project

Fisheries Research and Development Corporation Australia - Sagami Bay

Restoration Objective:

This study reports on the restoration of seaweed beds using management-free methods, to help conserve the natural ecosystem.

Site Selection Criteria:

Sites for the foundation construction for the Eisenia and Ecklonia bed restoration were selected within 100 m of a natural kelp bed and with a depth at 5 m for Eisenia bicyclis and about 11 m for Ecklonia cava, values based on their natural vertical distribution.

Cause Of Decline:

At high densities, sea urchins can create and maintain areas dominated by crustose coralline algae and devoid of macroalgae, commonly called barrens. When sea urchins are removed from these areas, kelps are frequently able to recolonise the area.

Key Reasons For Decline:

Physical Disturbance

Scientific Paper

Management-free techniques for restoration of Eisenia and Ecklonia beds along the central Pacific coast of Japan

T. Terawaki, H. Hasegawa, S. Arai, M. Ohno, , Journal of applied phycology, Vol. 13.


Fisheries Research and Development Corporation Australia

Site Observations:

Observation Date

15th Oct 1991 – 15th Oct 1999

Action Summary:

An artificial reef (24 x 22 x 1.27m) was constructed from Seasup concrete block and stone, and installed on a sandy bottom in Sagami Bay near Tokyo during September to November in 1991. Reefs were seeded with Eisenia bicyclis (5m depth) or Ecklonia cava (11m depth) spores.

Lessons Learned:

A height of 150cm for the artificial reef was necessary to avoid sand burial.

Project Outcomes:

The holdfasts of plants were observed grasping kelp knobs and forming an Ecklonia and Eisenia bed on the artificial reef after three years. The Ecklonia and Eisenia bed on the blocks has been maintained in a healthy condition for more than 8 years.

Key Reasons For Decline:

Physical Disturbance

Area of Restoration (In Square Metres)


Indicator Data:


Ending Value:

Starting Value:

Presence / Absence of Kelp

Cost Currency:USD