University of Southern California - Near Malibu

Restoration Project

University of Southern California - Near Malibu

Restoration Objective:

The giant kelp Macrocystis pyrifera has considerable ecological and economic value, as it provides habitat and food for valuable marine life and is associated with increased biological productivity and fishing success. This value, and the decline of this species in recent years, has prompted development of restoration techniques.

Cause Of Decline:

Presumably, the present lack of naturally occurring Macrocystis pyrifera beds in the harbour is the result of poor water quality in the past and the relatively poor reproductive dispersal ability of Macrocystis.

Key Reasons For Decline:

Multiple

Scientific Paper

New methods for mass culture of Macrocystis pyrifera sporophytes

J.S. Devinny, J. Leventhal
Aquaculture, Vol. 17.
https://doi.org/10.1016/0044-8486(79)90127-3

Organisation:

University of Southern California

Site Observations:

Observation Date

Action Summary:

Kelp blades were collected from wild Macrocystis pyrifera and transferred to spore bags to release spores in the lab. Nylon string was placed in the spore suspension to allow spores to settle on the string. The string was wound on struts to form 'looms' in order to culture gametophytes. Once cultured, strings were transplanted to the field by tying them around boulders. Eight successful cultures (about 5000m of string) were distributed at the harbour breakwaters.

Lessons Learned:

Project used mass culture and dispersal of juvenile sporophytes, then transplanted these to harbour sites. Transplantation was successful despite high mortalities, and survival was higher above 6m depth.

Project Outcomes:

Cultures transplanted to the breakwater continued to grow, although mortalities were high. Many plants reached 1 or 2 cm in length, only to be cropped by grazers. The successful growth of large numbers of plants showed that environmental conditions in Los Angeles harbour were adequate. There was also much lower success at depths below 6m for juveniles grown on strings and for those which were offspring of the transplanted adults.

Key Reasons For Decline:

Multiple

Area of Restoration (Ha)

0.5

Indicator Data:

Indicator:

Ending Value:

Starting Value:

Presence / Absence of Kelp

Transplant Info:
Adherence Method:Suspended Ropes
Life Stage:Juveniles
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