Norwegian kelp forest restauration - Kelp restoration actions in Norway, 1988-2022.

Sammendrag

The extensive kelp forests between 58 and 71oN along the Norwegian coastline have suffered greatly from sea urchin grazing since the 1970-ies (Mid and North Norway) and from turf/filamentous algal competition (South and Vest) the last 20 years. The first restoration effort was hammering sea urchins around a small island in 1988, giving the opportunity for a dense kelp recovery already in 1989. Despite this promising result and many proposals, successful sea urchin removal actions were not initiated until about 2005: two experiments with artificial reefs, three experiments with quicklime, one experiment with exclusion in cages, and some transplants of adult kelps. By the same time some very small efforts were tried in the turfing areas; transplants of juvenile and adult kelps, scraping of turf and sediments. Many methods seemed to be promising, but as long as the environmental conditions favored sea urchins and turf in their respective areas, the restored kelps were of limited duration. One exception is the large scale (70 hectare) quicklime experiment initiating a large-scale and lasting kelp recovery and with further expansion due to sea urchin predation by crabs. This is in accordance with an even more large-scale natural kelp recovery initiated by increasing crab populations reducing sea urchins. A starting Norwegian restoration effort is initiated by commercial harvest of sea urchins by newly developed methods (mainly baited traps) accompanied by voluntary groups (kelp watchers, ecotourism). There, new kelp beds are now appearing (2022). Continuous removing of sea urchins will compensate for the (so far) lack of sea urchin predators in this area. https://iss2023.net/2022/11/10/norwegian-kelp-forest-restoration/