Soru

The following transcript comes from an episode of the audio documentary series 'Bitácora Marina' examining coastal ecology in the Beagle Channel:

'When re-establishing degraded giant kelp canopies along the rocky sub-Antarctic coastline, traditional netting often tangles and suffocates emerging sporophytes. To overcome this, our field team developed porous volcanic-rock anchors. Each disc is inoculated with microscopic gametophytes in shore-based nursery tanks for twenty-one days before release. Divers place these discs in protected crevices at depths between six and eight meters, rather than using weighted plastic grids on open sandy beds. Furthermore, to prevent sea urchins from grazing on the young fronds, biologists release juvenile southern king crabs at a density of two individuals per square meter instead of applying chemical deterrents. Early monitoring reveals an eighty-five percent attachment success rate, allowing the holdfasts to self-anchor within four months before winter storms arrive.'

Based on the audio report, which specific method is used by researchers to prevent sea urchins from grazing on the young kelp fronds?