Cultivating Palmaria palmata - Bord Iascaigh Mhara

4.1 Collection and processing of reproductive Palmaria material
Collecting fertile Palmaria palmata:
Palmaria tetrasporophytes are reproductive during winter. The best time for collecting reproductive material (i.e.
when large numbers of spores are released and the settling and development of spores is most successful)
differs from site to site around the coast of Ireland. The main period of reproduction around Ireland‟s coasts is
between December and March/April. This period may be extended in the North, especially along the Irish Sea
coasts, where water temperature is a few degrees lower than in the South and Southwest.
As Palmaria palmata is most abundant at or below the boundary between the lower intertidal and upper subtidal
zones, the only time to collect fronds from the shore is during the low waters of spring tides. Palmaria is removed
from the stipes of kelps or other substrate and taken to the hatchery for further processing. Usually 3-4 kg wet
weight (1.5 – 2 onion bags) will provide enough material to seed 2-3 collectors. The collected material should be
kept moist and cool, preferably by immersion in seawater at ambient temperature (e.g. in an outdoor tank with a
continuous flow of seawater and/or aeration) until further processing.
Processing of collected material:
The algal material should be processed as soon as possible after return from the shore when the fronds are still
in good condition. It is possible to keep Palmaria in the bags for up to 24 hours, provided that the bags are fully
submerged in seawater with high water flow-through. If the fronds are closely packed and there is insufficient
water flow along the surface of each thallus, they will die quickly and the colour will change from dark red to
orange. The algal material should be processed at a relatively low room temperature (10-15°C) to avoid stress,
which may trigger early spore release. Clean pieces of frond showing dark red areas of sori are selected for
spore release (Fig. 4.1a-b). Any parts of Palmaria, which show attachment of other algae or animals, or unusual
coloration (e.g. brown spots indicating endophytic infection), which are commonly found on the oldest parts of the
algae, should be discarded (Fig. 4.1c-f).
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