Cultivating Palmaria palmata - Bord Iascaigh Mhara

4.2 Spore release and seeding collectors
Kuralon culture string wrapped around a frame, or nets
made with Kuralon (see Chapter 3.4), are used as
collectors. The frames or nets are placed in a tank or a
large tray (approx. 50x70 cm) and covered with UV-
filtered seawater to a depth of about 20 cm. The
reproductive material (i.e. the pieces of frond with sori)
is then placed directly on top of the collectors or placed
on a net lying on the collector which allows easier
removal of the frond parts after spore release (Fig. 4.2).
During the process of spore release, the containers are
kept under low light (i.e. 5-10 µmol m -2 s -1 ) at 10°C with
gentle aeration and a light:dark period of 12:12 hours.
The algal material is left in the container for three days, but should be gently stirred in the tank by hand once
every day to promote mixing and more even settlement of spores on the collectors.
4.3 Cultivation of seeded collectors
After three days of spore release, the algal material is removed and the seeded collectors are transferred to
larger holding tanks (capacity: 200 L or more) filled with UV-filtered seawater and supplemented with enrichment
medium (see Chapter 3.3 and Appendix 2). The light:dark period and temperature should be maintained but the
light intensity can be increased slightly to 15-20 µmol m -2 s -1 .
Spore development: Firm settlement of spores on the string occurs in a few days. Spores can be seen under
the microscope as small red dots. After settlement, the spores start to divide, and divisions are visible 3-4 days
after spore release. After about 7 days, female gametophytes are recognisable as small cell aggregates with a
filamentous outgrowth, the trichogyne, through which the spermatia from the male gametophyte will travel to
fertilise the egg cell at the base of the trichogyne. The male gametophyte shows at this stage some hump-like
outgrowths which develop into fronds (see Chapter 2.4 for development of spores).
An even distribution of settled spores over the whole collector is desirable for successful ongrowth in the sea,
ideally at a density of 50 or more spores per cm of string. During the first two weeks after settlement, however,
large numbers of spores (60-90%) frequently die off naturally. The reasons for this high mortality of spores are
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Fig. 4.2. Spore release from Palmaria: fertile pieces of
fronds placed on top of a collector carrying 2 nets.