BIOLOGY OF SEAWBEDS OP EUONOMIU IMPORTANUE
219
Thus the " perforating " disease reported by Suto and Umebayashi
(1964) could reduce the market value of the laver if of widespread
occurrence. A diseased condition of the Conchocelis-phme has been described in which orange-yellow spots appeared in the filamentous
growth within the shell. Infected cells had a high bacterial content,
but whether this was the cause, or was secondary to the disease, is not
known (Nozawa and Nozawa, 1957). A " yellow-patch " disease of
Conchocelis has been reported (Horida et al., 1960). There are no reports
on the severity of infection, or of possible spread of such conditions in
the Conchocelis culture tanks.
The occurrence of saprophytic fungi on fucoid algae has been
reported for many years (see review by Wilson, 1960; also Johnson and
Sparrow, 1961). Fungal hyphae have been observed in anatomical
investigations of seaweed meals (Bmrdseth, 1964). The pyrenomycete
Leptospheria chondri (Rostr.) Rosenvinge has been found on decaying
cystocarpic and tetrasporic pustules of Chondrus crispus (Marshall
et al., 1949). Certain of the fungi associated with decaying seaweeds
have been found to show some laminarase activity (Chesters et al., 1956),
and some degree of hydrolysis of sodium alginate was also recorded.
The same workers found that actinomycetes could hydrolyse insoluble
laminarin, and also showed some alginase activity.
2. Bacterial diseases
'' Black-spot " of Macrocystis pyrifera has been attributed to
bacteria, and can wipe out a kelp bed with the result that several
years will elapse before the standing crop returns to its pre-infection
status (see Chapman, 1950). A tenfold decrease in the available
Mucrocystis has been reported after severe infection of the kelp beds.
The disease appears t o be associated with high sea temperatures (18"2OoC), and the floating fronds are more susceptible than those in
deeper water. Harvesting in May and June keeps down the incidence
of the disease. Bunt (1955), describing the decomposition of thalli of
Durvillea antarctica, reported that penicillea, bacteria, protozoa and
yeasts were responsible, and that the yeasts attacked the stored carbohydrates within the tissues. Ando and Inoue (1961) reported on a
diseased condition of Laminuria japonica which appeared initially as
small perforations in the lamina and resulted in degeneration of the
bulk of the frond. A vibrio-type of bacterium producing an active
alginase, and with a pathogenic action on Laminaria, was isolated from
the infected fronds. The disease caused extensive damage to the
kombu beds near Wakkanai, Hokkaido, during 1959.
219
Thus the " perforating " disease reported by Suto and Umebayashi
(1964) could reduce the market value of the laver if of widespread
occurrence. A diseased condition of the Conchocelis-phme has been described in which orange-yellow spots appeared in the filamentous
growth within the shell. Infected cells had a high bacterial content,
but whether this was the cause, or was secondary to the disease, is not
known (Nozawa and Nozawa, 1957). A " yellow-patch " disease of
Conchocelis has been reported (Horida et al., 1960). There are no reports
on the severity of infection, or of possible spread of such conditions in
the Conchocelis culture tanks.
The occurrence of saprophytic fungi on fucoid algae has been
reported for many years (see review by Wilson, 1960; also Johnson and
Sparrow, 1961). Fungal hyphae have been observed in anatomical
investigations of seaweed meals (Bmrdseth, 1964). The pyrenomycete
Leptospheria chondri (Rostr.) Rosenvinge has been found on decaying
cystocarpic and tetrasporic pustules of Chondrus crispus (Marshall
et al., 1949). Certain of the fungi associated with decaying seaweeds
have been found to show some laminarase activity (Chesters et al., 1956),
and some degree of hydrolysis of sodium alginate was also recorded.
The same workers found that actinomycetes could hydrolyse insoluble
laminarin, and also showed some alginase activity.
2. Bacterial diseases
'' Black-spot " of Macrocystis pyrifera has been attributed to
bacteria, and can wipe out a kelp bed with the result that several
years will elapse before the standing crop returns to its pre-infection
status (see Chapman, 1950). A tenfold decrease in the available
Mucrocystis has been reported after severe infection of the kelp beds.
The disease appears t o be associated with high sea temperatures (18"2OoC), and the floating fronds are more susceptible than those in
deeper water. Harvesting in May and June keeps down the incidence
of the disease. Bunt (1955), describing the decomposition of thalli of
Durvillea antarctica, reported that penicillea, bacteria, protozoa and
yeasts were responsible, and that the yeasts attacked the stored carbohydrates within the tissues. Ando and Inoue (1961) reported on a
diseased condition of Laminuria japonica which appeared initially as
small perforations in the lamina and resulted in degeneration of the
bulk of the frond. A vibrio-type of bacterium producing an active
alginase, and with a pathogenic action on Laminaria, was isolated from
the infected fronds. The disease caused extensive damage to the
kombu beds near Wakkanai, Hokkaido, during 1959.