258
J. A. KITCHING AND F. J. EBLING
free from algae, whereas algae were abundant in areas where urchins
were less plentiful. We were able to show that algal growth is limited
by the grazing of Paracentrotus. Finally, during a study of the relationship of T h i s (Nucella) to its predators, we recognized the existence of
two forms, one more resistant to predation and the other better able to
adhere to wave-washed rocks.
B. M Y T I L U S E D U L I S
1. Distribution
The distribution of mussels in the Lough Ine area resembles that in
other places. Small mussels are abundant on the exposed Atlantic coast,
where there is a continuous intertidal belt. Within Lough Ine mussels
occur sparsely, except at the north end of the lough and in the Goleen;
these populations, also intertidal, include many large specimens (Fig.
56). Mussels also occur sublittorally on the Sill in the Rapids, although
their numbers fluctuate considerably from year to year. Straight and
hooked forms (corresponding respectively to M . edulis L. and M . galloprowincialis Lmk. of Hepper (1957), though not, according to Lewis and
Powell (1961), of two different species) are found in all these sites.
2. Transplantation Experiments
The ability of Mytilus to survive a t various levels from the upper
littoral to the shallow sublittoral in various parts of the Lough Ine area
(Fig. 2) was tested by experiments involving small mussels from Carrigathorna and mainly large mussels from the north end of the lough
(Kitching et al., 1959). Pieces of rock with Mytilus attached were removed from the shore with hammer and chisel, and after storage for
about 24 h in an open crate in the shallow sublittoral were cemented
with a quick setting mixture into their new positions. A t Carrigathorna,
where there is severe wave-action, they were fixed to a 50-kg concrete
block which was placed in a shallow depression in the Mytilus zone.
Small mussels disappeared quickly from all stations except the open
coast a t Carrigathorna (Figs. 57 and 58). Except a t the highest, levels,
they all remained alive and appeared healthy up to the time of their
disappearance. Undoubtedly they fell victim to predators; in general,
those higher up survived longer, which suggests that the predators were
mainly or entirely marine. Mussels placed in the Pelwetia zone, however,
died, gaped and eventually were broken up, probably by birds. The
small mussels replaced a t Carrigathorna survived much better than
those transferred from there to other stations.
Large mussels (from the north end of the lough) disappeared fairly
quickly from all lough stations except in extreme shelter a t East Goleen
J. A. KITCHING AND F. J. EBLING
free from algae, whereas algae were abundant in areas where urchins
were less plentiful. We were able to show that algal growth is limited
by the grazing of Paracentrotus. Finally, during a study of the relationship of T h i s (Nucella) to its predators, we recognized the existence of
two forms, one more resistant to predation and the other better able to
adhere to wave-washed rocks.
B. M Y T I L U S E D U L I S
1. Distribution
The distribution of mussels in the Lough Ine area resembles that in
other places. Small mussels are abundant on the exposed Atlantic coast,
where there is a continuous intertidal belt. Within Lough Ine mussels
occur sparsely, except at the north end of the lough and in the Goleen;
these populations, also intertidal, include many large specimens (Fig.
56). Mussels also occur sublittorally on the Sill in the Rapids, although
their numbers fluctuate considerably from year to year. Straight and
hooked forms (corresponding respectively to M . edulis L. and M . galloprowincialis Lmk. of Hepper (1957), though not, according to Lewis and
Powell (1961), of two different species) are found in all these sites.
2. Transplantation Experiments
The ability of Mytilus to survive a t various levels from the upper
littoral to the shallow sublittoral in various parts of the Lough Ine area
(Fig. 2) was tested by experiments involving small mussels from Carrigathorna and mainly large mussels from the north end of the lough
(Kitching et al., 1959). Pieces of rock with Mytilus attached were removed from the shore with hammer and chisel, and after storage for
about 24 h in an open crate in the shallow sublittoral were cemented
with a quick setting mixture into their new positions. A t Carrigathorna,
where there is severe wave-action, they were fixed to a 50-kg concrete
block which was placed in a shallow depression in the Mytilus zone.
Small mussels disappeared quickly from all stations except the open
coast a t Carrigathorna (Figs. 57 and 58). Except a t the highest, levels,
they all remained alive and appeared healthy up to the time of their
disappearance. Undoubtedly they fell victim to predators; in general,
those higher up survived longer, which suggests that the predators were
mainly or entirely marine. Mussels placed in the Pelwetia zone, however,
died, gaped and eventually were broken up, probably by birds. The
small mussels replaced a t Carrigathorna survived much better than
those transferred from there to other stations.
Large mussels (from the north end of the lough) disappeared fairly
quickly from all lough stations except in extreme shelter a t East Goleen