10
R. H. M I L T A R
Similarly Styela rustica (L.), a north polar species, breeds in January and
February in the southern part of its range (Lutzen, 1960). Unfortunately in neither case is the breeding season known in more northerly
areas.
%
%
25
FIG. 3. Breeding of Dendrodoa groaaularia. Percentage of semplos with incubating
embryos or larvae, in different size groups of adrdts. .-.. Essex (England),
o----o, Millport (Scotland). Sea temperatures at Essex, full line; and at Millport.
broken linc.
Even over a comparatively short distance variations in the temperature regimes are reflected in the breeding cycle. Thus Dendrodoa
grossularia (Van Beneden) in the Firth of Clyde breeds continuously
from early summer until autumn with only a slight reduction in August,
but in Esscx reproduction stops altogether for a short period in the
summer (Fig. 3) (Millar, 1954b).
R. H. M I L T A R
Similarly Styela rustica (L.), a north polar species, breeds in January and
February in the southern part of its range (Lutzen, 1960). Unfortunately in neither case is the breeding season known in more northerly
areas.
%
%
25
FIG. 3. Breeding of Dendrodoa groaaularia. Percentage of semplos with incubating
embryos or larvae, in different size groups of adrdts. .-.. Essex (England),
o----o, Millport (Scotland). Sea temperatures at Essex, full line; and at Millport.
broken linc.
Even over a comparatively short distance variations in the temperature regimes are reflected in the breeding cycle. Thus Dendrodoa
grossularia (Van Beneden) in the Firth of Clyde breeds continuously
from early summer until autumn with only a slight reduction in August,
but in Esscx reproduction stops altogether for a short period in the
summer (Fig. 3) (Millar, 1954b).