Ecology and population structure of the Recent brachiopod Terebratulina from Scotland
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The ecology and population structure of the Recent articulate brachiopod Terebratulina retusa (Linnaeus) are described. The population studied occurs around the margins of a depression of more than 220 m in the Firth of Lome, Scotland, and is predominantly attached to the horse-mussel Modiolus modiolus (Linnaeus). Spawning occurs regularly in late spring and late autumn, and is initiated at temperatures of 10-11°C. The highly synchronized reproductive cycle, from spawning to spatfall, occurs within 3 weeks in nature. Length-frequency histograms prepared from large representative samples collected at regular intervals during 1977-1979 are unimodal and right-skewed due to the predominance of juveniles. Regularly spaced subsidiary peaks in the histograms correspond to biannual settlement cohorts; in later life successive peaks merge to form a single annual peak. This pattern is identical to that predicted by computer-based simulations. Recently settled specimens grow rapidly to an average length of 2.75 mm within 3 months during both spring and autumn; thereafter the animals grow (initially by 4 mm per year) throughout life, although at a progressively reducing rate from the third year of life onwards. Growth slows or ceases in winter in all but recently settled specimens. The maximum life span is 7 years. The mortality rate remains constant, although the causes of death are not apparent. The growth-lines form biannually, at times of pronounced environmental and physiological disturbance.
Palaeontology - Volume 25 Part 2 Pages 227-246Palaeontology - Volume 25 Part 2 Pages 227-246
Citations
CURRY, G. B. 1982. Ecology and population structure of the Recent brachiopod Terebratulina from Scotland. Palaeontology, 25, 2, 227–246.