Aspects of the biology of the bryozoan Pentapora fascialis in the northwestern Mediterranean |
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Authors: | S Cocito S Sgorbini C N Bianchi |
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Institution: | (1) Marine Environment Research Centre, ENEA Santa Teresa, P.O. Box 316, I-19100 La Spezia, Italy, IT |
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Abstract: | Colonies of the bryozoan Pentapora fascialis (Pallas) were monitored photographically from January 1993 to March 1994, in two quadrats at depths of 11 and 22 m at Tino
Island (Ligurian Sea, Italy). Colony size, shape, growth and mortality were analysed. Zoarial growth was measured as change
in the two-dimensional area of substratum covered per unit time. Colonies ranged in size from less than 30 to 2760 cm2. Colony shape was normally depressed globular, with an elliptic or subcircular perimeter, but tended to elongate in crowded
situations. Although extremely variable in small colonies, growth was inversely related to colony size and was maximum in
spring. Highest net growth rate was 211% in 11 months. No recruitment was observed in the quadrats during the study period.
Partial mortality in colonies was low and was mainly due to overgrowth by algae and to siltation. Physical disturbance by
an exceptionally severe winter storm in December 1993 caused total mortality of almost all colonies in the shallow quadrat.
Received: 24 March 1997 / Accepted: 22 November 1997 |
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