Variation in zooid size in two west European species of Alcyonidium (Ctenostomatida)

John S. Ryland*, Joanne S. Porter

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

9 Citations (Scopus)


Two smooth species of Alcyonidium encrust macro-algae on western European shores: A. gelatinosum and A. polyoum. In > 140 collections made within the limits 42-62°N and 11°W-15°E, one or both were obtained from 28 of 48 coast-including geographic cells, 2° latitude × 2° longitude, for which sea surface temperature (SST) data were available from satellite imagery. The SSTs show east-west as well as north-south trends. A. gelatinosum is the more abundant, and is distributed from north Brittany to Shetland and Denmark; A. polyoum is more southerly (Spain to Scotland). Lengths, L, and widths, W, of 20 zooids from five colonies in each collection were measured; the differences in both L and calculated area, A, between colonies were frequently significant (ANOVA, P < 0.05) and between locations very great (P<< 0.001). L and W were often not correlated; A had a higher coefficient of variation (V *) than either L or W. In both species there was a significant negative correlation between zooid length and colony age, presumably reflecting the pattern of zooid ageing and/or colony growth found in Alcyonidium. This important and previously unreported phenomenon probably explains the lack of negative correlation of L and A with any manifestation of SST, the lack of positive correlation between V * for L and A with SST annual range, and the lack of any zooid size difference between the two species.

Original languageEnglish
Title of host publicationBryozoan Studies 2004
Subtitle of host publicationProceedings of the 13th International Bryozoology Association Conference
PublisherCRC Press
Number of pages9
ISBN (Electronic)9780203970799
ISBN (Print)9780415372930
Publication statusPublished - 17 Feb 2005
Event13th International Conference of the International Bryozoology Association 2004 - Concepcion, Chile
Duration: 11 Jan 200416 Jan 2004


Conference13th International Conference of the International Bryozoology Association 2004
Abbreviated titleIBA 2004

ASJC Scopus subject areas

  • Environmental Chemistry
  • Environmental Engineering


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