Effects of variation in eutrophication and in Diadema antillarum densities (grazing pressure) on the abundance and life history characteristics of Favia fragum on seven reefs along the west coast of Barbados were investigated. Densities of D. antillarum were negatively correlated with eutrophication levels, and interpretations of their effects have been made simultaneously. Abundance of F. fragum was lower on more eutrophic reefs with lower D. antillarum densities. This may result from effects of eutrophication and of D. antillarum on algal cover on reefs. Macrophytic algae were more abundant, and crustose coralline algae less abundant, on eutrophic reefs with lower D. antillarum densities; and macrophytic algal cover was negatively correlated with crustose coralline algal cover across reefs. F. fragum abundance was positively correlated with crustose coralline algal cover, and F. fragum occurred less frequently on reef areas where macrophytic algae were abundant. High eutrophication and low D. antillarum density (grazing pressure) may therefore reduce F. fragum abundance by increasing the cover of macrophytic algae relative to crustose coralline algae on reefs. Neither planulation periodicity, colony fecundity, nor polyp fecundity in F. fragum differed at different eutrophication levels and D. antillarum densities. Moreover, adult growth and adult mortality did not differ with eutrophication levels and D. antillarum densities on reefs. However, growth of juveniles appeared slower and mortality higher on eutrophic reefs with low D. antillarum densities. Moreover, larvae of F. fragum preferred to settle on crustose coralline algae than on turf algae (macrophytic algae), and the former are comparatively scarce on eutrophic reefs with low D. antillarum densities. The results suggest that the negative correlation between adult abundance of F. fragum and eutrophication levels/grazing pressure (D. antillarum densities) on Barbados reefs are caused primarily by effects
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.68217 |
| Date | January 1994 |
| Creators | Mann, Gary S. (Gary Seymour) |
| Contributors | Hunte, W. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Biology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001396079, proquestno: AAIMM94475, Theses scanned by UMI/ProQuest. |
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