Algal Structural Complexity Effect on Diversity and Abundance of Some Ostracod Species from Red Sea Coast, Egypt

摘要

Four species of macroalgae (Sargassum obtusifolium , Sargassum polyphyllum , Chnoospora minima , Nemacystus decipiens ) were collected monthly to study the changes in ostracod species abundance, richness and diversity between them during 12 months. Also, determine effect of algal structural complexity on ostracod abundance and diversity. Structural complexity was estimated by counting the number of branches cm~(-1) for each one of the four studied algae. There were significant differences in complexity between the 4 algal species. Sargassum obtusifolium had significantly more branches cm~(-1) than the remaining 3 algal species, and Sargassum polyphyllum had significantly more branches than Chnoospora minima , and Nemacystus decipiens . There were differences in abundance and diversity of ostracod assemblages between the fouralgal species. Where, Sargassum obtusifolium carried a higher abundance, species richness and diversity of ostracods during study period than that of the residual three algae. The ostracod samples of four studied algae nearly formed separate clusters, reflecting the difference between these algae throughout the year. Sixteen species of ostracod occurred on the algae, six only occurred at sufficient densities for determination of their life-cycles. Cylindroleberis sp., Ghardaglaia triebeli and Mosella striata occurred at high densities and had two generations per year. The other three abundant ostracod species; Loxoconcha ornatovalve , Paradoxostoma altecaudatum and Xestoleberis ghardaqe found at low densities and had one generation per year.