Colonization experiments were conducted in a tropical lagoon (Zanzibar Island, off the coast of Tanzania) to investigate the temporal dynamics and mode of colonization of the harpacticoid copepods community on dead coral fragments. There was fast colonization of the coral fragments attaining a substantial diversity after only two days. The ability to colonize dead coral fragments is thought to be related to the morphology and life style of different harpacticoid species. Phytal taxa (e.g. Tisbidae) were fast colonizers, reaching high abundances during the initial colonization phase. Sediment-associated and eurytopic taxa (e.g. Ameiridae, Miraciidae and Ectinosomatidae) showed lower colonization rates and became the dominant group during the later colonization phase. Most species are able to colonize the coral fragments through the water column. However, colonization along the substrate surface is also considered to be an important colonization mode, especially for sediment-associated taxa, which showed lower colonization rates when migration through the sediment was hindered.

Three microhabitat types (dead coral fragments, coral gravel and coral sand) were distinguished and sampled at two locations (Matemwe and Makunduchi) in a tropical lagoon (Zanzibar Island, Tanzania), and the community structure, habitat preferences and biodiversity of the associated harpacticoid copepod fauna was investigated. The harpacticoid fauna is affected by sediment granulometry and by the structural differences between coral and both gravel and sediment. The coral fragments contained a specific assemblage composed of typical ‘phytal’ taxa (Tisbe, Paradactylopodia and Dactylopusia) along with other eurytopic and sediment-dwelling forms (Ameira, Ectinosoma and Amphiascus), which may be attracted by the sediment retained between the coral branches. The assemblages of coral gravel and upper sediment layer did not differ significantly from each other and had mostly the same dominant genera. The sediment from Matemwe was dominated by the interstitial Paramesochridae and the sediment from Makunduchi by Tetragonicipitidae. The coral fragments from Makunduchi sustained a more diverse assemblage than gravel and the different sediment layers. It was assumed that coral form and complexity, with implications for habitable space, nutritional resources and level of predation, are important in structuring diversity of the associated assemblage.