Limitations to Long-term Species Accrual and Development of Microbial community structure in Aquatic “Islands”

ABSTRACT

Microbial (protistan and metazoan) colonization dynamics were compared in mature (4-yr old) and immature (newly formed) artificial aquatic islands to assess the role of internal and external forces during community development. The number of taxa in immature islands stabilized after 1 mo of colonization at a number considerably less than in mature islands. Turnover was directional in both immature and mature islands, although reduced rates in the latter indicated that the structure of the association was stabilizing. One immature island and one mature island were inoculated with small numbers of propagules from mature islands and a temporary pond, respectively. Taxon richness in the immature island exceeded all other islands within 16 d as 25% of the introduced species grew. Although fewer introduced species grew in the mature island, transport still had an impact on community structure. The structure of the microbial assemblage is strongly influenced by external transport processes and remains relatively open to invaders for a long period during development.