Effects of method of deployment of artificial units of habitat on microgastropod colonization
Chapman, M.G.; Underwood, A.J.; Blockley, D.
Marine Ecology Progress Series 366: 49-57
Artificial units of habitat (AUHs) are used to test theories about structure and configuration of habitat on colonization, effects of disturbances or patterns of biodiversity. They allow control of important components of habitat and where and how habitat is deployed for tests of specific and complex hypotheses. Plastic pot-scourers are widely used for assemblages of small invertebrates because they appear to mimic important characteristics of many biogenic habitats, such as turfing algae or beds of polychaetes. There has, however, been little investigation of the ways in which these AUHs are deployed in the field, although different studies have used different techniques. Here, AUHs were deployed flush with, or raised above the substratum to test hypotheses about rates of colonization by microgastropods according to the method and duration of deployment. In contrast to predictions, duration of deployment did not affect differences between raised and flush AUHs, but, for all periods from 1 to 12 wk, flush AUHs consistently acquired larger abundances of those species shared between the two treatments, There were, however, more species unique to the raised than to the flush AUHs. Abundances of common species increased through time from 1 to 12 wk, but this was not due to successional changes in the AUHs deployed for 12 wk; the increase was due to a rapid colonization event that occurred during the final period of deployment. Studies on colonization of habitat, whether using AUHs or not, need very careful consideration of experimental design to ensure that results are interpretable.