MEPS 150:65-74 (1997) - doi:10.3354/meps150065
Post-settlement movement of coral reef fishes and bias in survival estimates
Most coral reef fish have a bipartite life-history characterized by a pelagic larval phase followed by transformation and settlement into a benthic existence. There is increasing interest among marine ecologists in determining the importance of post-settlement processes to reef fish demography. This study distinguishes movement as an important post-settlement phenomenon affecting estimates of early survivorship of juvenile coral reef fishes. Individuals settling onto artificial patch habitats were collected, marked, released and monitored by visual census over 2 systems of isolated artificial patch habitats. Some recently settled juvenile fish moved as much as 100 m over open sand. Probability of movement was dependent on species; size was a significant factor among species, but not among conspecifics. Survivorship calculated from observations of uniquely marked individuals was contrasted with survivorship estimated by comparing the initial number of newly settled individuals at a site with the number of individuals there after a given time interval. The comparison revealed that new settlers and immigrants can mask the loss of individuals included in the original census and thereby inflate estimates of survivorship. Comparing survival estimates with and without accounting for movement demonstrated that survivorship can be underestimated when new settlers subsequently emigrate and survive at another site, but are unwittingly recorded as lost due to mortality. Significant differences were observed in survival experiences for different species and size classes. Where significant differences were found in survival times of mobile individuals versus sedentary, those that moved survived longer.
Coral reef fishes · Recruitment · Survival · Mortality · Movement · Artificial reefs
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