![]() Second, I monitored somatic and fish scale growth in the laboratory to measure the relationship between somatic growth and spacing between growth increments (intercirculus spacing). The body-scale size relationship was strongly positive and was unaffected by gender however, there did appear to be significant differences between certain populations. First, I established the relationship between scale growth and body size, and determined how variable this relationship was among populations. Somatic growth rates through ontogeny are one of the most important metrics for understanding fish populations and in Chapter 3, I evaluate the use of spacing between growth increments on fish scales (called circuli) as a measurement technique for assessing historical growth in F. Overall, these results highlight the potentially complex effects adult residents may have on shaping patterns of recruitment and the distributions of new juveniles. lapillum adults and Forsterygion varium ) increased predation risk in settlers of F. There was no evidence that combined or interacting effects between predators (F. Results suggested overall mortality attributable to cannibalism was low however, smaller settlers appeared to be more vulnerable to cannibalism. Using a laboratory-based experiment that used a “multiple predator effects” (MPE) design, I tested the hypothesis that increased settler mortality, caused by either (i) intercohort competition leading to enhanced predation risk or (ii) cannibalism by adults on juveniles, contributed to the observed negative relationship between juvenile and adult densities. ![]() The shape of this curve was temporally variable, but was otherwise unaffected by particular features of the site (algal species identity). The relationship between juvenile and adult densities followed a dome-shaped curve, with a negative correlation between juveniles and adults at higher adult densities. lapillum (within the preferred settlement habitats of juveniles) to investigate correlations between adult and juvenile densities potentially caused by age-class interactions. In Chapter 2, I evaluated spatial covariation in juvenile and adult densities of F. The larvae of many reef fishes settle into habitats that are already occupied by adults, and interactions between age classes (intercohort interactions) may affect spatial variation in recruitment strength across settlement sites. and finally, assessed how natal origin modifies larval survival probabilities among offspring (Chapter 6). evaluated how reproductive success is modified by the presence of ectoparasites (Chapter 5) explored how previous growth rates influence reproductive success (Chapter 4) verified methods to measure somatic growth rates during development using scale structures (Chapter 3) how the spatial distribution and survival of juveniles is influenced by age-class interactions (Chapter 2) In this thesis, I investigated how recruitment, growth and reproductive success varied among individuals of a small temperate reef fish, Forsterygion lapillum, the common triplefin, based upon their developmental histories, morphological traits, and habitat characteristics (including conspecific densities, regional locations, etc.). ![]() Finally, absolute reproductive success (i.e., the number of offspring that survive to reproductive age) may be dependent upon early larval mortality of offspring, and variation in larval mortality among spawning sites could have consequences for metapopulation dynamics. However, female preferences for particular phenotypes may also be modified by events occurring in adult life, such as parasite infection. For individuals that survive, variation in somatic growth histories during development may influence mating success among fish that successfully recruit into the adult population, and particular developmental histories may receive a disproportionate amount of a population’s reproductive output. For instance, the input of new individuals into a population (recruitment) is heavily shaped by mortality in the larval and juvenile stages, which is influenced by conspecific interactions and habitat characteristics. The population dynamics of reef fishes may be influenced by events occurring across multiple life stages, throughout the entire life cycle. In order to gain a comprehensive understanding of population dynamics, it is vital to identify the key factors that contribute to variation in both survival and reproductive success throughout the life history of an organism.
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