Understanding population dynamics of a numerically dominant species at hydrothermal vents: a matrix modeling approach

Abstract

Using a stage-based matrix model, we explored the population dynamics and life- history traits of the numerically dominant deep-sea limpet Lepetodrilus fucensis at hydrothermal vents on the Juan de Fuca Ridge, northeast Pacific, to determine the potential mechanisms for the success of this species in an ephemeral and variable ecosystem. The life-history traits of L. fucensis differed from those generally expected for species in fluctuating and unpredictable habitats, in that variation in survival of recruits had the largest effect on population growth, while perturbations in adult survival or fecundity had little influence. However, rapid individual growth rates were also nec- essary to achieve long-term population growth. The modeled stable stage distribution adequately represented the dynamics of settler and recruit stages, but did not match those of adult stages, in pop- ulations sampled from 3 different sites. This suggests that factors not accounted for within the model, such as changing individual behaviour across life stages in response to environmental stimuli, may be important in shaping the structure of L. fucensis populations in different microhabitats. In numer- ical experiments, density-dependent survival and growth of settlers resulted in fluctuations in popu- lation growth rate and suppressed total population size over time. Reproductive failure due to para- sitic infection decreased local recruitment, but did not result in population extinction. Faster growth rates allowed for population persistence under greater levels of chronic disturbance. Recovery time after a catastrophic disturbance fit within the time frames observed for eruptions in nature. Overall, our analyses emphasize the possible variation in life-history tactics exhibited by organisms in extreme and variable habitats, and demonstrate the high potential of models, originally developed for use in other ecosystems, to accelerate research in deep-sea communities.