Habitat Size, Recruitment, and Longevity as Factors Limiting Population Size in Stage-Structured Species

Abstract

Surprisingly little research has evaluated how habitat size may limit the population size of species that use different habitats at different stages of their lives. Here we develop simple discrete-time models to describe the population dynamics of species that use separate juvenile and adult habitats. Analytic solutions, model simulations, and elasticity and sensitivity analyses show that adult abundance is only limited by the size of the juvenile habitat when both adult habitat size and recruitment are much larger than juvenile habitat size. Juvenile habitat plays a marginally greater role in limiting population size for species with closed populations, where recruitment is proportional to adult abundance, versus open populations. Because adult populations often accumulate pulses of juveniles, adult habitat size can strongly limit population size over a broad range of parameter values, an effect that increases as the longevity of a species increases. Limited empirical research from a range of taxa supports these model predictions, although few studies were designed to actually test the limiting role of juvenile versus adult habitat. Future research must carefully evaluate whether and how processes at the juvenile stage affect adult abundance, and conservation efforts may be able to use this model to evaluate the cost-effectiveness, vis-a-vis increasing adult abundance, of time and money allocated to protecting juvenile habitats.

Habitat- and sex-specific life history patterns of yellow tang Zebrasoma flavescens in Hawaii, USA

“…Most studies on ontogenetic variation of habitat use have compared size distributions between habitats (Gillanders et al 2003), and therefore have not considered age structure, sex-specific habitat use patterns or the duration of the lifespan spent in each habitat. When available, information about age-based habitat use can improve conservation planning and design of MPAs (Mumby 2006, Parnell et al 2006) and lead to an understanding of how the amount of available juvenile and adult habitat may influence population size -a potential key to conservation and area-based fisheries management (Halpern et al 2005).…”

“…Most studies on ontogenetic variation of habitat use have compared size distributions between habitats (Gillanders et al 2003), and therefore have not considered age structure, sex-specific habitat use patterns or the duration of the lifespan spent in each habitat. When available, information about age-based habitat use can improve conservation planning and design of MPAs (Mumby 2006, Parnell et al 2006) and lead to an understanding of how the amount of available juvenile and adult habitat may influence population size -a potential key to conservation and area-based fisheries management (Halpern et al 2005).Many species of coral reef fish, including several species of surgeonfish, make ontogenetic shifts in habitat use-an important factor in the organization of fish communities (Robertson 1988, Lawson et al 1999, Lecchini & Galzin 2005, Robertson et al 2005, Pratchett et al 2008. Yellow tang in West Hawaii settle primarily into middepth (10 to 25 m) reef habitat with a high percentage of coral cover (hereafter deeper coral-rich habitat).…”

Habitat selectivity of substrate-spawning fish: modelling requirements for the Eurasian perch Perca fluviatilis

“…As in many aquatic organisms, distribution and abundance of early life stages of fish are critical determinants of the population size (Houde 1989, Wahle & Steneck 1991, but the characteristics and distribution of nursery areas, including spawning habitats, are usually poorly known. Research aiming at habitat mapping and identification of crucial habitat bottlenecks, such as critical environmental conditions constituting a spawning habitat of a species, is therefore essential for aquatic conservation (Halpern et al 2005, Sale et al 2005.…”

Habitat use and preference of adult perch (Perca fluviatilis L.) in a deep reservoir: variations with seasons, water levels and individuals

“…Fish habitat use is a key driver of population dynamics (Hayes et al, 2009) and an essential knowledge for predicting how populations will respond to management interventions (Koster et al, 2015;Cooke et al, 2016). In particular, the identification of crucial habitats is important for efficient aquatic conservation in areas with strong human influence (Halpern et al, 2005;Sale et al, 2005).…”