MEPS 329:211-223 (2007)  -  doi:10.3354/meps329211

ABSTRACT: Cownose rays Rhinoptera bonasus typify the K-selected life history strategy that makes their population dynamics susceptible to variation in natural and anthropogenic factors. We used an individual-based bioenergetics model, coupled to a matrix projection model, to predict how water temperatures warmer and cooler than current conditions would affect the individual growth and the population dynamics of cownose rays. The bioenergetics model simulated the daily growth, survival, and reproductive output of a cohort of female individuals from birth over their lifetime. Warmer and cooler temperature scenarios under alternative assumptions about ray movement were simulated. Under warmer conditions, daily consumption rate would have to increase by about 12% or weights-at-age would decrease by 10 to 17%, while under cooler conditions, daily consumption would have to decrease by about 14% or weights-at-age would increase by about 15%. Slowed individual growth under warmer water temperatures translated into slowed population growth rate, decreased net reproductive rate, longer generation time, and higher but delayed age-specific reproductive values. For example, under the scenario that resulted in the slowest individual growth rates, the population growth rate would decrease from 0.027 to 0.005 yr^–1. Population growth rates were more sensitive to variation in survival rates, especially those of mature age-classes, than to fertility rates. Our coupling of an individual-based bioenergetics model with a matrix projection model offers a potentially powerful approach for relating how, with limited to moderate information, changes in environmental variables and habitat that affect individual growth can be expressed as population-level responses.
Erratum

KEY WORDS: Cownose ray · Bioenergetics · Matrix model · Population dynamics · Global climate change · Movement