Population dynamics of the yellow clam Mesodesma mactroides: recruitment variability, density-dependence and stochastic processes

M Lima, A Brazeiro, O Defeo
2000 Marine Ecology Progress Series  
Recruitment of benthic marine invertebrates varies greatly at different spatio-temporal scales. For instance, population dynamics of the yellow clam Mesodesma mactroides at Uruguay exhibit large temporal fluctuations, mainly associated with recruitment. We used data from an 8 yr long-term study to develop an age-structured model to show that density-dependent and densityindependent forces acting together can jointly explain the population fluctuations in a sandy-beach bivalve population of the
more » ... ellow clam Mesodesma mactroides. The pure density-dependent deterministic model parameterised with empirical values estimated during the 8 yr study predicted stable dynamics. The dynamics of the deterministic skeleton was markedly influenced by the addition of a relatively small amount of stochastic variability to fertility rates. The yellow clam population dynamics seem to be driven by the combined forces of density-dependent and density-independent factors operating together. A combination of (uncorrelated) stochasticity in reproductive rates and asymmetric intercohort interactions (density-dependent recruitment and density-dependent survival rates) seems to be the key process generating large variability in recruitment. KEY WORDS: Mesodesma mactroides · Oscillations · Recruitment variability · Age-structured model · Marine invertebrates · Intercohort interactions Resale or republication not permitted without written consent of the publisher
doi:10.3354/meps207097 fatcat:ol7nbcw6vnfcrirmvvzxodjala