Many marine benthic invertebrates undergo a passive pelagic larval stage. As opposed to sessile adults, larvae can travel over great distances, transported by currents. However, patterns of ocean currents are known to vary across temporal scales, seasonally, inter-annually. Moreover, such variability is predicted to increase with ongoing climate change. Metapopulation theory predicts how the average and spatial distribution of connectivity can alter the stability of metapopulations, but little is known about the importance of spatiotemporal heterogeneity in connectivity and how it can affect metapopulation stability and persistence. To answer such question, we used a stochastic and stage-structured metapopulation models, with and without density-dependence in subpopulation growth. We analytically derived then simulated the stochastic growth rate distribution in relation to the regional mean. We applied our model to the British Colombia (Canada) coastal system and quantified the connectivity between sites from 1998-2007 with a biophysical model (Regional Oceanic Modeling System), and then assessed how statistical metrics of variable connectivity shape stochastic growth distribution. We further varied the spawning time and pelagic larval duration to assess how clusters of connectivity are affected by species intrinsic traits related to connectivity.
Our results revealed the importance of connectivity variance, pairwise covariance and autocorrelation for both density-dependent and density-independent growth. They also show that (1) fluctuations magnitude (variance) in connectivity decreases regional growth, (2) the asynchronous or synchronous (covariance) temporal exchange of larvae subsidies between spatially fragmented habitats and (3) pattern of temporal autocorrelation in connectivity itself can deflate or inflate the stochastic growth compare to deterministic counterpart. Furthermore, these three components of spatiotemporal connectivity are used to quantify risk of extinction. The risk of extinction varies with pelagic traits, physical transport, and growth regulation. While density independent growth predict monotonic increase of risk with larval duration, density-dependent growth predict non-monotonic (concave) relationship between risk and larval duration. We propose a framework that focus on important processes of stochastic marine dispersal; trait-based biophysical and ecological models of connectivity fluctuations that can contribute to the design of marine reserve networks, and will improve predictions of species response to scenarios of future climate and ocean transport variability.