Marine organisms often undergo a long dispersion stage in order to migrate from a spawning ground (source) to favorable nursery grounds (sink), a process that is essential for their long-term survival. Various species may adopt different dispersal strategies to harness ocean circulation for successful dispersion. Yet much is unknown about such dispersion processes given the difficulty of direct observation and tracking minute marine organisms during their dispersion stage. This proposal is about using ocean circulation models coupled with field data of the organisms? distribution to both rebuild drift pathways and to predict the most likely source location and timing of drift initialization. The focus of the analysis is on few species of fish and jellyfish. These organisms represent opposite ecological spectrums. Fish disperse mostly during the early life stages (eggs and larvae) while jellyfish disperse during the adult stages. A new class of semiparametric dynamic spatial regression models is proposed and the development of new statistical tools for sink-source reconstruction, and assessment of various dispersal strategies. The proposed methods provide a novel framework for assessing the significance of dispersal duration, spawning time distribution, and the contribution of organisms from particular sources. Furthermore, a dispersal-strategy selection criterion will be developped that will pick the dispersal strategy most consistent with survey data.
The research team consists of two marine ecologists, one statistician and one physical oceanographer. The proposed work will provide general tools for understanding the dispersal strategies of various species. Climate change may alter ocean circulation patterns, and our increased understanding of dispersal strategies can be useful for predicting the effects of climate change on population fluctuations of marine organisms. The methods may be extended for assessing dispersal strategies for organisms that use other media for their dispersal, e.g. wind. A computer package implementing the proposed methods will be freely available to the public. The team will continue to maintain strong record of training PhD students in cross-disciplinary research.
