Publications

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2007
Thorrold, SR, Zacherl DC, Levin LA.  2007.  Population connectivity and larval dispersal using geochemical signatures in calcified structures. Oceanography. 20:80-89.   dx.doi.org/10.5670/oceanog.2007.31   AbstractWebsite

The importance of larval dispersal to the population dynamics and biogeography of marine organisms has been recognized for almost a century (Hjort, 1914; Thorson, 1950). More recently, theoretical studies have highlighted the role that connectivity may play in determining the resilience of marine populations (Hastings and Botsford, 2006). Effective spatial management of marine capture fisheries, including the design of marine reserve networks, also requires an understanding of population connectivity (Sale et al., 2005). However, remarkably few empirical estimates of larval dispersal or population connectivity in ocean environments exist.

Becker, BJ, Levin LA, Fodrie FJ, McMillan PA.  2007.  Complex larval connectivity patterns among marine invertebrate populations. Proceedings of the National Academy of Sciences of the United States of America. 104:3267-3272.   10.1073/pnas.0611651104   AbstractWebsite

Based on the belief that marine larvae, which can spend days to months in the planktonic stage, could be transported considerable distances by ocean currents, it has long been assumed that populations of coastal species with a planktonic larval stage are demographically open and highly "connected." Such assumptions about the connectivity of coastal populations govern approaches to managing marine resources and shape our fundamental understanding of population dynamics and evolution, yet are rarely tested directly due to the small size and high mortality of marine larvae in a physically complex environment. Here, we document a successful application of elemental fingerprinting as a tracking tool to determine sources of settled invertebrates and show that coastal mussel larvae, previously thought to be highly dispersed, can be retained within 20-30 km of their natal origin. We compare two closely related and co-occurring species, Mytilus californianus and Mytilus galloprovincialis, and determine that, despite expected similarities, they exhibit substantially different connectivity patterns. Our use of an in situ larval culturing technique overcomes the previous challenge of applying microchemical tracking methods to species with completely planktonic development. The exchange of larvae and resulting connectivities among marine populations have fundamental consequences for the evolution and ecology of species and for the management of coastal resources.