Drivers of synchrony in giant kelp forests

A large group of us was funded for several years by the National Science Foundation to study spatial synchrony in canopy forming kelp off the West Coast of the USA (and, later, elsewhere, as well). Tom Bell (Woods Hole Oceanographic Institution) and Kyle Cavanaugh (UCLA) put together an astounding ongoing dataset on giant kelp dynamics by figuring out how to identify kelp canopy from space. The data span decades, are now worldwide, have quarterly-or-better temporal resolution and 30m spatial resolution, and are accompanied by data sets on kelp drivers. We used Reuman lab statistical methods and our geographic and time- and timescale-specific approaches to inferences of the drivers of synchrony to determine the nature, drivers, and ecological consequences of kelp synchrony in California kelp ecosystems, as well as the contribution of dispersal to kelp synchrony. The project also led to spinoff and related projects on a general theory of interactions between synchrony drivers, applications to kelp of our ideas on asymmetric tail associations in ecology, cross-system cascades of synchrony, changing synchrony in exploited fish and invertbrates, and a major review on synchrony and the importance of long-term data for ecology.

D.C. Reuman, J.A. Walter, L.W. Sheppard, V.A. Karatayev, E.S. Kadiyala, A.C. Lohmann, T.L. Anderson, N.J. Coombs, K.J. Haynes, L.M. Hallett, M.C.N. Castorani. 2025. Insights into spatial synchrony enabled by long-term data. Ecology Letters 28, e70112. doi: 10.1111/ele.70112.

V.A. Karatayev, S.B. Munch, T.L. Rogers, D.C. Reuman. 2024. Climate change could amplify weak synchrony in large marine ecosystems. Proceedings of the National Academy of Sciences 122, e2404155121. doi: 10.1073/pnas.2404155121.

M. Liang, T. Lamy, D.C. Reuman, S. Wang, T.W. Bell, K.C. Cavanaugh, M.C.N. Castorani. 2024. A marine heatwave changes the stabilizing effects of biodiversity in kelp forests. Ecology 105, e4288. doi: 10.1002/ecy.4288.

M.S. Wanner, J.A. Walter, D.C. Reuman, T.W. Bell, M.C.N. Castorani. 2024. Dispersal synchronizes giant kelp forests. Ecology 105, e4270. doi: 10.1002/ecy.4270.

J.A. Walter, K.A. Emery, J.E. Dugan, D.M. Hubbard, T.W. Bell, L.W. Sheppard, V.A. Karatayev, K.C. Cavanaugh, D.C. Reuman, M.C.N. Castorani. 2024. Spatial synchrony cascades across ecosystem boundaries and up food webs via resource subsidies. Proceedings of the National Academy of Sciences 121, e2310052120. doi: 10.1073/pnas.2310052120.

D.C. Reuman, M.C.N. Castorani, K.C. Cavanaugh, L.W. Sheppard, J.A. Walter, T.W. Bell. 2023. How environmental drivers of spatial synchrony interact. Ecography 10, e06795. doi: 10.1111/ecog.06795.

M.C.N. Castorani, T.W. Bell, J.A. Walter, D.C. Reuman, K.C. Cavanaugh, L.W. Sheppard. 2022. Disturbance and nutrients synchronize kelp forests across scales through interacting Moran effects. Ecology Letters 8, 1854-1868. doi 10.1111/ele.14066.

J.A. Walter, M.C.N. Castorani, T.W. Bell, L.W. Sheppard, K.C. Cavanaugh, D.C. Reuman. 2022. Tail-dependent spatial synchrony arises from nonlinear driver-response relationships. Ecology Letters 25, 1189-1201. doi: 10.1111/ele.13991.

People: Lawrence Sheppard, Jon Walter, Ethan Kadiyala, Vadim Karatayev, Nat Coombs, Dan Reuman