Max Castorani1, Tom Bell2, Kyle Cavanaugh3, Jenny Dugan4, Kyle Emery4, David Hubbard4, Ethan Kadiyala1, Vadim Karatayev5, Amanda Lohmann1, Daniel Reuman6, Lawrence Sheppard7, Jonathan Walter 8, Wanner Miriam1
1University of Virginia, USA, 2Woods Hole Oceanographic Institution, USA, 3University of California Los Angeles, USA, 4University of California Santa Barbara, USA, 5University of Maryland, USA, 6University of Kansas, USA, 7Marine Biological Association, UK, 8University of California Davies, USA
Spatial synchrony is a ubiquitous and important feature of population dynamics. Here we synthesize research on the patterns, causes, and consequences of synchrony in California giant kelp forests. A 40-year satellite time series revealed kelp dynamics synchronized over broad geographic ranges (100s of km) at varying timescales (years to decades) by the combined action of wave disturbance and seawater nitrate. These factors are underpinned by ocean climate fluctuations that cause synchronized booms and busts of kelp. Over shorter distances (up to several km), kelp is synchronized by spore dispersal. Hence, synchrony declines with distance, but shows distinct geographic patterns related to coastal oceanography. 20 years of diver surveys at the Santa Barbara Coastal LTER show that synchronous loss of kelp by large waves causes synchronous proliferation of understory algae in a cascade of synchrony driven by light competition. Heterogeneity over space and time in sea urchin grazing and sand burial reduces the chance of synchronous kelp collapse, stabilizing kelp forest–barren dynamics. Lastly, kelp synchrony is transmitted across ecosystem boundaries and up food chains via the transport of kelp wrack from the forest to sandy beaches. Wrack deposition is synchronized across beaches ( 50 km), thereby synchronizing local abundances of shorebirds that forage on wrack-associated invertebrates. These studies demonstrate how giant kelp has served as a model species to advance knowledge of synchrony, its response to climate, and the effects on community and ecosystem stability.
Biography
Max Castorani is a marine ecologist at the University of Virginia whose work focuses on how kelp forests and other coastal ecosystems respond to environmental change and variability. His research emphasizes long-term data (through the US LTER program), field experiments, and statistical modeling to understand the drivers of habitat dynamics, the consequences for biodiversity, and the implications for restoration. Castorani’s research emphasizes spatial dynamics at landscape to regional scales.