Maintaining ecosystem connectivity is a key factor in the resilience of ecosystems to climate change. Subsidies of material and energy from donor ecosystems can significantly influence the structure and dynamics of recipient communities and food webs. The largest observed cross-ecosystem fluxes are from marine to terrestrial systems, consist of exported primary production, and are driven by currents and tides. An exceptional example is the substantial subsidy of organic matter exported by highly productive nearshore kelp forests to sandy beaches. The wrack subsidies exported from kelp forests to beaches support their biodiversity and numerous ecosystem functions as well as fuel highly productive beach food webs. Kelp wrack inputs to beaches are highly dynamic, but the relative spatial scale at which this connectivity occurs is largely unknown. Here, we use local (100 m) to regional (100 km) scale measurements of kelp wrack inputs along with nearshore kelp supply, via Landsat-derived kelp canopy biomass estimates, to determine the scale at which connectivity between beaches and kelp forests is maximized. Our results indicated that connectivity is maximized at scales of less than 10 km. Further, these relationships are strongest in winter and weakest in summer. In addition, the form of kelp (wrack vs. whole plants) is an important factor in determining the spatial scale of connectivity with kelp forests. Elucidating the fine-scale variability in ecosystem subsidies will be critical as ecosystem connectivity is weakened through climate change and anthropogenic development.

Primary Presenter: Kyle Emery, University of California, Los Angeles (kyleemery@ucla.edu)

Authors:

Kyle Cavanaugh, University of California, Los Angeles  ()

David Hubbard, University of California, Santa Barbara  ()

Jessica Madden, University of California, Santa Barbara  ()

Jenifer Dugan, University of California, Santa Barbara  ()