Carr Mark H.

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Carr
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Mark H.
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  • Article
    A review of the opportunities and challenges for using remote sensing for management of surface-canopy forming kelps
    (Frontiers Media, 2021-10-20) Cavanaugh, Kyle C. ; Bell, Tom W. ; Costa, Maycira ; Eddy, Norah E. ; Gendall, Lianna ; Gleason, Mary G. ; Hessing-Lewis, Margot ; Martone, Rebecca ; McPherson, Meredith L. ; Pontier, Ondine ; Reshitnyk, Luba ; Beas-Luna, Rodrigo ; Carr, Mark H. ; Caselle, Jennifer E. ; Cavanaugh, Katherine C. ; Flores Miller, Rebecca ; Hamilton, Sara L. ; Heady, Walter N. ; Hirsh, Heidi K. ; Hohman, Rietta ; Lee, Lynn Chi ; Lorda, Julio ; Ray, James ; Reed, Daniel C. ; Saccomanno, Vienna R. ; Schroeder, Sarah B.
    Surface-canopy forming kelps provide the foundation for ecosystems that are ecologically, culturally, and economically important. However, these kelp forests are naturally dynamic systems that are also threatened by a range of global and local pressures. As a result, there is a need for tools that enable managers to reliably track changes in their distribution, abundance, and health in a timely manner. Remote sensing data availability has increased dramatically in recent years and this data represents a valuable tool for monitoring surface-canopy forming kelps. However, the choice of remote sensing data and analytic approach must be properly matched to management objectives and tailored to the physical and biological characteristics of the region of interest. This review identifies remote sensing datasets and analyses best suited to address different management needs and environmental settings using case studies from the west coast of North America. We highlight the importance of integrating different datasets and approaches to facilitate comparisons across regions and promote coordination of management strategies.
  • Article
    Large-scale shift in the structure of a kelp forest ecosystem co-occurs with an epizootic and marine heatwave
    (Nature Research, 2021-03-05) McPherson, Meredith L. ; Finger, Dennis J. I. ; Houskeeper, Henry F. ; Bell, Tom W. ; Carr, Mark H. ; Rogers-Bennett, Laura ; Kudela, Raphael M.
    Climate change is responsible for increased frequency, intensity, and duration of extreme events, such as marine heatwaves (MHWs). Within eastern boundary current systems, MHWs have profound impacts on temperature-nutrient dynamics that drive primary productivity. Bull kelp (Nereocystis luetkeana) forests, a vital nearshore habitat, experienced unprecedented losses along 350 km of coastline in northern California beginning in 2014 and continuing through 2019. These losses have had devastating consequences to northern California communities, economies, and fisheries. Using a suite of in situ and satellite-derived data, we demonstrate that the abrupt ecosystem shift initiated by a multi-year MHW was preceded by declines in keystone predator population densities. We show strong evidence that northern California kelp forests, while temporally dynamic, were historically resilient to fluctuating environmental conditions, even in the absence of key top predators, but that a series of coupled environmental and biological shifts between 2014 and 2016 resulted in the formation of a persistent, altered ecosystem state with low primary productivity. Based on our findings, we recommend the implementation of ecosystem-based and adaptive management strategies, such as (1) monitoring the status of key ecosystem attributes: kelp distribution and abundance, and densities of sea urchins and their predators, (2) developing management responses to threshold levels of these attributes, and (3) creating quantitative restoration suitability indices for informing kelp restoration efforts.