Browsing by Author "Dawson, Michael N."

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    A Decade of Death and Other Dynamics: Deepening Perspectives on the Diversity and Distribution of Sea Stars and Wasting
    (2023) Dawson, Michael N.; Duffin, Paige J.; Giakoumis, Melina; Schiebelhut, Lauren M.; Beas-Luna, Rodrigo; Bosley, Keith L.; Castilho, Rita; Ewers-Saucedo, Christine; Gavenus, Katie A.; Keller, Aimee; Konar, Brenda; Largier, John L.; Lorda, Julio; Miner, C. Melissa; Moritsch, Monica M.; Navarrete, Sergio A.; Traiger, Sarah B.; Turner, Mo S.; Wares, John P.
    Mass mortality events provide valuable insight into biological extremes and also ecological interactions more generally. The sea star wasting epidemic that began in 2013 catalyzed study of the microbiome, genetics, population dynamics, and community ecology of several high-profile species inhabiting the northeastern Pacific but exposed a dearth of information on the diversity, distributions, and impacts of sea star wasting for many lesser-known sea stars and a need for integration across scales. Here, we combine datasets from single-site to coast-wide studies, across time lines from weeks to decades, for 65 species. We evaluated the impacts of abiotic characteristics hypothetically associated with sea star wasting (sea surface temperature, pelagic primary productivity, upwelling wind forcing, wave exposure, freshwater runoff) and species characteristics (depth distribution, developmental mode, diet, habitat, reproductive period). We find that the 2010s sea star wasting outbreak clearly affected a little over a dozen species, primarily intertidal and shallow subtidal taxa, causing instantaneous wasting prevalence rates of 5%-80%. Despite the collapse of some populations within weeks, environmental and species variation protracted the outbreak, which lasted 2-3 years from onset until declining to chronic background rates of similar to 2% sea star wasting prevalence. Recruitment began immediately in many species, and in general, sea star assemblages trended toward recovery; however, recovery was heterogeneous, and a marine heatwave in 2019 raised concerns of a second decline. The abiotic stressors most associated with the 2010s sea star wasting outbreak were elevated sea surface temperature and low wave exposure, as well as freshwater discharge in the north. However, detailed data speaking directly to the biological, ecological, and environmental cause(s) and consequences of the sea star wasting outbreak remain limited in scope, unavoidably retrospective, and perhaps always indeterminate. Redressing this shortfall for the future will require a broad spectrum of monitoring studies not less than the taxonomically broad cross-scale framework we have modeled in this synthesis.
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    Questioning the Rise of Gelatinous Zooplankton in the World's Oceans
    (2012) Condon, Robert H.; Graham, William M.; Duarte, Carlos M.; Pitt, Kylie A.; Lucas, Cathy H.; Haddock, Steven H. D.; Sutherland, Kelly R.; Robinson, Kelly L.; Dawson, Michael N.; Decker, Mary Beth; Mills, Claudia E.; Purcell, Jennifer E.; Malej, Alenka; Mianzan, Hermes; Uye, Shin-Ichi; Gelcich, Stefan; Madin, Laurence P.
    During the past several decades, high numbers of gelatinous zooplankton species have been reported in many estuarine and coastal ecosystems. Coupled with media-driven public perception, a paradigm has evolved in which the global ocean ecosystems are thought to be heading toward being dominated by "nuisance" jellyfish. We question this current paradigm by presenting a broad overview of gelatinous zooplankton in a historical context to develop the hypothesis that population changes reflect the human-mediated alteration of global ocean ecosystems. To this end, we synthesize information related to the evolutionary context of contemporary gelatinous zooplankton blooms, the human frame of reference for changes in gelatinous zooplankton populations, and whether sufficient data are available to have established the paradigm. We conclude that the current paradigm in which it is believed that there has been a global increase in gelatinous zooplankton is unsubstantiated, and we develop a strategy for addressing the critical questions about long-term, human-related changes in the sea as they relate to gelatinous zooplankton blooms.