Thums Michele

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Thums
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Michele
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  • Article
    Global collision-risk hotspots of marine traffic and the world’s largest fish, the whale shark
    (National Academy of Sciences, 2022-05-17) Womersley, Freya C. ; Humphries, Nicolas E. ; Queiroz, Nuno ; Vedor, Marisa ; da Costa, Ivo ; Furtado, Miguel ; Tyminski, John P. ; Abrantes, Katya ; Araujo, Gonzalo ; Bach, Steffen S. ; Barnett, Adam ; Berumen, Michael L. ; Bessudo Lion, Sandra ; Braun, Camrin D. ; Clingham, Elizabeth ; Cochran, Jesse E. M. ; de la Parra, Rafael ; Diamant, Stella ; Dove, Alistair D. M. ; Dudgeon, Christine L. ; Erdmann, Mark V. ; Espinoza, Eduardo ; Fitzpatrick, Richard ; Gonzalez Cano, Jaime ; Green, Jonathan R. ; Guzman, Hector M. ; Hardenstine, Royale ; Hasan, Abdi ; Hazin, Fabio H. V. ; Hearn, Alex R. ; Hueter, Robert ; Jaidah, Mohammed Y. ; Labaja, Jessica ; Ladino, Felipe ; Macena, Bruno C. L. ; Morris, John J. Jr. ; Norman, Bradley M. ; Penaherrera-Palma, Cesar ; Pierce, Simon J. ; Quintero, Lina M. ; Ramirez-Macias, Deni ; Reynolds, Samantha D. ; Richardson, Anthony J. ; Robinson, David P. ; Rohner, Christoph A. ; Rowat, David R. L. ; Sheaves, Marcus ; Shivji, Mahmood ; Sianipar, Abraham B. ; Skomal, Gregory B. ; Soler, German ; Syakurachman, Ismail ; Thorrold, Simon R. ; Webb, D. Harry ; Wetherbee, Bradley M. ; White, Timothy D. ; Clavelle, Tyler ; Kroodsma, David A. ; Thums, Michele ; Ferreira, Luciana C. ; Meekan, Mark G. ; Arrowsmith, Lucy M. ; Lester, Emily K. ; Meyers, Megan M. ; Peel, Lauren R. ; Sequeira, Ana M. M. ; Eguiluz, Victor M. ; Duarte, Carlos M. ; Sims, David W.
    Marine traffic is increasing globally yet collisions with endangered megafauna such as whales, sea turtles, and planktivorous sharks go largely undetected or unreported. Collisions leading to mortality can have population-level consequences for endangered species. Hence, identifying simultaneous space use of megafauna and shipping throughout ranges may reveal as-yet-unknown spatial targets requiring conservation. However, global studies tracking megafauna and shipping occurrences are lacking. Here we combine satellite-tracked movements of the whale shark, Rhincodon typus, and vessel activity to show that 92% of sharks’ horizontal space use and nearly 50% of vertical space use overlap with persistent large vessel (>300 gross tons) traffic. Collision-risk estimates correlated with reported whale shark mortality from ship strikes, indicating higher mortality in areas with greatest overlap. Hotspots of potential collision risk were evident in all major oceans, predominantly from overlap with cargo and tanker vessels, and were concentrated in gulf regions, where dense traffic co-occurred with seasonal shark movements. Nearly a third of whale shark hotspots overlapped with the highest collision-risk areas, with the last known locations of tracked sharks coinciding with busier shipping routes more often than expected. Depth-recording tags provided evidence for sinking, likely dead, whale sharks, suggesting substantial “cryptic” lethal ship strikes are possible, which could explain why whale shark population declines continue despite international protection and low fishing-induced mortality. Mitigation measures to reduce ship-strike risk should be considered to conserve this species and other ocean giants that are likely experiencing similar impacts from growing global vessel traffic.
  • Preprint
    Convergence of marine megafauna movement patterns in coastal and open oceans
    ( 2017-09) Sequeira, Ana M. M. ; Rodríguez, Jorge P. ; Eguíluz, Víctor M. ; Harcourt, Robert ; Hindell, Mark ; Sims, David W. ; Duarte, Carlos M. ; Costa, Daniel P. ; Fernández-Gracia, Juan ; Ferreira, Luciana C. ; Hays, Graeme ; Heupel, Michelle R. ; Meekan, Mark G. ; Aven, Allen ; Bailleul, Frédéric ; Baylis, Alastair M. M. ; Berumen, Michael L. ; Braun, Camrin D. ; Burns, Jennifer ; Caley, M. Julian ; Campbell, R. ; Carmichael, Ruth H. ; Clua, Eric ; Einoder, Luke D. ; Friedlaender, Ari S. ; Goebel, Michael E. ; Goldsworthy, Simon D. ; Guinet, Christophe ; Gunn, John ; Hamer, D. ; Hammerschlag, Neil ; Hammill, Mike O. ; Hückstädt, Luis A. ; Humphries, Nicolas E. ; Lea, Mary-Anne ; Lowther, Andrew D. ; Mackay, Alice ; McHuron, Elizabeth ; McKenzie, J. ; McLeay, Lachlan ; McMahon, Cathy R. ; Mengersen, Kerrie ; Muelbert, Monica M. C. ; Pagano, Anthony M. ; Page, B. ; Queiroz, N. ; Robinson, Patrick W. ; Shaffer, Scott A. ; Shivji, Mahmood ; Skomal, Gregory B. ; Thorrold, Simon R. ; Villegas-Amtmann, Stella ; Weise, Michael ; Wells, Randall S. ; Wetherbee, Bradley M. ; Wiebkin, A. ; Wienecke, Barbara ; Thums, Michele
    The extent of increasing anthropogenic impacts on large marine vertebrates partly depends on the animals’ movement patterns. Effective conservation requires identification of the key drivers of movement including intrinsic properties and extrinsic constraints associated with the dynamic nature of the environments the animals inhabit. However, the relative importance of intrinsic versus extrinsic factors remains elusive. We analyse a global dataset of 2.8 million locations from > 2,600 tracked individuals across 50 marine vertebrates evolutionarily separated by millions of years and using different locomotion modes (fly, swim, walk/paddle). Strikingly, movement patterns show a remarkable convergence, being strongly conserved across species and independent of body length and mass, despite these traits ranging over 10 orders of magnitude among the species studied. This represents a fundamental difference between marine and terrestrial vertebrates not previously identified, likely linked to the reduced costs of locomotion in water. Movement patterns were primarily explained by the interaction between species-specific traits and the habitat(s) they move through, resulting in complex movement patterns when moving close to coasts compared to more predictable patterns when moving in open oceans. This distinct difference may be associated with greater complexity within coastal micro-habitats, highlighting a critical role of preferred habitat in shaping marine vertebrate global movements. Efforts to develop understanding of the characteristics of vertebrate movement should consider the habitat(s) through which they move to identify how movement patterns will alter with forecasted severe ocean changes, such as reduced Arctic sea ice cover, sea level rise and declining oxygen content.
  • Article
    Taxonomic, spatial and temporal patterns of bleaching in anemones inhabited by anemonefishes
    (Public Library of Science, 2013-08-08) Hobbs, Jean-Paul A. ; Frisch, Ashley J. ; Ford, Benjamin M. ; Thums, Michele ; Saenz-Agudelo, Pablo ; Furby, Kathryn A. ; Berumen, Michael L.
    Rising sea temperatures are causing significant destruction to coral reef ecosystems due to coral mortality from thermally-induced bleaching (loss of symbiotic algae and/or their photosynthetic pigments). Although bleaching has been intensively studied in corals, little is known about the causes and consequences of bleaching in other tropical symbiotic organisms. This study used underwater visual surveys to investigate bleaching in the 10 species of anemones that host anemonefishes. Bleaching was confirmed in seven anemone species (with anecdotal reports of bleaching in the other three species) at 10 of 19 survey locations spanning the Indo-Pacific and Red Sea, indicating that anemone bleaching is taxonomically and geographically widespread. In total, bleaching was observed in 490 of the 13,896 surveyed anemones (3.5%); however, this percentage was much higher (19–100%) during five major bleaching events that were associated with periods of elevated water temperatures and coral bleaching. There was considerable spatial variation in anemone bleaching during most of these events, suggesting that certain sites and deeper waters might act as refuges. Susceptibility to bleaching varied between species, and in some species, bleaching caused reductions in size and abundance. Anemones are long-lived with low natural mortality, which makes them particularly vulnerable to predicted increases in severity and frequency of bleaching events. Population viability will be severely compromised if anemones and their symbionts cannot acclimate or adapt to rising sea temperatures. Anemone bleaching also has negative effects to other species, particularly those that have an obligate relationship with anemones. These effects include reductions in abundance and reproductive output of anemonefishes. Therefore, the future of these iconic and commercially valuable coral reef fishes is inextricably linked to the ability of host anemones to cope with rising sea temperatures associated with climate change.