Meekan Mark G.

No Thumbnail Available
Last Name
First Name
Mark G.

Search Results

Now showing 1 - 3 of 3
  • 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
    Genetic identity determines risk of post-settlement mortality of a marine fish
    (Ecological Society of America, 2007-05) Vigliola, Laurent ; Doherty, Peter J. ; Meekan, Mark G. ; Drown, Devin M. ; Jones, M. Elizabeth ; Barber, Paul H.
    Longitudinal sampling of four cohorts of Neopomacentrus filamentosus, a common tropical damselfish from Dampier Archipelago, Western Australia, revealed the evolution of size structure after settlement. Light traps collected premetamorphic individuals from the water column (“settlers”) to establish a baseline for each cohort. Subsequently, divers collected benthic juveniles (“recruits”) at 1–3-month intervals to determine the relative impacts of post-settlement mortality during the first three months. Growth trajectories for individual fish were back-calculated from otolith records and compared with nonlinear mixed-effects models. Size-selective mortality was detected in all cohorts with the loss of smaller, slower growing individuals. Three months after settlement, recruits showed significantly faster growth as juveniles, faster growth as larvae, and larger sizes as hatchlings. The timing and intensity of post-settlement selection differed among cohorts and was correlated with density at settlement. The cohort with the greatest initial abundance experienced the strongest selective mortality, with most of this mortality occurring between one and two months after settlement when juveniles began foraging at higher positions in the water column. Significant genetic structure was found between settlers and three-month-old recruits in this cohort as a result of natural selection that changed the frequency of mtDNA haplotypes measured at the control region. The extent of this genetic difference was enlarged or reduced by artificially manipulating the intensity of size-based selection, thus establishing a link between phenotype and haplotype. Sequence variation in the control region of the mitochondrial genome has been linked to mitochondrial efficiency and weight gain in other studies, which provides a plausible explanation for the patterns observed here.