Campbell-Malone Regina

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Campbell-Malone
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Regina
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  • Thesis
    Biomechanics of North Atlantic right whale bone : mandibular fracture as a fatal endpoint for blunt vessel-whale collision modeling
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2007-09) Campbell-Malone, Regina
    The North Atlantic right whale, Eubalaena glacialis, one of the most critically endangered whales in the world, is subject to high anthropogenic mortality. Vessel-whale collisions and entanglement in fishing gear were indicated in 27 (67.5%) of the 40 right whales necropsied between 1970 and December 2006. Of those, at least 9 deaths (22.5%) resulted from blunt contact with a vessel. To reduce the likelihood of fatal collisions, speed restrictions are being considered for vessels traversing critical habitat, although the effects of speed on collision outcomes have not been specifically evaluated from a biomechanics perspective. The ultimate goal of a larger collaborative project is to evaluate the efficacy of speed restrictions for reducing blunt collision mortality using a multi-scale finite element model. Complete, transverse fracture of the right whale mandible, an injury seen only in right whales killed by vessels, is used as a proxy for mortality in the model. Vital for that model are the material properties and biomechanical behavior of the right whale mandible. Here, the internal structure and physical properties of right whale jawbone tissue are reported. The average apparent densities, 0.4258 g/cc ±0.0970 and 1.2370 g/cc ±0.0535 for trabecular and cortical bone respectively, indicate that the bone is of relatively low density. Average ash content for trabecular bone (64.38% ±1.1330) is comparable with values from other species, indicating that low density results from a reduction of bone mass, not mineralization. Mechanical properties of right whale bone (Young’s modulus of elasticity and Poisson’s ratio) were determined via uniaxial compression testing. These data are incorporated into the finite element model simulating different loading conditions (e.g. vessel speeds) that likely lead to mandibular failure and thereby mortality from blunt vessel collisions. Model results (e.g. risk of fracture) are used to determine the effect of speed restrictions on collision outcomes.
  • Preprint
    Mechanics of the right whale mandible : full scale testing and finite element analysis
    ( 2009-03-11) Tsukrov, Igor ; DeCew, Judson C. ; Baldwin, Kenneth C. ; Campbell-Malone, Regina ; Moore, Michael J.
    In an effort to better understand the mechanics of ship-whale collision and to reduce the associated mortality of the critically endangered North Atlantic right whale, a comprehensive biomechanical study has been conducted by the Woods Hole Oceanographic Institution and the University of New Hampshire. The goal of the study is to develop a numerical modeling tool to predict the forces and stresses during impact and thereby the resulting mortality risk to whales from ship strikes. Based on post-mortem examinations, jaw fracture was chosen as a fatal endpoint for the whales hit by a vessel. In this paper we investigate the overall mechanical behavior of a right whale mandible under transverse loading and develop a finite element analysis model of the bone. The equivalent elastic modulus of the cortical component of right whale mandible is found by comparing full-scale bending tests with the results of numerical modeling. The finite element model of the mandible can be used in conjunction with a vessel-whale collision event model to predict bone fracture for various ship strike scenarios.
  • Preprint
    Quantitative computed tomography of humpback whale (Megaptera novaeangliae) mandibles : mechanical implications for rorqual lunge-feeding
    ( 2010-01-25) Field, Daniel J. ; Campbell-Malone, Regina ; Goldbogen, Jeremy A. ; Shadwick, Robert E.
    Rorqual whales (Balaenopteridae) lunge at high speed with mouth open to nearly 90 degrees in order to engulf large volumes of prey-laden water. This feeding process is enabled by extremely large skulls and mandibles that increase mouth area, thereby facilitating the flux of water into the mouth. When these mandibles are lowered during lunge-feeding, they are exposed to high drag and therefore may be subject to significant bending forces. We hypothesized that these mandibles exhibited a mechanical design (shape and density distribution) that enables these bones to accommodate high loads during lunge-feeding without exceeding their breaking strength. We used quantitative computed tomography (QCT) to determine the three-dimensional geometry and density distribution of a pair of sub-adult humpback whale (Megaptera novaeangliae) mandibles (length = 2.10 m). QCT data indicated highest bone density and crosssectional area, and therefore high resistance to bending and deflection, from the coronoid process to the middle of the dentary, which then decreased towards the anterior end of the mandible. These results differ from the caudorostral trends of increasing mandibular bone density in mammals such as humans and the right whale, Eubalaena glacialis, indicating that adaptive bone remodeling is a significant contributing factor in establishing mandibular bone density distributions in rorquals.
  • Working Paper
    Report of large whale restraint workshop
    ( 2006-07-27) Bogomolni, Andrea L. ; Campbell-Malone, Regina ; Lysiak, Nadine S. J. ; Moore, Michael J.
    A number of large cetacean species are seriously injured and killed by entanglement in fishing gear used in the waters off the eastern United States and Canada. Entanglement most frequently involves rope or lines wrapped around the head, the flippers, body, in the mouth, around the tail flukes or any combination of the aforementioned body parts. Consequences of entanglement are particularly grave for North Atlantic right whales, which currently number about 300 whales and are declining due, in part, to this entanglement-related mortality. Right whales are frequently intractable and are very difficult and potentially unsafe to work with while attempting to disentangle the animal. Modifications and technological advances are needed to control, restrain and overall increase the success rate at which right whales are able to be cut free from entangling gear.