Publications by authors named "Katharine J Mach"

21 Publications

  • Page 1 of 1

Reframing strategic, managed retreat for transformative climate adaptation.

Science 2021 06;372(6548):1294-1299

Disaster Research Center, University of Delaware, Newark, DE, USA.

Human societies will transform to address climate change and other stressors. How they choose to transform will depend on what societal values they prioritize. Managed retreat can play a powerful role in expanding the range of possible futures that transformation could achieve and in articulating the values that shape those futures. Consideration of retreat raises tensions about what losses are unacceptable and what aspects of societies are maintained, purposefully altered, or allowed to change unaided. Here we integrate research on retreat, transformational adaptation, climate damages and losses, and design and decision support to chart a roadmap for strategic, managed retreat. At its core, this roadmap requires a fundamental reconceptualization of what it means for retreat to be strategic and managed. The questions raised are relevant to adaptation science and societies far beyond the remit of retreat.
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http://dx.doi.org/10.1126/science.abh1894DOI Listing
June 2021

The role of international organizations in equitable and just planned relocation.

J Environ Stud Sci 2021 May 13:1-12. Epub 2021 May 13.

Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL USA.

Since 2010, States party to the United Nations Framework Convention on Climate Change have recognized planned relocation as a viable adaptation to climate change. Planned relocation has been attempted in many communities globally and has raised serious issues of equity in some cases. Implementation driven by principles of equity is crucial in ensuring successful planned relocations that decrease loss and damage. In this Policy Analysis, we put forth a framework for equitable planned relocation rooted in theories of justice as a basis for implementation. The framework centers around three principles: comprehensive recognition of affected stakeholders in decision-making, consideration of socio-cultural risk factors relevant to relocation, and evaluation of multiple measures of well-being. There are many actors involved in planned relocation. Unique features and abilities of international organizations lend themselves to promoting equitable planned relocation in partnership with other stakeholders. Through the exploration of case studies, we identify best practices that international organizations have available to influence the design, implementation, and evaluation of planned relocation processes. These practices are relevant when striving for equity for all affected individuals and communities. Points of intervention include agenda-setting and advocacy, funding and implementation standards, and facilitation of international cooperation. International organizations also face barriers to supporting equitable planned relocation. Limitations include lack of enforcement mechanisms, limited resources, and fundamental dependence on existing governance structures and global collaboration. As the necessity of planned relocations grows, the need for leadership from international organizations in implementation is magnified, underscoring the importance of developing and evaluating approaches to just implementation.
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http://dx.doi.org/10.1007/s13412-021-00698-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8117123PMC
May 2021

Climate-informed hydrologic modeling and policy typology to guide managed aquifer recharge.

Sci Adv 2021 Apr 21;7(17). Epub 2021 Apr 21.

Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, USA.

Harvesting floodwaters to recharge depleted groundwater aquifers can simultaneously reduce flood and drought risks and enhance groundwater sustainability. However, deployment of this multibeneficial adaptation option is fundamentally constrained by how much water is available for recharge (WAFR) at present and under future climate change. Here, we develop a climate-informed and policy-relevant framework to quantify WAFR, its uncertainty, and associated policy actions. Despite robust and widespread increases in future projected WAFR in our case study of California (for 56/80% of subbasins in 2070-2099 under RCP4.5/RCP8.5), strong nonlinear interactions between diversion infrastructure and policy uncertainties constrain how much WAFR can be captured. To tap future elevated recharge potential through infrastructure expansion under deep uncertainties, we outline a novel robustness-based policy typology to identify priority areas of investment needs. Our WAFR analysis can inform effective investment decisions to adapt to future climate-fueled drought and flood risk over depleted aquifers, in California and beyond.
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http://dx.doi.org/10.1126/sciadv.abe6025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8059926PMC
April 2021

Risk screening methods for extreme heat: Implications for equity-oriented adaptation.

PLoS One 2020 4;15(11):e0240841. Epub 2020 Nov 4.

Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, United States of America.

Morbidity and mortality impacts of extreme heat amplified by climate change will be unequally distributed among communities given pre-existing differences in socioeconomic, health, and environmental conditions. Many governments are interested in adaptation policies that target those especially vulnerable to the risks, but there are important questions about how to effectively identify and support communities most in need of heat adaptations. Here, we use an equity-oriented adaptation program from the state of California as a case study to evaluate the implications of the currently used environmental justice index (CalEnviroScreen 3.0) for the identification of socially vulnerable communities with climate change adaptation needs. As CalEnviroScreen is geared towards air and water pollution, we assess how community heat risks and adaptation needs would be evaluated differently under two more adaptation-relevant vulnerability indices: the Social Vulnerability Index and the Heat-Health Action Index. Our analysis considers communities at the census tract scale, as well as the patterns emerging at the regional scale. Using the current index, the state designates 25% of its census tracts as "disadvantaged" communities eligible for special adaptation funds. However, an additional 12.6% of the state's communities could be considered vulnerable if the two other indices were considered instead. Only 13.4% of communities are vulnerable across all three vulnerability indices studied. Choice of vulnerability index shapes statewide trends in extreme heat risk and is linked to a community's likelihood of receiving heat-related California Climate Investments (CCI) projects. Tracts that are vulnerable under the current pollution-focused index, but not under the heat-health specific index, received four times the number of heat-related interventions as tracts vulnerable under the reverse scenario. This study demonstrates important nuances relevant to implementing equity-oriented adaptation and explores the challenges, trade-offs, and opportunities in quantifying vulnerability.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0240841PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7641348PMC
December 2020

Directions for Research on Climate and Conflict.

Earths Future 2020 Jul 3;8(7):e2020EF001532. Epub 2020 Jul 3.

Department of Peace and Conflict Research Uppsala University Uppsala Sweden.

The potential links between climate and conflict are well studied, yet disagreement about the specific mechanisms and their significance for societies persists. Here, we build on assessment of the relationship between climate and organized armed conflict to define crosscutting priorities for future directions of research. They include (1) deepening insight into climate-conflict linkages and conditions under which they manifest, (2) ambitiously integrating research designs, (3) systematically exploring future risks and response options, responsive to ongoing decision-making, and (4) evaluating the effectiveness of interventions to manage climate-conflict links. The implications of this expanding scientific domain unfold in real time.
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http://dx.doi.org/10.1029/2020EF001532DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7379239PMC
July 2020

Managed retreat through voluntary buyouts of flood-prone properties.

Sci Adv 2019 10 9;5(10):eaax8995. Epub 2019 Oct 9.

Stanford Woods Institute for the Environment, Stanford University, Stanford, CA 94305, USA.

Retreat from some areas will become unavoidable under intensifying climate change. Existing deployments of managed retreat are at small scale compared to potential future needs, leaving open questions about where, when, and how retreat under climate change will occur. Here, we analyze more than 40,000 voluntary buyouts of flood-prone properties in the United States, in which homeowners sell properties to the government and the land is restored to open space. In contrast to model-based evaluation of potential future retreat, local governments in counties with higher population and income are more likely to administer buyouts. The bought-out properties themselves, however, are concentrated in areas of greater social vulnerability within these counties, pointing to the importance of assessing the equity of buyout implementation and outcomes. These patterns demonstrate the challenges associated with locally driven implementation of managed retreat and the potential benefits of experimentation with different approaches to retreat.
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http://dx.doi.org/10.1126/sciadv.aax8995DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6785245PMC
October 2019

The case for strategic and managed climate retreat.

Science 2019 Aug;365(6455):761-763

Department of Earth System Science, Stanford University, Stanford, CA, USA.

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http://dx.doi.org/10.1126/science.aax8346DOI Listing
August 2019

Climate as a risk factor for armed conflict.

Nature 2019 07 12;571(7764):193-197. Epub 2019 Jun 12.

Peace Research Institute Oslo, Oslo, Norway.

Research findings on the relationship between climate and conflict are diverse and contested. Here we assess the current understanding of the relationship between climate and conflict, based on the structured judgments of experts from diverse disciplines. These experts agree that climate has affected organized armed conflict within countries. However, other drivers, such as low socioeconomic development and low capabilities of the state, are judged to be substantially more influential, and the mechanisms of climate-conflict linkages remain a key uncertainty. Intensifying climate change is estimated to increase future risks of conflict.
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http://dx.doi.org/10.1038/s41586-019-1300-6DOI Listing
July 2019

High-tide flooding disrupts local economic activity.

Sci Adv 2019 02 15;5(2):eaau2736. Epub 2019 Feb 15.

Department of Earth System Science, Stanford University, Stanford, CA 94305, USA.

Evaluation of observed sea level rise impacts to date has emphasized sea level extremes, such as those from tropical cyclones. Far less is known about the consequences of more frequent high-tide flooding. Empirical analysis of the disruption caused by high-tide floods, also called nuisance or sunny-day floods, is challenging due to the short duration of these floods and their impacts. Through a novel approach, we estimate the effects of high-tide flooding on local economic activity. High-tide flooding already measurably affects local economic activity in Annapolis, Maryland, reducing visits to the historic downtown by 1.7% (95% confidence interval, 1.0 to 2.6%). With 3 and 12 inches of additional sea level rise, high-tide floods would reduce visits by 3.6% (3.2 to 4.0%) and 24% (19 to 28%), respectively. A more comprehensive understanding of the impacts of high-tide flooding can help to guide efficient responses from local adaptations to global mitigation of climate change.
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http://dx.doi.org/10.1126/sciadv.aau2736DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6377275PMC
February 2019

Climate Change Mitigation, Air Pollution, and Environmental Justice in California.

Environ Sci Technol 2018 09 4;52(18):10829-10838. Epub 2018 Sep 4.

Climate change mitigation policies can have significant co-benefits for air quality, including benefits to disadvantaged communities experiencing substantial air pollution. However, the effects of these mitigation policies have rarely been evaluated with respect to their influence on disadvantaged communities. Here we assess the air pollution and environmental justice implications of California's cap-and-trade mitigation program through analysis of (1) the sources of air pollution in disadvantaged communities, (2) emissions-reduction offset usage under the cap-and-trade program, and (3) the relationship between reductions in greenhouse gas emissions and reductions in co-pollutant emissions. Our analysis suggests that the cap-and-trade program has limited impacts, including limited disproportionate impacts, on air quality in disadvantaged communities. The sources of most air pollution in these communities have not been subject to the cap-and-trade program, and the use of emissions-reduction offsets is only marginally higher in disadvantaged communities than in other communities. Furthermore, reductions in greenhouse gas emissions imply smaller proportional reductions in co-pollutant emissions. While climate policies lead to important air quality co-benefits in some contexts, especially through reduced coal usage, targeted air quality policies and regulations may be more effective for reducing air pollution in disadvantaged communities in California and throughout the state.
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http://dx.doi.org/10.1021/acs.est.8b00908DOI Listing
September 2018

Net-zero emissions energy systems.

Science 2018 06;360(6396)

Institute for Data, Systems, and Society, Massachusetts Institute of Technology, Cambridge, MA, USA.

Some energy services and industrial processes-such as long-distance freight transport, air travel, highly reliable electricity, and steel and cement manufacturing-are particularly difficult to provide without adding carbon dioxide (CO) to the atmosphere. Rapidly growing demand for these services, combined with long lead times for technology development and long lifetimes of energy infrastructure, make decarbonization of these services both essential and urgent. We examine barriers and opportunities associated with these difficult-to-decarbonize services and processes, including possible technological solutions and research and development priorities. A range of existing technologies could meet future demands for these services and processes without net addition of CO to the atmosphere, but their use may depend on a combination of cost reductions via research and innovation, as well as coordinated deployment and integration of operations across currently discrete energy industries.
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http://dx.doi.org/10.1126/science.aas9793DOI Listing
June 2018

Near-term deployment of carbon capture and sequestration from biorefineries in the United States.

Proc Natl Acad Sci U S A 2018 05 23;115(19):4875-4880. Epub 2018 Apr 23.

Department of Earth System Science, Stanford University, Stanford, CA 94305.

Capture and permanent geologic sequestration of biogenic CO emissions may provide critical flexibility in ambitious climate change mitigation. However, most bioenergy with carbon capture and sequestration (BECCS) technologies are technically immature or commercially unavailable. Here, we evaluate low-cost, commercially ready CO capture opportunities for existing ethanol biorefineries in the United States. The analysis combines process engineering, spatial optimization, and lifecycle assessment to consider the technical, economic, and institutional feasibility of near-term carbon capture and sequestration (CCS). Our modeling framework evaluates least cost source-sink relationships and aggregation opportunities for pipeline transport, which can cost-effectively transport small CO volumes to suitable sequestration sites; 216 existing US biorefineries emit 45 Mt CO annually from fermentation, of which 60% could be captured and compressed for pipeline transport for under $25/tCO A sequestration credit, analogous to existing CCS tax credits, of $60/tCO could incent 30 Mt of sequestration and 6,900 km of pipeline infrastructure across the United States. Similarly, a carbon abatement credit, analogous to existing tradeable CO credits, of $90/tCO can incent 38 Mt of abatement. Aggregation of CO sources enables cost-effective long-distance pipeline transport to distant sequestration sites. Financial incentives under the low-carbon fuel standard in California and recent revisions to existing federal tax credits suggest a substantial near-term opportunity to permanently sequester biogenic CO This financial opportunity could catalyze the growth of carbon capture, transport, and sequestration; improve the lifecycle impacts of conventional biofuels; support development of carbon-negative fuels; and help fulfill the mandates of low-carbon fuel policies across the United States.
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http://dx.doi.org/10.1073/pnas.1719695115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5948974PMC
May 2018

Geospatial analysis of near-term potential for carbon-negative bioenergy in the United States.

Proc Natl Acad Sci U S A 2018 03 12;115(13):3290-3295. Epub 2018 Mar 12.

Department of Energy Resources Engineering, Stanford University, Stanford, CA 94305.

Bioenergy with carbon capture and storage (BECCS) is a negative-emissions technology that may play a crucial role in climate change mitigation. BECCS relies on the capture and sequestration of carbon dioxide (CO) following bioenergy production to remove and reliably sequester atmospheric CO Previous BECCS deployment assessments have largely overlooked the potential lack of spatial colocation of suitable storage basins and biomass availability, in the absence of long-distance biomass and CO transport. These conditions could constrain the near-term technical deployment potential of BECCS due to social and economic barriers that exist for biomass and CO transport. This study leverages biomass production data and site-specific injection and storage capacity estimates at high spatial resolution to assess the near-term deployment opportunities for BECCS in the United States. If the total biomass resource available in the United States was mobilized for BECCS, an estimated 370 Mt CO⋅y of negative emissions could be supplied in 2020. However, the absence of long-distance biomass and CO transport, as well as limitations imposed by unsuitable regional storage and injection capacities, collectively decrease the technical potential of negative emissions to 100 Mt CO⋅y Meeting this technical potential may require large-scale deployment of BECCS technology in more than 1,000 counties, as well as widespread deployment of dedicated energy crops. Specifically, the Illinois basin, Gulf region, and western North Dakota have the greatest potential for near-term BECCS deployment. High-resolution spatial assessment as conducted in this study can inform near-term opportunities that minimize social and economic barriers to BECCS deployment.
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http://dx.doi.org/10.1073/pnas.1720338115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5879697PMC
March 2018

Rightsizing carbon dioxide removal.

Science 2017 May 18;356(6339):706-707. Epub 2017 May 18.

Department of Earth System Science, Stanford University, CA 94305, USA.

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http://dx.doi.org/10.1126/science.aam9726DOI Listing
May 2017

Long-term, high frequency in situ measurements of intertidal mussel bed temperatures using biomimetic sensors.

Sci Data 2016 10 11;3:160087. Epub 2016 Oct 11.

University of California, Davis, Bodega Marine Reserve, Bodega Bay, California 94923, USA.

At a proximal level, the physiological impacts of global climate change on ectothermic organisms are manifest as changes in body temperatures. Especially for plants and animals exposed to direct solar radiation, body temperatures can be substantially different from air temperatures. We deployed biomimetic sensors that approximate the thermal characteristics of intertidal mussels at 71 sites worldwide, from 1998-present. Loggers recorded temperatures at 10-30 min intervals nearly continuously at multiple intertidal elevations. Comparisons against direct measurements of mussel tissue temperature indicated errors of ~2.0-2.5 °C, during daily fluctuations that often exceeded 15°-20 °C. Geographic patterns in thermal stress based on biomimetic logger measurements were generally far more complex than anticipated based only on 'habitat-level' measurements of air or sea surface temperature. This unique data set provides an opportunity to link physiological measurements with spatially- and temporally-explicit field observations of body temperature.
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http://dx.doi.org/10.1038/sdata.2016.87DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5058338PMC
October 2016

A multistage crucible of revision and approval shapes IPCC policymaker summaries.

Sci Adv 2016 08 5;2(8):e1600421. Epub 2016 Aug 5.

Department of Global Ecology, Carnegie Institution for Science, Stanford, CA 94305, USA.

Intergovernmental Panel on Climate Change (IPCC) member governments approve each report's summary for policymakers (SPM) by consensus, discussing and agreeing on each sentence in a plenary session with scientist authors. A defining feature of IPCC assessment, the governmental approval process builds joint ownership of current knowledge by scientists and governments. The resulting SPM revisions have been extensively discussed in anecdotes, interviews, and perspectives, but they have not been comprehensively analyzed. We provide an in-depth evaluation of IPCC SPM revisions, establishing an evidential basis for understanding their nature. Revisions associated with governmental review and approval generally expand SPMs, with SPM text growing by 17 to 53% across recent assessment reports. Cases of high political sensitivity and failure to reach consensus are notable exceptions, resulting in SPM contractions. In contrast to recent claims, we find that IPCC SPMs are as readable, for multiple metrics of reading ease, as other professionally edited assessment summaries. Across reading-ease metrics, some SPMs become more readable through governmental review and approval, whereas others do not. In an SPM examined through the entire revision process, most revisions associated with governmental review and approval occurred before the start of the government-approval plenary session. These author revisions emphasize clarity, scientific rigor, and explanation. In contrast, the subsequent plenary revisions place greater emphasis especially on policy relevance, comprehensiveness of examples, and nuances of expert judgment. Overall, the value added by the IPCC process emerges in a multistage crucible of revision and approval, as individuals together navigate complex science-policy terrain.
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http://dx.doi.org/10.1126/sciadv.1600421DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4975554PMC
August 2016

Make climate-change assessments more relevant.

Nature 2016 06;534(7609):613-5

Department of Global Ecology, Carnegie Institution for Science, Stanford, California, USA.

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http://dx.doi.org/10.1038/534613aDOI Listing
June 2016

Failure by fatigue in the field: a model of fatigue breakage for the macroalga Mazzaella, with validation.

J Exp Biol 2011 May;214(Pt 9):1571-85

Hopkins Marine Station of Stanford University, Pacific Grove, CA 93950, USA.

Seaweeds inhabiting the extreme hydrodynamic environment of wave-swept shores break frequently. However, traditional biomechanical analyses, evaluating breakage due to the largest individual waves, have perennially underestimated rates of macroalgal breakage. Recent laboratory testing has established that some seaweeds fail by fatigue, accumulating damage over a series of force impositions. Failure by fatigue may thus account, in part, for the discrepancy between prior breakage predictions, based on individual not repeated wave forces, and reality. Nonetheless, the degree to which fatigue breaks seaweeds on wave-swept shores remains unknown. Here, we developed a model of fatigue breakage due to wave-induced forces for the macroalga Mazzaella flaccida. To test model performance, we made extensive measurements of M. flaccida breakage and of wave-induced velocities experienced by the macroalga. The fatigue-breakage model accounted for significantly more breakage than traditional prediction methods. For life history phases modeled most accurately, 105% (for female gametophytes) and 79% (for tetrasporophytes) of field-observed breakage was predicted, on average. When M. flaccida fronds displayed attributes such as temperature stress and substantial tattering, the fatigue-breakage model underestimated breakage, suggesting that these attributes weaken fronds and lead to more rapid breakage. Exposure to waves had the greatest influence on model performance. At the most wave-protected sites, the model underpredicted breakage, and at the most wave-exposed sites, it overpredicted breakage. Overall, our fatigue-breakage model strongly suggests that, in addition to occurring predictably in the laboratory, fatigue-induced breakage of M. flaccida occurs on wave-swept shores.
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http://dx.doi.org/10.1242/jeb.051623DOI Listing
May 2011

Mechanical and biological consequences of repetitive loading: crack initiation and fatigue failure in the red macroalga Mazzaella.

Authors:
Katharine J Mach

J Exp Biol 2009 Apr;212(Pt 7):961-76

Hopkins Marine Station of Stanford University, Pacific Grove, CA 93950, USA.

On rocky shores, wave-swept macroalgae experience dramatic and repeated wave-induced hydrodynamic forces. However, previous studies of macroalgal mechanics have shown that individual waves are not forceful enough to account for observed rates of breakage. Instead, fatigue may contribute to algal breakage, with damage accumulating over time in conditions of repeated loading. Here I examine the entire process of fatigue, from crack initiation to eventual specimen fracture, in the common red alga Mazzaella. Propensity for fatigue failure in laboratory tests varied with life history phase and species: at a given repeated loading stress, male gametophytes endured more loading cycles before breakage than tetrasporophytes, which in turn lasted longer than female gametophytes; likewise, M. splendens withstood more loading cycles at a given repeated loading stress than M. flaccida. Fatigue failure begins with formation of cracks, the timing and location of which were assessed. Cracks formed, on average, after approximately 80-90% of cycles required for failure had passed, although crack timing varied with life history phase. Also, crack formation frequently occurred in association with endophytes and female gametophyte reproductive structures, suggesting a cost of endophyte infection and a tradeoff between reproduction and mechanical survival. Comparison between laboratory and field loading conditions provides robust confirmation that fatigue breaks fronds in natural M. flaccida populations. Large, female gametophyte fronds are predicted to be most susceptible to fatigue failure in the field, whereas small, male gametophyte fronds are least likely to break.
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http://dx.doi.org/10.1242/jeb.026989DOI Listing
April 2009

Death by small forces: a fracture and fatigue analysis of wave-swept macroalgae.

J Exp Biol 2007 Jul;210(Pt 13):2231-43

Hopkins Marine Station of Stanford University, Pacific Grove, CA 93950, USA.

Wave-swept macroalgae are subjected to large hydrodynamic forces as each wave breaks on shore, loads that are repeated thousands of times per day. Previous studies have shown that macroalgae can easily withstand isolated impositions of maximal field forces. Nonetheless, macroalgae break frequently. Here we investigate the possibility that repeated loading by sub-lethal forces can eventually cause fracture by fatigue. We determine fracture toughness, in the form of critical strain energy release rate, for several flat-bladed macroalgae, thereby assessing their resistance to complete fracture in the presence of cracks. Critical energy release rates are evaluated through single-edge-notch, pull-to-break tests and single-edge-notch, repeated-loading tests. Crack growth at sub-critical energy release rates is measured in repeated-loading tests, providing a first assessment of algal breakage under conditions of repeated loading. We then estimate the number of imposed waves required for un-notched algal blades to reach the point of complete fracture. We find that, if not checked by repair, fatigue crack growth from repeated sub-lethal stresses may completely fracture individuals within days. Our results suggest that fatigue may play an important role in macroalgal breakage.
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http://dx.doi.org/10.1242/jeb.001578DOI Listing
July 2007

Techniques for predicting the lifetimes of wave-swept macroalgae: a primer on fracture mechanics and crack growth.

J Exp Biol 2007 Jul;210(Pt 13):2213-30

Hopkins Marine Station of Stanford University, Pacific Grove, CA 93950, USA.

Biomechanical analyses of intertidal and shallow subtidal seaweeds have elucidated ways in which these organisms avoid breakage in the presence of exceptional hydrodynamic forces imposed by pounding surf. However, comparison of algal material properties to maximum hydrodynamic forces predicts lower rates of breakage and dislodgment than are actually observed. Why the disparity between prediction and reality? Most previous research has measured algal material properties during a single application of force, equivalent to a single wave rushing past an alga. In contrast, intertidal macroalgae may experience more than 8000 waves a day. This repeated loading can cause cracks - introduced, for example, by herbivory or abrasion - to grow and eventually cause breakage, yet fatigue crack growth has not previously been taken into account. Here, we present methods from the engineering field of fracture mechanics that can be used to assess consequences of repeated force imposition for seaweeds. These techniques allow quantification of crack growth in wave-swept macroalgae, a first step towards considering macroalgal breakage in the realistic context of repeated force imposition. These analyses can also be applied to many other soft materials.
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http://dx.doi.org/10.1242/jeb.001560DOI Listing
July 2007
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