11 results on '"McClanahan TR"'
Search Results
2. Macroalgae exhibit diverse responses to human disturbances on coral reefs.
- Author
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Cannon, SE, Donner, SD, Liu, A, González Espinosa, PC, Baird, AH, Baum, JK, Bauman, AG, Beger, M, Benkwitt, CE, Birt, MJ, Chancerelle, Y, Cinner, JE, Crane, NL, Denis, V, Depczynski, M, Fadli, N, Fenner, D, Fulton, CJ, Golbuu, Y, Graham, NAJ, Guest, J, Harrison, HB, Hobbs, J-PA, Hoey, AS, Holmes, TH, Houk, P, Januchowski-Hartley, FA, Jompa, J, Kuo, C-Y, Limmon, GV, Lin, YV, McClanahan, TR, Muenzel, D, Paddack, MJ, Planes, S, Pratchett, MS, Radford, B, Reimer, JD, Richards, ZT, Ross, CL, Rulmal, J, Sommer, B, Williams, GJ, Wilson, SK, Cannon, SE, Donner, SD, Liu, A, González Espinosa, PC, Baird, AH, Baum, JK, Bauman, AG, Beger, M, Benkwitt, CE, Birt, MJ, Chancerelle, Y, Cinner, JE, Crane, NL, Denis, V, Depczynski, M, Fadli, N, Fenner, D, Fulton, CJ, Golbuu, Y, Graham, NAJ, Guest, J, Harrison, HB, Hobbs, J-PA, Hoey, AS, Holmes, TH, Houk, P, Januchowski-Hartley, FA, Jompa, J, Kuo, C-Y, Limmon, GV, Lin, YV, McClanahan, TR, Muenzel, D, Paddack, MJ, Planes, S, Pratchett, MS, Radford, B, Reimer, JD, Richards, ZT, Ross, CL, Rulmal, J, Sommer, B, Williams, GJ, and Wilson, SK
- Abstract
Scientists and managers rely on indicator taxa such as coral and macroalgal cover to evaluate the effects of human disturbance on coral reefs, often assuming a universally positive relationship between local human disturbance and macroalgae. Despite evidence that macroalgae respond to local stressors in diverse ways, there have been few efforts to evaluate relationships between specific macroalgae taxa and local human-driven disturbance. Using genus-level monitoring data from 1205 sites in the Indian and Pacific Oceans, we assess whether macroalgae percent cover correlates with local human disturbance while accounting for factors that could obscure or confound relationships. Assessing macroalgae at genus level revealed that no genera were positively correlated with all human disturbance metrics. Instead, we found relationships between the division or genera of algae and specific human disturbances that were not detectable when pooling taxa into a single functional category, which is common to many analyses. The convention to use percent cover of macroalgae as an indication of local human disturbance therefore likely obscures signatures of local anthropogenic threats to reefs. Our limited understanding of relationships between human disturbance, macroalgae taxa, and their responses to human disturbances impedes the ability to diagnose and respond appropriately to these threats.
- Published
- 2023
3. Protection efforts have resulted in ~10% of existing fish biomass on coral reefs.
- Author
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Caldwell IR, McClanahan TR, Oddenyo RM, Graham NAJ, Beger M, Vigliola L, Sandin SA, Friedlander AM, Randriamanantsoa B, Wantiez L, Green AL, Humphries AT, Hardt MJ, Caselle JE, Feary DA, Karkarey R, Jadot C, Hoey AS, Eurich JG, Wilson SK, Crane N, Tupper M, Ferse SCA, Maire E, Mouillot D, and Cinner JE
- Subjects
- Animals, Humans, Coral Reefs, Biomass, Fishes physiology, Conservation of Natural Resources methods
- Abstract
The amount of ocean protected from fishing and other human impacts has often been used as a metric of conservation progress. However, protection efforts have highly variable outcomes that depend on local conditions, which makes it difficult to quantify what coral reef protection efforts to date have actually achieved at a global scale. Here, we develop a predictive model of how local conditions influence conservation outcomes on ~2,600 coral reef sites across 44 ecoregions, which we used to quantify how much more fish biomass there is on coral reefs compared to a modeled scenario with no protection. Under the assumptions of our model, our study reveals that without existing protection efforts there would be ~10% less fish biomass on coral reefs. Thus, we estimate that coral reef protection efforts have led to approximately 1 in every 10 kg of existing fish biomass., Competing Interests: Competing interests statement:The authors declare no competing interest.
- Published
- 2024
- Full Text
- View/download PDF
4. Testing for concordance between predicted species richness, past prioritization, and marine protected area designations in the western Indian Ocean.
- Author
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McClanahan TR, Friedlander AM, Wickel J, Graham NAJ, Bruggemann JH, Guillaume MMM, Chabanet P, Porter S, Schleyer MH, Azali MK, and Muthiga NA
- Subjects
- Indian Ocean, Animals, Anthozoa physiology, Conservation of Natural Resources methods, Biodiversity, Fishes physiology, Coral Reefs
- Abstract
Scientific advances in environmental data coverage and machine learning algorithms have improved the ability to make large-scale predictions where data are missing. These advances allowed us to develop a spatially resolved proxy for predicting numbers of tropical nearshore marine taxa. A diverse marine environmental spatial database was used to model numbers of taxa from ∼1000 field sites, and the predictions were applied to all 7039 6.25-km
2 reef cells in 9 ecoregions and 11 nations of the western Indian Ocean. Our proxy for total numbers of taxa was based on the positive correlation (r2 = 0.24) of numbers of taxa of hard corals and 5 highly diverse reef fish families. Environmental relationships indicated that the number of fish species was largely influenced by biomass, nearness to people, governance, connectivity, and productivity and that coral taxa were influenced mostly by physicochemical environmental variability. At spatial delineations of province, ecoregion, nation, and strength of spatial clustering, we compared areas of conservation priority based on our total species proxy with those identified in 3 previous priority-setting reports and with the protected area database. Our method identified 119 locations that fit 3 numbers of taxa (hard coral, fish, and their combination) and 4 spatial delineations (nation, ecoregion, province, and reef clustering) criteria. Previous publications on priority setting identified 91 priority locations of which 6 were identified by all reports. We identified 12 locations that fit our 12 criteria and corresponded with 3 previously identified locations, 65 that aligned with at least 1 past report, and 28 that were new locations. Only 34% of the 208 marine protected areas in this province overlapped with identified locations with high numbers of predicted taxa. Differences occurred because past priorities were frequently based on unquantified perceptions of remoteness and preselected priority taxa. Our environment-species proxy and modeling approach can be considered among other important criteria for making conservation decisions., (© 2024 The Authors. Conservation Biology published by Wiley Periodicals LLC on behalf of Society for Conservation Biology.)- Published
- 2024
- Full Text
- View/download PDF
5. Stimulating the capacity to govern the commons.
- Author
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McClanahan TR and Oddenyo RM
- Abstract
The ability to strengthen governance institutions and fisheries restrictions and laws is needed to improve conservation and management of common-pool resources. We evaluated the potential for stimulating change with modest interventions by studying fishing village households before and after a 27-month intervention period in a high-priority coral reef conservation area. Interventions included training in catch monitoring, stock assessment, mapping fishing grounds, microcredit, gender inclusion, theatrical skills, fuel efficient stoves, and participation in the planning of a conservation proposal. There was a background increase in reported formal education, household size, group membership, and household wealth but a decrease in fish consumption and public services. Of conservation importance, the perceived strength of 13 governance institutions and benefits of 6 fisheries restrictions increased over the intervention period. Finally, correspondence between knowledge of and agreement with recent national fisheries laws was moderate to high and positively correlated. The intervention period was stronger than demographic factors that often influence perceptions, such as village, government services, gender, household size, membership in community groups, and age responses. In general, perceptions of strengths of governance and benefits of restrictions increased more among women and youth than adult men respondents. The largest changes in perceptions of increased benefits were among strict restrictions initially ranked low, specifically fisheries closures, parks, and species restrictions. Consequently, capacity building overrode demographic factors common to poor people with limited employment capacity that can have negative perceptions of strict conservation., (© 2024 Society for Conservation Biology.)
- Published
- 2024
- Full Text
- View/download PDF
6. Usage and coordination of governance principles to address proximate and distal drivers of conflicts in fisheries commons.
- Author
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McClanahan TR
- Subjects
- Animals, Humans, Kenya, Hunting, Fisheries, Conservation of Natural Resources
- Abstract
Commons' problems and solutions have the elements of local, proximate, and large-scale distal processes. Solutions, therefore, require accessing, implementing, and coordinating information and actions at multiple scales. Restoring commons, such as fisheries, will require a better understanding of how stakeholders access and use information at various scales to resolve governance and restrictions problems. In 179 household interviews, perceptions of fisheries conflicts and their causes were identified, and 16 management committee key informants described their methods for mediating hypothetical small-scale fisheries problems in Kenya. The 6 studied sites varied in human development and demographic contexts but had notable similarities that reflected a respondent's focus on localized, direct, and proximate fishing conflicts. The most cited problems included limited space, disagreement about gears, poor resource conditions, and locally inadequate benefits. The most cited sources of information were local households and the community, and there was considerably less acknowledgment of distal problems and solutions. Key informants selected a limited number of local community-focused solutions. For example, informants chose to mediate conflicts between neighbors with local community meetings rather than through formal national institutions. Therefore, distal solutions were likely to be perceived as ineffectual, possibly due to the challenges of polycentric governance coordination. However, widespread overfishing arises from overarching distal processes not fully amenable to local solutions. Therefore, a focus on local action is expected to limit the ability to address distal problems. These include conflicting values, demographic changes, supportive governance frameworks, emerging technologies, resolving conflicting local rules, fair between-group enforcement, responding to temporary shortages of fish, and intercommunity border and rule disputes. Improved coordination and integration of information and institutions to simultaneously address both proximate and distal common's problems are recommended., (© 2023 Society for Conservation Biology.)
- Published
- 2024
- Full Text
- View/download PDF
7. Tropical fishery nutrient production depends on biomass-based management.
- Author
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Galligan BP and McClanahan TR
- Abstract
The need to enhance nutrient production from tropical ecosystems to feed the poor could potentially create a new framework for fisheries science and management. Early recommendations have included targeting small fishes and increasing the species richness of fish catches, which could represent a departure from more traditional approaches such as biomass-based management. To test these recommendations, we compared the outcomes of biomass-based management with hypothesized factors influencing nutrient density in nearshore artisanal fish catches in the Western Indian Ocean. We found that enhancing nutrient production depends primarily on achieving biomass-based targets. Catches dominated by low- and mid-trophic level species with smaller body sizes and faster turnover were associated with modest increases in nutrient densities, but the variability in nutrient density was small relative to human nutritional requirements. Therefore, tropical fishery management should focus on restoring biomass to achieve maximum yields and sustainability, particularly for herbivorous fishes., Competing Interests: The authors declare no competing interests., (© 2024 The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
8. Diversification of refugia types needed to secure the future of coral reefs subject to climate change.
- Author
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McClanahan TR, Darling ES, Beger M, Fox HE, Grantham HS, Jupiter SD, Logan CA, Mcleod E, McManus LC, Oddenyo RM, Surya GS, Wenger AS, Zinke J, and Maina JM
- Subjects
- Animals, Ecosystem, Refugium, Climate Change, Conservation of Natural Resources, Coral Reefs, Anthozoa
- Abstract
Identifying locations of refugia from the thermal stresses of climate change for coral reefs and better managing them is one of the key recommendations for climate change adaptation. We review and summarize approximately 30 years of applied research focused on identifying climate refugia to prioritize the conservation actions for coral reefs under rapid climate change. We found that currently proposed climate refugia and the locations predicted to avoid future coral losses are highly reliant on excess heat metrics, such as degree heating weeks. However, many existing alternative environmental, ecological, and life-history variables could be used to identify other types of refugia that lead to the desired diversified portfolio for coral reef conservation. To improve conservation priorities for coral reefs, there is a need to evaluate and validate the predictions of climate refugia with long-term field data on coral abundance, diversity, and functioning. There is also the need to identify and safeguard locations displaying resistance toprolonged exposure to heat waves and the ability to recover quickly after thermal exposure. We recommend using more metrics to identify a portfolio of potential refugia sites for coral reefs that can avoid, resist, and recover from exposure to high ocean temperatures and the consequences of climate change, thereby shifting past efforts focused on avoidance to a diversified risk-spreading portfolio that can be used to improve strategic coral reef conservation in a rapidly warming climate., (© 2023 The Authors. Conservation Biology published by Wiley Periodicals LLC on behalf of Society for Conservation Biology.)
- Published
- 2024
- Full Text
- View/download PDF
9. Macroalgae exhibit diverse responses to human disturbances on coral reefs.
- Author
-
Cannon SE, Donner SD, Liu A, González Espinosa PC, Baird AH, Baum JK, Bauman AG, Beger M, Benkwitt CE, Birt MJ, Chancerelle Y, Cinner JE, Crane NL, Denis V, Depczynski M, Fadli N, Fenner D, Fulton CJ, Golbuu Y, Graham NAJ, Guest J, Harrison HB, Hobbs JA, Hoey AS, Holmes TH, Houk P, Januchowski-Hartley FA, Jompa J, Kuo CY, Limmon GV, Lin YV, McClanahan TR, Muenzel D, Paddack MJ, Planes S, Pratchett MS, Radford B, Reimer JD, Richards ZT, Ross CL, Rulmal J Jr, Sommer B, Williams GJ, and Wilson SK
- Subjects
- Animals, Humans, Coral Reefs, Ecosystem, Pacific Ocean, Seaweed physiology, Anthozoa physiology
- Abstract
Scientists and managers rely on indicator taxa such as coral and macroalgal cover to evaluate the effects of human disturbance on coral reefs, often assuming a universally positive relationship between local human disturbance and macroalgae. Despite evidence that macroalgae respond to local stressors in diverse ways, there have been few efforts to evaluate relationships between specific macroalgae taxa and local human-driven disturbance. Using genus-level monitoring data from 1205 sites in the Indian and Pacific Oceans, we assess whether macroalgae percent cover correlates with local human disturbance while accounting for factors that could obscure or confound relationships. Assessing macroalgae at genus level revealed that no genera were positively correlated with all human disturbance metrics. Instead, we found relationships between the division or genera of algae and specific human disturbances that were not detectable when pooling taxa into a single functional category, which is common to many analyses. The convention to use percent cover of macroalgae as an indication of local human disturbance therefore likely obscures signatures of local anthropogenic threats to reefs. Our limited understanding of relationships between human disturbance, macroalgae taxa, and their responses to human disturbances impedes the ability to diagnose and respond appropriately to these threats., (© 2023 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)
- Published
- 2023
- Full Text
- View/download PDF
10. Fish catch responses to Covid-19 disease curfews dependent on compliance, fisheries management, and environmental contexts.
- Author
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McClanahan TR, Azali MK, and Kosgei JK
- Abstract
The responses of small-scale coastal fisheries to pauses in effort and trade are an important test of natural resource management theories with implications for the many challenges of managing common-pool resources. Three Covid-19 curfews provided a natural experiment to evaluate fisheries responses adjacent a marine reserve and in a management system that restricted small-mesh drag nets. Daily catch weights in ten fish landings were compared before and after the curfew period to test the catch-only hypothesis that the curfew would reduce effort and increase catch per unit effort, per area yields, and incomes. Interviews with key informants indicated that fisheries effort and trade were disrupted but less so in the gear-restricted rural district than the more urbanized reserve landing sites. The expected increase in catches and incomes was evident in some sites adjacent the reserve but not the rural gear restricted fisheries. Differences in compliance and effort initiated by the curfew, changes in gear, and various negative environmental conditions are among the explanations for the variable catch responses. Rates of change over longer periods in CPUE were stable among marine reserve adjacent landing sites but declined faster after the curfew in the gear-restricted fisheries. Two landing sites nearest the southern end of the reserve displayed a daily 45 % increase in CPUE, 25-30 % increase in CPUA, and a 45-56 % increase in incomes. Results suggest that recovering stocks will succeed where authorities can achieve compliance, near marine reserves, and fisheries lacking additional environmental stresses., (© 2022 Elsevier Ltd. All rights reserved.)
- Published
- 2022
- Full Text
- View/download PDF
11. Decadal shifts in traits of reef fish communities in marine reserves.
- Author
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Hadj-Hammou J, McClanahan TR, and Graham NAJ
- Subjects
- Animals, Biodiversity, Biomass, Body Size physiology, Conservation of Natural Resources methods, Coral Reefs, Ecosystem, Hunting, Phenotype, Fishes growth & development, Fishes physiology
- Abstract
Marine reserves are known to impact the biomass, biodiversity, and functions of coral reef fish communities, but the effect of protective management on fish traits is less explored. We used a time-series modelling approach to simultaneously evaluate the abundance, biomass, and traits of eight fish families over a chronosequence spanning 44 years of protection. We constructed a multivariate functional space based on six traits known to respond to management or disturbance and affect ecosystem processes: size, diet, position in the water column, gregariousness, reef association, and length at maturity. We show that biomass increased with a log-linear trend over the time-series, but abundance only increased after 20 years of closure, and with more variation among reserves. This difference is attributed to recovery rates being dependent on body sizes. Abundance-weighted traits and the associated multivariate space of the community change is driven by increased proportions over time of the trait categories: 7-15 cm body size; planktivorous; species low in the water column; medium-large schools; and species with high levels of reef association. These findings suggest that the trait compositions emerging after the cessation of fishing are novel and dynamic., (© 2021. The Author(s).)
- Published
- 2021
- Full Text
- View/download PDF
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