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Stable mangrove, mangrove gain and loss areas for two regions on Aldabra Atoll; Malabar (left column) and East Grande Terre (right column).
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Mangrove forests, vital for the conservation of biodiversity, protection of coastlines, and carbon capture, are decreasing globally at a rate higher than most other tropical forests. They are threatened by sea level rise, drought and storm surge, especially on low-lying islands where forests are directly exposed to the elements and have limited lan...
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... Malabar, the overall change trend was a notable increase along the landward mangrove extent (Fig. 3). The majority of the landward gains occurred from 2004 to 2009, which was consistent with the large increase observed across the atoll for that time period (Fig. 4). Over the next five years, while the landward extent continued to increase on Malabar, mangroves exposed to the sea were lost. The loss in mangroves was almost parallel to the coastline while the landward gains occurred primarily to the west or east of the stable mangrove areas at the mangrove-pemphis ...
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... East Grande Terre (Fig. 4) changes were more varied, with some regions having persistent mangrove areas, while others showed intermittent mangrove expansion and retraction. During 2009During -2014, we identified the largest proportion (30%) of mangrove loss to the scrub and sand land covers. The landward gains and losses around East Grande Terre were directional ...
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... with some regions having persistent mangrove areas, while others showed intermittent mangrove expansion and retraction. During 2009During -2014, we identified the largest proportion (30%) of mangrove loss to the scrub and sand land covers. The landward gains and losses around East Grande Terre were directional along the Bras Cinq Cases waterway (Fig. 4). On the more exposed boundary between the lagoon and the mangroves, to the west of the Bras Cinq Cases area, substantial loss of mangroves occurred between 2009 and 2014, which had not recovered by 2018 (Fig. 4). Our assessment of the change in the size of mangrove extent showed that 91% of the total gains and losses identified between ...
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... scrub and sand land covers. The landward gains and losses around East Grande Terre were directional along the Bras Cinq Cases waterway (Fig. 4). On the more exposed boundary between the lagoon and the mangroves, to the west of the Bras Cinq Cases area, substantial loss of mangroves occurred between 2009 and 2014, which had not recovered by 2018 (Fig. 4). Our assessment of the change in the size of mangrove extent showed that 91% of the total gains and losses identified between 1997 and 2018 occurred within areas of < 2 ...
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... contracted severely during droughts (Mafi-Gholami et al., 2020). Conversely, on Aldabra, the greatest extent of mangroves in our study was in 2009, which was among the driest drought periods on the atoll since 2000 (Haverkamp et al., 2017). Our study showed that mangrove extent increased inland into the scrub and grassland on East Grande Terre (Fig. 4) during the longer drought. The expansion could have been due to the dependence of the surrounding vegetation on rainfall ( Haverkamp et al., 2017). Inherently, mangrove trees are also remarkably adept at maintaining water uptake in saline conditions ( Reef and Lovelock, 2015), including through condensation and foliar water uptake ( ...
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... Malabar, the overall change trend was a notable increase along the landward mangrove extent (Fig. 3). The majority of the landward gains occurred from 2004 to 2009, which was consistent with the large increase observed across the atoll for that time period (Fig. 4). Over the next five years, while the landward extent continued to increase on Malabar, mangroves exposed to the sea were lost. The loss in mangroves was almost parallel to the coastline while the landward gains occurred primarily to the west or east of the stable mangrove areas at the mangrove-pemphis ...
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... East Grande Terre (Fig. 4) changes were more varied, with some regions having persistent mangrove areas, while others showed intermittent mangrove expansion and retraction. During 2009During -2014, we identified the largest proportion (30%) of mangrove loss to the scrub and sand land covers. The landward gains and losses around East Grande Terre were directional ...
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... with some regions having persistent mangrove areas, while others showed intermittent mangrove expansion and retraction. During 2009During -2014, we identified the largest proportion (30%) of mangrove loss to the scrub and sand land covers. The landward gains and losses around East Grande Terre were directional along the Bras Cinq Cases waterway (Fig. 4). On the more exposed boundary between the lagoon and the mangroves, to the west of the Bras Cinq Cases area, substantial loss of mangroves occurred between 2009 and 2014, which had not recovered by 2018 (Fig. 4). Our assessment of the change in the size of mangrove extent showed that 91% of the total gains and losses identified between ...
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... scrub and sand land covers. The landward gains and losses around East Grande Terre were directional along the Bras Cinq Cases waterway (Fig. 4). On the more exposed boundary between the lagoon and the mangroves, to the west of the Bras Cinq Cases area, substantial loss of mangroves occurred between 2009 and 2014, which had not recovered by 2018 (Fig. 4). Our assessment of the change in the size of mangrove extent showed that 91% of the total gains and losses identified between 1997 and 2018 occurred within areas of < 2 ...
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... contracted severely during droughts (Mafi-Gholami et al., 2020). Conversely, on Aldabra, the greatest extent of mangroves in our study was in 2009, which was among the driest drought periods on the atoll since 2000 (Haverkamp et al., 2017). Our study showed that mangrove extent increased inland into the scrub and grassland on East Grande Terre (Fig. 4) during the longer drought. The expansion could have been due to the dependence of the surrounding vegetation on rainfall ( Haverkamp et al., 2017). Inherently, mangrove trees are also remarkably adept at maintaining water uptake in saline conditions ( Reef and Lovelock, 2015), including through condensation and foliar water uptake ( ...
Citations
... Additionally, crab fisheries' productivity and landings correlate positively with mangrove coverage (Aburto-Oropeza et al., 2008;Carrasquilla-Henao et al., 2013;Manson et al., 2005). On Aldabra, seabird nutrient subsidies boost mangrove forest nutrient status , and increases in mangrove extent coincide with seabird colonies (Constance et al., 2021). By improving mangrove forest health, seabird nutrient subsidies can indirectly enhance not only mangrove crab fisheries but also other income-generating activities like ecotourism and critical services such as coastal protection, suggesting that seabird populations can play an important role in promoting mangrove ecosystem service delivery (Plazas-Jiménez & Cianciaruso, 2020). ...
Invertebrates have a central role in food webs and ecosystem functioning. By boosting productivity, allochthonous nutrient inputs influence the food webs of recipient communities. Understanding how allochthonous nutrient subsidies affect invertebrates is crucial, particularly in highly productive coastal areas. Here, we examine how mangrove macroinvertebrates are impacted by nutrient‐rich guano delivered by nesting seabird populations at Aldabra Atoll in the Indian Ocean. We compare nitrogen and carbon stable isotope ratios and nitrogen composition of basal resources and macroinvertebrate consumers in mangroves with and without nesting seabirds. Seabird‐derived nutrient enrichment increased the nitrogen content of basal food sources and herbivorous littorinid gastropods and sesarmid crabs. In mangroves with breeding seabirds, mean carapace widths of sesarmid and omnivorous portunid crabs were 6% and 11% larger, respectively. Isotopic niches of littorinid gastropods and sesarmid crabs were larger and had higher overlap at seabird compared to non‐seabird sites. Epiphytic macroalgae and guano comprised >50% of resource contributions to littorinid gastropods and sesarmid crabs at seabird sites. This differed markedly from non‐seabird sites where the main resource contributions were 77% mangrove leaves for littorinid gastropods, 36% sediment organic matter, and 41% mangrove leaves for sesarmid crabs. The increased sizes of mangrove crabs suggest that seabird nutrient enrichment can promote mangrove crab fisheries productivity and benefit the provisioning of mangrove ecosystem services. By shifting resource use of functionally important macroinvertebrates, we discuss how seabirds modify trophic interactions, with potential consequences for mangrove ecosystem processes and resilience.
... In addition, Aldabra is a largely pristine marine area that supports a wealth of endemic and threatened biodiversity, including the world's largest population of giant tortoises 26 and the second-largest breeding population of green turtles in the Western Indian Ocean 27,28 . Strong linkages exist between the distribution of animals, habitats, and shoreline processes on Aldabra 25,[29][30][31] . Given these linkages and the 2-3 mm yr −1 sea level rise for coastal areas within the Mozambique Channel from 1993 to 2013 18 , it is important to assess the rate and location of shoreline change at this ecologically important site. ...
... 25% of its yearly mean rainfall of 975 mm 37 . From November to April, the wet northwest trade wind brings calmer conditions 31,36 . Aldabra's south and east shorelines experience higher wave activity and are more exposed to the prevailing wind and waves than the north coast 29 . ...
... Mangroves predominantly cover the limestone boundary of the lagoon, finding niches within crevices, limestone blocks, or undercut creeks where soil has accumulated. The presence of mangroves suggests specific substrate conditions, as well as tidal and wave influences, that support tree growth 29,31 and thus accurately approximate the island's boundary with the lagoon. Further, these two boundaries (limestone shelf-ocean and mangrove-lagoon) are discernible from remotely sensed imagery. ...
Atolls are at risk of losing their ability to physically adapt due to rising sea levels and coral reefs’ reduced sediment supply, resulting in faster erosion of reef islands. This research examines Aldabra, a raised atoll and UNESCO World Heritage Site in the Indian Ocean with diverse coastal ecosystems, to track shoreline changes against a regional sea level rise of 2–3 mm yr⁻¹. Aerial and satellite images in 1960 and 2011 were used to study 85% of the atoll’s shoreline through a Digital Shoreline Analysis System. Over 51 years, 61% of the shoreline remained unchanged, while 24% changed at an average rate of 0.25 ± 0.36 m yr⁻¹, a low rate compared to global atoll changes. Among the areas that did change, rates of accretion and erosion in absolute values were nearly balanced and affected similar percentages (12%) of the shoreline. However, localized changes were pronounced: for example, part of the lagoon shoreline transformed from a sandy beach to a mangrove habitat, accreting by 214 m over the period. Erosion occurred at crucial turtle nesting sites and the research station. The lagoon shoreline underwent more rapid changes than the erosion-resistant ocean shoreline, particularly in areas exposed to wind and waves. Despite its dynamic shoreline, Aldabra maintained its net shoreline and likely total land area over the past 51 years, akin to other Indo-Pacific atolls—underscoring its adaptive capacity. Our research suggests that current knowledge of geomorphological processes of low reef islands is transferable to the raised Aldabra Atoll, reconfirming similar mechanisms of island-building processes at the island crest. These insights highlight an urgent need to minimize local impacts on sediment availability and transfer that might alter the natural dynamics of the shoreline of reef islands and hence limit adaptation potential. Ongoing shoreline monitoring will remain crucial for informing timely adaptation strategies for the conservation of Aldabra’s unique ecosystem.
... Also in Kiribati, the mangrove lagoon of the Nooto Ramsar Site on North Tarawa of 1 km in extent showed mangroves expanding and prograding seawards 1998-2013, increasing by 17%, at a rate of 604 m 2 /year (Ellison et al. 2017). In the Indian Ocean, 21 years of mangrove shoreline analysis on Aldabra showed mangroves to be mostly stable, with some loss to seaward and some mangrove migration inland (Constance et al. 2021). In the Marshall Islands, Jaluit mangrove shorelines showed progradation of up to 3 m/year between 1945 and 2019 (Crameri and Ellison 2022). ...
... Mangrove shorelines on low energy coastlines of Jaluit Atoll showed extensive progradation across 14.6 km, concurring with smaller-scale atoll studies finding mangrove progradation (Rankey 2011;Ellison et al. 2017;Constance et al. 2021). Spatial analysis of non-mangrove shorelines elsewhere in the Marshall Islands has shown dynamic results, with a mix of erosion and accretion (Ford 2013;Ford and Kench 2016). ...
Low-lying islands are vulnerable to coastal erosion, and mangroves, which can mitigate erosion, have suffered enormous losses in recent decades owing to human impacts. Previous studies have little investigated mangrove shores on atolls, which may face combined multiple threats. We analysed the large Marshall Islands atoll of Jaluit, at a higher resolution than previous spatial change studies, finding that mangrove shorelines prograded seawards over the last seven decades. Biogeomorphic colonisation processes were characterised from transects along ~ 14.6 km of shorelines. Mangrove progradation occurred in patterns of arc-shapes evident of long-shore drift deposition, patch expansion of offshore mangrove colonisers, and linear shoreline advance. Significant differences in the rates of expansion were identified, with arc-shaped colonisation showing the fastest rates of expansion. However, linear shoreline advance was the most frequent expansion pattern showing greater than threefold more classified transects than arc-shaped colonisation and patch expansion. These results have implications for low island mangrove restoration. Applying mangrove planting patterns mimicking these different natural colonisation processes may enhance restoration success in ecosystem-based adaptation projects to mitigate sea level rise vulnerability. Results from this study show that atoll mangrove shorelines demonstrate resilience during past sea level rise rates, and that rates of expansion vary according to patterns of biogeomorphic colonisation.
... 40 However, in contrast to Belize, some of the greatest increases in mangrove extent on Aldabra over the past two decades coincided with seabird nesting locations. 61 Furthermore, mangroves on Aldabra are far from urban or agricultural centers compared to Belize, and are therefore not influenced by additional anthropogenic nutrient sources. Natural nutrient sources provide N and P in optimal ratios, 62,63 generating contrasting responses in coastal habitat structure and functions compared to anthropogenic sources. ...
... 10 Indeed, both mangroves and mangrove-nesting seabird populations on Aldabra have increased over the last few decades. 23, 61 Multiple pathways of energy and nutrient flow exist in mangrove food webs due to the wide range of available food sources, such as plankton, benthic microalgae, mangroves, macroalgae, and macrophytes. 4,65 By assessing the trophic transfer of seabird-derived nutrients, we found that seabirds also enriched the mangrove invertebrate food web. ...
... 84 Mangrove sediments are mainly sand (53%) and loamy sand (26%) and with an average salinity of 8.3 G 3.1 (practical salinity scale). 61 Aldabra is influenced by a semi-diurnal meso-tidal regime (range: 2-3 m), resulting in strong tidal currents that drain approximately 75% of the lagoon at low tide through the main channels. 82,85 Rainfall patterns on Aldabra show marked seasonal variations influenced by monsoon winds. ...
Eutrophication by human-derived nutrient enrichment is a major threat to mangroves, impacting productivity, ecological functions, resilience, and ecosystem services. Natural mangrove nutrient enrichment processes, however, remain largely uninvestigated. Mobile consumers such as seabirds are important vectors of cross-ecosystem nutrient subsidies to islands but how they influence mangrove ecosystems is poorly known. We assessed the contribution, uptake, cycling, and transfer of nutrients from seabird colonies in remote mangrove systems free of human stressors. We found that nutrients from seabird guano enrich mangrove plants, reduce nutrient limitations, enhance mangrove invertebrate food webs, and are exported to nearby coastal habitats through tidal flow. We show that seabird nutrient subsidies in mangroves can be substantial, improving the nutrient status and health of mangroves and adjacent coastal habitats. Conserving mobile consumers, such as seabirds, is therefore vital to preserve and enhance their role in mangrove productivity, resilience, and provision of diverse functions and services.
... Mangroves can be found in tropical and subtropical climates (Jaelani et al., 2021) and in the intertidal zones and estuaries (Constance et al., 2021). These ecosystems are among the most productive and complex on the planet, growing under extreme environmental conditions (Nguyen et al., 2020a) such as places with high salinity, high temperatures and the muddy substrates (Gopalakrishnan et al., 2021). ...
... In addition, these adjustments include orthorectification, image visualization enhancement and cloud masking (Diniz et al., 2019). The goal of atmospheric correction is to produce a new image that is free of atmospheric noise (Constance et al., 2021). ...
... The geophysical component refers to sea level, tidal properties and weather conditions. The geomorphic component refers to sedimentation and topographic influences along with the geomorphic process of the area, such as river or tidal influences (Constance et al., 2021). The biological component refers to the competition between species in a particular area in different plant communities (Emch & Peterson, 2006). ...
Mangroves are ecosystems within the intertidal zone of tropical and subtropical coasts; they offer ecosystem services such as protection from coastal erosion and storms and flood control, act as carbon sinks and are also sources of income by providing various forest products. However, their cover is rapidly disappearing worldwide, which makes the diagnosis and monitoring of the state of these important ecosystems, as well as their restoration and conservation, a challenge. Remote sensing is a promising technique that provides accurate and efficient results in the mapping and monitoring of these ecosystems. The Landsat sensor provides the most used medium-resolution images for this type of study. The main objective of this article is to provide an updated review of the main remote sensing techniques, specifically Landsat satellite imagery, used in the detection of changes and mapping of mangrove forests, as well as a review of climatic and/or chemical factors related to changes in the spatial distribution of these ecosystems.
... A key feature of lagoons is the mangroves growing in this transitional environment between land and open ocean (Vadineanu, 2004). Lagoonal mangroves on oceanic islands usually occur within a carbonate setting (i.e., coralline islands) and are exposed to high wave energy and lower sediment input than mangroves in estuarine or deltaic environments (Ewel et al., 1998, Twilley et al., 2018, Raw et al., 2019, Constance et al., 2021. In these harsh environmental conditions, productivity and mangrove aboveground biomass (AGB) tend to be lower than in other mangrove ecosystems (Schaeffer-Novelli et al., 1990, Ewel et al., 1998, Worthington et al., 2020. ...
... Aldabra's mangrove forests occur on the coastal areas inside the atoll's lagoon, with an estimated total extent of 1720 ha (Walton et al., 2019). A recent study using remotely-sensed data found that the extent of mangrove forests on the atoll has increased by 60 ha over the past 20 years (Constance et al., 2021), although there was considerable variation within this period. Seven species of mangroves have been recorded on Aldabra: Avicennia marina; Bruguiera gymnorhiza; Ceriops tagal; Rhizophora mucronata; Lumnitzera racemosa; Sonneratia alba; Xylocarpus granatum (Macnae et al., 1971). ...
Lagoonal mangrove ecosystems are vital for carbon capture, protection of coastlines and conservation of biodiversity. Yet, they are decreasing globally at a higher rate than other mangrove ecosystems. In addition to human drivers, local environmental factors influence the functioning of lagoonal mangrove ecosystems, but their importance and combined effects are relatively unknown. Here, we investigate the drivers of mangrove functioning, approximated by mangrove aboveground biomass (AGB), in a protected lagoonal mangrove ecosystem on Aldabra Atoll, Seychelles. Based on a survey of the mangrove forest structure in 54 plots, we estimated that the mean mangrove forest AGB was 82 ± 13 Mg ha⁻¹. The total AGB of the mangrove area (1720 ha) was nearly 140,600 Mg, equivalent to about 66,100 Mg of carbon stored in the standing biomass on Aldabra. To assess the direct and indirect effects of soil nutrient content, water level variation and soil salinity on mangrove AGB, we used a structural equation model. Our structural equation model explained 82 % of the variation in mangrove AGB. The soil nutrient content (concentration of essential macronutrients in the soil column) had the greatest influence on mangrove AGB variation. Additionally, high variation in water level (change in water depth covering a location) increased mangrove AGB by increasing nutrient content levels. Our results highlight the important contribution of Aldabra's lagoonal ecosystem to Seychelles' carbon storage and the role of hydroperiod as a regulator controlling the availability of crucial nutrients needed for the functioning of mangroves within lagoonal systems. We suggest conservation managers worldwide focus on a holistic ecosystem-level perspective for successful mangrove conservation, including the protection and maintenance of nutrient cycling and hydrological processes.
... Mangrove forests have multiple functions and cannot be replaced by other ecosystems and function physically as land stabilizers, which play a role in mangrove roots accumulating mud substrate so that they can withstand coastal abrasion and block the intrusion into the mainland of seawater. Therefore, for the preservation of mangrove forests, community and government participation is needed [2]- [4]. The existence of the mangrove forest must be retained by all actors who have an interest in it. ...
According to the results of interactions between humans and mangrove forests, the causes of mangrove forest destruction are developing very dynamically. In the sub-district of East Luwuk, Banggai Regency, this study aims to determine the causes of mangrove forest damage. With descriptive analysis, this study utilizes qualitative methods. To determine the factors causing damage to mangroves was done by purposive sampling through interviews. The results showed that the damage to mangrove forests was caused by the conversion of mangrove forests into ponds, rice fields, and settlements. By carrying out restoration, rehabilitation, and restoration of damaged areas and recommending pond management by implementing a silvofishery pattern that can meet community welfare and maintain the survival of the mangrove ecosystem.
... Over the twenty-first century, RSLR and the lack of higher elevation migration areas will become a vulnerability for the mangroves on Jaluit, similar to settings on other atoll islands (Oppenheimer et al. 2019;Constance et al. 2021). The low tidal range (Table 7) adds vulnerability, as mangrove sediment soil redox conditions and a sulfate reduction realm (Ward and de Lacerda 2021) bring risks for successful relocation onto what is currently dry land. ...
Climate change threatens global mangroves, which are already among the world's most impacted ecosystems. Vulnerability components of exposure, sensitivity and adaptive capacity were evaluated on mangroves of atoll settings on Jaluit Atoll, in the Marshall Islands, assessing spatial changes of mangrove cover 1945-2018/19, sea-level trends 1968-2019, and reviewing available information. Inland mangrove depressions occur on Jaluit, as well as coastal lagoon margin mangroves, and both were assessed using the same methods. Spatial analysis results showed both inland and coastal mangroves have increased in area. Inland mangroves on eight of Jaluit's islands mostly expanded after 1976 from 40 to 50 hectares, with progradation and tidal creek infill closing lagoon connections. Shoreline mangroves showed 88-100% of transects prograding 0.1-0.51 m year-1 and 0-11.5% of transects eroding 0-0.18 m year-1. Assessment of a combination of aerial/satellite images, literature and on-the-ground photos indicated that the mangroves are in healthy condition. Vulnerability assessment results showed both inland and coastal mangroves to have similar strengths and weaknesses in resilience, with intrinsic areas of vulnerability persisting during increased future sea level rise, limited sediment supply and extremely low elevations.
Supplementary information:
The online version contains supplementary material available at 10.1007/s11273-022-09878-0.
... The debate is also largely informed by studies of marine processes of deposition, with far less attention given to aeolian processes (but see [35]), and processes driven from oceans across reefs rather than across lagoons (though erosion on lagoon-side shores is also a significant problem). The role of mangroves and seagrasses, which are prevalent in lagoons, is also scarcely considered, though these too play a role in island morphology and habitability [36][37][38]. ...
Atoll societies have adapted their environments and social systems for thousands of years, but the rapid pace of climate change may bring conditions that exceed their adaptive capacities. There is growing interest in the use of ‘nature-based solutions' to facilitate the continuation of dignified and meaningful lives on atolls through a changing climate. However, there remains insufficient evidence to conclude that these can make a significant contribution to adaptation on atolls, let alone to develop standards and guidelines for their implementation. A sustained programme of research to clarify the potential of nature-based solutions to support the habitability of atolls is therefore vital. In this paper, we provide a prospectus to guide this research programme: we explain the challenge climate change poses to atoll societies, discuss past and potential future applications of nature-based solutions and outline an agenda for transdisciplinary research to advance knowledge of the efficacy and feasibility of nature-based solutions to sustain the habitability of atolls.
This article is part of the theme issue ‘Nurturing resilient marine ecosystems’.
... Interestingly, the bulkhead damage was not different by Key, whereas other shoreline types were most damaged on the eastern-most island of Big Pine Key. The variation in mangrove damage across islands suggest that mangrove shorelines may be more resilient than hardened shorelines at lower inundation values and slower wind speeds (Constance et al., 2021). This is further supported by the high damages to mangroves reported in areas of high inundation and high wind speeds (east of the storm). ...
... Mangroves also cost less to maintain (Table 3), because mangrove shorelines can mature, strengthen, and even expand over time in the right conditions (Spalding et al., 2014;Constance et al., 2021). Whereas hardened structures are rigid and face degradation over time (Sutton-Grier et al., 2018). ...
Hurricanes have large and lasting effects along coastlines, representing one of the deadliest and costliest natural hazards. Among the rapidly growing literature on the impacts of hurricanes, an increasing topic of interest is the potential role of mangroves, and other coastal habitats, as nature-based strategies (NBS) for coastal defense. In addition to coastal protection, NBS have been shown to provide many ecological, economic, and social co-benefits. However, few studies have assessed coastal resident perceptions or residential-scale performance of NBS, particularly in the wake of major hurricanes. Through a survey of 288 residents of the Lower Florida Keys 1 year after Hurricane Irma, this paper describes hurricane impacts on mangroves, beaches, and hardened shorelines. Specifically, we measured perceptions of shoreline damage and shoreline effectiveness for coastal protection at the community- and parcel-levels. At the parcel scale, we also measured performance outcomes through the cost to repair or replace residential shorelines. At both community- and parcel-levels, beaches were perceived as the most damaged shoreline type, followed by mangroves, and then hardened shorelines as the least damaged. Specifically at the parcel-level, repair actions were not taken by many residents with a hardened shoreline (43.2%) due to their shoreline receiving no damage. However, when repair actions were taken, the average cost to repair or replace parcel-level mangroves (105.14 (USD) ± SE 38.57 per meter). Additionally, 44% of residents reported that no repair or recovery actions were needed after the storm for damaged mangroves, whereas when hardened structures were damaged, many required at least minor repairs (29.5%). Mangroves were also perceived as the most effective shoreline for storm protection (54% very to extremely effective) at the community-level. Our findings indicate local community-level awareness of the storm protective properties mangroves provide but also display a disconnect between perceptions and performance outcomes at parcel scales. Although mangroves cost less to repair and are perceived as the most effective at storm protection, the majority of Florida Keys residents own hardened shorelines. Considering the diverse co-benefits mangroves provide and the local support mangroves have, their conservation and restoration could be well-supported for coastal adaptation.
