Subsistence in isolation: Fishing dependence and perceptions of change on Kiritimati, the world's largest atoll

Watson, Maryann S.; Claar, Danielle C.

doi:10.1016/j.ocecoaman.2016.01.012

Cited by 35 publications

(48 citation statements)

References 31 publications

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“…Effective fisheries management requires a sound understanding the space use and habitat preferences of a species (Sale et al 2005;Grüss et al 2011), and reef predators like giant trevally play an essential role in economic development and ecosystem function throughout the atolls of the tropical Indo-Pacific. As the popularity of this species continues to grow, recreational catch and release tourism for giant trevally could provide alternative livelihoods that improve the stability of coastal communities (Allison and Ellis 2001;Wood et al 2013;Watson et al 2016). However, this species is increasingly threatened by exploitation and anthropogenic development, and as a result understanding their habitat needs is essential to their conservation (Friedlander and Dalzell 2004;Friedlander et al 2015;McLeod 2016).…”

Section: Discussionmentioning

confidence: 99%

Manual Acoustic Tracking Reveals the Spatial Ecology of Giant Trevally at a Remote South Pacific Atoll, with Implications for Their Management

Filous¹,

Lennox²,

Danylchuk³

et al. 2019

Preprint

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<div>Giant trevally (<i>Caranx ignobilis</i>) are important predators on the reefs of the tropical Indo-Pacific and research into their spatial ecology is needed to improve our understanding of their behavior and assist fisheries management. We used active acoustic telemetry to describe the fine-scale movements of giant trevally at Tetiaroa Atoll, including their home range, site fidelity, habitat use and spatial overlap with a small (21 km2) Marine Protected Area (MPA). The home ranges of giant trevally were small but varied among individuals (Minimum Convex Polygon 𝑋𝑋 = 3.2 ± 2.5 km2). All giant trevally exhibited site fidelity to their respective home ranges with a 31% average overlap in daily space use, but there was limited overlap in home ranges among individuals, with intra-individual spatial overlap significantly greater than inter-individual overlap (t = -4.93, df = 16.87, p-value = <0.001). There was only modest overlap (19 ± 19%) of giant trevally home ranges within the MPA and high spatial overlap of home ranges with deep lagoon habitats (90 ± 0.09 %). Our results indicate that MPAs could be an effective tool for the conservation of this species if they are implemented on an atoll-wide scale. However, in the case of managing recreational catch-and-release fisheries, rotational smallscale temporal closures could be effective in regulating the angling pressure imposed upon giant trevally, provided post-release mortality is minimized. The results of this study provide the first detailed account of habitat use in this species and highlight the need for additional research on the factors contributing to the survival of caught-and-released giant trevally in predator dominated atolls, especially as their popularity as a target of recreational fisheries continues to grow, and fishing operations and agencies are faced with the need to manage their fisheries.</div>

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Section: Discussionmentioning

confidence: 99%

Manual Acoustic Tracking Reveals the Spatial Ecology of Giant Trevally at a Remote South Pacific Atoll, with Implications for Their Management

Filous¹,

Lennox²,

Danylchuk³

et al. 2019

Preprint

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“…Specifically, we first generated a geographical buffer (in arcgis ) to determine human population size within 2 km of each site. Nearly all individuals live in villages, and village location was mapped based on published field surveys (Watson et al., 2016). Population size for each village was extracted from the 2015 Population and Housing Census from the Kiribati National Statistics Office (Ministry of Finance).…”

Section: Methodsmentioning

confidence: 99%

“…Second, we generated a kernel density function with 10 steps based on mapped fishing intensity from Watson et al. (2016). This metric accounts for the more diffuse, but still important, effects of subsistence fishing on the reef ecosystem.…”

Section: Methodsmentioning

confidence: 99%

“…Our aim here was to advance understanding of how the diversity and community structure of two vital groups of microorganisms residing within corals, Symbiodiniaceae and bacteria, respond to chronic local disturbance in a natural ecosystem. We examined paired communities of coral‐associated Symbiodiniaceae and bacteria across a spatial gradient of chronic human disturbance on Kiritimati atoll (Christmas Island, Republic of Kiribati, 01°52′N, 157°24′W; Walsh, 2011; Watson, Claar, & Baum, 2016) for seven different coral species that span a range of life history strategies. Within this natural experimental context, we tested two hypotheses: first, that alpha and beta diversity of both the Symbiodiniaceae and bacterial communities would increase with increasing chronic disturbance (McDevitt‐Irwin et al., 2017; Zaneveld et al., 2017); and second, that although bacterial communities would be more sensitive to disturbance and exhibit more site‐to‐site variability than Symbiodiniaceae communities, chronic human disturbance would still cause qualitatively similar responses in these two groups, resulting in broad concordance (i.e., similarity of multidimensional community shape) across the disturbance gradient, because of coral species‐specific associations within both communities.…”

Section: Introductionmentioning

confidence: 99%

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Increased diversity and concordant shifts in community structure of coral‐associated Symbiodiniaceae and bacteria subjected to chronic human disturbance

et al. 2020

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Both coral‐associated bacteria and endosymbiotic algae (Symbiodiniaceae spp.) are vitally important for the biological function of corals. Yet little is known about their co‐occurrence within corals, how their diversity varies across coral species, or how they are impacted by anthropogenic disturbances. Here, we sampled coral colonies (n = 472) from seven species, encompassing a range of life history traits, across a gradient of chronic human disturbance (n = 11 sites on Kiritimati [Christmas] atoll) in the central equatorial Pacific, and quantified the sequence assemblages and community structure of their associated Symbiodiniaceae and bacterial communities. Although Symbiodiniaceae alpha diversity did not vary with chronic human disturbance, disturbance was consistently associated with higher bacterial Shannon diversity and richness, with bacterial richness by sample almost doubling from sites with low to very high disturbance. Chronic disturbance was also associated with altered microbial beta diversity for Symbiodiniaceae and bacteria, including changes in community structure for both and increased variation (dispersion) of the Symbiodiniaceae communities. We also found concordance between Symbiodiniaceae and bacterial community structure, when all corals were considered together, and individually for two massive species, Hydnophora microconos and Porites lobata, implying that symbionts and bacteria respond similarly to human disturbance in these species. Finally, we found that the dominant Symbiodiniaceae ancestral lineage in a coral colony was associated with differential abundances of several distinct bacterial taxa. These results suggest that increased beta diversity of Symbiodiniaceae and bacterial communities may be a reliable indicator of stress in the coral microbiome, and that there may be concordant responses to chronic disturbance between these communities at the whole‐ecosystem scale.

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“…1; Supplementary Fig. S1 85,86 ). We quantified the intensity of chronic local human disturbance at each site, using spatial data for two separate metrics, human population densities and fishing pressure ( Supplementary Table S2).…”

Section: Methodsmentioning

confidence: 99%

Chronic disturbance modulates symbiont (Symbiodiniaceae) beta diversity on a coral reef

Claar

Tietjen

Cox

et al. 2020

Sci Rep

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chronic disturbance can disrupt ecological interactions including the foundational symbiosis between reef-building corals and the dinoflagellate family Symbiodiniaceae. Symbiodiniaceae are photosynthetic endosymbionts necessary for coral survival, but many Symbiodiniaceae can also be found free-living in the environment. Since most coral species acquire new Symbiodiniaceae from the environment each generation, free-living Symbiodiniaceae represent important pools for coral symbiont acquisition. Yet, little is known about the diversity of, or impacts of disturbance on, freeliving Symbiodiniaceae. To determine how chronic and pulse disturbances influence Symbiodiniaceae communities, we sampled three reef habitat compartments-sediment, water, and coral (Pocillopora grandis, Montipora aequituberculata, Porites lobata)-at sites exposed to different levels of chronic anthropogenic disturbance, before, during, and after a major storm. Almost no (4%) Symbiodiniaceae amplicon sequence variants (ASVs) were found in all three compartments, and over half were found uniquely in coral. Sites experiencing chronic disturbance were typically associated with higher symbiont beta diversity (i.e., variability and turnover) across reef habitat compartments. Pulse stress, from the storm, exhibited some influence on symbiont beta diversity but the effect was inconsistent. This suggests that in this ecosystem, the effects of chronic disturbance are more prominent than temporal variability during a pulse disturbance for shaping symbiont communities. Disturbances, both natural and anthropogenic, can alter species diversity and cause stress on ecosystem structure and function. Disturbance can manifest as chronic disturbance (i.e., long-term or press disturbance) or pulse disturbance (i.e., short-term or acute disturbances events) 1,2. Both types of disturbance can alter not only alpha diversity (i.e., species diversity within a community; e.g. 3,4) but also beta diversity (i.e., differences in species composition among communities 5,6), which has emerged as a sensitive indicator of ecosystem change under stress 7,8. Beta diversity metrics can be split into two working definitions: 'turnover' is defined as compositional changes of species assemblages across a gradient, while 'variation' is defined as the amount of variability among species assemblages within each community 9. When communities are analyzed in a multivariate context, 'turnover' represents multivariate location, while 'variation' represents multivariate spread (beta dispersion). A growing body of literature has shown that for macro-organisms, disturbances often cause a decrease in beta diversity, leading to 'biotic homogenization' (i.e., communities become simplified and more similar to one another 10-13). In microorganisms , however, emerging evidence suggests that disturbance can have the opposite effect, resulting in elevated beta diversity (e.g. 14-16 ; reviewed in 17). This effect has been attributed to the ' Anna Karenina' principle, wherein stress causes an increase in ...

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Subsistence in isolation: Fishing dependence and perceptions of change on Kiritimati, the world's largest atoll

Cited by 35 publications

References 31 publications

Manual Acoustic Tracking Reveals the Spatial Ecology of Giant Trevally at a Remote South Pacific Atoll, with Implications for Their Management

Manual Acoustic Tracking Reveals the Spatial Ecology of Giant Trevally at a Remote South Pacific Atoll, with Implications for Their Management

Increased diversity and concordant shifts in community structure of coral‐associated Symbiodiniaceae and bacteria subjected to chronic human disturbance

Chronic disturbance modulates symbiont (Symbiodiniaceae) beta diversity on a coral reef

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