Spatial dependency in abundance of Queen conch, <i>Aliger gigas</i>, in the Caribbean, indicates the importance of surveying deep‐water distributions

Boman, Erik; Graaf, M. de; Kough, Andrew S.; Izioka-Kuramae, Ayumi; Zuur, Alain F.; Smaal, A.C.; Nagelkerke, L.A.J.

doi:10.1111/ddi.13392

Cited by 8 publications

(4 citation statements)

References 47 publications

(57 reference statements)

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“…As illustrated by our results (Figures 4-7), estimated ecological connectivity patterns are sensitive to assumptions regarding both the distributions of queen conch populations and their reproductive output. Thus, we highlight the need for updated demographic and habitat information for queen conch, strongly corroborating needs identified in previous studies (Prada et al, 2017;Kough et al, 2017;Truelove et al, 2017;Kitson-Walters et al, 2018;Boman et al, 2021). To refine larval connectivity estimates and fully understand conch demographics at both broad and smaller spatial scales within jurisdictionsthe following are needed: 1) representative surveys of conch population densities across a range of habitats, along with a precise understanding of the areas over which these densities can be extrapolated (Prada et al, 2017;Kough et al, 2017); 2) densities of individuals categorized as juveniles and adults and/ or detailed stock size structure reported; 3) detailed maps and/or areal estimates of conch habitat (i.e., areas where the species currently or has historically occurred) in each jurisdiction; and 4) surveys of conch populations located in depths below the typical range of fishing (i.e., >30m) to assess the contribution of mesophotic populations that might serve as deep refugia for shallow populations and which remain largely excluded from conch surveys (Boman et al, 2021).…”

Section: Management Implicationssupporting

confidence: 89%

“…Overall, our results support that estimates of contemporary demographic rates, and thus of fecundity, need to be considered for ecological connectivity studies (Lowe and Allendorf, 2010;Castorani et al, 2017;Johnston et al, 2018). Moreover, our results strongly corroborate advice for international management and conservation of queen conch, as well as research needs identified in previous conch studies (Prada et al, 2017;Kough et al, 2017;Stoner et al, 2019;Delgado and Glazer 2020;Boman et al, 2021). However, given the high likelihood of local settlement and distribution of distinct metapopulations, replenishment processes through larval dispersal are likely to occur only within the metapopulation spatial scales.…”

Section: Management Implicationssupporting

confidence: 88%

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Exploitation Drives Changes in the Population Connectivity of Queen Conch (Aliger gigas)

et al. 2022

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The queen conch, Aliger gigas, is an endemic and iconic marine gastropod of the Wider Caribbean region that has been harvested for thousands of years. Conch are slow-moving and require contact to mate; overfishing has reduced populations in many areas compromising its rates of reproduction. Long-range dispersal and mixing between distinct populations occur in the queen conch’s early life history stages, when pelagic larvae are transported by oceanic currents. Genetic studies suggest that gene flow between populations decreases as the distance between populations increases. Here, we assessed how the population connectivity of conch changes with spatially variable patterns of fishing exploitation by simulating larval dispersal and comparing the potential connectivity under an unexploited and a contemporary exploited reproductive scenario. Results demonstrate that reduced egg production, due to heterogeneous fishing pressure and localized depletion, significantly alters population connectivity patterns as well as the structuring of populations and metapopulations across the species’ range. This strongly suggests that estimates of contemporary demographic rates, together with estimates of reproductive output need to be included in population connectivity studies. The existence of self-sustained metapopulations of queen conch throughout the Wider Caribbean suggests that replenishment through larval dispersal occurs primarily within sub-regional spatial scales, emphasizing the need for regional and local conservation and management measures to build and protect reproductively active populations and nursery habitat across multiple jurisdictions.

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Section: Management Implicationssupporting

confidence: 89%

Section: Management Implicationssupporting

confidence: 88%

Exploitation Drives Changes in the Population Connectivity of Queen Conch (Aliger gigas)

et al. 2022

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“…In The Bahamas and across the Caribbean, the best determinant of maturity in conch is a shell lip thickness of at least 15 mm (Boman et al, 2018); here, individuals with a lip thickness of at least 15 mm were categorized as adults and thinner lipped individuals as juveniles. Conch distributions are patchy (Boman et al, 2021), which interacted with the nonstandardized spatial effort during time‐based drift dives and required multiple terms to capture in statistical models (Kough et al, 2019). Here, the same negative binomial generalized linear model approach was used to explain variable counts of conch relative to continuous variables distance swept, maximum distance between individuals, and an interaction between the two, as well as a factor for surveys within the ECLSP (Kough et al, 2019).…”

Section: Methodsmentioning

confidence: 99%

Empirical support of predicted larval connectivity patterns demand conservation action for queen conch (Aliger gigas) in The Bahamas

Kough

2024

Conservat Sci and Prac

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The conservation and spatial management of marine species with limited adult mobility, such as queen conch, is dictated by larval connectivity. Effectively placed reserves provide larval spillover to harvested areas while replenishing their own population. In past studies proximate to the Exuma Cays Land and Sea Park (ECLSP), surveys and probabilistic larval transport modeling demonstrated a spillover effect from the ECLSP to surrounding fished areas, while suggesting that incoming larval sources are lacking. Previous work was expanded in both upstream and downstream directions, enabling the statistical examination of (1) how queen conch abundance was linked to predicted larval transport from breeding populations in the ECLSP and (2) how age and size changed throughout the island chain as divided by management and connectivity. Biophysical modeling predictions of larval transport from breeding within the ECLSP were significantly associated with the relative abundance of juvenile conch observed across a nearly 200‐km span. Further, the abundance and shell lip thickness (relative age) of adults and the size of juveniles were significantly larger in ECLSP than unprotected areas. This empirical support for an effective, well‐enforced marine reserve and for using biophysical larval transport modeling as a spatial planning tool should be strongly considered in conch conservation and management.

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“…Internal factors include species dispersal patterns and colonial breeding habits (Dormann, 2007). The second category is external environmental factors, which have their own pattern of spatial autocorrelation that they introduce into species data (Boman et al, 2021). Potential external factors include humidity, rainfall, and soil type.…”

Section: Previous Researchmentioning

confidence: 99%

Spatial modeling of the relative abundance of wading birds in peninsular Florida using citizen science data

Lee

Skripnikov

2023

Ecosphere

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Recent literature has shown citizen science data that include reported counts, such as observations from the eBird database, can be used to model the relative abundance of selected species. The objective of our study was to extend on both the methodology and the range of species considered by previous research on relative abundance modeling; we selected the Floridian peninsula as our geographical area of interest. We confirmed that, much like for other bird species and geographical areas, modeling such data with a classic Poisson generalized linear model was not appropriate due to overdispersion. Moreover, assuming linearity for the effects of all environmental and observer effort covariates on relative abundance was shown to be overly simplistic. These concerns led us to consider a variety of potentially suitable modeling techniques; the quasi‐Poisson generalized additive model displayed the best combination of flexibility, strong predictive performance, and ease of interpretation. Expanding on previous research for eBird data, we chose to explicitly incorporate spatial dependence into the modeling task by performing hierarchical generalized additive modeling with a spatial conditional autoregressive structure for random effects. This practice allows us to account for spatial factors not represented by model covariates, such as species dispersal patterns or colonial breeding habits. After conducting appropriate testing procedures and fitting spatially explicit models, we found that our data contain moderate spatial dependence and that spatially explicit models have overall superior predictive performance to models that do not account for spatial dependence. Upon closer inspection, spatially explicit models perform especially well compared with their nonspatial counterparts in identifying situations with low abundance, with a negligible trade‐off in prediction accuracy for situations with high abundance. We conclude that quasi‐Poisson hierarchical generalized additive models with spatial random effects provide the best representation of the relative abundance of bird populations. Moreover, our spatially explicit models are more realistic based on domain knowledge when regarding the impact of environmental covariates, which is important when considering conservation implications and future projections.

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Spatial dependency in abundance of Queen conch, Aliger gigas, in the Caribbean, indicates the importance of surveying deep‐water distributions

Abstract: This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 8 publications

References 47 publications

Exploitation Drives Changes in the Population Connectivity of Queen Conch (Aliger gigas)

Exploitation Drives Changes in the Population Connectivity of Queen Conch (Aliger gigas)

Empirical support of predicted larval connectivity patterns demand conservation action for queen conch (Aliger gigas) in The Bahamas

Spatial modeling of the relative abundance of wading birds in peninsular Florida using citizen science data

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