Environmental Drivers of Fine-Scale Predator and Prey Spatial Dynamics in Sydney Harbour, Australia, and Adjacent Coastal Waters

Estuaries and Coasts, Journal Year: 2021, Volume and Issue: 45(5), P. 1465 - 1479

Published: Nov. 16, 2021

Abstract Greater Sydney is the largest coastal city in Australia and where bull sharks ( Carcharhinus leucas ) are present every summer autumn. A decade of acoustic telemetry data was used to identify drivers space use for their potential prey, according standardised 6-h intervals using dynamic Brownian bridge movement models. Influences environmental, physical, biological variables on areas use, location, predator–prey co-occurrence were investigated with generalised additive mixed Rainfall catchment affected all animals (i.e. teleost species both sexes sharks), varying temporal responses. Male responded most promptly high rainfall moving upstream < 1 day, followed by teleosts (2 7 days), female after 4 days. Environmental luminosity male shark dispersal possibly indicating visual cues foraging. Physical characteristics habitat important factors driving spatial overlaps between predator prey estuarine areas. In sandy embayments 10-m deep, males overlapped different species, whereas silver trevally Pseudocaranx georgianus co-occurred deep holes (> 30 m). Shark size influenced overlap sexes, smaller females less likely co-occur larger (~ 50 cm). Variability suggests segregation sex sharks, individuals targeting similar yet either or at times, ultimately enabling them exploit resources when same habitats.

Language: Английский

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Estimated life-history traits and movements of the Caribbean reef shark (Carcharhinus perezi) in The Bahamas based on tag-recapture data

Marine Biology, Journal Year: 2022, Volume and Issue: 169(5)

Published: April 4, 2022

Language: Английский

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Baseline genetic distinctiveness supports structured populations of thornback ray in the Mediterranean Sea

Aquatic Conservation Marine and Freshwater Ecosystems, Journal Year: 2023, Volume and Issue: 33(5), P. 458 - 471

Published: April 4, 2023

Abstract The thornback ray ( Raja clavata ) is the most important chondrichthyan in terms of landings Mediterranean Sea. Intense harvesting may induce negative genetic effects reducing resilience overfished species. For this reason, diversity information should be considered fisheries management and conservation policies. Microsatellite markers were used to unravel features (variability, connectivity, sex‐biased dispersal) R. populations, both at small (around coast Sardinia, western Sea) larger spatial scales (at pan‐Mediterranean level, between Atlantic Ocean Sea). Individual clustering, multivariate variance analyses rejected hypothesis homogeneity, with significant differences rays, as well within Sea its eastern basins. data indicated that Strait Gibraltar Sicilian Channel seem effective limiting dispersal individuals, but a further structuring was identified, differentiation populations located Algero‐Provençal Tyrrhenian Such fine‐scale arrangement suggests occurrence additional barriers species dispersal. A lack differentiation, stable over years, measured local scale among Sardinian samples. Several possible mechanisms, biological abiotic (e.g. migratory behaviour, waterfronts oceanographic discontinuities), are discussed. Overall, presented, regional could represent baseline for temporal monitoring assessing present or future fisheries‐related actions. obtained paramount importance minimizing gaps our current knowledge rays maximizing needed correct protection populations.

Language: Английский

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A review of the life history and ecology of euryhaline and estuarine sharks and rays

Reviews in Fish Biology and Fisheries, Journal Year: 2023, Volume and Issue: 34(1), P. 65 - 89

Published: Oct. 23, 2023

Abstract One-third of all elasmobranchs (sharks and rays) are threatened with extinction. Euryhaline estuarine generalist a group 29 species that occupy non-marine environments during particular life-stages. These poorly known disproportionately threatened, 72.4% at risk extinction or Data Deficient. A detailed knowledge species’ life history characteristics, movement ecology, habitat use, population structure required for the implementation appropriate management conservation measures. To date, research on euryhaline has lagged behind marine species. Here, literature review gap analysis was conducted to identify gaps in 14 key parameters management. Of species, only Bull Shark ( Carcharhinus leucas ) Largetooth Sawfish Pristis pristis had information majority assessed. Nine lack most parameters, while Broadnose Wedgefish Rhynchobatus springeri lacks but one investigated. There is high level understanding age- size-at-maturity, size-at-birth, growth five nine have estimates natural mortality. Comprehensive reproductive biology data unavailable six Both short- long-term ecology well-understood two use Population been studied eight structure, requirements urgently develop strategies secure populations.

Language: Английский

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An R-based tool for identifying sex-linked markers from restriction site-associated DNA sequencing with applications to elasmobranch conservation

Conservation Genetics Resources, Journal Year: 2023, Volume and Issue: 16(1), P. 11 - 16

Published: Nov. 16, 2023

Abstract Identifying sex-linked markers from genomic data has both theoretical and applied importance, especially in conservation. Yet, few methods tools exist to detect such Restriction-site-Associated DNA sequencing reads even fewer can identify existing genotyped data. Here, we describe a new R function that species with partially non-recombining sex chromosomes. We test the accuracy speed of our an example dataset conservation concern, White Shark, Carcharodon carcharias . further compare method against other approaches find detects more be reliably mapped reference genomes. Overall, provide fisheries-relevant tool efficiently assign genetic heterogametic demonstrate its utility by developing sex-identification PCR for Sharks.

Language: Английский

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Comparative population genomics of manta rays has global implications for management

Molecular Ecology, Journal Year: 2023, Volume and Issue: unknown

Published: Nov. 23, 2023

Understanding population connectivity and genetic diversity is of fundamental importance to conservation. However, in globally threatened marine megafauna, challenges remain due their elusive nature wide-ranging distributions. As overexploitation continues threaten biodiversity across the globe, such knowledge gaps compromise both suitability effectiveness management actions. Here, we use a comparative framework investigate differentiation manta rays, one most iconic yet vulnerable groups elasmobranchs on planet. Despite recent divergence, show how oceanic rays (Mobula birostris) display significantly higher heterozygosity than reef alfredi) that M. birostris populations worldwide. Through inferring modes colonization, reveal contemporary historical forces have likely influenced these patterns, with important implications for management. Our findings highlight potential fisheries disrupt dynamics at local global scales therefore direct relevance international conservation species.

Language: Английский

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Global genetic diversity and historical demography of the Bull Shark

Journal of Biogeography, Journal Year: 2023, Volume and Issue: 51(4), P. 632 - 648

Published: Dec. 11, 2023

Abstract Aim Biogeographic boundaries and genetic structuring have important effects on the inferences interpretation of effective population size ( N e ) temporal variations, a key genetics parameter. We reconstructed historical demography divergence history vulnerable coastal high‐trophic shark using genomics assessed our ability to detect recent bottleneck events. Location Western Central Indo‐Pacific (IPA), Tropical Atlantic (WTA) Eastern Pacific (EPA). Taxon Carcharhinus leucas (Müller & Henle, 1839). Methods A DArTcap™ approach was used sequence 475 samples assess global structuring. Three demographic models were tested each population, an ABC‐RF framework coupled with coalescent simulations, investigate within‐cluster structure. Divergence times between clusters computed, testing multiple scenarios, fastsimcoal . variations STAIRWAYPLOT. Coalescent simulations performed determine detectability under estimated trend for datasets this size. Results corresponding IPA, WTA EPA regions identified, agreeing previous studies. The IPA presented highest diversity consistently identified as oldest. No significant detected. increased globally, earlier onset in during last glacial period. showed that weak bottlenecks could not be detected dataset, while old and/or strong would erase observed ancestral expansion. Main Conclusions This study further confirms role marine biogeographic breaks shaping large mobile predators. increases are potentially linked extended habitat availability. limited suggests can monitored over ocean basins. Due insufficient amount available data, it cannot concluded whether overfishing is impacting Bull Shark diversity, calling whole‐genome sequencing.

Language: Английский

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Population genetic structure of the bottlenose and whitespotted wedgefishes (Rhynchobatus) from the Southwest Indian Ocean using a dual marker approach

Endangered Species Research, Journal Year: 2024, Volume and Issue: 53, P. 409 - 427

Published: Jan. 17, 2024

Wedgefishes (Rhinidae) are threatened by unsustainable fishing globally, and especially in the Southwest Indian Ocean (SWIO), due to their high-value fins shark trade. The whitespotted wedgefish Rhynchobatus djiddensis bottlenose R. australiae both classified as Critically Endangered on IUCN Red List of Threatened Species, yet a lack species-specific knowledge taxonomic uncertainty still exists within this genus. Genetic approaches aid classification identifying distinct populations for targeted conservation. Morphological specimen identification samples (n = 189) collected across SWIO was confirmed based cytochrome oxidase c subunit I ( COI ) and/or nicotinamide adenine dehydrogenase 2 ND2 gene regions. genetic diversity population structure between species sampling locations were investigated using dual marker approach: (1) concatenated mitochondrial regions, namely control region 117), (2) 9 nuclear microsatellite markers 146). overall moderate, with an indication that different evolutionary forces at play versus level. delineated types, , South Africa Mozambique genetically homogeneous. For significant differentiation found locations, Madagascar Tanzania being most similar. This information provides critical insights into distribution range complex can support sustainable management wedgefishes.

Language: Английский

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Retrospective genomics highlights changes in genetic composition of tiger sharks (Galeocerdo cuvier) and potential loss of a south-eastern Australia population

Scientific Reports, Journal Year: 2022, Volume and Issue: 12(1)

Published: April 21, 2022

Abstract Over the last century, many shark populations have declined, primarily due to overexploitation in commercial, artisanal and recreational fisheries. In addition, some locations use of control programs also has had an impact on numbers. Still, there is a general perception that large ocean predators cover wide areas therefore their diversity less susceptible local anthropogenic disturbance. Here we report temporal genomic analyses tiger ( Galeocerdo cuvier ) DNA samples were collected from eastern Australia over past century. Using Single Nucleotide Polymorphism (SNP) loci, documented significant change genetic composition sharks born between ~1939 2015. The was most likely shift time relative contribution two well-differentiated, but hitherto cryptic populations. Our data strongly indicate dramatic these overall abundance east coast Australia, possibly associated with differences direct or indirect exploitation rates.

Language: Английский

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Age-Dependent Dispersal and Relatedness in Tiger Sharks (Galeocerdo cuvier)

Frontiers in Marine Science, Journal Year: 2022, Volume and Issue: 9

Published: July 18, 2022

Understanding dispersal in large marine fauna is necessary for conservation, but movement patterns often vary widely by sex and life stage. In sharks, genetic studies have shown evidence of widespread male-biased dispersal, though tagging tracking on the same populations show both sexes using site fidelity, including philopatry, moving similar distances. We used a suite microsatellite loci DNA samples from 362 previously-tagged tiger sharks (Galeocerdo cuvier) northwestern Atlantic, number residential juveniles, to evaluate reproductive light demographic published data. found that lumping size classes together resulted panmixia across sites, systematic removal individuals showed significant population-level differentiation three separate population clusters among juveniles less than 260 cm total length. Tests relatedness 8.9% our sample set was composed first-order related pairs (N = 16), several full siblings different litters, sign multi-cycle monogamy which carries implications effective size. By mapping assignments we identified signature fine-scale structure suggesting broad biparental fidelity habitat northeast Gulf Mexico, concordant with Taken together, these findings demonstrate how stages may obscure structure, confounding future conservation efforts.

Language: Английский

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