Spatial connectivity of reef manta rays across the Raja Ampat archipelago, Indonesia

Royal Society Open Science, Journal Year: 2024, Volume and Issue: 11(4)

Published: April 1, 2024

The reef manta ray Mobula alfredi is present throughout most island groups that form the Raja Ampat archipelago, Indonesia. species protected regionally and nationally currently managed as a single homogeneous population within 6.7 million ha archipelago. However, scientific evidence lacking regarding spatial connectivity structure of M. this Using network analysis an array 34 acoustic receivers deployed between February 2016 September 2021, we examined movements 72 subadult adult tagged in seven regions Ampat. A total 1094 were recorded primarily concentrated nearby receiver stations, highlighting frequent local within, limited long-distance regional arrays. Network revealed highly connected nodes acting hubs important for movements. community detection algorithm further indicated clusters network. Our results suggest existence metapopulation comprising three demographically geographically distinct subpopulations They also reveal importance Eagle Rock critical node movement network, justifying urgent inclusion site marine area

Language: Английский

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A unified paradigm for defining elasmobranch aggregations

ICES Journal of Marine Science, Journal Year: 2023, Volume and Issue: 80(6), P. 1551 - 1566

Published: June 29, 2023

Abstract Elasmobranchs are highly diverse in movement, sensory capacity, and behavioural responses to the environment, leading differences function nature of associations interactions between individuals, populations, species. The term “aggregation” has been widely variably used describe co-occurrence across elasmobranch species, but its defining criteria remain vague indeterminate. lack standardized terminology hinders comparisons studies, systems. It can cause misinterpretation about drivers aggregation formation or grouping behaviour limits impact research. Here, we propose generalizable definitions supporting terms, adapted from more mature socioecological theory other systems, which be applied elasmobranchs. We discuss types aggregations, detail required identify an based on our definition, offer direction future methods reporting advance field. These proposed protocols standardize study socioecology, will generate greater understanding mechanisms underlying distribution support cross-system comparisons. Finally, this information predictive power into when how aggregations may form, proactive management strategies mitigate anthropogenic threats.

Language: Английский

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Examining coastal habitat co-utilization of chimaeras using social network analysis

Research Square (Research Square), Journal Year: 2025, Volume and Issue: unknown

Published: March 19, 2025

Group living determines how animals interact with others and their habitat. Elephant fish (Callorhinchus milii) are chimaeras (Class Chondrichthyes, subclass Holocephali) that migrate to coastal waters for reproduction throughout its southern Australian range. However, there is limited information about they co-utilize these areas. This study used social network analysis (SNA) passive acoustic monitoring data examine associations between adult elephant in an estuary southeastern Tasmania, Australia (42°53.710′S 147°34.228′E), specifically Pitt Water (PW) Frederick Henry Bay (FHB) from January 2012 December 2013. The influence of sex on the structure was also investigated. As a result, two distinct groups (clusters) were found across both years: resident female cluster remained upper (UP) mixed-sex group whose movements varied seasonally. These clusters formed cohesive community, potentially playing critical role connecting population members. split into temporary aggregations, so-called fission-fusion society relies seasonal reproductive patterns. Furthermore, by investigating all individuals (including clusters), spatial segregation evident. suitable conditions part egg-laying mating dynamics may shape association observed. findings highlight importance essential habitats emphasize need management strategies incorporate space co-utilization patterns, address sex-based segregation, recognize females maintaining ensure stability connectivity.

Language: Английский

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Preliminary insights into manta ray (Mobula alfredi and M. birostris) population demographics and distribution in South Africa

Environmental Biology of Fishes, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 8, 2025

Abstract Both the reef manta ray, Mobula alfredi and oceanic ray M. birostris , are repeatedly observed in South Africa, yet little is known about distributions of either species. In this study, we collated citizen science observations since 2003 to reveal six areas KwaZulu-Natal (KZN) Eastern Cape provinces, where rays have been sighted across multiple years. Using their unique ventral spot patterning, 184 individuals were photo-identified, comprising 139 45 . Most photo-identified encountered iSimangaliso Wetland Park (IWP) KZN (89%; n = 119) for Aliwal Shoal (48%; 22). We identified 32 new transboundary records 28 also photographed Inhambane Province, Mozambique, demonstrating connectivity, specifically Závora ( 27). One individual traveled times between IWP Závora, totaling 1305 km, another from Pondoland MPA a distance over 600 km. Further, extend southern range Africa by 500 km Mdumbi Beach Port Ngqura, Cape. These collective findings represent Africa’s first in-water assessment aggregations, showing particular be critical habitat movements documented here suggest population one most mobile globally. hope baseline data provided will drive increased research management along coastlines.

Language: Английский

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Smart sharks: a review of chondrichthyan cognition

Animal Cognition, Journal Year: 2022, Volume and Issue: 26(1), P. 175 - 188

Published: Nov. 17, 2022

Abstract 450 million years of evolution have given chondrichthyans (sharks, rays and allies) ample time to adapt perfectly their respective everyday life challenges cognitive abilities played an important part in that process. The diversity niches sharks occupy corresponds matching brains behaviour, but we only scratched the surface terms investigating cognition this group animals. handful species been cognitively assessed some detail over last decade provided enough data safely conclude are on par with most other vertebrates, including mammals birds. Experiments lab as well wild pose own unique challenges, mainly due handling maintenance these animals controlling environmental conditions elimination confounding factors. Nonetheless, significant advancements obtained fields spatial social cognition, discrimination learning, memory retention several others. Most studies focused behaviour underlying neural substrates involved information processing still largely unknown. Our understanding shark has multiple practical benefits for welfare conservation management there obvious gaps our knowledge. Like marine animals, face threats. effects climate change, pollution resulting ecosystem changes stingrays remain poorly investigated can speculate what likely impacts might be based research bony fishes. Lastly, suffer from bad reputation mindless killers heavily targeted by commercial fishing operations fins. This public relations issue clouds people’s expectations intelligence is a serious impediment conservation. In light fascinating results presented here, it seems general perception status sentient, needs urgently revisited.

Language: Английский

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Intraspecific differences in short- and long-term foraging strategies of reef manta ray (Mobula alfredi) in the Chagos Archipelago

Global Ecology and Conservation, Journal Year: 2023, Volume and Issue: 46, P. e02636 - e02636

Published: Sept. 14, 2023

Assessing the foraging ecology of a threatened species is necessary to understand their movement behaviour and habitat use patterns, which are essential for developing effective protection strategies. Here, reef manta rays (Mobula alfredi) in Chagos Archipelago, region encompassed by vast no-take marine protected area (MPA), was investigated using stable isotope analysis skin muscle tissue. Enriched δ13C values suggest population predominantly forages nearshore environments. Skin increased with rainfall, likely associated boosts primary production zooplankton biomass due coastal advection seabird guano. Annual variations were observed consistent reduced nutrient transport effects Indian Ocean Dipole oscillations, including deepening thermocline, suppression cold-water upwelling, rainfall. Short- long-term strategies locations identified applying hierarchical clustering, isotopic niche analysis, Bayesian mixing models δ15N paired tissue samples. Two isotopically distinct groups M. alfredi identified, employing either local restricted specific or wide-ranging that mean they engage regular migrations throughout archipelago. Ninety-eight percent estimated switch between utilising connecting multiple discrete habitats, emphasising role ecosystem functioning facilitating nutrients across boundaries. However, illegal, unreported, unregulated fishing lost abandoned gear commonly occur within MPA. Locations particular concern Egmont Atoll as it highly active aggregation location Peros Banhos where IUU frequently occurs be heavily reliant upon foraging. Frequent atolls also raises over vulnerability these activities along migration corridors. This research bridges current knowledge gaps this population's concomitant should inform conservation region.

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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Behavior, site use and demographics of shortfin devil rays, Mobula kuhlii, at a newly-discovered cleaning area in South Africa

Marine Biology, Journal Year: 2024, Volume and Issue: 171(6)

Published: May 14, 2024

Abstract Many shark and ray species show affinity to specific sites, making these areas critical for their survival. These include cleaning stations: locations on reefs where cleaner fish remove parasites clean wounds, which is important maintaining health. Cleaning stations also function as social gathering or resting points, courtship mating can occur. In this study, we identify an aggregation site the shortfin devil ray, Mobula kuhlii (Family Mobulidae) within Aliwal Shoal Marine Protected Area in KwaZulu-Natal (KZN), South Africa, document behavior. Remote underwater video was used collect footage of M. being cleaned by blue streak wrasse, Labroides dimidiatus . Generalized additive models (GAMs) were assess environmental predictors presence Shoal. Mixed same correlation with mean duration number L. bites per second at identified station site. present 56% observation days, group numbers up > 150 individuals. Sea surface temperature a significant predictor presence, while north south current significantly associated longer durations. results support findings mobulid studies KZN that increased habitat use during summer temperatures (24–25 °C) suggest sites be individual health interaction. We hope development location-specific management plans safeguard Endangered species.

Language: Английский

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Individual flexibility in group foraging behaviour of reef manta rays (Mobula alfredi)

Behavioral Ecology and Sociobiology, Journal Year: 2024, Volume and Issue: 78(7)

Published: June 29, 2024

Abstract Flexibility in animal foraging strategies can increase overall feeding efficiency for individuals. For example, group the of resource exploitation; conversely solo reduce intraspecific competition, particularly at low densities. The cost–benefit trade-off such flexibility is likely to differ within and among Reef manta rays ( Mobula alfredi ) are large filter-feeding elasmobranchs that often aggregate feed on ephemeral upwellings zooplankton. Over three years Maldives, we free-dived film 3106 events involving 343 individually identifiable M. . Individuals fed either or groups with a clear leader plus between one eight followers. were significantly more forage than high just prior tide when aggregations larger. Within aggregations, individuals foraged larger food was available, relatively suggesting beneficial abundant, costs competition outweighed by resulting from strategies. Females, sex, lead males. within-individual variance (over 70%), suggested unpredictable across all behaviours, thus individual cannot be classified into types specialists. Instead, each capable considerable behavioural flexibility, as predicted species reliant spatially temporally resources. Significance statement ), listed “Vulnerable” IUCN Red List, risk targeted by-catch fisheries due their slow life history aggregative behaviour. together short-lived glut microscopic filmed Manta larger, attracted influx Foraging included plankton abundant. However, flipped did not specialise. most led females, sex. very flexible how they foraged, which makes sense relies source varies enormously when, where long it available. Understanding ray behaviour will help conservation management efforts predict responses climate change.

Language: Английский

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Comparative population genomics of manta rays has global implications for management

bioRxiv (Cold Spring Harbor Laboratory), Journal Year: 2023, Volume and Issue: unknown

Published: June 21, 2023

Abstract 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. populations worldwide. Through inferring modes colonisation, 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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