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  1. Article: The α-minimum convex polygon as a relevant tool for isotopic niche statistics

    Fey, Pauline / Letourneur, Yves / Bonnabel, Silvère

    Ecological indicators. 2021 Nov., v. 130

    2021  

    Abstract: Ecological (isotopic) niche refers to a surface in a two-dimensional space, where the axes correspond to environmental variables that reflect values of stable isotopes incorporated in an animal's tissues. Carbon and nitrogen stable isotope ratios (δ¹³C-δ¹ ...

    Abstract Ecological (isotopic) niche refers to a surface in a two-dimensional space, where the axes correspond to environmental variables that reflect values of stable isotopes incorporated in an animal's tissues. Carbon and nitrogen stable isotope ratios (δ¹³C-δ¹⁵N) notably provide precious information about trophic ecology, resource and habitat use, and population dynamics. Various metrics allow for isotopic niche size and overlap assessment. In this paper, we advocate α-minimum convex polygons (MCP) - that have long been used for home range estimation – as a relevant tool for isotopic niche size, overlap, and characteristics. The method allows for outlier rejection while being suited to data that are not Gaussian in the bivariate isotopic (δ¹³C-δ¹⁵N) space. The proposed indicators are compared to other existing approaches and are shown to be complementary. Notably an indicator of divergence within the niche is introduced, and allows for comparisons at low (n > 6) and different sample sizes. The R code is made publicly available and will enable ecologists to perform isotopic niche comparison, contraction and expansion assessment, and overlap, based on various methods.
    Keywords animals ; carbon ; home range ; nitrogen ; population dynamics ; stable isotopes ; statistics
    Language English
    Dates of publication 2021-11
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2036774-0
    ISSN 1872-7034 ; 1470-160X
    ISSN (online) 1872-7034
    ISSN 1470-160X
    DOI 10.1016/j.ecolind.2021.108048
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  2. Article ; Online: Metallic trace elements in marine sponges living in a semi-enclosed tropical lagoon.

    Maggioni, Federica / Stenger, Pierre-Louis / Letourneur, Yves / Jourand, Philippe / Majorel, Clarisse

    Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine

    2023  Volume 37, Issue 1, Page(s) 157–169

    Abstract: The ability of marine filter feeders to accumulate metals could help monitor the health of the marine environment. This study examined the concentration of metallic trace elements (MTE) in two marine sponges, Rhabdastrella globostellata and Hyrtios ... ...

    Abstract The ability of marine filter feeders to accumulate metals could help monitor the health of the marine environment. This study examined the concentration of metallic trace elements (MTE) in two marine sponges, Rhabdastrella globostellata and Hyrtios erectus, from three sampling zones of the semi-enclosed Bouraké Lagoon (New Caledonia, South West Pacific). MTE in sponge tissues, seawater, and surrounding sediments was measured using inductively coupled plasma with optical emission spectroscopy. The variability in sponge MTE concentrations between species and sampling zones was visually discriminated using a principal component analysis (PCA). Sponges showed Fe, Mn, Cr, Ni, and Zn concentrations 2 to 10 times higher than in the surrounding sediments and seawater. Hyrtios erectus accumulated 3 to 20 times more MTE than R. globostellata, except for Zn. Average bioconcentration factors in sponge tissues were (in decreasing order) Zn > Ni > Mn > Fe > Cr relate to sediments and Fe > Ni > Mn > Cr > Zn relate to seawater. The PCA confirmed higher MTE concentrations in H. erectus compared to R. globostellata. Our results confirm that marine sponges can accumulate MTE to some extent and could be used as a tool for assessing metals contamination in lagoon ecosystems, particularly in New Caledonia, where 40% of the lagoon is classified as a UNESCO World Heritage Site.
    MeSH term(s) Animals ; Trace Elements/analysis ; Ecosystem ; Environmental Monitoring/methods ; Water Pollutants, Chemical ; Metals ; Porifera ; Geologic Sediments/analysis ; Geologic Sediments/chemistry ; Metals, Heavy
    Chemical Substances Trace Elements ; Water Pollutants, Chemical ; Metals ; Metals, Heavy
    Language English
    Publishing date 2023-09-19
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 1112688-7
    ISSN 1572-8773 ; 0966-0844
    ISSN (online) 1572-8773
    ISSN 0966-0844
    DOI 10.1007/s10534-023-00536-3
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  3. Article ; Online: C and N stable isotopes enlighten the trophic behaviour of the dugong (Dugong dugon).

    Thibault, Martin / Letourneur, Yves / Cleguer, Christophe / Bonneville, Claire / Briand, Marine J / Derville, Solène / Bustamante, Paco / Garrigue, Claire

    Scientific reports

    2024  Volume 14, Issue 1, Page(s) 896

    Abstract: The dugong (Dugong dugon), a large marine mammal herbivore of the Indo-Pacific, is vulnerable to extinction at a global scale due to a combination of human-related threats including habitat degradation. The species forages on seagrass habitats (marine ... ...

    Abstract The dugong (Dugong dugon), a large marine mammal herbivore of the Indo-Pacific, is vulnerable to extinction at a global scale due to a combination of human-related threats including habitat degradation. The species forages on seagrass habitats (marine phanerogams) and plays a key role in the functioning and sensitivity of these declining coastal ecosystems. The trophic behaviour and plasticity of dugong populations in response to extrinsic and intrinsic factors are therefore crucial features to both dugong and seagrass conservation. Yet, this knowledge remains limited to few visual observations and analyses of mouth, stomach or faecal contents of stranded individuals. We take advantage of a long-term monitoring of stranded individuals from the endangered New Caledonian population to depict features of dugongs' trophic ecology from Carbon and Nitrogen stable isotopes. A total of 59 dugong skin samples were used to portrait the stable isotope niche of dugongs according to their sex and maturity. In light of previous work conducted in New Caledonia, a subset of these samples was used to model the trophic mix of dugong males and females. Our stable isotope mixing models used C and N isotope values of 10 taxa bbelonging to five divisions of metazoans, plants, and chromists. Our results represent the first estimate of the species dietary niche in the isotopic space. They suggest that the diet of dugong calves overlaps more with that of adult females (δ
    MeSH term(s) Humans ; Adult ; Female ; Male ; Animals ; Cattle ; Dugong ; Ecosystem ; Lactation ; Health Behavior ; Nitrogen Isotopes ; Caniformia ; Cetacea
    Chemical Substances Nitrogen Isotopes
    Language English
    Publishing date 2024-01-09
    Publishing country England
    Document type Journal Article
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-023-50578-3
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  4. Article ; Online: Sponge organic matter recycling: Reduced detritus production under extreme environmental conditions.

    Maggioni, Federica / Bell, James J / Pujo-Pay, Mireille / Shaffer, Megan / Cerrano, Carlo / Lemonnier, Hugues / Letourneur, Yves / Rodolfo-Metalpa, Riccardo

    Marine pollution bulletin

    2023  Volume 190, Page(s) 114869

    Abstract: Sponges are a key component of coral reef ecosystems and play an important role in carbon and nutrient cycles. Many sponges are known to consume dissolved organic carbon and transform this into detritus, which moves through detrital food chains and ... ...

    Abstract Sponges are a key component of coral reef ecosystems and play an important role in carbon and nutrient cycles. Many sponges are known to consume dissolved organic carbon and transform this into detritus, which moves through detrital food chains and eventually to higher trophic levels via what is known as the sponge loop. Despite the importance of this loop, little is known about how these cycles will be impacted by future environmental conditions. During two years (2018 and 2020), we measured the organic carbon, nutrient recycling, and photosynthetic activity of the massive HMA, photosymbiotic sponge Rhabdastrella globostellata at the natural laboratory of Bouraké in New Caledonia, where the physical and chemical composition of seawater regularly change according to the tide. We found that while sponges experienced acidification and low dissolved oxygen at low tide in both sampling years, a change in organic carbon recycling whereby sponges stopped producing detritus (i.e., the sponge loop) was only found when sponges also experienced higher temperature in 2020. Our findings provide new insights into how important trophic pathways may be affected by changing ocean conditions.
    MeSH term(s) Animals ; Ecosystem ; Coral Reefs ; Seawater/chemistry ; Carbon/metabolism ; Nutrients/metabolism ; Porifera/metabolism
    Chemical Substances Carbon (7440-44-0)
    Language English
    Publishing date 2023-04-05
    Publishing country England
    Document type Journal Article
    ZDB-ID 2001296-2
    ISSN 1879-3363 ; 0025-326X
    ISSN (online) 1879-3363
    ISSN 0025-326X
    DOI 10.1016/j.marpolbul.2023.114869
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  5. Article: Diel changes in structure and trophic functions of motile benthic invertebrates on coral reefs at Rapa Nui (Easter Island)

    Zapata-Hernández, Germán / Hinojosa, Iván A. / Sellanes, Javier / Rios, Rodrigo S. / Letourneur, Yves

    Marine biology. 2021 Oct., v. 168, no. 10

    2021  

    Abstract: Coral reefs are structurally complex habitats that provide diverse shelter for motile benthic invertebrates (MBI), including those with cryptic and nocturnal behaviors. In this study, diel changes in MBI structure (species composition, density, and ... ...

    Abstract Coral reefs are structurally complex habitats that provide diverse shelter for motile benthic invertebrates (MBI), including those with cryptic and nocturnal behaviors. In this study, diel changes in MBI structure (species composition, density, and biomass) and functions (trophic groups and isotopic diversity indices) were examined on coral reefs at Rapa Nui (27° S, 109° W). Diurnal and nocturnal surveys (March 2016) revealed that echinoderms were the dominant invertebrates throughout the diel cycle in terms of density, biomass, and their trophic role. The density and biomass of MBI were higher at night than during the day. Significant diel changes were detected in the structure of MBI and trophic groups, where the diurnal assemblages were mostly herbivores and the nocturnal assemblages were mostly detritivores. Moreover, the isotopic uniqueness index indicated that nocturnal MBI were trophically more redundant than their diurnal counterparts; consequently, the high nocturnal biodiversity did not necessarily increase trophic diversity. This time and trophic partitioning of MBI could have important consequences for energy transfer on the reefs and must be considered in future monitoring programs. Endemic taxa represented approximately a quarter of the species (26%), but had low density and biomass during both time periods, suggesting a modest influence on energy transfers on these coral reefs. However, their restricted geographic distribution and current low abundances could make these species vulnerable to extinction; therefore, management and conservation actions in the new multiple-use marine protected area of Rapa Nui should include these species.
    Keywords biomass ; corals ; detritivores ; energy transfer ; extinction ; geographical distribution ; marine protected areas ; species diversity ; Pacific Ocean Islands
    Language English
    Dates of publication 2021-10
    Size p. 154.
    Publishing place Springer Berlin Heidelberg
    Document type Article
    ZDB-ID 1117-4
    ISSN 1432-1793 ; 0025-3162
    ISSN (online) 1432-1793
    ISSN 0025-3162
    DOI 10.1007/s00227-021-03957-1
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  6. Article ; Online: Sponge organic matter recycling: Reduced detritus production under extreme environmental conditions

    Maggioni, Federica / Bell, James J. / Pujo-Pay, Mireille / Shaffer, Megan / Cerrano, Carlo / Lemonnier, Hugues / Letourneur, Yves / Rodolfo-Metalpa, Riccardo

    Marine Pollution Bulletin. 2023 May, v. 190 p.114869-

    2023  

    Abstract: Sponges are a key component of coral reef ecosystems and play an important role in carbon and nutrient cycles. Many sponges are known to consume dissolved organic carbon and transform this into detritus, which moves through detrital food chains and ... ...

    Abstract Sponges are a key component of coral reef ecosystems and play an important role in carbon and nutrient cycles. Many sponges are known to consume dissolved organic carbon and transform this into detritus, which moves through detrital food chains and eventually to higher trophic levels via what is known as the sponge loop. Despite the importance of this loop, little is known about how these cycles will be impacted by future environmental conditions. During two years (2018 and 2020), we measured the organic carbon, nutrient recycling, and photosynthetic activity of the massive HMA, photosymbiotic sponge Rhabdastrella globostellata at the natural laboratory of Bouraké in New Caledonia, where the physical and chemical composition of seawater regularly change according to the tide. We found that while sponges experienced acidification and low dissolved oxygen at low tide in both sampling years, a change in organic carbon recycling whereby sponges stopped producing detritus (i.e., the sponge loop) was only found when sponges also experienced higher temperature in 2020. Our findings provide new insights into how important trophic pathways may be affected by changing ocean conditions.
    Keywords acidification ; coral reefs ; detritus ; dissolved organic carbon ; dissolved oxygen ; marine pollution ; photosymbiosis ; photosynthesis ; seawater ; temperature ; New Caledonia ; Sponge loop ; Organic matter recycling ; Sponge metabolism ; Extreme environments ; Bouraké
    Language English
    Dates of publication 2023-05
    Publishing place Elsevier Ltd
    Document type Article ; Online
    Note Use and reproduction
    ZDB-ID 2001296-2
    ISSN 1879-3363 ; 0025-326X
    ISSN (online) 1879-3363
    ISSN 0025-326X
    DOI 10.1016/j.marpolbul.2023.114869
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  7. Article ; Online: Isotopic and biochemical trophic markers reveal the complexity of interactions at the base of pelagic food webs (Mediterranean sea)

    Chen, Chia-Ting / Carlotti, François / Harmelin-Vivien, M. L. / Letourneur, Yves / Savoye, Nicolas / Guillou, Gaël / Lebreton, Benoit / Tesán-Onrubia, Javier A. / Barani, Aude / Cornet, Véronique / Guilloux, Loïc / Esposito, Anaïs / Ré, Christian / Bănaru, Daniela

    Marine Environmental Research. 20232023 Sept. 04, Aug. 04, v. 190 p.106123-

    2023  

    Abstract: To gain insight into the impact of bottom-up changes in the plankton community on planktivorous fish in the context of the decline of small pelagic fisheries in the Northwestern Mediterranean Sea, we have conducted an extensive year-long study. The ... ...

    Abstract To gain insight into the impact of bottom-up changes in the plankton community on planktivorous fish in the context of the decline of small pelagic fisheries in the Northwestern Mediterranean Sea, we have conducted an extensive year-long study. The investigation combined biochemical analyses (proteins, carbohydrates, and lipids) with C and N stable isotope analyses (SIA) to simultaneously study phytoplankton, zooplankton, and eight planktivorous fish species (Engraulis encrasicolus, Sardina pilchardus, Sardinella aurita, Sprattus sprattus, Cepola macrophthalma, Chromis chromis, Boops boops, and Spicara maena). This study is the first to analyze both stable isotope and biochemical compositions in coastal particulate organic matter (POM) size classes (0.7–2.7 μm, 2.7–20 μm, and 20–200 μm), zooplankton size classes (200–300 μm, 300–500 μm, 500–1000 μm, 1000–2000 μm, and >2000 μm), and taxonomic groups. We demonstrated that: (1) POM stable isotope compositions varied based on its spatial origin, the taxonomic composition of its biota, and its biochemical content; (2) δ¹⁵N values increased with zooplankton size classes and groups, indicating different trophic levels; (3) Phytoplankton exhibited a lipid-rich composition (∼55%), while zooplankton and fish muscles were protein-rich (∼61% and ∼66%, respectively). Bayesian stable isotope mixing models revealed that, on average: (1) POM from oceanic waters contributed the most to the POM in the bay (>51%), with a dominance of pico-POM (∼43%); (2) The 200–1000 μm zooplankton primarily consumed nano-POM, the 1000–2000 μm zooplankton mostly consumed micro-POM (∼64%), and the >2000 μm zooplankton also mostly consumed micro-POM; (3) Mesozooplankton (200–2000 μm) constituted the main portion (∼42%) of the diet for planktivorous fish species, while macrozooplankton organisms (>2000 μm) were the primary food resource (∼43%) for both B. boops and S. sprattus. Our study underscores the complexity of the pelagic food web and highlights the bottom-up transfer of organic matter from the smallest phytoplankton size fractions to planktivorous fish.
    Keywords Bayesian theory ; Boops boops ; Cepola ; Chromis ; Engraulis encrasicolus ; Sardina pilchardus ; Sardinella aurita ; Spicara maena ; Sprattus sprattus ; diet ; fish ; food webs ; particulate organic matter ; phytoplankton ; planktivores ; research ; stable isotopes ; taxonomy ; zooplankton ; Mediterranean Sea ; Small pelagic fish ; Plankton ; Carbon and nitrogen isotopic compositions ; Biochemical composition ; Organic matter transfer ; Mixing model
    Language English
    Dates of publication 2023-0804
    Publishing place Elsevier Ltd
    Document type Article ; Online
    ZDB-ID 1502505-6
    ISSN 1879-0291 ; 0141-1136
    ISSN (online) 1879-0291
    ISSN 0141-1136
    DOI 10.1016/j.marenvres.2023.106123
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  8. Article ; Online: Isotopic and biochemical trophic markers reveal the complexity of interactions at the base of pelagic food webs (Mediterranean sea).

    Chen, Chia-Ting / Carlotti, François / Harmelin-Vivien, Mireille / Letourneur, Yves / Savoye, Nicolas / Guillou, Gaël / Lebreton, Benoit / Tesán-Onrubia, Javier A / Barani, Aude / Cornet, Véronique / Guilloux, Loïc / Esposito, Anaïs / Ré, Christian / Bănaru, Daniela

    Marine environmental research

    2023  Volume 190, Page(s) 106123

    Abstract: To gain insight into the impact of bottom-up changes in the plankton community on planktivorous fish in the context of the decline of small pelagic fisheries in the Northwestern Mediterranean Sea, we have conducted an extensive year-long study. The ... ...

    Abstract To gain insight into the impact of bottom-up changes in the plankton community on planktivorous fish in the context of the decline of small pelagic fisheries in the Northwestern Mediterranean Sea, we have conducted an extensive year-long study. The investigation combined biochemical analyses (proteins, carbohydrates, and lipids) with C and N stable isotope analyses (SIA) to simultaneously study phytoplankton, zooplankton, and eight planktivorous fish species (Engraulis encrasicolus, Sardina pilchardus, Sardinella aurita, Sprattus sprattus, Cepola macrophthalma, Chromis chromis, Boops boops, and Spicara maena). This study is the first to analyze both stable isotope and biochemical compositions in coastal particulate organic matter (POM) size classes (0.7-2.7 μm, 2.7-20 μm, and 20-200 μm), zooplankton size classes (200-300 μm, 300-500 μm, 500-1000 μm, 1000-2000 μm, and >2000 μm), and taxonomic groups. We demonstrated that: (1) POM stable isotope compositions varied based on its spatial origin, the taxonomic composition of its biota, and its biochemical content; (2) δ
    MeSH term(s) Animals ; Food Chain ; Mediterranean Sea ; Bayes Theorem ; Carbon Isotopes/analysis ; Phytoplankton ; Zooplankton ; Fishes/physiology
    Chemical Substances Carbon Isotopes
    Language English
    Publishing date 2023-08-04
    Publishing country England
    Document type Journal Article
    ZDB-ID 1502505-6
    ISSN 1879-0291 ; 0141-1136
    ISSN (online) 1879-0291
    ISSN 0141-1136
    DOI 10.1016/j.marenvres.2023.106123
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  9. Article: Differential uses of coral reef habitats by a poorly‐known cryptic fish predator

    Morat, Fabien / Briand, Marine J. / Pécheyran, Christophe / Letourneur, Yves

    Journal of fish biology. 2019 Jan., v. 94, no. 1

    2019  

    Abstract: This study used otolith microchemistry to evaluate whether the moray eel Gymnothorax chilospilus uses different habitats throughout its life (mainly juvenile and adult phases). Of the most informative trace elements within otoliths (the twelve isotopes ²³ ...

    Abstract This study used otolith microchemistry to evaluate whether the moray eel Gymnothorax chilospilus uses different habitats throughout its life (mainly juvenile and adult phases). Of the most informative trace elements within otoliths (the twelve isotopes ²³Na, ²⁵Mg, ⁴³Ca, ⁵⁵Mn, ⁵⁹Co, ⁶⁰Ni, ⁶³Cu, ⁶⁶Zn, ⁸⁶Sr, ¹¹¹Cd, ¹³⁸Ba and ²⁰⁸Pb) only three ratios of Ca (Na:Ca, Sr:Ca and Ba:Ca) were informative and therefore used in a multivariate regression‐tree analysis. Using a multivariate partitioning, three main phases were described from profiles, including the larval life phase (leptocephali), the intermediate phase (longest section between the larval life phase and the terminal phase) and the terminal phase (final section i.e., the most recent months preceding the death of fish). According to concentrations of the three ratios to Ca, G. chilospilus can be separated into three groups during their larval life stage (very different in Sr and Na), four groups during the intermediate phase (few differences in Sr and Na) and three groups during the terminal phase (differences in Sr), illustrating that G. chilospilus inhabit different habitats during these three phases. Our results showed that the leptocephali encountered different oceanic water masses with fluctuating Sr:Ca ratios during the early larval phase. During the intermediate phase (main part of their life‐span), they lived in lagoonal waters such as fringing reefs or reef flats of lagoonal islets, characterized by a lower Sr:Ca ratio. During the latter part of their life, approximately one third of G. chilospilus encountered more oceanic waters close to or at barrier reefs, suggesting possible movements of these fish along a coast‐to‐ocean gradient.
    Keywords Gymnothorax ; adults ; coral reefs ; death ; eel ; juveniles ; leptocephalus larvae ; otoliths
    Language English
    Dates of publication 2019-01
    Size p. 53-61.
    Publishing place Blackwell Publishing Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 410564-3
    ISSN 1095-8649 ; 0022-1112
    ISSN (online) 1095-8649
    ISSN 0022-1112
    DOI 10.1111/jfb.13853
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  10. Article ; Online: Differential uses of coral reef habitats by a poorly-known cryptic fish predator.

    Morat, Fabien / Briand, Marine J / Pécheyran, Christophe / Letourneur, Yves

    Journal of fish biology

    2018  Volume 94, Issue 1, Page(s) 53–61

    Abstract: This study used otolith microchemistry to evaluate whether the moray eel Gymnothorax chilospilus uses different habitats throughout its life (mainly juvenile and adult phases). Of the most informative trace elements within otoliths (the twelve ... ...

    Abstract This study used otolith microchemistry to evaluate whether the moray eel Gymnothorax chilospilus uses different habitats throughout its life (mainly juvenile and adult phases). Of the most informative trace elements within otoliths (the twelve isotopes
    MeSH term(s) Animals ; Behavior, Animal ; Coral Reefs ; Ecosystem ; Eels/physiology ; Multivariate Analysis ; Otolithic Membrane/chemistry ; Seafood ; Trace Elements/analysis
    Chemical Substances Trace Elements
    Language English
    Publishing date 2018-12-10
    Publishing country England
    Document type Journal Article
    ZDB-ID 410564-3
    ISSN 1095-8649 ; 0022-1112
    ISSN (online) 1095-8649
    ISSN 0022-1112
    DOI 10.1111/jfb.13853
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