Paleolimnological reconstructions from the mid and high latitudes in the Southern Hemisphere are ... more Paleolimnological reconstructions from the mid and high latitudes in the Southern Hemisphere are still relatively scarce. Anthropogenic impacts have evidenced trophic state changes and an increase in cyanobacterial blooms in the lacustrine system of San Pedro de la Paz in the last decades. Here, we reconstructed primary production and sedimentological changes spanning the past 2500 years in two coastal lakes in Mediterranean Chile. A multiproxy approach including sedimentological, biogenic silica, carbon and nitrogen isotopes and fossil pigments analysis in sediment cores was performed in Laguna Grande (LGSP) and Laguna Chica de San Pedro (LCSP). A marked change in the sedimentology of the lakes, likely related to the terrigenous sediment inputs derived by a transition from an arid condition in the mid-Holocene to a more humid condition in the late Holocene that favoured arboreal forest establishment at 100 BC–AD 150. A period of low primary production was identified between 850 to ...
Mediterranean Posidonia oceanica meadows shelter an important biomass and biodiversity of amphipo... more Mediterranean Posidonia oceanica meadows shelter an important biomass and biodiversity of amphipod crustaceans that graze on epiphytes. However, their actual significance for ecosystem functional processes is hard to estimate, due to the lack of adequate data. Here, a field microcosm-based inclusion experiment was used to test if three of the dominant taxa of the amphipod community (Apherusa chiereghinii, Dexamine spiniventris and Gammarus spp.) could exert top-down control on seagrass leaf epiphytes. Influence of amphipod activity on nutrient availability for the host species was also investigated. All grazer taxa significantly reduced biomasses of erect macroalgae and erect sessile animals present on leaves. None of them consumed encrusting epiflora or epifauna. This selective top-down control could have important implications for the structure of the epiphytic community on leaves of P. oceanica, which is one of the most diverse and abundant of all seagrass species. Grazing activi...
At Makemo Atoll (French Polynesia), the carapid fish Onuxodon fowleri lives in symbiosis with the... more At Makemo Atoll (French Polynesia), the carapid fish Onuxodon fowleri lives in symbiosis with the black-lip pearl oyster Pinctada margaritifera. Although the symbiont seems to live inside its host bivalve by using it as a shelter, additional data are still needed to better understand the exact nature of this association. For this purpose, we implemented an approach using stable isotope ratios of carbon (13C/12C) and nitrogen (15N/14N). The δ13C and δ15N values were measured in tissues of the pearl oyster (gonads, gills, mantle and muscles), white muscle tissue from the fish and other food sources. This stable isotope approach was also complemented by the analysis of stomach contents in the carapid fish. Overall, the isotopic compositions measured in the present study support a commensal relationship between O. fowleri and P. margaritifera. In addition, our isotopic data bring new information about another guest living inside P. margaritifera, namely the palaemonid shrimp Conchodytes...
Harlequin crabs, Lissocarcinus orbicularis, are commensals found on the integument and in the buc... more Harlequin crabs, Lissocarcinus orbicularis, are commensals found on the integument and in the buccal/cloacal cavity of several species of holothuroids. The population of these crabs was investigated on holothuroids of the barrier reef of Toliara (South-West of Madagascar) from 2002 to 2008. Seventeen holothuroid species were observed and eight were crab hosts. There is generally one adult crab or a heterosexual pair per infested holothuroid but up to ten juveniles were recorded on a Thelenota ananas. Carapace length of the observed L. orbicularis was from 0.3 to 1.4 cm from the tip of the rostrum to the end of the cephalothorax, with a mean length of 0.85 cm. L. orbicularis is characterized by a weak sexual dimorphism (females are bigger than males) and the presence of pereiopods morphologically adapted to fixation on the host integument. Gravid females were observed at each month of the survey indicating that the crab reproduces all the year. Considering our results and personal ob...
Rapid communications in mass spectrometry : RCM, Jan 26, 2018
The grey seal, Halichoerus grypus (GS), and the northern elephant seal, Mirounga angustirostris (... more The grey seal, Halichoerus grypus (GS), and the northern elephant seal, Mirounga angustirostris (NES), come ashore for reproduction. This period involves intense physiological processes such as lactation in females and a developmental post-weaning fast in juveniles. Previous studies have shown that δ C and δ N values are affected by starvation, but the precise effects of fasting associated to lactation and post-weaning fast in seals remain poorly understood. To examine the effect of lactation and post-weaning fast on stable isotope ratios in GS and NES, blood and hair were sampled from twenty-one GS mother-pup pairs on the Isle of May and on twenty-two weaned NES pups at Año Nuevo State Reserve during their respective breeding seasons. Milk samples were also collected from GS mothers. Stable isotope measurements were performed with an isotope ratio mass spectrometer coupled to an N-C elemental analyser. Changes in stable isotope ratios in blood components during fasting were similar...
Comparative biochemistry and physiology. Part A, Molecular & integrative physiology, Mar 1, 2017
Oviparous females need to allocate resources optimally to their eggs in order to maximize their f... more Oviparous females need to allocate resources optimally to their eggs in order to maximize their fitness. Among these resources, dietary antioxidants, acquired by females and transferred to the eggs during egg formation, can greatly affect the development and survival of the embryo and chick. In crested penguins, incubation starts after the second and last egg is laid and, as opposed to many other bird species, this egg hatches first, thereby enhancing the survival of the chick. Here, we assessed whether antioxidant and isotopic composition could underlie these differences between eggs within clutches of southern rockhopper penguins (Eudyptes chrysocome chrysocome). The second-laid egg had higher total antioxidant capacity than the first-laid egg, although this was not due to higher antioxidant concentration but to its higher mass. This suggests that resources are allocated by females at a constant rate in both eggs within clutches. Accordingly, we found a strong correlation for isot...
Humpback whales, Megaptera novaeangliae, breeding off la Reunion Island (Indian Ocean) undergo la... more Humpback whales, Megaptera novaeangliae, breeding off la Reunion Island (Indian Ocean) undergo large-scale seasonal migrations between summer feeding grounds near Antarctica and their reproductive winter grounds in the Indian Ocean. The main scope of the current study was to investigate chemical exposure of humpback whales breeding in the Indian Ocean by providing the first published data on this breeding stock concerning persistent organic pollutants (POPs), namely polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), DDT and its metabolites (DDTs), chlordane compounds (CHLs), polybrominated diphenyl ethers (PBDEs), and methoxylated PBDEs (MeO-PBDEs). Analyses of stable isotopes δ(13)C and δ(15)N in skin resulted in further insight in their feeding ecology, which was in agreement with a diet focused mainly on low trophic level prey species, such as krill from Antarctica. POPs were measured in all humpback whales in the order of HCB > DDTs >...
ABSTRACT Colonization of new habitats by a biological community is conspicuous and this dynamic p... more ABSTRACT Colonization of new habitats by a biological community is conspicuous and this dynamic process is one of the architectural forces of the biogeographical distribution we know today. Within the meiofauna (<1mm), copepods (Crustacea) have successfully adapted to nearly every ecosystem and heir colonization power of permanent habitats is therefore well-established. However, few studies tackled the colonization of new naturally occurring provisional habitats, which are of ecological interest since they are rich in organic material, structurally complex and devoted of native fauna. Hence, the present study investigated the copepod colonization of provisional macrophytodetritus (mainly composed of senescent leaves and drift macroalgae) accumulated on bare sand patches inside a Mediterranean Posidonia oceanica seagrass meadow. General motive of colonization such as food and shelter are well-defined. However, little is known regarding the mode of the colonization and source pool of the associated colonists. Here, an in situ experiment was deployed in order to understand the mode of copepod’s colonization to fauna deprived macrophytodetritus. The objectives were: (1) assessing the adjacent colonist’s source pool (i.e. sediment, water column or P. oceanica canopy), (2) investigating the speed of settlement and (3) quantifying the species composition of the colonizing copepods. In summary: (1) species from every source pool actively colonized the macrophytodetritus through the water column and through the sediment-macrophytodetritus interface. (2) The initial settlement occurred within the first 24 hours. (3) The species composition showed to be different than the source’s composition. After 24h, the composition was similar to 45% of the P. oceanica, 28% of the water column and 25% of the sediments. After 96h, the composition was similar to 24% of the P. oceanica, 13% of the water column and 10% of the sediments. Indicating an evolution towards a macrophytodetritus copepod specific community composed of a mixture of the adjacent habitats first colonizers.
ABSTRACT Within the Southern Ocean, amphipods have achieved a conspicuous ecological radiation wh... more ABSTRACT Within the Southern Ocean, amphipods have achieved a conspicuous ecological radiation which gave rise to the development of numerous feeding strategies. The aim of this study is to apply the carbon and nitrogen stable isotope ratio methodology to delineate the trophic relationships involving benthic amphipods in the eastern Weddell Sea food webs. The interest of the isotope technique relies upon the direct relationship between the carbon 1'3C/t'C1 and nitrogen lt5NltN; stable isotope ratios of the animal tissues and its diet. Our results demonstrate the efficiency of the isotope ratio method to distinguish species displaying different feeding strategies. The large range (from 18 to-l9.5yoo for carbon and from 5.8 to l2.9yoo for nitrogen) of isotopic ratios attests the wide spectrum of amphipod nutrition patterns.
Abstract:[en] More than 21 500 harbour seals were killed by Phocine Distempter Virus in the North... more Abstract:[en] More than 21 500 harbour seals were killed by Phocine Distempter Virus in the North Sea and adjacent waters in 2002. After the second seal die-off had ceased, seals were captured alive (and then released) on a sandbank (Schleswig-Holstein, Germany) for health and ecotoxicological investigations. Stable carbon and nitrogen ratios (δ13C and δ15N) were measured by mass spectrometry in clotted blood cells of 24 harbour seals captured between 2002 and 2003. Total mercury (Hg) concentrations were determined by ...
ABSTRACT Epiphytes living fixed on Posidonia oceanica L. (Delile) are important faunal and floral... more ABSTRACT Epiphytes living fixed on Posidonia oceanica L. (Delile) are important faunal and floral components of seagrass meadow ecosystems. They are involved as main actors in trophic web and major ecosystem processes of this endangered coastal habitat. This paper aims to assess the seasonality and the bathymetric variability of epiphytic Bryozoa which are the most important animal group in terms of both diversity and abundance living on P. oceanica leaves. Posidonia shoots were collected from the Revellata Bay (Corsica, France) in four seasons from 7 to 30 m depth. Colony densities reached more than 87000 colonies.m -2 at 10 m depth in spring. The bryozoan species distribution and abundance changed substantially according to seasons and depths, being maximum in spring and minimal in winter. Dominant colony morphotypes change according to depth, probably in relation with water motion gradient. This confirms that there are bathymetric and seasonal variability for different epiphytic organisms colonizing the Posidonia leaves. This enlightens the importance to protect Posidonia meadow on its full depth extension and in its connectivity with other habitats to conserve optimal epiphytic biodiversity and functions. Résumé : Biodiversité des Bryozoaires chilostomes épiphytes des feuilles de Posidonia oceanica d'un herbier méditerranéen en fonction de la saison et de la profondeur. Les organismes épiphytes vivant attachés sur les feuilles de la posidonie Posidonia oceanica (L.) Delile sont d'importants composants de la faune et de la flore de ces écosystèmes. Ils sont parmi les acteurs principaux du réseau trophique associé et participent aux processus écologiques majeurs de cet écosystème méditerranéen côtier menacé. Notre étude tente d'établir quantitativement la variabilité saisonnière et bathymétrique des Bryozoaires chilostomes, un des groupes épiphyte animal dominant installé sur les feuilles de posidonies. Des faisceaux de posidonies ont été collectés en 4 occasions entre 7 et 30 mètres de profondeur dans la baie de la Revellata (Corse, France). La densité des colonies atteignait un maximum de 87.000 colonies.m -2 à 10 mètres de profondeur au printemps. L'abondance et la distribution des espèces changent substantiellement selon la saison et la profondeur, avec des abondances maximales au printemps et minimales en hiver. Les morphotypes dominant des colonies changent également en fonction de la profondeur, probablement en fonction des effets de l'hydrodynamisme. Ceci confirme qu'il s'agit d'une observation générale pour les différents types d'épiphytes colonisant les feuilles de posidonies. Ces observations démontrent également l'importance de protéger l'herbier de posidonies sur l'ensemble de son extension bathymétrique afin de conserver une biodiversité épiphytique optimale.
Paleolimnological reconstructions from the mid and high latitudes in the Southern Hemisphere are ... more Paleolimnological reconstructions from the mid and high latitudes in the Southern Hemisphere are still relatively scarce. Anthropogenic impacts have evidenced trophic state changes and an increase in cyanobacterial blooms in the lacustrine system of San Pedro de la Paz in the last decades. Here, we reconstructed primary production and sedimentological changes spanning the past 2500 years in two coastal lakes in Mediterranean Chile. A multiproxy approach including sedimentological, biogenic silica, carbon and nitrogen isotopes and fossil pigments analysis in sediment cores was performed in Laguna Grande (LGSP) and Laguna Chica de San Pedro (LCSP). A marked change in the sedimentology of the lakes, likely related to the terrigenous sediment inputs derived by a transition from an arid condition in the mid-Holocene to a more humid condition in the late Holocene that favoured arboreal forest establishment at 100 BC–AD 150. A period of low primary production was identified between 850 to ...
Mediterranean Posidonia oceanica meadows shelter an important biomass and biodiversity of amphipo... more Mediterranean Posidonia oceanica meadows shelter an important biomass and biodiversity of amphipod crustaceans that graze on epiphytes. However, their actual significance for ecosystem functional processes is hard to estimate, due to the lack of adequate data. Here, a field microcosm-based inclusion experiment was used to test if three of the dominant taxa of the amphipod community (Apherusa chiereghinii, Dexamine spiniventris and Gammarus spp.) could exert top-down control on seagrass leaf epiphytes. Influence of amphipod activity on nutrient availability for the host species was also investigated. All grazer taxa significantly reduced biomasses of erect macroalgae and erect sessile animals present on leaves. None of them consumed encrusting epiflora or epifauna. This selective top-down control could have important implications for the structure of the epiphytic community on leaves of P. oceanica, which is one of the most diverse and abundant of all seagrass species. Grazing activi...
At Makemo Atoll (French Polynesia), the carapid fish Onuxodon fowleri lives in symbiosis with the... more At Makemo Atoll (French Polynesia), the carapid fish Onuxodon fowleri lives in symbiosis with the black-lip pearl oyster Pinctada margaritifera. Although the symbiont seems to live inside its host bivalve by using it as a shelter, additional data are still needed to better understand the exact nature of this association. For this purpose, we implemented an approach using stable isotope ratios of carbon (13C/12C) and nitrogen (15N/14N). The δ13C and δ15N values were measured in tissues of the pearl oyster (gonads, gills, mantle and muscles), white muscle tissue from the fish and other food sources. This stable isotope approach was also complemented by the analysis of stomach contents in the carapid fish. Overall, the isotopic compositions measured in the present study support a commensal relationship between O. fowleri and P. margaritifera. In addition, our isotopic data bring new information about another guest living inside P. margaritifera, namely the palaemonid shrimp Conchodytes...
Harlequin crabs, Lissocarcinus orbicularis, are commensals found on the integument and in the buc... more Harlequin crabs, Lissocarcinus orbicularis, are commensals found on the integument and in the buccal/cloacal cavity of several species of holothuroids. The population of these crabs was investigated on holothuroids of the barrier reef of Toliara (South-West of Madagascar) from 2002 to 2008. Seventeen holothuroid species were observed and eight were crab hosts. There is generally one adult crab or a heterosexual pair per infested holothuroid but up to ten juveniles were recorded on a Thelenota ananas. Carapace length of the observed L. orbicularis was from 0.3 to 1.4 cm from the tip of the rostrum to the end of the cephalothorax, with a mean length of 0.85 cm. L. orbicularis is characterized by a weak sexual dimorphism (females are bigger than males) and the presence of pereiopods morphologically adapted to fixation on the host integument. Gravid females were observed at each month of the survey indicating that the crab reproduces all the year. Considering our results and personal ob...
Rapid communications in mass spectrometry : RCM, Jan 26, 2018
The grey seal, Halichoerus grypus (GS), and the northern elephant seal, Mirounga angustirostris (... more The grey seal, Halichoerus grypus (GS), and the northern elephant seal, Mirounga angustirostris (NES), come ashore for reproduction. This period involves intense physiological processes such as lactation in females and a developmental post-weaning fast in juveniles. Previous studies have shown that δ C and δ N values are affected by starvation, but the precise effects of fasting associated to lactation and post-weaning fast in seals remain poorly understood. To examine the effect of lactation and post-weaning fast on stable isotope ratios in GS and NES, blood and hair were sampled from twenty-one GS mother-pup pairs on the Isle of May and on twenty-two weaned NES pups at Año Nuevo State Reserve during their respective breeding seasons. Milk samples were also collected from GS mothers. Stable isotope measurements were performed with an isotope ratio mass spectrometer coupled to an N-C elemental analyser. Changes in stable isotope ratios in blood components during fasting were similar...
Comparative biochemistry and physiology. Part A, Molecular & integrative physiology, Mar 1, 2017
Oviparous females need to allocate resources optimally to their eggs in order to maximize their f... more Oviparous females need to allocate resources optimally to their eggs in order to maximize their fitness. Among these resources, dietary antioxidants, acquired by females and transferred to the eggs during egg formation, can greatly affect the development and survival of the embryo and chick. In crested penguins, incubation starts after the second and last egg is laid and, as opposed to many other bird species, this egg hatches first, thereby enhancing the survival of the chick. Here, we assessed whether antioxidant and isotopic composition could underlie these differences between eggs within clutches of southern rockhopper penguins (Eudyptes chrysocome chrysocome). The second-laid egg had higher total antioxidant capacity than the first-laid egg, although this was not due to higher antioxidant concentration but to its higher mass. This suggests that resources are allocated by females at a constant rate in both eggs within clutches. Accordingly, we found a strong correlation for isot...
Humpback whales, Megaptera novaeangliae, breeding off la Reunion Island (Indian Ocean) undergo la... more Humpback whales, Megaptera novaeangliae, breeding off la Reunion Island (Indian Ocean) undergo large-scale seasonal migrations between summer feeding grounds near Antarctica and their reproductive winter grounds in the Indian Ocean. The main scope of the current study was to investigate chemical exposure of humpback whales breeding in the Indian Ocean by providing the first published data on this breeding stock concerning persistent organic pollutants (POPs), namely polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), DDT and its metabolites (DDTs), chlordane compounds (CHLs), polybrominated diphenyl ethers (PBDEs), and methoxylated PBDEs (MeO-PBDEs). Analyses of stable isotopes δ(13)C and δ(15)N in skin resulted in further insight in their feeding ecology, which was in agreement with a diet focused mainly on low trophic level prey species, such as krill from Antarctica. POPs were measured in all humpback whales in the order of HCB > DDTs >...
ABSTRACT Colonization of new habitats by a biological community is conspicuous and this dynamic p... more ABSTRACT Colonization of new habitats by a biological community is conspicuous and this dynamic process is one of the architectural forces of the biogeographical distribution we know today. Within the meiofauna (<1mm), copepods (Crustacea) have successfully adapted to nearly every ecosystem and heir colonization power of permanent habitats is therefore well-established. However, few studies tackled the colonization of new naturally occurring provisional habitats, which are of ecological interest since they are rich in organic material, structurally complex and devoted of native fauna. Hence, the present study investigated the copepod colonization of provisional macrophytodetritus (mainly composed of senescent leaves and drift macroalgae) accumulated on bare sand patches inside a Mediterranean Posidonia oceanica seagrass meadow. General motive of colonization such as food and shelter are well-defined. However, little is known regarding the mode of the colonization and source pool of the associated colonists. Here, an in situ experiment was deployed in order to understand the mode of copepod’s colonization to fauna deprived macrophytodetritus. The objectives were: (1) assessing the adjacent colonist’s source pool (i.e. sediment, water column or P. oceanica canopy), (2) investigating the speed of settlement and (3) quantifying the species composition of the colonizing copepods. In summary: (1) species from every source pool actively colonized the macrophytodetritus through the water column and through the sediment-macrophytodetritus interface. (2) The initial settlement occurred within the first 24 hours. (3) The species composition showed to be different than the source’s composition. After 24h, the composition was similar to 45% of the P. oceanica, 28% of the water column and 25% of the sediments. After 96h, the composition was similar to 24% of the P. oceanica, 13% of the water column and 10% of the sediments. Indicating an evolution towards a macrophytodetritus copepod specific community composed of a mixture of the adjacent habitats first colonizers.
ABSTRACT Within the Southern Ocean, amphipods have achieved a conspicuous ecological radiation wh... more ABSTRACT Within the Southern Ocean, amphipods have achieved a conspicuous ecological radiation which gave rise to the development of numerous feeding strategies. The aim of this study is to apply the carbon and nitrogen stable isotope ratio methodology to delineate the trophic relationships involving benthic amphipods in the eastern Weddell Sea food webs. The interest of the isotope technique relies upon the direct relationship between the carbon 1'3C/t'C1 and nitrogen lt5NltN; stable isotope ratios of the animal tissues and its diet. Our results demonstrate the efficiency of the isotope ratio method to distinguish species displaying different feeding strategies. The large range (from 18 to-l9.5yoo for carbon and from 5.8 to l2.9yoo for nitrogen) of isotopic ratios attests the wide spectrum of amphipod nutrition patterns.
Abstract:[en] More than 21 500 harbour seals were killed by Phocine Distempter Virus in the North... more Abstract:[en] More than 21 500 harbour seals were killed by Phocine Distempter Virus in the North Sea and adjacent waters in 2002. After the second seal die-off had ceased, seals were captured alive (and then released) on a sandbank (Schleswig-Holstein, Germany) for health and ecotoxicological investigations. Stable carbon and nitrogen ratios (δ13C and δ15N) were measured by mass spectrometry in clotted blood cells of 24 harbour seals captured between 2002 and 2003. Total mercury (Hg) concentrations were determined by ...
ABSTRACT Epiphytes living fixed on Posidonia oceanica L. (Delile) are important faunal and floral... more ABSTRACT Epiphytes living fixed on Posidonia oceanica L. (Delile) are important faunal and floral components of seagrass meadow ecosystems. They are involved as main actors in trophic web and major ecosystem processes of this endangered coastal habitat. This paper aims to assess the seasonality and the bathymetric variability of epiphytic Bryozoa which are the most important animal group in terms of both diversity and abundance living on P. oceanica leaves. Posidonia shoots were collected from the Revellata Bay (Corsica, France) in four seasons from 7 to 30 m depth. Colony densities reached more than 87000 colonies.m -2 at 10 m depth in spring. The bryozoan species distribution and abundance changed substantially according to seasons and depths, being maximum in spring and minimal in winter. Dominant colony morphotypes change according to depth, probably in relation with water motion gradient. This confirms that there are bathymetric and seasonal variability for different epiphytic organisms colonizing the Posidonia leaves. This enlightens the importance to protect Posidonia meadow on its full depth extension and in its connectivity with other habitats to conserve optimal epiphytic biodiversity and functions. Résumé : Biodiversité des Bryozoaires chilostomes épiphytes des feuilles de Posidonia oceanica d'un herbier méditerranéen en fonction de la saison et de la profondeur. Les organismes épiphytes vivant attachés sur les feuilles de la posidonie Posidonia oceanica (L.) Delile sont d'importants composants de la faune et de la flore de ces écosystèmes. Ils sont parmi les acteurs principaux du réseau trophique associé et participent aux processus écologiques majeurs de cet écosystème méditerranéen côtier menacé. Notre étude tente d'établir quantitativement la variabilité saisonnière et bathymétrique des Bryozoaires chilostomes, un des groupes épiphyte animal dominant installé sur les feuilles de posidonies. Des faisceaux de posidonies ont été collectés en 4 occasions entre 7 et 30 mètres de profondeur dans la baie de la Revellata (Corse, France). La densité des colonies atteignait un maximum de 87.000 colonies.m -2 à 10 mètres de profondeur au printemps. L'abondance et la distribution des espèces changent substantiellement selon la saison et la profondeur, avec des abondances maximales au printemps et minimales en hiver. Les morphotypes dominant des colonies changent également en fonction de la profondeur, probablement en fonction des effets de l'hydrodynamisme. Ceci confirme qu'il s'agit d'une observation générale pour les différents types d'épiphytes colonisant les feuilles de posidonies. Ces observations démontrent également l'importance de protéger l'herbier de posidonies sur l'ensemble de son extension bathymétrique afin de conserver une biodiversité épiphytique optimale.
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