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1. Biogeographical diet variation within and between the rabbitfishes Siganus corallinus, Siganus doliatus, Siganus trispilos and Siganus virgatus.

Author

Zarco‐Perello, Salvador, Martin, Storm B., and Hoey, Andrew

Subjects
*CORAL reefs & islands, *DIET, *MARINE ecology, *CORALS, *MARINE algae, *CORAL bleaching, *COASTAL wetlands
Abstract

Feeding habits of herbivorous fishes play an important role in shaping the form and function of coastal marine ecosystems. Rabbitfishes (Siganidae) are important consumers of macroalgae on Indo‐West Pacific coral reefs. However, it is unclear how their diet varies among and within species at biogeographical scales, casting doubt on their precise functional roles across different regions. The present study assessed the inter‐ and intra‐specific diet variation of four rabbitfishes (Siganus trispilos, Siganus corallinus, Siganus virgatus and Siganus doliatus) factored by morphological relatedness among populations from Ningaloo Reef (western Australia), the Great Barrier Reef (GBR, eastern Australia) and the Yaeyama Islands (Okinawa Prefecture, Japan). Results showed that the region had a strong effect on diet, effectively reducing the expected effect of morphologic similitude. While intra‐specific differences were only significant when populations inhabited different regions; interspecific differences were not as predicted, with different morphotypes having similar diets when populations inhabited the same regions. Rabbitfishes consumed more corticated and filamentous macroalgae on the GBR, more foliose and membranous macroalgae at the Yaeyama Islands, and more leathery macroalgae at Ningaloo Reef. The findings indicate that rabbitfishes have high diet plasticity, and hence their functional role as mediators of competition between macroalgae and corals can change across biogeographic regions. Local context is therefore important when assessing the diet and functional role of herbivorous fishes. As climate change unfolds, shifts in the distribution, trophic behaviour and function of species are expected, making the study of trophic plasticity more important. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Biogeographical diet variation within and between the rabbitfishes Siganus corallinus, Siganus doliatus, Siganus trispilos and Siganus virgatus

Author

Salvador Zarco‐Perello, Storm B. Martin, and Andrew Hoey

Subjects
coral reefs, herbivory, inter‐specific variation, intra‐specific variation, trophic niche, trophic plasticity, Ecology, QH540-549.5
Abstract

Abstract Feeding habits of herbivorous fishes play an important role in shaping the form and function of coastal marine ecosystems. Rabbitfishes (Siganidae) are important consumers of macroalgae on Indo‐West Pacific coral reefs. However, it is unclear how their diet varies among and within species at biogeographical scales, casting doubt on their precise functional roles across different regions. The present study assessed the inter‐ and intra‐specific diet variation of four rabbitfishes (Siganus trispilos, Siganus corallinus, Siganus virgatus and Siganus doliatus) factored by morphological relatedness among populations from Ningaloo Reef (western Australia), the Great Barrier Reef (GBR, eastern Australia) and the Yaeyama Islands (Okinawa Prefecture, Japan). Results showed that the region had a strong effect on diet, effectively reducing the expected effect of morphologic similitude. While intra‐specific differences were only significant when populations inhabited different regions; interspecific differences were not as predicted, with different morphotypes having similar diets when populations inhabited the same regions. Rabbitfishes consumed more corticated and filamentous macroalgae on the GBR, more foliose and membranous macroalgae at the Yaeyama Islands, and more leathery macroalgae at Ningaloo Reef. The findings indicate that rabbitfishes have high diet plasticity, and hence their functional role as mediators of competition between macroalgae and corals can change across biogeographic regions. Local context is therefore important when assessing the diet and functional role of herbivorous fishes. As climate change unfolds, shifts in the distribution, trophic behaviour and function of species are expected, making the study of trophic plasticity more important.

Published
2024
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3. Low redundancy among caddisflies sharing a mid-mountain stream.

Author

Pacini, Nic, Travagliante, Emanuele, Methu, Stephen Wanjiku, Gumiero, Bruna, Brilli, Mauro, and Harper, David Malcolm

Subjects
*CADDISFLIES, *WATER quality, *DETRITUS, *LARVAE, *SHARING, *MOTHS
Abstract

In fast-flowing streams, caddisfly larvae are responsible for processes that collectively determine the efficiency with which the detritivore community is able to decompose autochthonous and allochthonous detritus. This ecosystem function ensures high water quality and represents a precious service for resident rural communities. The analysis of δ13C and δ15N in eight caddisfly taxa from a mid-mountain stream evidenced a remarkable complementarity in their feeding preferences. An aquatic moth mimicking the caddis mode of life was also included in the survey and its feeding niche appeared to be in between the one of caddis taxa. Moderate niche overlap was interpreted in terms of low functional redundancy, implying that in case of a reduction in diversity, no taxon could be a perfect substitute for another, with a loss of functional efficiency. Low redundancy could be caused by niche segregation due to avoidance of competition/interference between taxa. The broad range of δ13C and δ15N described in this study warns against attributing single δ13C and δ15N to Trichoptera as a group, or even to single families. These results contribute to the still poorly known distribution of East African caddisflies and to the characterisation of feeding preferences of Afrotropical trichopteran larvae. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Marine heatwaves modulate the genotypic and physiological responses of reef‐building corals to subsequent heat stress.

Author

Brown, Kristen T., Genin, Amatzia, Mello‐Athayde, Matheus A., Bergstrom, Ellie, Campili, Adriana, Chai, Aaron, Dove, Sophie G., Ho, Maureen, Rowell, Devin, Sampayo, Eugenia M., and Radice, Veronica Z.

Subjects
*CORAL bleaching, *MARINE heatwaves, *CORAL reefs & islands, *CORALS, *GENOTYPES, *HEAT waves (Meteorology), *GENETIC variation
Abstract

Back‐to‐back marine heatwaves in 2016 and 2017 resulted in severe coral bleaching and mortality across the Great Barrier Reef (GBR). Encouragingly, some corals that survived these events exhibit increased bleaching resistance and may represent thermally tolerant populations that can better cope with ocean warming. Using the GBR as a natural laboratory, we investigated whether a history of minimal (Heron Island) or severe (Lizard Island) coral bleaching in 2016 and 2017 equates to stress tolerance in a successive heatwave (2020). We examined the genetic diversity, physiological performance, and trophic plasticity of juvenile (<10 cm) and adult (>25 cm) corals of two common genera (Pocillopora and Stylophora). Despite enduring greater cumulative heat stress (6.3°C week−1 vs. 5.6°C week−1), corals that experienced the third marine heatwave in 5 years (Lizard) exhibited twice as high survival and visual bleaching thresholds compared to corals that had not experienced significant bleaching in >10 years (Heron). Surprisingly, only one shared host–Symbiodiniaceae association was uncovered between locations (Stylophora pistillata–Cladocopium "C8 group") and there was no genetic overlap in Pocillopora–Cladocopium partnerships, suggesting turnover in species composition from recent marine heatwaves. Corals within the species complex Pocillopora that survived the 2016 and 2017 marine heatwaves at Lizard Island were the most resilient, exhibiting three times greater calcification rates than conspecifics at Heron Island. Further, surviving corals (Lizard) had distinct isotopic niches, lower host carbon, and greater host protein, while conspecifics that had not experienced recent bleaching (Heron) had two times greater symbiont carbon content, suggesting divergent trophic strategies that influenced survival (i.e., greater reliance on heterotrophy vs. symbiont autotrophy, respectively). Ultimately, while corals may experience less bleaching and survive repeated thermal stress events, species‐specific trade‐offs do occur, leaving open many questions related to the long‐term health and recovery of coral reef ecosystems in the face of intensifying marine heatwaves. [ABSTRACT FROM AUTHOR]

Published
2023
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5. Symbiont genus determines the trophic strategy of corals: Implications for intraspecific competition for energy sources in coral reefs

Author

Qifang Wang, Xinqing Zheng, Xijie Zhou, Han Zhang, Ling Cai, Jonathan Y.S. Leung, and Lingfeng Huang

Subjects
Adaptation, Reef-building coral, Stable isotope analysis, Symbiosis, Trophic niche, Trophic plasticity, Ecology, QH540-549.5
Abstract

Coral reefs are typically found in nutrient-limited waters, which may restrict the growth and expansion of corals. Nevertheless, corals are mixotrophs that may adjust to the variation in the availability of energy sources by switching their major nutritional mode between autotrophy (i.e., synthesizing their own food by symbionts) and heterotrophy (i.e., consuming external food sources). Such trophic plasticity may, however, be subject to symbiont genus and environmental conditions. Using a widespread coral species (Pocillopora damicornis), we examine how symbiont genus (Cladocopium vs. Durusdinium) affects the physiological traits (biomass, symbiont density, C:N ratio and chlorophyll content) of corals and their trophic strategy across seasons (summer and winter) based on stable isotope markers (δ13C and δ15N). We found that corals dominated by Cladocopium (PdC) had a lower symbiont density, but higher autotrophic capacity (higher cellular chlorophyll content and higher δ13C) than those by Durusdinium (PdD). Across seasons, the trophic strategy of PdC was flexible that the autotrophic capacity was reduced by 37.1 % from summer to winter, whereas the trophic strategy of PdD remained relatively unchanged. PdC had a greater heterotrophic capacity in winter, while PdD in summer. Our findings suggest that symbiont genus can determine the trophic flexibility of corals and drive trophic niche differentiation between conspecific corals. By adaptively changing trophic strategy, intraspecific competition of corals for energy sources can be reduced, possibly allowing them to persist in oligotrophic waters and adapt to the future oceanic climate.

Published
2024
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6. High consistency of trophic niches in generalist arthropod species (Oribatida, Acari) across soil depth and forest type.

Author

Lu, Jing‐Zhong, Cordes, Peter Hans, Maraun, Mark, and Scheu, Stefan

Subjects
*SOIL depth, *ACARIFORMES, *FOREST soils, *MITES, *STABLE isotope analysis, *SPECIES
Abstract

Many traits including trophic niche parameters are attributed to species. However, generalist species may vary in trophic niches with environments, making species‐based knowledge hard to extrapolate beyond local food webs. Here we tested trophic consistency in oribatid mite species (Acari), one of the most abundant arthropods that occupy all trophic levels in soil food webs. We used stable isotope analysis to compare trophic niches of 40 Oribatida species that co‐occur in litter (OL) and soil (0–5 cm, mainly OF/H, AH) of five forest types (native European beech, non‐native Douglas fir, range‐expanding Norway spruce, two beech–conifer mixed forests). Although stable isotope signatures of bulk material differed between litter and soil, 13C and 15 N values of Oribatida species were remarkably stable irrespective of soil depth. Furthermore, Oribatida were more enriched in 13C in European beech than in coniferous forests, but forest type little affected 15 N values of Oribatida across a range of site conditions. We conclude that Oribatida species occupy virtually identical trophic niches (δ13C and δ15N values) irrespective of the soil depth they colonize and that forest management including non‐native tree species little affects trophic position (δ15N values) of oribatid mites. Our findings suggest that the trophic position can be used as a trait in community analysis of Oribatida across forest ecosystems. Our results further indicate that trophic niches of generalist species can be highly consistent irrespective of environment. [ABSTRACT FROM AUTHOR]

Published
2022
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7. Ecological Traits and Trophic Plasticity in The Greater Pipefish Syngnathus acus in the NW Iberian Peninsula.

Author

Planas, Miquel

Subjects
*FISH ecology, *AMPHIPODA, *SEAGRASSES, *PENINSULAS, *ISOPODA, *SEX ratio, *FISH populations, *SIZE of fishes
Abstract

Simple Summary: The population of the pipefish Syngnathus acus inhabiting Cíes Archipelago (NW Spain) was monitored in 2017–2018 for spatial and temporal changes in abundances, reproduction traits, trophic niche occupancy, and dietary regimes across reproduction states, through an isotopic (δ13C and δ15N) approach. The population consisted almost exclusively of large adults, whose abundances decreased significantly from mid-autumn after the breeding season. S. acus is a secondary consumer that prefers amphipods, but mature specimens were less selective than immature fish. The present study highlights the outstanding size of the fish and the exceptional occurrence of breeders on the studied area. The great pipefish Syngnathus acus is one of the most representative European syngnathids, being highly associated with seagrass and macroalgal beds. Surprisingly, the ecology of this large ovoviviparous marine fish has received scanty attention. The population inhabiting three sites on Cíes Archipelago (Atlantic Islands National Park, NW Spain) was monitored in 2017–2018 for spatial and temporal changes in abundances, reproduction traits, trophic niche occupancy, and dietary regimes across reproduction states, through an isotopic (δ13C and δ15N) approach. Abundances were highly variable across seasons and sites, decreasing significantly from mid-autumn. The population consisted almost exclusively of large adults that migrate by the end of the breeding season, which extended from mid-spring to summer. Operational sex ratios suggest that the species is sex-role reversed. S. acus is a secondary consumer (Trophic position = 3.36 ± 0.05), preferring amphipods but displaying annual and seasonal dietary plasticity. Mature fish were less selective than immatures (especially females), with a higher preference for amphipods (36–68%) in the former. The second most-preferred prey were carideans, copepods, or isopods, depending on the year and the reproduction state. Overall, the wider trophic niches in females and immature specimens compared to males and mature fish would indicate a higher variability in both the use of prey resources and/or their origin. The present study highlights the trophic plasticity and unique features of S. acus population in the Cíes Archipelago, especially regarding the outstanding size of the fish and the exceptional occurrence of breeders. [ABSTRACT FROM AUTHOR]

Published
2022
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8. Foraging in the Anthropocene: Feeding plasticity of an opportunistic predator revealed by long term monitoring

Author

Jazel Ouled-Cheikh, Virginia Morera-Pujol, Álvaro Bahillo, Francisco Ramírez, Marta Cerdà-Cuéllar, and Raül Ramos

Subjects
Dietary assessments, Longitudinal studies, Larus michahellis, Stable isotope analysis, Trophic plasticity, Yellow-legged gull, Ecology, QH540-549.5
Abstract

For centuries, human activities have altered the population dynamics of wildlife. New anthropogenic food sources provide a predictable and abundant food supply that often induces very significant changes in the size, distribution, and behaviour of many populations, with ultimate consequences on the structure and functioning of natural ecosystems. Here, we combine historical and contemporary feather samples of a population of a superabundant, opportunistic predator, the yellow-legged gull Larus michahellis, to assess its trophic ecology and relate it to human activities in the long term. Dietary assessments were based on stable isotope analysis of carbon, nitrogen, and sulphur (δ13C, δ15N and δ34S), and were conducted through three end-point (marine prey, waste from landfills-slaughterhouses, and terrestrial invertebrates) Bayesian mixing models. Our results suggest that gulls’ diet showed a progressive decrease in the consumption of marine prey throughout the most recent period (late 20th century onwards), linked to an increase in the consumption of meat waste and small terrestrial invertebrates. Reported dietary changes over the sampling period correlated positively with the availability of marine resources around the breeding area. We provide evidence suggesting that the ability of gulls to exploit efficiently diverse anthropogenic food subsidies likely resulted in the exponential demographic increase of this population throughout the 20th century. In addition, current regulations affecting the availability of these food resources (e.g., fishing discards and landfill waste) likely reversed this trend over the last decade. Long-term evidence of population trophic plasticity, like the one we present here, is essential to implement and support management and conservation actions that limit the availability of anthropogenic resources, especially when it comes to superabundant, problematic species.

Published
2021
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9. Ecological Traits and Trophic Plasticity in The Greater Pipefish Syngnathus acus in the NW Iberian Peninsula

Author

Miquel Planas

Subjects
pipefish, Syngnathus acus, biology, ecology, reproduction, trophic plasticity, Biology (General), QH301-705.5
Abstract

The great pipefish Syngnathus acus is one of the most representative European syngnathids, being highly associated with seagrass and macroalgal beds. Surprisingly, the ecology of this large ovoviviparous marine fish has received scanty attention. The population inhabiting three sites on Cíes Archipelago (Atlantic Islands National Park, NW Spain) was monitored in 2017–2018 for spatial and temporal changes in abundances, reproduction traits, trophic niche occupancy, and dietary regimes across reproduction states, through an isotopic (δ13C and δ15N) approach. Abundances were highly variable across seasons and sites, decreasing significantly from mid-autumn. The population consisted almost exclusively of large adults that migrate by the end of the breeding season, which extended from mid-spring to summer. Operational sex ratios suggest that the species is sex-role reversed. S. acus is a secondary consumer (Trophic position = 3.36 ± 0.05), preferring amphipods but displaying annual and seasonal dietary plasticity. Mature fish were less selective than immatures (especially females), with a higher preference for amphipods (36–68%) in the former. The second most-preferred prey were carideans, copepods, or isopods, depending on the year and the reproduction state. Overall, the wider trophic niches in females and immature specimens compared to males and mature fish would indicate a higher variability in both the use of prey resources and/or their origin. The present study highlights the trophic plasticity and unique features of S. acus population in the Cíes Archipelago, especially regarding the outstanding size of the fish and the exceptional occurrence of breeders.

Published
2022
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10. Symbiont genus determines the trophic strategy of corals: Implications for intraspecific competition for energy sources in coral reefs.

Author

Wang, Qifang, Zheng, Xinqing, Zhou, Xijie, Zhang, Han, Cai, Ling, Leung, Jonathan Y.S., and Huang, Lingfeng

Subjects
*CORAL reefs & islands, *COMPETITION (Biology), *CORAL bleaching, *CORALS, *MARINE west coast climate, *STABLE isotopes
Abstract

• Trophic flexibility of corals with different symbionts (PdC or PdD) was assessed. • PdC had a higher autotrophic capacity than PdD, despite lower symbiont density. • Trophic strategy of PdC was more flexible than that of PdD across seasons. • Corals relied more on autotrophy in summer, but heterotrophy in winter. • Symbiont genus can determine the nutritional strategy and adaptability of corals. Coral reefs are typically found in nutrient-limited waters, which may restrict the growth and expansion of corals. Nevertheless, corals are mixotrophs that may adjust to the variation in the availability of energy sources by switching their major nutritional mode between autotrophy (i.e., synthesizing their own food by symbionts) and heterotrophy (i.e., consuming external food sources). Such trophic plasticity may, however, be subject to symbiont genus and environmental conditions. Using a widespread coral species (Pocillopora damicornis), we examine how symbiont genus (Cladocopium vs. Durusdinium) affects the physiological traits (biomass, symbiont density, C:N ratio and chlorophyll content) of corals and their trophic strategy across seasons (summer and winter) based on stable isotope markers (δ13C and δ15N). We found that corals dominated by Cladocopium (PdC) had a lower symbiont density, but higher autotrophic capacity (higher cellular chlorophyll content and higher δ13C) than those by Durusdinium (PdD). Across seasons, the trophic strategy of PdC was flexible that the autotrophic capacity was reduced by 37.1 % from summer to winter, whereas the trophic strategy of PdD remained relatively unchanged. PdC had a greater heterotrophic capacity in winter, while PdD in summer. Our findings suggest that symbiont genus can determine the trophic flexibility of corals and drive trophic niche differentiation between conspecific corals. By adaptively changing trophic strategy, intraspecific competition of corals for energy sources can be reduced, possibly allowing them to persist in oligotrophic waters and adapt to the future oceanic climate. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Predation and Competition Differentially Affect the Interactions and Trophic Niches of a Neotropical Amphibian Guild

Author

Rosa Arribas, Justin C. Touchon, and Ivan Gomez-Mestre

Subjects
competition, predation, growth rate, community ecology, trophic niche, trophic plasticity, Evolution, QH359-425, Ecology, QH540-549.5
Abstract

Competition and predation alter individual traits of organisms, and these effects can scale-up to have consequences on community structure and dynamics. The relative importance of competition and predation will depend largely on the local assemblage of species, the type of predators, or the degree of niche segregation. We experimentally investigated the interplay of competition and predation on the structure and trophic level (measured via stable isotope analysis) of a seven-species Neotropical freshwater guild using a mesocosm approach in central Panama. We tested the effect of two types of predators (dragonfly nymphs or adult water bugs) in combination with the presence/absence of a common competitor, the red-eyed treefrog (Agalychnis callidryas), on four core species of tadpoles. We also distinguished between consumptive and non-consumptive effects of each type of predator by presenting them to tadpoles caged or freely roaming. Dragonfly larvae were more efficient predators than water bugs, but these effects were not uniform for all tadpole species. All amphibian species grew bigger when raised in the presence of an uncaged dragonfly nymph, presumably due to reduced competition through thinning, but tadpoles were smaller when exposed to caged dragonfly nymphs indicating the existence of non-consumptive predator effects as well. Predator presence also altered the relative trophic position of the different amphibian species, causing some tadpole species to increase and others to decrease their trophic status. Despite the presumed ecological similarity of tadpole species in the guild, the interplay of competition and predation had varying effects on the trophic status of nearly every species. Our results indicate that community composition can greatly affect the trophic level of larval amphibians, and that predation may have a greater role than competition in structuring Neotropical larval amphibian guilds.

Published
2018
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12. Variación interpoblacional y ontogenética en la dieta de la rana llorona Physalaemus albonotatus (Anura: Leiuperidae) Interpopulation and ontogenetic variation in the diet of the menwig frog Physalaemus albonotatus (Anura: Leiuperidae)

Author

Diego Alejandro Falico, Javier Alejandro López, Carolina Elizabet Antoniazzi, and Adolfo Héctor Beltzer

Subjects
anuros, hábitats de forrajeo, ambiente urbano, humedal fluvial, plasticidad trófica, solapamiento trófico, anurans, foraging habitat, urban environment, floodplain wetland, trophic plasticity, trophic overlap, Biology (General), QH301-705.5
Abstract

Se analizó y comparó el espectro trófico de 2 poblaciones de Physalaemus albonotatus que habitan en ecosistemas diferentes: a) un terreno baldío urbano y b) un área protegida del valle aluvial del río Paraná Medio. La dieta de Physalaemus albonotatus está compuesta fundamentalmente de hormigas, coleópteros, colémbolos e isópodos, pero con numerosas presas secundarias. Al comparar 3 grupos etarios de los individuos en cada población (adultos, subadultos y jóvenes) se encontró una variación ontogenética relacionada con el volumen, cantidad y tipo de presa ingerida. Los anfibios adultos consumieron mayor cantidad de presas y más voluminosas, pero el nicho trófico de los jóvenes fue más amplio. Entre los adultos, la similitud de la dieta entre sexos fue muy elevada, aunque las hembras consumieron más hormigas que los machos. Si bien el solapamiento trófico entre las poblaciones fue elevado, la amplitud trófica resultó mayor en la población del humedal fluvial. Las diferencias en la alimentación encontradas entre las 2 poblaciones y lo registrado en otros trabajos realizados en diferentes ambientes reflejan la plasticidad trófica de este anuro, característica que le permite prosperar en hábitats diversos, incluso en los muy antropizados.We analyzed and compared the feeding of 2 populations of Physalaemus albonotatus inhabiting different ecosystems: a) an urban vacant lot, and b) a protected area of Middle Paraná River floodplain. The diet of Physalaemus albonotatus is mainly composed by ants, beetles, springtails and woodlouses, but also included several secondary preys. While comparing adults, subadults and juveniles diet on each population, we found an ontogenetic diet variation related to changes in prey type and volume as well as in number of prey items per gut. Bigger frogs consumed a greater amount of prey and more voluminous arthropods, while juveniles had a larger trophic niche breadth. Despite the great similarity in diet between sexes, adult females consumed a larger amount of ants than males did. Although trophic niche overlap between both populations was high, trophic niche breadth was wider for Paraná River floodplain population. Feeding differences found between studied populations and populations inhabiting other environments as described on literature reflects the trophic plasticity of this species and its capacity to thrive at different habitats, including markedly anthropogenically impacted environments.

Published
2012

13. Diet-induced phenotypic plasticity in head morphology in European eel elvers (Anguilla anguilla): the effects of hard vs soft food

Author

Jens De Meyer

Subjects
Feeding Behavior, morphology, dimorphism, Trophic plasticity, elver eel stage, Science, General. Including nature conservation, geographical distribution, QH1-199.5
Abstract

By bone remodeling and changing of muscle volume, fish can adapt to changes in mechanical loads they are confronted with, including dietary changes such as prey hardness. This capability of a genotype to develop different phenotypes in response to varying environment is known as phenotypic plasticity. Differences in prey type being consumed might trigger such a phenotypic plasticity in fish. In European eel, two morphotypes exist: broadheads and narrowheads. Studies based on gut content have shown that broadheads consume larger and harder prey, such as fish, whereas narrowheads feed on smaller prey, such as benthic invertebrates. These studies, however, are performed on yellow eels with a minimum length of 30 cm, and only provide indirect evidence that head shape is affected by diet differences. Here, we performed a feeding experiment on glass eels that just swam up the European rivers to start feeding. These glass eels were captured and separated in three groups: one group was given hard feed requiring biting, the second group got soft feed that could be sucked in and the final group, which acted as a control group, was given a mixture of both. We found that hard feeders developed a broader general head width and postorbital region than soft feeders. This region is associated with the location of the jaw muscles, indicating that hard feeders develop larger muscles to cope with the harder prey. Hard feeders, however, also grew more slowly than soft feeders, suggesting that net energy uptake of hard feeders was lower as prey handling required more energy and time. Specimens of the control group, finally, developed intermediate head widths, implying that they are not fully adapted to feed on either hard or soft prey. In conclusion, this study provides the first direct evidence that diet influences the head shape of European eel.

Published
2015
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14. Diet-induced phenotypic plasticity in European eel (Anguilla anguilla).

Author

De Meyer, Jens, Christiaens, Joachim, and Adriaens, Dominique

Subjects
*ANGUILLA anguilla, *PHENOTYPIC plasticity, *FISH feeds, *DIMORPHISM (Biology), *FISH growth, *HYDRODYNAMICS, *PHYSIOLOGY, *FISHES
Abstract

Two phenotypes are present within the European eel population: broad-heads and narrow-heads. The expression of these phenotypes has been linked to several factors, such as diet and differential growth. The exact factors causing this dimorphism, however, are still unknown. In this study, we performed a feeding experiment on glass eels from the moment they start to feed. Eels were either fed a hard diet, which required biting and spinning behavior, or a soft diet, which required suction feeding. We found that the hard feeders develop a broader head and a larger adductor mandibulae region than eels that were fed a soft diet, implying that the hard feeders are capable of larger bite forces. Next to this, soft feeders develop a sharper and narrower head, which could reduce hydrodynamic drag, allowing more rapid strikes towards their prey. Both phenotypes were found in a control group, which were given a combination of both diets. These phenotypes were, however, not as extreme as the hard or the soft feeding group, indicating that some specimens are more likely to consume hard prey and others soft prey, but that they do not selectively eat one of both diets. In conclusion, we found that diet is a major factor influencing head shape in European eel and this ability to specialize in feeding on hard or soft prey could decrease intra-specific competition in European eel populations. [ABSTRACT FROM AUTHOR]

Published
2016
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15. Local flexibility in feeding behaviour and contrasting microhabitat use of an omnivore across latitudes

Author

Dominique Davoult, João N. Franco, Thomas Wernberg, Hartvig Christie, Morten Foldager Pedersen, Karen Filbee-Dexter, Thibaut de Bettignies, Jean-Charles Leclerc, Florian de Bettignies, Cédric Leroux, Adaptation et diversité en milieu marin (AD2M), Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Universidad Católica de la Santísima Concepción (UCSC), Patrimoine naturel (PatriNat), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Office français de la biodiversité (OFB), The University of Western Australia (UWA), Norwegian Institute for Water Research (NIVA), Interdisciplinary Centre of Marine and Environmental Research [Matosinhos, Portugal] (CIIMAR), Universidade do Porto, Marine and Environmental Sciences Centre [Portugal] (MARE), Instituto Universitário de Ciências Psicológicas, Sociais e da Vida (ISPA), Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Roskilde University

Subjects
0106 biological sciences, Echinus esculentus, Food Chain, Opportunism, Foraging, Biology, 010603 evolutionary biology, 01 natural sciences, Predation, Animals, Laminaria hyperborea, 14. Life underwater, Ecology, Evolution, Behavior and Systematics, Ecosystem, Trophic level, Ecology, Norway, 010604 marine biology & hydrobiology, Food web, Feeding Behavior, 15. Life on land, biology.organism_classification, Kelp forest, 13. Climate action, Ectotherm, Sea Urchins, [SDE]Environmental Sciences, Trophic plasticity, Omnivore, France, Urchin grazing
Abstract

Funding Funding for this work was provided by the Australian Research Council (TW: FT110100174, TW, KFD: DP190100058), the University of Western Australia Research Collaboration Awards (TW, TdB, JCL, DD, JNF, HC), the France-Australia Science Innovation Collaboration 2014 program (TdB, TW, JCL, DD), Metabomer and Corsaire Core Facility (CL), the French Government run by the National Research Agency with regards to the investment expenditure programme IDEALG ANR-10-BTBR-04 (JCL, DD) and the Norwegian Research Council (TW, MFP, KFD, KELPEX 255085/E40). As the environment is getting warmer and species are redistributed, consumers can be forced to adjust their interactions with available prey, and this could have cascading effects within food webs. To better understand the capacity for foraging flexibility, our study aimed to determine the diet variability of an ectotherm omnivore inhabiting kelp forests, the sea urchin Echinus esculentus, along its entire latitudinal distribution in the northeast Atlantic. Using a combination of gut content and stable isotope analyses, we determined the diet and trophic position of sea urchins at sites in Portugal (42° N), France (49° N), southern Norway (63° N), and northern Norway (70° N), and related these results to the local abundance and distribution of putative food items. With mean estimated trophic levels ranging from 2.4 to 4.6, omnivory and diet varied substantially within and between sites but not across latitudes. Diet composition generally reflected prey availability within epiphyte or understorey assemblages, with local affinities demonstrating that the sea urchin adjusts its foraging to match the small-scale distribution of food items. A net “preference” for epiphytic food sources was found in northern Norway, where understorey food was limited compared to other regions. We conclude that diet change may occur in response to food source redistribution at multiple spatial scales (microhabitats, sites, regions). Across these scales, the way that key consumers alter their foraging in response to food availability can have important implication for food web dynamics and ecosystem functions along current and future environmental gradients. info:eu-repo/semantics/publishedVersion

Published
2021

16. Foraging in the Anthropocene: Feeding plasticity of an opportunistic predator revealed by long term monitoring

Author

Álvaro Bahillo, Raül Ramos, Jazel Ouled-Cheikh, Marta Cerdà-Cuéllar, Virginia Morera-Pujol, Francisco Ramírez, Producció Animal, Sanitat Animal, CSIC - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Ministerio de Ciencia e Innovación (España), Fundación Biodiversidad, Ministerio de Transición Ecológica (España), European Commission, Generalitat de Catalunya, Ministerio de Economía, Industria y Competitividad (España), and Agencia Estatal de Investigación (España)

Subjects
Marine conservation, Stable isotope analysis, Gavines, Yellow-legged gull, Foraging, Population, Wildlife, General Decision Sciences, Adaptació animal, Dietary assessments, Predation, Larus michahellis, Alimentació animal, education, Animal adaptation, QH540-549.5, Animal feeding, Ecology, Evolution, Behavior and Systematics, Trophic level, education.field_of_study, Ecology, biology, Longitudinal studies, biology.organism_classification, Discards, Gulls, Trophic plasticity
Abstract

10 pages, 4 figures, 4 tables, supplementary data https://doi.org/10.1016/j.ecolind.2021.107943, For centuries, human activities have altered the population dynamics of wildlife. New anthropogenic food sources provide a predictable and abundant food supply that often induces very significant changes in the size, distribution, and behaviour of many populations, with ultimate consequences on the structure and functioning of natural ecosystems. Here, we combine historical and contemporary feather samples of a population of a superabundant, opportunistic predator, the yellow-legged gull Larus michahellis, to assess its trophic ecology and relate it to human activities in the long term. Dietary assessments were based on stable isotope analysis of carbon, nitrogen, and sulphur (δ13C, δ15N and δ34S), and were conducted through three end-point (marine prey, waste from landfills-slaughterhouses, and terrestrial invertebrates) Bayesian mixing models. Our results suggest that gulls’ diet showed a progressive decrease in the consumption of marine prey throughout the most recent period (late 20th century onwards), linked to an increase in the consumption of meat waste and small terrestrial invertebrates. Reported dietary changes over the sampling period correlated positively with the availability of marine resources around the breeding area. We provide evidence suggesting that the ability of gulls to exploit efficiently diverse anthropogenic food subsidies likely resulted in the exponential demographic increase of this population throughout the 20th century. In addition, current regulations affecting the availability of these food resources (e.g., fishing discards and landfill waste) likely reversed this trend over the last decade. Long-term evidence of population trophic plasticity, like the one we present here, is essential to implement and support management and conservation actions that limit the availability of anthropogenic resources, especially when it comes to superabundant, problematic species, This work was supported by FAU2008-00012-C02-01 from INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Spain), CGL2009-11278/BOS from Ministerio de Ciencia e Innovación from the Spanish Government, Fondos FEDER, 2017/2349 of the PLEAMAR programme with the collaboration of the Fundación Biodiversidad, from the Ministerio para la Transición Ecológica (Spain), cofounded by the EMFF (European Union), and REN2003-07050 Aplicación de biomarcadores a la gestión de una especie problemática (Larus cachinnans). CERCA Programme from Generalitat de Catalunya is also acknowledged. RR was supported by a postdoctoral Ramón y Cajal contract (RYC-2017-22055) and VMP was supported by a pre-doctoral contract BES-2014-068025 both from the Spanish Ministerio de Economía, Industria y Competitividad, With the institutional support of the ‘Severo OchoaCentre of Excellence’ accreditation (CEX2019-000928-S)

Published
2021

17. Diet, bromatological and parasitological aspects in a non-native fish species in the Jupiá Reservoir, upper Paraná River

Author

Garves, José Daniel Soler [UNESP], Universidade Estadual Paulista (Unesp), Ramos, Igor Paiva [UNESP], and Ribeiro, Cristiéle da Silva [UNESP]

Subjects
Introduced species, Trophic plasticity, Região Neotropical, Plasticidade trófica, Bacia do alto rio Paraná, Neotropical region, Qualidade do filé, Fillet quality, Espécie introduzida, Upper Paraná River basin
Abstract

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No. of bitstreams: 1 garves_jds_me_bot_par.pdf: 799365 bytes, checksum: 8133e6f54737ddc3f70c7332313e9722 (MD5) Previous issue date: 2020-02-28 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Empreendimentos hidroelétricos podem desencadear alterações no ciclo hidrológico, desequilíbrio dos ecossistemas aquáticos e facilitar a introdução de espécies de peixes não-nativas. Contudo, essas espécies também podem apresentar grande representatividade na pesca artesanal e esportiva, tornando-se uma importante fonte de renda local. Dessa forma, o estudo de espécies não-nativas, suas origens, hábitos e posições tróficas, além de suas habilidades que garantem a permanência e o sucesso no estabelecimento em novos ambientes, são relevantes. Dentre tais espécies não-nativas, Geophagus sveni destaca-se como uma das espécies mais importantes para pesca artesanal na região Noroeste do estado de São Paulo. O presente trabalho teve como objetivo caracterizar e correlacionar a composição alimentar, composição bromatológica do tecido muscular, perfil de ácidos graxos do tecido muscular e hepático, além de identificar possíveis parasitos musculares em G. sveni nos períodos chuvoso e seco, no reservatório de Jupiá, alto rio Paraná, Brasil. Foram realizadas duas coletas, uma ao final do período chuvoso (março/2018) e outra ao final do período seco (agosto/2018), no reservatório de Jupiá (20°30'33.4"S 51°27'19.7"W). Os espécimes coletados foram eutanasiados e, em seguida, tiveram mensuradas massa total, comprimento padrão e o sexo determinado visualmente. Geophagus sveni apresentou hábito alimentar detritívoro, além de plasticidade e oportunismo trófico. Sua composição alimentar foi significativamente diferente entre os períodos avaliados, adicionalmente, a composição bromatológica apresentou diferenças significativas entre os períodos e entre os sexos. De forma geral, o tecido muscular foi considerado magro, com menor percentual de lipídeos e maior de proteína bruta. Para o perfil de ácidos graxos avaliado, apenas o do tecido muscular apresentou diferenças significativas entre os períodos chuvoso e seco. Tais resultados sugerem que flutuações sazonais influenciam diretamente a disponibilidade de recursos e consumo de itens alimentares de diversas fontes por G. sveni, o que altera os padrões de incorporação nutricional no tecido muscular da espécie. Além disso, não foram encontrados parasitos intramusculares nos espécimes avaliados, o que confirma que G. sveni, por ser introduzido no reservatório de Jupiá, pode beneficiar-se da Teoria do Escape do Inimigo. Dessa maneira, por ser uma das espécies mais capturadas pela pesca artesanal na região Noroeste do estado de São Paulo e apresentar equilibrado valor energético e nutricional, além de ausência de parasitos no tecido muscular, G. sveni pode ser considerada uma boa fonte de proteína animal baseado nas avaliações realizadas. Hydroelectric developments can trigger changes in the hydrological cycle, imbalance in aquatic ecosystems and facilitate the introduction of non-native fish species. However, these species can also be highly representative in artisanal and sport fishing, becoming an important source of local income. Thus, the study of non-native species, their origins, habits and trophic positions, in addition to their skills that guarantee permanence and success in the establishment of new environments, are relevant. Among these non-native species, Geophagus sveni is provided as one of the most important species for artisanal fisheries in the Northwest region of the state of São Paulo. This study aimed to characterize and correlate the food composition, the bromatological composition of muscle tissue, the fatty acid profile of the muscle and liver tissue, in addition to identifying possible muscle parasites of Geophagus sveni in the rainy and dry periods, in the Jupiá reservoir, on the Paraná River, Brazil. Two collections were made, one at the end of the rainy period (March/2018) and another at the end of the dry period (August/2018), at the Jupiá reservoir (20°30'33.4"S 51°27'19.7"W). The collected specimens were euthanized and, afterwards, total mass and standard length were measured, as well as sex determined visually. Geophagus sveni presented detritivorous eating habits, in addition to plasticity and trophic opportunism. Their food composition was significantly different only between the periods evaluated, while their bromatological composition showed significant differences between periods and between sexes. In general, muscle tissue was considered lean, with a lower percentage of lipids and higher of crude protein. For the fatty acid profile evaluated, only the muscle tissue showed significant differences between the rainy and dry periods. Such results suggest that seasonal fluctuations directly influence the availability of resources and consumption of food items from different sources by G. sveni, which alters the patterns of nutritional incorporation in the muscle tissue of the species. Furthermore, intramuscular parasites were not found in the evaluated specimens, which confirms that G. sveni, being introduced in the Jupiá reservoir, can benefit from the Enemy Escape Theory. Thus, as it is one of the most important species for artisanal fisheries in the Northwest region of the state of São Paulo and has a balanced energy and nutritional value, in addition to the absence of parasites in the muscle tissue, G. sveni can be considered a good source of protein, based on the evaluations performed. CAPES: 001 FAPESP: 2018/00281-3

Published
2020

18. Trophic adaptability of late juvenile Atlantic spadefish Chaetodipterus faber (Teleostei: Ephippidae) related to habitat preferences in an estuary in northeastern Brazil.

Author

Barros, Breno, Sakai, Yoichi, Abrunhosa, Fernando, and Vallinoto, Marcelo

Subjects
*EPHIPPIDAE, *INFANCY of fishes, *HABITATS, *ESTUARIES, *FISH feeds, *FISH adaptation
Abstract

We tested the hypothesis that the highly flexible feeding repertoire of juvenile Chaetodipterus faber reflects their trophic adaptability by quantifying the feeding behaviour of juveniles in situ, for the first time, in a northeastern Brazilian estuary. The fishes presented a preference for alga-rich habitats, irrespective of the substrate type chosen during feeding bouts. The analysis of stomach contents revealed omnivorous feeding habits, indicating that the ingestion of plant material occurs incidentally during foraging for benthic prey hidden under the alga. Particulate feeding in the water column was often as important as bottom feeding on alga-rich substrates. The results of this study are consistent with those of other ephippid species in different coastal environments, which typically exploit an ample diversity of food items from different substrates. Therefore, the flexibility observed in the feeding behavior of the most ephippid species may be a fundamental determinant of the ecological success of this group. [ABSTRACT FROM AUTHOR]

Published
2013
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19. Notes on the feeding behavior of Teratocoris saundersi (Hemiptera: Miridae) in Iceland: phytophagy, zoophagy, and adventitious biting.

Author

WHEELER, Alfred G. and SKAFTASON, Johannes F.

Subjects
*MIRIDAE, *AGROSTIS, *ELYMUS, *LARVAE, *DIPTERA, *HEMIPTERA
Abstract

Host plants of the stenodemine mirid Teratocoris saundersi Douglas & Scott, 1869 in Iceland include the grasses Agrostis capillaris, Deschampsia cespitosa, Elymus repens, and Leymus arenarius (Poaceae), and sedges, Carex spp. (Cyperaceae). Specific host associations for T. saundersi in Iceland previously were unknown. Larvae and adults fed mainly on leaves and stems of their graminoid hosts; during cloudy weather, the bugs were observed in thatch beneath host plants. An adult fed on nectar from a flower of arctic sea rocket, Cakile arctica (Brassicaceae). Larvae and adults fed occasionally as predators or scavengers on small Diptera and pierced human skin. Observations on zoophagy further document the use of animal matter by species of Teratocoris Fieber, 1858, whereas adventitious biting by T. saundersi is reported for the first time. The zoophagous tendencies of T. saundersi might contrast with the feeding habits of stenodemines that are regarded as strict phytophages, for example, most species of Stenodema Laporte, 1833 and Trigonotylus Fieber, 1858. [ABSTRACT FROM AUTHOR]

Published
2010

20. Experimental herbivory of native Australian macrophytes by the introduced Mozambique tilapia Oreochromis mossambicus.

Author

DOUPÉ, ROBERT G., KNOTT, MATTHEW J., SCHAFFER, JASON, BURROWS, DAMIEN W., and LYMBERY, ALAN J.

Subjects
*MOZAMBIQUE tilapia, *FISHES, *PERIPHYTON, *PLANT species, *BODY weight
Abstract

This study describes experimental herbivory and detritivory of three common native aquatic macrophyte species by the introduced Mozambique tilapia Oreochromis mossambicus (Peters) (Pisces: Cichlidae), and its physiological response to their consumption. There was a highly significant effect of fish herbivory on plant weight for each of the macrophyte species, but this effect was not influenced by any preference for periphyton. Despite the herbivory, there was a highly significant loss of fish body weight across all plant species and weight could only be maintained by supplementary feeding of a high protein fish flake. These results suggest that despite eating these plants, an alternative food resource may be needed for survival and may trigger trophic plasticity in O. mossambicus. [ABSTRACT FROM AUTHOR]

Published
2010
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21. Foraging in the Anthropocene: Feeding plasticity of an opportunistic predator revealed by long term monitoring.

Author

Ouled-Cheikh, Jazel, Morera-Pujol, Virginia, Bahillo, Álvaro, Ramírez, Francisco, Cerdà-Cuéllar, Marta, and Ramos, Raül

Subjects
*STABLE isotope analysis, *MARINE resources, *POPULATION dynamics, *PREDATORY animals, *CARBON analysis, *MARINE toxins
Abstract

• Yellow-legged gull's diet has changed over the last decades. • Yellow-legged gulls adapt their diet to anthropogenic food subsidies availability. • Anthropogenic food subsidies availability may be key in adjusting population size. For centuries, human activities have altered the population dynamics of wildlife. New anthropogenic food sources provide a predictable and abundant food supply that often induces very significant changes in the size, distribution, and behaviour of many populations, with ultimate consequences on the structure and functioning of natural ecosystems. Here, we combine historical and contemporary feather samples of a population of a superabundant, opportunistic predator, the yellow-legged gull Larus michahellis , to assess its trophic ecology and relate it to human activities in the long term. Dietary assessments were based on stable isotope analysis of carbon, nitrogen, and sulphur (δ 13C, δ 15N and δ 34S), and were conducted through three end-point (marine prey, waste from landfills-slaughterhouses, and terrestrial invertebrates) Bayesian mixing models. Our results suggest that gulls' diet showed a progressive decrease in the consumption of marine prey throughout the most recent period (late 20th century onwards), linked to an increase in the consumption of meat waste and small terrestrial invertebrates. Reported dietary changes over the sampling period correlated positively with the availability of marine resources around the breeding area. We provide evidence suggesting that the ability of gulls to exploit efficiently diverse anthropogenic food subsidies likely resulted in the exponential demographic increase of this population throughout the 20th century. In addition, current regulations affecting the availability of these food resources (e.g., fishing discards and landfill waste) likely reversed this trend over the last decade. Long-term evidence of population trophic plasticity, like the one we present here, is essential to implement and support management and conservation actions that limit the availability of anthropogenic resources, especially when it comes to superabundant, problematic species. [ABSTRACT FROM AUTHOR]

Published
2021
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22. Trophic ecology of sympatric batoid species (Chondrichthyes: Batoidea) assessed by multiple biogeochemical tracers (δ13C, δ15N and total Hg).

Author

Bezerra, M.F., Seminoff, J.A., Lemons, G.E., Slotton, D.G., Watanabe, K., and Lai, C.T.

Subjects
*WATER pollution, *CHONDRICHTHYES, *ANIMAL populations, *MERCURY poisoning, *WATER quality, *FOOD chains, *AQUATIC biodiversity, *ECOLOGICAL niche
Abstract

Aquatic pollution is known to reduce biodiversity and disrupt wildlife populations. Mercury (Hg) pollution is pervasive worldwide, contributing to the degradation of ecosystems, and causing deleterious effects to exposed organisms and populations. Batoids have a life history linked to the benthic substrate of coastal areas and occupy upper trophic levels. These combined with large bodies, long lifespan, and slow growth rates contributes to increased uptake and accumulation of Hg. However, mechanisms governing these associations are not well understood. Using multiple biogeochemical tracers (δ13C, δ15N and total Hg), we describe trophic interactions of three sympatric batoid species inhabiting an urbanized estuary and identify diet sources that contribute to Hg accumulation and trophic position among these mesopredators. We also use the Bat-ray (Myliobatis californica) as a model species, to compare diet composition, trophic position, and isotopic niche between two populations in two Californian bays. Trophic plasticity in M. californica was characterized by isotopic niche, diet proportions, and trophic position estimates using Bayesian statistics. We found diet and local contamination background strongly associated with Hg accumulation, and Hg levels that exceed EPA water quality criterion (<0.3 μg.g−1 w.w.) in all studied species. • Sympatric batoids occupy similar trophic positions but distinct foraging niches. • Batoids with overlapping isotopic niche present distinct contamination levels. • Hg levels were associated to differences in species-specific diets. • Plasticity in diet and isotopic niche of Myliobatis californica are described. [ABSTRACT FROM AUTHOR]

Published
2021
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23. Diet-induced phenotypic plasticity in European eel (Anguilla anguilla)

Author

Joachim Christiaens, Jens De Meyer, and Dominique Adriaens

Subjects
0106 biological sciences, 0301 basic medicine, DIVERGENCE HYPOTHESIS, animal structures, Physiology, media_common.quotation_subject, Population, Zoology, Aquatic Science, Biology, 010603 evolutionary biology, 01 natural sciences, Head shape, Competition (biology), Dimorphism, Predation, SEXUAL-DIMORPHISM, 03 medical and health sciences, Animals, education, Molecular Biology, Elver eel stage, Ecology, Evolution, Behavior and Systematics, SNAKES, media_common, education.field_of_study, Phenotypic plasticity, Ecology, Feeding, JAPONICA, Skull, Soft diet, Biology and Life Sciences, Anguilla, EVOLUTION, Diet, MODEL, Sexual dimorphism, SIZE, 030104 developmental biology, Biting, Predatory Behavior, Insect Science, Trophic plasticity, MORPHOLOGY, Animal Science and Zoology, HEAD-SHAPE, BODY SHAPE
Abstract

Two phenotypes are present within the European eel population: broad-heads and narrow-heads. The expression of these phenotypes has been linked to several factors, such as diet and differential growth. The exact factors causing this dimorphism, however, are still unknown. In this study, we performed a feeding experiment on glass eels from the moment they start to feed. Eels were either fed a hard diet, which required biting and spinning behavior, or a soft diet, which required suction feeding. We found that the hard feeders develop a broader head and a larger adductor mandibulae region than eels that were fed a soft diet, implying that the hard feeders are capable of larger bite forces. Next to this, soft feeders develop a sharper and narrower head, which could reduce hydrodynamic drag, allowing more rapid strikes towards their prey. Both phenotypes were found in a control group, which were given a combination of both diets. These phenotypes were, however, not as extreme as the hard or the soft feeding group, indicating that some specimens are more likely to consume hard prey and others soft prey, but that they do not selectively eat one of both diets. In conclusion, we found that diet is a major factor influencing head shape in European eel and this ability to specialize in feeding on hard or soft prey could decrease intra-specific competition in European eel populations.

Published
2016

24. Predation and competition differentially affect the interactions and trophic niches of a Neotropical amphibian guild

Author

Ministerio de Economía y Competitividad (España), Arribas, Rosa, Touchon, J. C., Gómez-Mestre, Iván, Ministerio de Economía y Competitividad (España), Arribas, Rosa, Touchon, J. C., and Gómez-Mestre, Iván

Abstract

Competition and predation alter individual traits of organisms, and these effects can scale-up to have consequences on community structure and dynamics. The relative importance of competition and predation will depend largely on the local assemblage of species, the type of predators, or the degree of niche segregation. We experimentally investigated the interplay of competition and predation on the structure and trophic level (measured via stable isotope analysis) of a seven-species Neotropical freshwater guild using a mesocosm approach in central Panama. We tested the effect of two types of predators (dragonfly nymphs or adult water bugs) in combination with the presence/absence of a common competitor, the red-eyed treefrog (Agalychnis callidryas), on four core species of tadpoles. We also distinguished between consumptive and non-consumptive effects of each type of predator by presenting them to tadpoles caged or freely roaming. Dragonfly larvae were more efficient predators than water bugs, but these effects were not uniform for all tadpole species. All amphibian species grew bigger when raised in the presence of an uncaged dragonfly nymph, presumably due to reduced competition through thinning, but tadpoles were smaller when exposed to caged dragonfly nymphs indicating the existence of non-consumptive predator effects as well. Predator presence also altered the relative trophic position of the different amphibian species, causing some tadpole species to increase and others to decrease their trophic status. Despite the presumed ecological similarity of tadpole species in the guild, the interplay of competition and predation had varying effects on the trophic status of nearly every species. Our results indicate that community composition can greatly affect the trophic level of larval amphibians, and that predation may have a greater role than competition in structuring Neotropical larval amphibian guilds.

Published
2018

25. Predation and Competition Differentially Affect the Interactions and Trophic Niches of a Neotropical Amphibian Guild

Author

Ivan Gomez-Mestre, Justin C. Touchon, Rosa Arribas, and Ministerio de Economía y Competitividad (España)

Subjects
0106 biological sciences, media_common.quotation_subject, lcsh:Evolution, Predation, Zoology, 010603 evolutionary biology, 01 natural sciences, Competition (biology), lcsh:QH540-549.5, lcsh:QH359-425, Community ecology, Ecology, Evolution, Behavior and Systematics, Stable isotopes, Trophic level, media_common, Competition, Growth rate, Ecology, biology, Community, 010604 marine biology & hydrobiology, Amphibian larvae, Niche segregation, biology.organism_classification, Dragonfly, Tadpole, Trophic niche, Guild, Trophic plasticity, lcsh:Ecology
Abstract

Competition and predation alter individual traits of organisms, and these effects can scale-up to have consequences on community structure and dynamics. The relative importance of competition and predation will depend largely on the local assemblage of species, the type of predators, or the degree of niche segregation. We experimentally investigated the interplay of competition and predation on the structure and trophic level (measured via stable isotope analysis) of a seven-species Neotropical freshwater guild using a mesocosm approach in central Panama. We tested the effect of two types of predators (dragonfly nymphs or adult water bugs) in combination with the presence/absence of a common competitor, the red-eyed treefrog (Agalychnis callidryas), on four core species of tadpoles. We also distinguished between consumptive and non-consumptive effects of each type of predator by presenting them to tadpoles caged or freely roaming. Dragonfly larvae were more efficient predators than water bugs, but these effects were not uniform for all tadpole species. All amphibian species grew bigger when raised in the presence of an uncaged dragonfly nymph, presumably due to reduced competition through thinning, but tadpoles were smaller when exposed to caged dragonfly nymphs indicating the existence of non-consumptive predator effects as well. Predator presence also altered the relative trophic position of the different amphibian species, causing some tadpole species to increase and others to decrease their trophic status. Despite the presumed ecological similarity of tadpole species in the guild, the interplay of competition and predation had varying effects on the trophic status of nearly every species. Our results indicate that community composition can greatly affect the trophic level of larval amphibians, and that predation may have a greater role than competition in structuring Neotropical larval amphibian guilds.

Published
2018

26. Influence of maturity condition and habitat type on food resources utilization by Octopus tehuelchus in Atlantic Patagonian coastal ecosystems

Author

Maite Andrea Narvarte, Florencia Botto, Oscar Iribarne, and Lorena Pia Storero

Subjects
0106 biological sciences, Otras Ciencias Biológicas, Population, Aquatic Science, 010603 evolutionary biology, 01 natural sciences, TROPHIC PLASTICITY, DIET, Predation, purl.org/becyt/ford/1 [https], Ciencias Biológicas, STABLE ISOTOPE ANALYSIS, FOOD WEB, Juvenile, Ecosystem, purl.org/becyt/ford/1.6 [https], education, Ecology, Evolution, Behavior and Systematics, OCTOPUS, education.field_of_study, Ecology, biology, COASTAL, 010604 marine biology & hydrobiology, Physiological condition, biology.organism_classification, Food web, Habitat, Octopus (genus), CIENCIAS NATURALES Y EXACTAS
Abstract

This study evaluates differences in Octopus tehuelchus diet in relation to sex and maturity condition (juvenile, mature, post-spawning) in two contrasting habitat types (sandy vs. rocky). Muscle of O. tehuelchus and of its associated food sources were analyzed for δ13C and δ15N. There was no correlation between δ13C or δ15N and octopus size. δ13C and δ15N values were similar betweensexes indicating similar diets. The Bayesian mixing model (MixSIAR) showed that the proportional contribution of the sources varied with the maturity condition of octopuses, and between habitat types. Our results show differences in the proportions of alternative prey in the diet of O. tehuelchus related to their physiological condition and the habitat characteristics. The differential food source utilization may be related to differential prey energy contribution andcould explain the differences in the growth pattern and life span, as well as in the reproductive traits and recruitment success of O. tehuelchus in sandy and rocky habitats. Our results highlight the importance of considering such differences in octopus diet, since they may have consequences for population dynamics, but also in the species? trophic niche and its functional role in communities. Fil: Storero, Lorena Pia. Universidad Nacional del Comahue. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni". - Provincia de Río Negro. Ministerio de Agricultura, Ganadería y Pesca. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni". - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni"; Argentina. Universidad Nacional del Comahue; Argentina Fil: Botto, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Narvarte, Maite Andrea. Universidad Nacional del Comahue. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni". - Provincia de Río Negro. Ministerio de Agricultura, Ganadería y Pesca. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni". - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni"; Argentina. Universidad Nacional del Comahue; Argentina Fil: Iribarne, Oscar Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Published
2016

27. Small-scale spatial variability of food partitioning between cultivated oysters and associated suspension-feeding species, as revealed by stable isotopes

Author

Sébastien Lefebvre, Julio César Marin-Léal, Stanislas F. Dubois, Michel Ropert, and Francis Orvain

Subjects
0106 biological sciences, Oyster, Ecology, biology, 010604 marine biology & hydrobiology, Intertidal zone, Interspecific competition, Sessile epibionts, Aquatic Science, Spatial variability, 010603 evolutionary biology, 01 natural sciences, Intraspecific competition, Spatial heterogeneity, Oysters, biology.animal, Guild, Trophic plasticity, 14. Life underwater, Ecology, Evolution, Behavior and Systematics, Stable isotopes, Shellfish, Trophic level
Abstract

Oyster culture structures support a host of epibionts belonging to the same suspension-feeding guild, which are considered to be potential competitors for food with cultivated oysters. In an intertidal shellfish ecosystem on the northern French coast, an approach based on stable isotopes (C-13 and N-15) was used to investigate intra- and interspecific food resource partitioning among cultivated oysters and the main associated wild sessile epibionts such as polychaetes, barnacles, mussels and ascidians. The main objective of the present study was to determine inter- and intraspecific food partitioning, along with small-scale spatial variability, within the guild of suspension feeders. We demonstrated that interspecific competition was limited among co-occurring suspension-feeders (ascidians, serpulid and terebellid polychaetes, bivalves and barnacles). None of the studied species had similar delta C-13 and delta N-15 signatures, indicating that relative contributions of organic matter sources may differ for each suspension-feeding species. Spatial variability was investigated both from the view of intra- and interspecific variability. Intraspecific variability was examined with regard to species' feeding biology and the trophic plasticity of co-occurring suspension-feeders. Mantel tests indicated that spatial heterogeneity resulted not only from environmental conditions, such as elevation above sea level (a.s.l.) and sediment features, but also from the inherent spatial structure of isotopic signatures. Our results show that isotopic approaches that are limited to sampling in one area and at one time are at risk of mistaking trophic interactions.

Published
2007

28. Comparison of the feeding apparatus and diet of European sardines Sardina pilchardus of Atlantic and Mediterranean waters: ecological implications

Author

Isabel Palomera, Susana Garrido, and David Costalago

Subjects
Mediterranean climate, Diet composition, Range (biology), Gill rakers, Small pelagic fish, Aquatic Science, Biology, Predation, Mediterranean sea, Phytoplankton, Mediterranean Sea, Animals, Atlantic Ocean, Ecology, Evolution, Behavior and Systematics, Ecosystem, Trophic level, Ecology, Sardine, Fishes, Gastrointestinal Contents, Diet, Predatory Behavior, Trophic plasticity, Upwelling, Seasons
Abstract

15 pages, 4 figures, 3 tables, In this study, the feeding apparatus (gill rakers, GR) and the diet composition of European sardine Sardina pilchardus populations living in two contrasting environments were compared: the upwelling area off western Iberia and the comparatively less productive region of the north-western Mediterranean Sea. The importance of local adaptations in the trophic ecology of this species was estimated. Sardina pilchardus from the Atlantic Iberian coast and from the north-western Mediterranean Sea have clear differences in the feeding apparatus and diet compositions. Those from the Atlantic Iberian coast have significantly more GRs than S. pilchardus of the same size range in the Mediterranean Sea. While S. pilchardus from the Mediterranean Sea mostly depend on prey ranging between 750-1500 and 3000-4000μm, corresponding mostly to cladocerans, decapods and copepods, those from the Atlantic depend on smaller prey (50-500 and 1000-1500μm) that include phytoplankton and copepods, particularly during summer months, and S. pilchardus eggs during the winter. The marked difference between the trophic ecology of S. pilchardus in the two areas studied appears to have originated from different dietary strategies that the two populations have adopted in contrasting feeding environments. These differences are shown to profoundly affect the size and quality of prey consumed, and the effect of cannibalism on the populations. © 2015 The Fisheries Society of the British Isles

Published
2014

29. Trophic plasticity of the gastropod Hydrobia ulvae within an intertidal bay (Roscoff, France): A stable isotope evidence

Author

Pascal Riera, Ecogéochimie et Fonctionnement des Ecosystèmes Benthiques (EFEB), Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff [Roscoff] (SBR), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
0106 biological sciences, Trophic Plasticity, [SDV]Life Sciences [q-bio], Intertidal zone, Aquatic Science, Oceanography, 010603 evolutionary biology, 01 natural sciences, Purple Bacteria, Hydrobiidae, Gastropoda, 14. Life underwater, Ecology, Evolution, Behavior and Systematics, Trophic level, Detritus, biology, Ecology, 010604 marine biology & hydrobiology, Stable Isotopes, biology.organism_classification, Hydrobia Ulvae, Hydrobia, [SDE]Environmental Sciences, Spartina maritima, Bay
Abstract

International audience; The study investigated the trophic ecology of the gastropod Hydrobia ulvae in different habitat types within an intertidal bay. The results point out two major trophic pathways involving H.ulvae in this bay. On the one hand, in sandy/muddy sediments Hydrobia derives most of its energy from allochtonous detritus derived from Enteromorpha sp and the total SOM pool. In addition, in these sediments, the phototrophic purple bacteria mats played a substantial trophic role in the diet of Hydrobia. On the other hand, in a Spartina maritima marsh, the gastropod appears firstly dependent of autochtonous detritus derived from this plant. The minor contribution of microphytobenthos to the diet of Hydrobia is consistent with a relatively low presence of epipelic diatoms at the sampling sites. These results provide evidence that the trophic ecology of H.ulvae inhabiting intertidal sediments is quite plastic and does not necessarily rely primarly on microphytobenthos. Consequently, in a single bay, the small spatial scale variability in the origin and availability of detritus have direct implications on the food incorporation by H.ulvae.

Published
2010

30. A dynamic model of plant growth with interactions between development and functional mechanisms to study plant structural plasticity related to trophic competition

Author

Véronique Letort, Amélie Mathieu, Daniel Barthélémy, P. de Reffye, Paul-Henry Cournède, Mathématiques Appliquées aux Systèmes - EA 4037 (MAS), Ecole Centrale Paris, Botanique et Modélisation de l'Architecture des Plantes et des Végétations (UMR AMAP), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Methods, algorithms and software in automatic control (METALAU), Inria Paris-Rocquencourt, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), and Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD [France-Sud])

Subjects
0106 biological sciences, Interactions, MESH: Plants, F62 - Physiologie végétale - Croissance et développement, Plant Science, F50 - Anatomie et morphologie des plantes, 01 natural sciences, Architectural pattern, Biomasse, Functional–structural models, media_common, Trophic level, Plant growth, [SDE.BE.BIOI]Environmental Sciences/Biodiversity and Ecology/domain_sde.be.bioi, Port de la plante, dynamic, U10 - Informatique, mathématiques et statistiques, Ecology, Anatomie végétale, Trophic plasticity, Abies, Modèle mathématique, Développement biologique, media_common.quotation_subject, functional-structural models, Plant Development, Context (language use), system, Biology, Arbre, 010603 evolutionary biology, Models, Biological, Competition (biology), [SDV.BV]Life Sciences [q-bio]/Vegetal Biology, Croissance, Phenotypic plasticity, MESH: Models, Biological, plant growth, Original Articles, interactions, 15. Life on land, Dynamic system, Plant ecology, Plant morphology, GreenLab, Adaptation, Modèle végétal, 010606 plant biology & botany
Abstract

International audience; BACKGROUND AND AIMS: The strong influence of environment and functioning on plant organogenesis has been well documented by botanists but is poorly reproduced in most functional-structural models. In this context, a model of interactions is proposed between plant organogenesis and plant functional mechanisms. METHODS: The GreenLab model derived from AMAP models was used. Organogenetic rules give the plant architecture, which defines an interconnected network of organs. The plant is considered as a collection of interacting 'sinks' that compete for the allocation of photosynthates coming from 'sources'. A single variable characteristic of the balance between sources and sinks during plant growth controls different events in plant development, such as the number of branches or the fruit load. KEY RESULTS: Variations in the environmental parameters related to light and density induce changes in plant morphogenesis. Architecture appears as the dynamic result of this balance, and plant plasticity expresses itself very simply at different levels: appearance of branches and reiteration, number of organs, fructification and adaptation of ecophysiological characteristics. CONCLUSIONS: The modelling framework serves as a tool for theoretical botany to explore the emergence of specific morphological and architectural patterns and can help to understand plant phenotypic plasticity and its strategy in response to environmental changes.

Published
2009

31. Spatial heterogeneity in the food web of a heavily modified Mediterranean coastal lagoon: stable isotope evidence

Author

Pascal Riera, Antoine Carlier, Jean-Michel Amouroux, Antoine Grémare, Jean-Yves Bodiou, Martin Desmalades, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie biologique de Banyuls (LOBB), Observatoire océanologique de Banyuls (OOB), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Ecogéochimie et Fonctionnement des Ecosystèmes Benthiques (EFEB), Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), French Ministry of Education Research and Technology, European Project: 28974,MARBEF, Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École pratique des hautes études (EPHE), Institut Universitaire Européen de la Mer (IUEM), and Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)

Subjects
0106 biological sciences, Delta, 010504 meteorology & atmospheric sciences, Shellfish aquaculture, Aquatic Science, Biology, Oceanography, 01 natural sciences, Isotopic signature, Water column, 14. Life underwater, Ecology, Evolution, Behavior and Systematics, delta N-15, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, 0105 earth and related environmental sciences, Trophic level, Ecology, 010604 marine biology & hydrobiology, Food web, Lagoon, 15. Life on land, Northwestern Mediterranean, Spatial heterogeneity, 13. Climate action, Benthic zone, Trophic plasticity, delta C-13, Spatial variability, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

International audience; We investigated the food web structure of the Salses-Leucate Lagoon (northwestern Mediterranean) through delta C-13 and delta N-15 analysis of its benthic macrofauna and potential food sources. This lagoon was heavily human-modified during the 1970s, allowing permanent exchange with the open sea and an increase in salinity from that time. As a result, it exhibits a much less marked salinity gradient than the neighbouring lagoon ecosystems, which Suggests a priori that its food web structure is more homogeneous. In this environmental context, we assessed spatial variability in the isotopic composition of non-vagrant macrofauna in Salses-Leucate in relation to degree of connection with the open sea, anthropogenic inputs and the presence of oyster aquaculture. Overall, the main trophic pathway is based on suspended particulate organic matter and sedimented organic matter. However, there were marked spatial differences (at different scales) in both delta C-13 and delta N-15 values of macrofauna, which suggests an important feeding plasticity within each category of primary consumers at a small spatial scale. delta C-13 data showed that the contributions of the different food sources to the diet of primary consumers changed depending on distance from continental inputs, connection with the open sea and local primary producer coverage. Small-scale delta N-15 variability revealed a very localised influence of anthropogenic nitrogen output. Regarding the possible effect of aquaculture, the isotopic ratios of sediment and macrobenthos were not modified underneath the oyster lines with respect to the neighbouring area. Conversely, the isotopic signature of consumers living on the oyster lines contrasted with those living underneath. Therefore, our results suggest that a decoupling exists between the trophic pathways that occur in the water column and on the soft bottom of this shallow water ecosystem.

Published
2009

32. Small-scale spatial variability of food partitioning between cultivated oysters and associated suspension-feeding species, as revealed by stable isotopes

Author

Dubois, Stanislas, Orvain, Francis, Marin Leal, Julio César, Ropert, Michel, Lefebvre, Sébastien, Dubois, Stanislas, Orvain, Francis, Marin Leal, Julio César, Ropert, Michel, and Lefebvre, Sébastien

Abstract

Oyster culture structures support a host of epibionts belonging to the same suspension-feeding guild, which are considered to be potential competitors for food with cultivated oysters. In an intertidal shellfish ecosystem on the northern French coast, an approach based on stable isotopes (C-13 and N-15) was used to investigate intra- and interspecific food resource partitioning among cultivated oysters and the main associated wild sessile epibionts such as polychaetes, barnacles, mussels and ascidians. The main objective of the present study was to determine inter- and intraspecific food partitioning, along with small-scale spatial variability, within the guild of suspension feeders. We demonstrated that interspecific competition was limited among co-occurring suspension-feeders (ascidians, serpulid and terebellid polychaetes, bivalves and barnacles). None of the studied species had similar delta C-13 and delta N-15 signatures, indicating that relative contributions of organic matter sources may differ for each suspension-feeding species. Spatial variability was investigated both from the view of intra- and interspecific variability. Intraspecific variability was examined with regard to species' feeding biology and the trophic plasticity of co-occurring suspension-feeders. Mantel tests indicated that spatial heterogeneity resulted not only from environmental conditions, such as elevation above sea level (a.s.l.) and sediment features, but also from the inherent spatial structure of isotopic signatures. Our results show that isotopic approaches that are limited to sampling in one area and at one time are at risk of mistaking trophic interactions.

Published
2007
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33. Amphibian trophic ecology in increasingly human-altered Wetlands

Author

López, J. A., Scarabotti, P. A., and Romina Ghirardi

Subjects
Ciencias Biológicas, Flood Plain Ponds, purl.org/becyt/ford/1 [https], Hylidae, Trophic Plasticity, Otras Ciencias Biológicas, Habitat Alteration, Prey Availability, purl.org/becyt/ford/1.6 [https], CIENCIAS NATURALES Y EXACTAS
Abstract

Habitat destruction and alteration are among the major causes of worldwide amphibian declines. Resource limitation in altered environments can potentially affect trophic ecology of amphibians and contribute to decline. In this work, we analyzed changes in resource availability and use, and the population abundance of eight amphibian species from six wetlands that differ in type and degree of human disturbance. Food resource availability varied among sites and the occurrence of some arthropods was correlated with type of disturbance regime. Diet evenness, richness, and niche breadth were similar among sites or months. Nevertheless, diet composition showed significant variation among samples for all species. Diet composition changes among populations were correlated with resource availability in four species (Lysapsus limellum, Dendropsophus nanus, Hypsiboas pulchellus and H. punctatus), but not in the remaining species (D. sanborni, H. raniceps, Scinax nasicus and S. squalirostris). These results suggest that species that are able to adjust their diets according to prey availability may have an adaptive advantage in changing environments associated with anthropogenic disturbances. Given the increasing rate of alteration of wetlands by urbanization, agriculture, and livestock grazing, understanding trophic processes in these habitats is important for preserving the great biodiversity living in these habitats. Fil: Lopez, Javier Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina Fil: Scarabotti, Pablo Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina Fil: Ghirardi, Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina

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