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Andrade D, García-Cegarra AM, Docmac F, Ñacari LA, Harrod C. Multiple stable isotopes (C, N & S) provide evidence for fin whale (Balaenoptera physalus) trophic ecology and movements in the Humboldt Current System of northern Chile. MARINE ENVIRONMENTAL RESEARCH 2023; 192:106178. [PMID: 37776807 DOI: 10.1016/j.marenvres.2023.106178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 09/04/2023] [Accepted: 09/11/2023] [Indexed: 10/02/2023]
Abstract
Reflecting the intense coastal upwelling and high primary productivity characteristic of the Humboldt Current System (HCS), the northern coast of Chile supports a diverse and productive community of marine consumers, including worldwide important pelagic fisheries resources. Although marine mammals are relatively understudied in the region, recent studies have demonstrated that fin whale (Balaenoptera physalus) is the most frequently encountered whale species, and forages in these waters year-round. However, a current lack of information limits our understanding of whether fin whales actively feed and/or remain resident in these waters or whether whales are observed feeding as they migrate along this part of the Pacific. Here, we use stable isotope ratios of carbon, nitrogen and sulphur of fin whale skin samples collected in early summer 2020 (n = 18) and in late winter 2021 (n = 22) to examine evidence of temporal isotopic shifts that could provide information on potential migratory movements and to estimate likely consumption patterns of putative prey (i.e. zooplankton, krill, pelagic fishes and Pleuroncodes sp.). We also analysed prey items in fin whale faecal plumes (n = 8) collected during the study period. Stable isotope data showed significant differences in the isotopic values of fin whales from summer and winter. On average, summer individuals were depleted in 15N and 34S relative to those sampled during winter. Whales sampled in summer showed greater isotopic variance than winter individuals, with several showing values that were atypical for consumers from the HCS. During winter, fin whales showed far less inter-individual variation in stable isotope values, and all individuals had values indicative of prey consumption in the region. Analysis of both stable isotopes and faeces indicated that fin whales sighted off the Mejillones Peninsula fed primarily on krill (SIA median contribution = 32%; IRI = 65%) and, to a lesser extent, zooplankton (SIA zooplankton = 29%; IRI copepod = 33%). These are the first isotopic-based data regarding the trophic ecology of fin whales in the north of Chile. They provide evidence that fin whales are seasonally resident in the area, including individuals with values that likely originated outside the study area. The information presented here serves as a baseline for future work. It highlights that many aspects of the ecology of fin whales in the Humboldt Current and wider SE Pacific still need to be clarified.
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Affiliation(s)
- Diego Andrade
- Programa de Magíster en Ecología de Sistemas Acuáticos, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta Chile, Chile; Instituto de Ciencias Naturales Alexander von Humboldt, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Chile
| | - Ana M García-Cegarra
- Instituto de Ciencias Naturales Alexander von Humboldt, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Chile; Laboratorio de Estudio de Megafauna Marina, CETALAB, Universidad de Antofagasta, Chile.
| | - Felipe Docmac
- Instituto de Ciencias Naturales Alexander von Humboldt, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Chile; Universidad de Antofagasta Stable Isotope Facility, Instituto Antofagasta, Universidad de Antofagasta, Chile; INVASAL, Concepción, Chile
| | - Luis A Ñacari
- Universidad de Antofagasta Stable Isotope Facility, Instituto Antofagasta, Universidad de Antofagasta, Chile; INVASAL, Concepción, Chile; Laboratorio de Ecología y Evolución de Parásitos, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Chile
| | - Chris Harrod
- Instituto de Ciencias Naturales Alexander von Humboldt, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de Antofagasta, Chile; Universidad de Antofagasta Stable Isotope Facility, Instituto Antofagasta, Universidad de Antofagasta, Chile; INVASAL, Concepción, Chile
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Soil δ 13C and δ 15N baselines clarify biogeographic heterogeneity in isotopic discrimination of European badgers (Meles meles). Sci Rep 2022; 12:200. [PMID: 34997035 PMCID: PMC8741785 DOI: 10.1038/s41598-021-04011-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 12/10/2021] [Indexed: 12/02/2022] Open
Abstract
Isotopic techniques have been used to study phenomena in the geological, environmental, and ecological sciences. For example, isotopic values of multiple elements elucidate the pathways energy and nutrients take in the environment. Isoscapes interpolate isotopic values across a geographical surface and are used to study environmental processes in space and time. Thus, isoscapes can reveal ecological shifts at local scales, and show distribution thresholds in the wider environment at the macro-scale. This study demonstrates a further application of isoscapes, using soil isoscapes of 13C/12C and 15N/14N as an environmental baseline, to understand variation in trophic ecology across a population of Eurasian badgers (Meles meles) at a regional scale. The use of soil isoscapes reduced error, and elevated the statistical signal, where aggregated badger hairs were used, and where individuals were identified using genetic microarray analysis. Stable isotope values were affected by land-use type, elevation, and meteorology. Badgers in lowland habitats had diets richer in protein and were adversely affected by poor weather conditions in all land classes. It is concluded that soil isoscapes are an effective way of reducing confounding biases in macroscale, isotopic studies. The method elucidated variation in the trophic and spatial ecology of economically important taxa at a landscape level. These results have implications for the management of badgers and other carnivores with omnivorous tendencies in heterogeneous landscapes.
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Shipley ON, Kelly JB, Bizzarro JJ, Olin JA, Cerrato RM, Power M, Frisk MG. Evolution of realized Eltonian niches across
Rajidae
species. Ecosphere 2021. [DOI: 10.1002/ecs2.3368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Oliver N. Shipley
- School of Marine and Atmospheric Sciences Stony Brook University Stony Brook New York11794USA
| | - Joseph B. Kelly
- Department for Ecology and Evolution Stony Brook University Stony Brook New York11794USA
| | - Joseph J. Bizzarro
- Moss Landing Marine Laboratories California State University 8272 Moss Landing Road Moss Landing California95039USA
- Cooperative Institute for Marine Ecosystems and Climate University of California, Santa Cruz 110 McAllister Way Santa Cruz California95060USA
| | - Jill A. Olin
- Great Lakes Research Center Michigan Technological University Houghton Michigan49931USA
| | - Robert M. Cerrato
- School of Marine and Atmospheric Sciences Stony Brook University Stony Brook New York11794USA
| | - Michael Power
- Department of Biology University of Waterloo 200 University Avenue West Waterloo OntarioN2L 3G1Canada
| | - Michael G. Frisk
- School of Marine and Atmospheric Sciences Stony Brook University Stony Brook New York11794USA
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Human disturbance increases trophic niche overlap in terrestrial carnivore communities. Proc Natl Acad Sci U S A 2020; 117:26842-26848. [PMID: 33046630 DOI: 10.1073/pnas.2012774117] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Animal foraging and competition are defined by the partitioning of three primary niche axes: space, time, and resources. Human disturbance is rapidly altering the spatial and temporal niches of animals, but the impact of humans on resource consumption and partitioning-arguably the most important niche axis-is poorly understood. We assessed resource consumption and trophic niche partitioning as a function of human disturbance at the individual, population, and community levels using stable isotope analysis of 684 carnivores from seven communities in North America. We detected significant responses to human disturbance at all three levels of biological organization: individual carnivores consumed more human food subsidies in disturbed landscapes, leading to significant increases in trophic niche width and trophic niche overlap among species ranging from mesocarnivores to apex predators. Trophic niche partitioning is the primary mechanism regulating coexistence in many communities, and our results indicate that humans fundamentally alter resource niches and competitive interactions among terrestrial consumers. Among carnivores, niche overlap can trigger interspecific competition and intraguild predation, while the consumption of human foods significantly increases human-carnivore conflict. Our results suggest that human disturbances, especially in the form of food subsidies, may threaten carnivores by increasing the probability of both interspecific competition and human-carnivore conflict. Ultimately, these findings illustrate a potential decoupling of predator-prey dynamics, with impacts likely cascading to populations, communities, and ecosystems.
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Kwan KY, Bopp J, Huang S, Chen Q, Wang CC, Wang X, Zhen W, Zhu J, Huang X. Ontogenetic resource use and trophic dynamics of endangered juvenile Tachypleus tridentatus among diversified nursery habitats in the northern Beibu Gulf, China. Integr Zool 2020; 16:908-928. [PMID: 32978891 DOI: 10.1111/1749-4877.12495] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Horseshoe crabs, the most well-known example of "living fossils", are iconic and ecologically important macroinvertebrates in coastal and estuarine ecosystems. Their blood is a crucial resource for manufacturing Limulus or Tachypleus amebocyte lysate to detect bacterial endotoxins or fungal contamination in drug and medical devices. An enhanced understanding of their ecological roles and trophic interactions in the food webs is fundamental to facilitate resource management for the declining populations in Asia. Foraging information of the Asian species, however, is mainly derived from preliminary, scattered reports from a limited number of study locations. In this study, resource utilization, trophic niche dynamics, and trophic interaction of the juvenile tri-spine horseshoe crab, Tachypleus tridentatus (instars 1-12, approximately 0.5-8 years old) across ontogeny was assessed in diversified nursery habitats along the northern Beibu Gulf, China, using carbon and nitrogen stable isotopes. Our results suggest that: (i) T. tridentatus are ecological generalists given the vast range of carbon isotopic values and trophic niche width estimates exhibited between multiple instar groups; (ii) juvenile T. tridentatus across most habitat types predominantly assimilated energy from a variety of basal production sources in the food web, but primarily depended on sedimentary organic matter and seagrass resource pools; (iii) ontogenetic shifts in juvenile dietary proportions were evident, with decreased reliance on sedimentary organic matter, coupled with increased reliance on benthic macroinvertebrate grazers, detritivores, and omnivores with age; and (iv) nearly all juvenile instars occupied similar trophic positions in the food web with slight shifts in trophic position present with increasing size. Our findings indicate that resource availability and ontogenetic diet shifts strongly influence horseshoe crab trophic dynamics, and age should be accounted when formulating habitat conservation measures based on resource use for Asian horseshoe crabs.
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Affiliation(s)
- Kit Yue Kwan
- College of Marine Sciences, Beibu Gulf University, Qinzhou, China.,Guangxi Key Laboratory of Beibu Gulf Marine Biodiversity Conservation, Qinzhou, China
| | - Justin Bopp
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, USA
| | - Shuyan Huang
- College of Marine Sciences, Beibu Gulf University, Qinzhou, China.,Futian-CityU Mangrove R&D Center, City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
| | - Qiao Chen
- College of Marine Sciences, Beibu Gulf University, Qinzhou, China
| | - Chun-Chieh Wang
- Guangxi Key Laboratory of Marine Environmental Science, Guangxi Beibu Gulf Marine Research Center, Guangxi Academy of Sciences, Nanning, China
| | - Xueping Wang
- College of Marine Sciences, Beibu Gulf University, Qinzhou, China.,Guangxi Key Laboratory of Marine Disaster in the Beibu Gulf, Qinzhou, China
| | - Wenquan Zhen
- College of Marine Sciences, Beibu Gulf University, Qinzhou, China.,Guangxi Key Laboratory of Beibu Gulf Marine Biodiversity Conservation, Qinzhou, China
| | - Junhua Zhu
- College of Marine Sciences, Beibu Gulf University, Qinzhou, China.,Guangxi Key Laboratory of Beibu Gulf Marine Biodiversity Conservation, Qinzhou, China
| | - Xing Huang
- College of Marine Sciences, Beibu Gulf University, Qinzhou, China.,Guangxi Key Laboratory of Marine Disaster in the Beibu Gulf, Qinzhou, China
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Seasonal and ontogenetic variation of whiting diet in the Eastern English Channel and the Southern North Sea. PLoS One 2020; 15:e0239436. [PMID: 32966332 PMCID: PMC7511009 DOI: 10.1371/journal.pone.0239436] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 09/05/2020] [Indexed: 11/19/2022] Open
Abstract
An accurate description of trophic interactions is crucial to understand ecosystem functioning and sustainably manage marine ecosystems exploitation. Carbon and nitrogen stable isotopes were coupled with stomach content analyses to investigate whiting (Merlangius merlangus, Linnaeus, 1758) feeding behavior in the Eastern English Channel and Southern North Sea. Whiting juveniles and adults were sampled in autumn and winter to investigate both ontogenetic and seasonal changes. In addition, queen scallops (Aequipecten opercularis) samples were collected along with fish to be used as isotopic benthic baseline. Results indicated an ontogenetic diet change from crustaceans to fish and cephalopods. In autumn, δ15N values generally increased with fish size while in winter, a decrease of δ15N values with fish size was observed, as a potential result of spatial variation in baseline δ15N values. In winter, a nutrient-poor period, an increase in feeding intensity was observed, especially on the copepod Temora longicornis. This study provides further insights into whiting trophic ecology in relation to ontogenetic and seasonal variations, and it confirms the importance of combining several trophic analysis methods to understand ecosystem functioning.
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Studying animal niches using bulk stable isotope ratios: an updated synthesis. Oecologia 2020; 193:27-51. [DOI: 10.1007/s00442-020-04654-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 04/11/2020] [Indexed: 10/24/2022]
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Biological and environmental drivers of trophic ecology in marine fishes - a global perspective. Sci Rep 2019; 9:11415. [PMID: 31388030 PMCID: PMC6684618 DOI: 10.1038/s41598-019-47618-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 07/22/2019] [Indexed: 11/18/2022] Open
Abstract
Dietary niche width and trophic position are key functional traits describing a consumer’s trophic ecology and the role it plays in a community. However, our understanding of the environmental and biological drivers of both traits is predominantly derived from theory or geographically restricted studies and lacks a broad empirical evaluation. We calculated the dietary niche width and trophic position of 2,938 marine fishes and examined the relationship of both traits with species’ maximum length and geographic range, in addition to species richness, productivity, seasonality and water temperature within their geographic range. We used Generalized Additive Models to assess these relationships across seven distinct marine habitat types. Fishes in reef associated habitats typically had a smaller dietary niche width and foraged at a lower trophic position than those in pelagic or demersal regions. Species richness was negatively related to dietary niche width in each habitat. Species range and maximum length both displayed positive associations with dietary niche width. Trophic position was primarily related to species maximum length but also displayed a non-linear relationship with dietary niche width, whereby species of an intermediate trophic position (3–4) had a higher dietary niche width than obligate herbivores or piscivores. Our results indicate that trophic ecology of fishes is driven by several interlinked factors. Although size is a strong predictor of trophic position and the diversity of preys a species can consume, dietary niche width of fishes is also related to prey and competitor richness suggesting that, at a local level, consumer trophic ecology is determined by a trade-off between environmental drivers and biological traits.
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