The effects of spatial scale and isoscape on consumer isotopic niche width

Abstract Species interactions are central to community assembly and ecosystem functioning. Sea snakes play an important role as mesopredators and as intermediate links in coastal marine food webs. However, they are impacted by anthropogenic pressures such as fisheries throughout their range. We investigated differences in resource use between two sympatric sea snake species from the west coast of India, Hydrophis curtus and H. schistosus, and described the impacts of fishing on the interactions of these species. We compared habitat use, diet, and isotopic niche width between species to determine resource overlap. We then compared trophic overlap of each species with the fisheries in the region and tested the effect of fishing intensity on their isotopic niche width. We found that H. curtus used deeper habitats than H. schistosus, resulting in increased spatial overlap with fisheries. The two species also had distinct trophic niches and H. curtus prey formed a larger proportion of fishery catch on average than H. schistosus. This greater overlap could make H. curtus more vulnerable to the effects of fisheries. Both species exhibited expansion in short-term and long-term isotopic niche width along a gradient of fishing intensity which may indicate behavioural changes associated with the presence of fisheries. Hydrophis curtus is a trophic generalist, competes with syntopic species and is dominant in most assemblages. However, H. schistosus exhibits higher plasticity in resource use and may have an advantage over H. curtus. Thus, fishing could alter the relative abundance of these mesopredators with cascading effects through coastal food webs.

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Can variations in the spatial distribution at sea and isotopic niche width be associated with consistency in the isotopic niche of a pelagic seabird species?

Marine Biology ◽

10.1007/s00227-014-2468-9 ◽

2014 ◽

Vol 161 (8) ◽

pp. 1861-1872 ◽

Cited By ~ 29

Author(s):

Filipe R. Ceia ◽

Vitor H. Paiva ◽

Stefan Garthe ◽

João C. Marques ◽

Jaime A. Ramos

Keyword(s):

Spatial Distribution ◽

Niche Width ◽

Isotopic Niche ◽

Seabird Species ◽

Pelagic Seabird ◽

Isotopic Niche Width

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Isotopic niche width differentiation between common bottlenose dolphin ecotypes and sperm whales in the Gulf of California

Marine Mammal Science ◽

10.1111/mms.12465 ◽

2017 ◽

Vol 34 (2) ◽

pp. 440-457 ◽

Cited By ~ 3

Author(s):

Raúl E. Díaz-Gamboa ◽

Diane Gendron ◽

Geraldine Busquets-Vass

Keyword(s):

Bottlenose Dolphin ◽

Gulf Of California ◽

Niche Width ◽

Isotopic Niche ◽

Sperm Whales ◽

Common Bottlenose Dolphin ◽

Isotopic Niche Width

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Isotopic Niche Partitioning and Individual Specialization in an Arctic Raptor Guild

10.21203/rs.3.rs-369610/v1 ◽

2021 ◽

Author(s):

Devin L. Johnson ◽

Michael T. Henderson ◽

David L. Anderson ◽

Travis L. Booms ◽

Cory T. Williams

Keyword(s):

Resource Availability ◽

Niche Overlap ◽

Niche Width ◽

Foraging Strategies ◽

Foraging Efficiency ◽

Isotopic Niche ◽

Individual Specialization ◽

Niche Specialization ◽

Niche Variation ◽

Golden Eagles

Abstract Intra- and inter-specific resource partitioning within predator communities is a fundamental component of trophic ecology, and one proposed mechanism for how populations partition resources is through individual niche variation. The Niche Variation Hypothesis (NVH) predicts that interindividual trait variation leads to functional trade-offs in foraging efficiency, resulting in populations comprised of individual dietary specialists. A modified version of the NVH [mNVH] predicts niche specialization is plastic and responsive to fluctuating resource availability. We quantified niche overlap and tested the mNVH within an Arctic raptor guild, focusing on three species that employ different foraging strategies: Golden Eagles (generalists); Gyrfalcons (facultative specialists); and Rough-legged Hawks (specialists). Tundra ecosystems exhibit cyclic populations of arvicoline rodents (lemmings and voles), providing a unique system under which to examine interannual fluctuations in predator resource availability. Using blood δ13C & δ15N values from 189 raptor nestlings on Alaska’s Seward Peninsula (2014–2019), we calculated isotopic niche width and used Bayesian stable isotope mixing models (BSIMMs) to characterize individual specialization and test the mNVH. We observed a high degree of isotopic niche overlap between the three species and variable trophic responses to different stages of the arvicoline rodent cycle. Elevated arvicoline rodent abundance corresponded to reduced niche overlap among species and increased individual specialization in Golden Eagles and Gyrfalcons. Further, Gyrfalcons displayed a positive relationship between individual specialization and population niche width on an interannual basis consistent with the mNVH. Our findings suggest plasticity in niche specialization may reduce intra- and inter-specific resource competition under dynamic ecological conditions.

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Seasonal isotopic niche of a rodent: High between‐individual variation but no changes in individual niche width during the rich‐resource period

Biotropica ◽

10.1111/btp.12921 ◽

2021 ◽

Author(s):

Nícholas F. Camargo ◽

Guilherme G. Reis ◽

Anna Carla L. Camargo ◽

Gabriela B. Nardoto ◽

Jamie M. Kneitel ◽

...

Keyword(s):

Individual Variation ◽

Niche Width ◽

Isotopic Niche ◽

The Rich

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Trophic partitioning between abundant demersal sharks coexisting in the North Aegean Sea

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315419000110 ◽

2019 ◽

Vol 99 (5) ◽

pp. 1213-1219 ◽

Cited By ~ 4

Author(s):

Emre Yemisken ◽

Joan Navarro ◽

Manuela Forero ◽

Persefoni Megalofonou ◽

Lutfiye Eryilmaz

Keyword(s):

Stable Isotope ◽

Trophic Position ◽

Feeding Strategy ◽

Aegean Sea ◽

Trophic Niche ◽

Niche Width ◽

Isotopic Niche ◽

Shark Species ◽

The North ◽

Eastern Aegean

AbstractWe examined the feeding ecology (diet, trophic width and trophic position) of five demersal shark species (Mustelus mustelus Linnaeus, 1758, Galeus melastomus Rafinesque, 1810, Scyliorhinus canicula Linnaeus, 1758, Scyliorhinus stellaris Linnaeus, 1758, Squalus blainville, Risso, 1826) coexisting in the north-eastern Aegean Sea (around Gökçeda Island) by combining stomach content and stable isotope analyses. The results indicate clear differences in diet between the five sharks. Cephalopods were mainly found in diet of S. stellaris and M. mustelus and the stomachs of G. melastomus, S. canicula and S. blainville included fish. S. blainville showed the highest trophic position in respect of stable isotope analysis (TPsia = 4.89) around Gökçeada Island. It was followed by G. melastomus (TPsia = 4.57). Direct isotopic values (both stable nitrogen and carbon) and isotopic niche width based on the Standard Ellipse Area (SEA) clearly differed among the five shark species. In particular, S. blainville was isotopically segregated from the other shark species studied, showing a narrow isotopic trophic niche and higher trophic level. In contrast, M. mustelus had the widest trophic niche of the five species studied. The niche width of S. stellaris was narrower than M. mustelus and S. canicula but wider than S. blainville and G. melastomus. SEA showed that G. melastomus has a specialized feeding strategy in the area. There is no overlap between S. canicula and S. stellaris in trophic width.

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