isotopic niche
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Diversity ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 56
Author(s):  
Claudia Andrade ◽  
Cristóbal Rivera ◽  
Erik Daza ◽  
Eduardo Almonacid ◽  
Fernanda Ovando ◽  
...  

The southern king crab Lithodes santolla is one of the most economically important fishery species in the southern waters of the Atlantic and Pacific Oceans. A combination of stomach content and stable isotope analyses was used to reveal the potential dietary characteristics, isotopic niche, overlap among maturity stages and sexes, and trophic relationships of an L. santolla population in the Nassau Bay, Cape Horn region. Stable isotope analyses indicated that L. santolla assimilated energy from a basal carbon source, the giant kelp Macrocystis pyrifera, forming the trophic baseline of the benthic food web. Moreover, the trophic position of L. santolla varied among late juveniles and adults, suggesting that the southern king crab does undergo an ontogenetic diet shift. L. santolla exhibited intraspecific isotopic niche variation, reflecting niche differentiation which allows the species to partition resources. The trophic relationships of L. santolla with the associated fauna suggested some potential interactions for food resources/habitat use when they are limited. This study is the first attempt to characterize the trophic dynamics of the southern king crab in the Cape Horn area and, by generating more data, contributes to the conservation of the king crab population and the long-term management of local fisheries that rely on this resource.


Water ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 58
Author(s):  
Donghoon Shin ◽  
Tae Hee Park ◽  
Chung-Il Lee ◽  
Kangseok Hwang ◽  
Doo Nam Kim ◽  
...  

The aim of this study was to assess seasonal variation in the food-web structure of fish assemblages in the East (two sites) and the South (one site) Seas of Korea, and to compare the isotopic niche areas between the regions. To do this, we analyzed the community structures and the δ13C and δ15N values for fish assemblages, and their potential food sources collected during May and October 2020. There were spatial differences in the diversity and dominant species of fish assemblages between the two seas. The fish assemblages in the South Sea had relatively wide ranges of δ13C and δ15N (−22.4‰ to −15.3‰ and 7.4‰ to 13.8‰, respectively) compared to those (−22.1‰ to −18.0‰ and 9.8‰ to 13.6‰, respectively) in the East Sea. The δ13C and δ15N values of suspended particulate organic matter, zooplankton, and fish assemblages differed significantly among sites and between seasons (PERMANOVA, p < 0.05, in all cases). Moreover, isotopic niche indices were relatively higher in the South Sea compared to those in the East Sea. Such differences in food-web characteristics among sites are likely due to the specific environmental effects (especially, major currents) on the differences in the species compositions and, therefore, their trophic relationships. Overall, these results allow for a deeper understanding of the changing trophic diversity and community structure of fish assemblages resulting from climate variability.


2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Alistidia Mwijage ◽  
Theresia John Lyasenga ◽  
Dativa Joseph Shilla ◽  
John Andrew Marco Mahugija ◽  
Lydia Gaspare ◽  
...  

Diverse anthropogenic activities including alteration of hydrological regime and agricultural development in the upstream of the river catchments modify the structural components and ecological roles of the species in estuarine ecosystems. The present study compared the diet, carbon (δ13C) and nitrogen (δ15N) isotopic signals, trophic niches and metrics of trophic redundancy of predatory fish and their potential phytodetritivore prey-fish between two estuaries with different degrees of anthropogenic disturbances. The δ13C and δ15N signals, Bayesian mixing models and stomach content analyses were adopted. It was revealed that the diet among the predators Arius africanus, Epinephelus coioides, Sillago sihama and Pomadasys argenteus and their isotopic signals including their phytodetritivore-prey, Valamugil buchanani were significantly different between Wami and Pangani estuaries (PERMANOVA, Pseudo –F ≥ 3.1, p = 0.05). The total isotopic niche area between estuaries accounted by the comparable Bayesian standard ellipse area (SEAb) was significantly smaller in Wami than that of Pangani (t-test, t = 4.3, p < .001). The ANOVA test further confirmed significant variation in SEAb among fish populations in two estuaries (F = 27.84, p < 0.001). The Layman metric indices of trophic diversity and redundancy of Wami estuary were substantially smaller than those observed at Pangani estuary. These findings mean that despite Wami estuary being under conservation status, the extent of disturbances in the upstream is high enough to induce the ecological changes at the base of the food web, subsequently cascading its effect up to the higher-order consumers of the ecosystem. As a result, the ecological redundancy and ecosystem complexity of Wami is somewhat compromised relative to that of Pangani estuary. Therefore, the degree of anthropogenic disturbances in river catchments affect differently the trophic niches of predatory and phytodetritivore fish and hence overall food web structures, trophic redundancy and complexity of estuarine ecosystems.


2021 ◽  
Vol 8 ◽  
Author(s):  
Camila Arnés-Urgellés ◽  
Pelayo Salinas-de-León ◽  
Etienne Rastoin-Laplane ◽  
Leandro Vaca-Pita ◽  
Jenifer Suárez-Moncada ◽  
...  

Climatic variability changes ocean productivity and generates systematic cascading effects in marine food webs. Studying the feeding ecology of top predators, such as sharks, can provide insights into the overall health of marine ecosystems. We conducted a 4-year study to evaluate seasonal and inter-annual trophic variations and their relationship with El Niño Southern Oscillation (ENSO) on the largest aggregation of scalloped hammerhead shark (Sphyrna lewini) in the Tropical Eastern Pacific (TEP). We used δ13C and δ15N signatures to gain a better understanding of hammerheads’ feeding strategies as well as variations of their isotopic niche. Our results suggest that the hammerhead sharks in the Galapagos Marine Reserve respond to climatic fluctuations, with La Niña event potentially benefiting their trophic needs as the overall marine productivity increased in the region. This work is the first of its kind in the TEP and provides insights on how climate variability influences the feeding ecology of this critically endangered species. It also highlights the need to incorporate climate-related conservation strategies into the management of this species since ENSO events become more frequent and intense in the face of climate change.


2021 ◽  
Vol 173 ◽  
pp. 112991
Author(s):  
Alexander M. Jardine ◽  
Jennifer F. Provencher ◽  
Isabeau Pratte ◽  
Erika R. Holland ◽  
Julia E. Baak ◽  
...  
Keyword(s):  

2021 ◽  
pp. 105541
Author(s):  
Lydia Källberg Normark ◽  
Camilla Liénart ◽  
Deena Pillay ◽  
Andrius Garbaras ◽  
Candida Savage ◽  
...  

2021 ◽  
Vol 8 (12) ◽  
Author(s):  
Philip M. Riekenberg ◽  
Jaime Camalich ◽  
Elisabeth Svensson ◽  
Lonneke L. IJsseldijk ◽  
Sophie M. J. M. Brasseur ◽  
...  

Baleen from mysticete whales is a well-preserved proteinaceous material that can be used to identify migrations and feeding habits for species whose migration pathways are unknown. Analysis of δ 13 C and δ 15 N values from bulk baleen have been used to infer migration patterns for individuals. However, this approach has fallen short of identifying migrations between regions as it is difficult to determine variations in isotopic shifts without temporal sampling of prey items. Here, we apply analysis of δ 15 N values of amino acids to five baleen plates belonging to three species, revealing novel insights on trophic position, metabolic state and migration between regions. Humpback and minke whales had higher reconstructed trophic levels than fin whales (3.7–3.8 versus 3–3.2, respectively) as expected due to different feeding specialization. Isotopic niche areas between baleen minima and maxima were well separated, indicating regional resource use for individuals during migration that aligned with isotopic gradients in Atlantic Ocean particulate organic matter. Phenylanine δ 15 N values confirmed regional separation between the niche areas for two fin whales as migrations occurred and elevated glycine and threonine δ 15 N values suggested physiological changes due to fasting. Simultaneous resolution of trophic level and physiological changes allow for identification of regional migrations in mysticetes.


Author(s):  
Henry Masters ◽  
Christine R Maher

Species can alleviate competition by reducing diet overlap. Nonnative coyotes (Canis latrans (Say, 1823)) and historically native gray foxes (Urocyon cinereoargenteus (Schreber, 1775)) have expanded their ranges and may compete with native red foxes (Vulpes vulpes (Linnaeus, 1758)). To examine potential competition among canids in Maine, we compared δ13C and δ15N from muscle and hair samples to assess relative resource use, and we compared frequency of occurrence of prey items from stomach contents to assess diets. For these species, red foxes consumed anthropogenically-based foods the most in fall-early winter, gray foxes consumed anthropogenically-based foods the most in summer, and coyotes consumed anthropogenically-based foods the least in all seasons. Coyotes held the highest relative trophic position in fall-early winter, red foxes held the highest relative trophic position in summer, and gray foxes held the lowest relative trophic position. Based on stomach contents, gray foxes had the broadest diet and consumed the most plants, and coyotes had the narrowest diet. Red foxes were the only species to show isotopic niche overlap with both potential competitors across seasons. Thus they may be most susceptible to competitive exclusion among these canids, with implications for community dynamics as ranges shift due to human activity.


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