Trophic relationships between sperm whales and jumbo squid using stable isotopes of C and N

Stomach contents and carbon (C) and nitrogen (N) stable isotope analysis were used to evaluate trophic relationships of jumbo squid, Dosidicus gigas. Buccal masses, beaks and stomach contents of large and medium maturing-sized jumbo squid and muscle from its main prey, the myctophid Benthosema panamense, were collected in the Gulf of California, Mexico during 1996, 1997 and 1999. Both the quantified C and N-isotope ratios in muscle, and stomach content analysis revealed that larger-sized maturing squid showed a higher trophic position than medium-sized individuals. However, a discrepancy between stomach contents versus stable isotope analyses was found in evaluating trophic relationships. Simple dilution models as a function of growth were used to estimate the C and N renewal dietary shift for jumbo squid. Estimates of the initial C and N pools in D. gigas with an initial age of 70 days and 210 days indicated isotopic shifts of 32% after a threefold biomass increase and 25% after a fourfold biomass increase, respectively. Additionally, beak samples of jumbo squid were evaluated as an alternative tissue to estimate squid trophic position using stable isotopes. The results showed a significant correlation between stable isotope ratios from muscle and beak samples. Muscle isotope values were higher than beak by 1% and 4% for δ13C and δ15N respectively. A test with jumbo squid beaks collected from a stomach of a stranded sperm whale confirmed the viability of this method.

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Assessment of trophic relationships between symbiotic tropical ophiuroids using C and N stable isotope analysis

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315406014494 ◽

2006 ◽

Vol 86 (6) ◽

pp. 1443-1447 ◽

Cited By ~ 3

Author(s):

D. Fourgon ◽

G. Lepoint ◽

I. Eeckhaut

Keyword(s):

Stable Isotopes ◽

Potential Benefit ◽

Feeding Habits ◽

Isotope Analysis ◽

Tracer Experiment ◽

Trophic Relationships ◽

Nitrogen Stable Isotopes ◽

Carbon And Nitrogen ◽

C And N ◽

The One

Analyses of the natural abundance of carbon and nitrogen stable isotopes were performed to investigate the feeding habits of two ophiuroids, Ophiomastix venosa and Ophiocoma scolopendrina, and to assess the potential benefit obtained by the symbiotic Ophiomastix venosa juveniles. A tracer experiment was also carried out to clarify the contribution of algae to the nitrogen uptake amongst the tested ophiuroids. Our results suggest that Ophiocoma scolopendrina adults occupy a higher position in the food web than Ophiomastix venosa and mainly feed on neuston. In contrast, O. venosa adults feed on the alga Sargassum densifolium and on organic matter associated with sediment. Free juveniles and symbiotic juveniles of O. venosa have intermediate δ13C values between both adult species. The high proportion of 13C in the symbiotic juveniles compared to the one in their conspecific adults indicates that their diet slightly differs from the latter and is closer to that of Ophiocoma scolopendrina. This raises the hypothesis that symbiotic juveniles steal neuston from their associated host, O. scolopendrina.

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Feeding Habits of the Glass Eel Anguilla japonica Determined by C and N Stable Isotopes in the Nakdong River Estuary of the Korean Peninsula

The Sea ◽

10.7850/jkso.2016.21.1.36 ◽

2016 ◽

Vol 21 (1) ◽

pp. 36-43

Author(s):

JEONG BAE KIM ◽

WON-CHAN LEE ◽

HYUNG CHUL KIM ◽

SOKJIN HONG ◽

KYEONG DONG PARK

Keyword(s):

Stable Isotopes ◽

Korean Peninsula ◽

Feeding Habits ◽

River Estuary ◽

Anguilla Japonica ◽

Nakdong River ◽

Glass Eel ◽

C And N ◽

The Nakdong River

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‘Taking Fishers’ Knowledge to the Lab’: An Interdisciplinary Approach to Understand Fish Trophic Relationships in the Brazilian Amazon

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.723026 ◽

2021 ◽

Vol 9 ◽

Author(s):

Paula Evelyn Rubira Pereyra ◽

Gustavo Hallwass ◽

Mark Poesch ◽

Renato Azevedo Matias Silvano

Keyword(s):

Stable Isotopes ◽

Food Webs ◽

Fish Species ◽

Trophic Interactions ◽

Brazilian Amazon ◽

Trophic Levels ◽

Trophic Relationships ◽

Ecological Knowledge ◽

Data Limitations ◽

Combining Data

Trophic levels can be applied to describe the ecological role of organisms in food webs and assess changes in ecosystems. Stable isotopes analysis can assist in the understanding of trophic interactions and use of food resources by aquatic organisms. The local ecological knowledge (LEK) of fishers can be an alternative to advance understanding about fish trophic interactions and to construct aquatic food webs, especially in regions lacking research capacity. The objectives of this study are: to calculate the trophic levels of six fish species important to fishing by combining data from stable isotopes analysis and fishers’ LEK in two clear water rivers (Tapajós and Tocantins) in the Brazilian Amazon; to compare the trophic levels of these fish between the two methods (stable isotopes analysis and LEK) and the two rivers; and to develop diagrams representing the trophic webs of the main fish prey and predators based on fisher’s LEK. The fish species studied were Pescada (Plagioscion squamosissimus), Tucunaré (Cichla pinima), Piranha (Serrasalmus rhombeus), Aracu (Leporinus fasciatus), Charuto (Hemiodus unimaculatus), and Jaraqui (Semaprochilodus spp.). A total of 98 interviews and 63 samples for stable isotopes analysis were carried out in both rivers. The average fish trophic levels did not differ between the stable isotopes analysis and the LEK in the Tapajós, nor in the Tocantins Rivers. The overall trophic level of the studied fish species obtained through the LEK did not differ from data obtained through the stable isotopes analysis in both rivers, except for the Aracu in the Tapajós River. The main food items consumed by the fish according to fishers’ LEK did agree with fish diets as described in the biological literature. Fishers provided useful information on fish predators and feeding habits of endangered species, such as river dolphin and river otter. Collaboration with fishers through LEK studies can be a viable approach to produce reliable data on fish trophic ecology to improve fisheries management and species conservation in tropical freshwater environments and other regions with data limitations.

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