A stable isotope study of a neotropical stream food web prior to the extirpation of its large amphibian community

Rapid and massive amphibian population declines have been reported throughout upland areas of the Neotropics. The abundance and species richness of Neotropical amphibian communities suggest that losses of this magnitude are likely to have strong effects at the ecosystem level. To improve understanding of the implications of their loss we used stable isotope analysis to examine trophic relationships in an ecosystem in which amphibians are dominant in a second-order forest stream at 750 m asl in Parque Nacional Omar Torrijos Herrera, Panama. We analysed δ13C, δ15N and C:N ratios of major biotic components (basal resources, invertebrates, amphibians, fish and reptiles) in the stream and of the adjacent riparian food web. Tadpoles (mean δ15N = 4.49‰) and adult amphibians (mean δ15N = 5.45‰) were intermediate links in the aquatic and terrestrial food web respectively. High δ15N signatures identified fish as top predators in the aquatic food web and snakes and the toad Bufo as top predators in the terrestrial food web. Isotopic signatures clearly distinguished between trophic groups of tadpoles: microbial feeders (Centrolenidae, δ15N range = 0.91–3.05‰), herbivores (Rana and Hyla, δ15N range = 4.74–5.15‰) and neuston feeders (Colostethus, δ15N range = 5.31–6.40‰). Dependence on autotrophic production was indicated by enriched signatures of carbon isotopes in pool dwellers versus those that reside in faster-flowing sections of the stream. High nitrogen concentrations in detrital matter (average 0.8%, C:N = 10.3) suggested that grazing tadpoles enhanced nitrogen fluxes and improved the quality of organic matter available to detritivores.

Download Full-text

Trophic ecology of a tropical aquatic and terrestrial food web: insights from stable isotopes (15N)

Journal of Tropical Ecology ◽

10.1017/s0266467406003336 ◽

2006 ◽

Vol 22 (4) ◽

pp. 469-476 ◽

Cited By ~ 32

Author(s):

Alexander Kupfer ◽

Reinhard Langel ◽

Stefan Scheu ◽

Werner Himstedt ◽

Mark Maraun

Keyword(s):

Food Web ◽

Trophic Ecology ◽

Isotope Analysis ◽

Trophic Levels ◽

Trophic Relationships ◽

Isotopic Signatures ◽

Top Predators ◽

Aquatic Vertebrates ◽

Aquatic Food ◽

Litter Invertebrates

We used stable isotope analysis (15N/14N) to characterize the trophic relationships of consumer communities of an aquatic food web (a permanent pond) and the adjacent terrestrial food web (secondary dry dipterocarp forest) from a seasonal tropical field site in north-eastern Thailand. In general, isotopic signatures of aquatic vertebrates were higher (δ15N range = 4.51–9.90‰) than those of invertebrates (δ15N range = 1.10–6.00‰). High 15N signatures identified water snakes and swamp eels as top predators in the pond food web. In the terrestrial food web 15N signatures of saprophagous litter invertebrates (diplopods, earthworms), termites, ants and beetle larvae were lower than in those of predatory invertebrates (scolopendrids, scorpions, whip spiders). Predatory terrestrial frogs and caecilians had lower 15N signatures than snakes, indicating that snakes are among the top predators in the terrestrial web. Based on the distribution of isotopic signatures, we estimated five trophic levels for both the aquatic and terrestrial food web. The food chains of a seasonal tropical site studied were rather short, which implies similarities to the structure of temperate food webs.

Download Full-text

Trophic relationships in a tropical stream food web assessed by stable isotope analysis

Freshwater Biology ◽

10.1111/j.1365-2427.2008.02149.x ◽

2009 ◽

Vol 54 (5) ◽

pp. 1028-1041 ◽

Cited By ~ 36

Author(s):

SOPHIE COAT ◽

DOMINIQUE MONTI ◽

CLAUDE BOUCHON ◽

GILLES LEPOINT

Keyword(s):

Stable Isotope ◽

Food Web ◽

Stable Isotope Analysis ◽

Isotope Analysis ◽

Trophic Relationships ◽

Tropical Stream

Download Full-text

Stable Isotope Analyses of Multiple Tissues of Great Shearwaters (Ardenna Gravis) Reveals Long-Term Dietary Stability, Short-Term Changes in Diet, and Can be Used as a Tool to Monitor Food Webs

Diversity ◽

10.3390/d11090163 ◽

2019 ◽

Vol 11 (9) ◽

pp. 163 ◽

Cited By ~ 1

Author(s):

Hong ◽

Wiley ◽

Powers ◽

Michener ◽

Kaufman ◽

...

Keyword(s):

Stable Isotope ◽

Food Web ◽

Food Webs ◽

Trophic Level ◽

Isotope Analysis ◽

Diet Shift ◽

Turnover Rates ◽

Δ13c And Δ15n ◽

Isotopic Signatures ◽

Over Time

The great shearwater (Ardenna gravis) is a common pelagic bird with a distribution that spans almost the entire Atlantic basin, which in conjunction with its relatively high abundance, makes great shearwaters an effective bio indicator. We compared δ13C and δ15N values from the feathers, red blood cells (RBCs), and plasma of great shearwaters collected in 2014 and 2015 from the waters off Massachusetts and Cape Cod. The δ13C and δ15N values of RBCs were quite constant between sampling periods and years, suggesting a generally stable food web over that time period. However, the δ13C of plasma indicates a small seasonal change in diet between July and September for both years, with plasma δ15N values suggesting a slight increase in trophic level late in summer. Comparison of the δ15N of RBCs and plasma indicates that great shearwaters experienced a diet shift during the first few weeks of summer 2014, but not in 2015. Comparisons with other studies suggest that these shearwaters feed at a lower trophic level than great shearwaters sampled in the Bay of Fundy and that there is a decrease in δ13C with increasing latitude, which could indicate a more pelagic diet in northern waters. Stable isotope analysis of the sixth primary feathers provided evidence that these feathers are molted in the Northern Hemisphere and that the diet of great shearwaters shortly after arrival was different in 2014 and 2015. This study demonstrates that within species comparisons of tissue isotopic signatures over time and comparisons of isotopic signatures of tissues with different turnover rates, can detect changes in diet and be used as a tool to monitor for changes in marine food webs over time and space. The relevant signals remain informative even in the absence of species-specific data on tissue-diet discrimination factors, tissue turnover rates, or knowledge of dietary components and their stable isotopic signatures, suggesting dietary changes indicative of a corresponding change in the food web.

Download Full-text

Stable Isotope Analysis of Ozark Hellbender (Cryptobranchus alleganiensis bishopi) Living and Preserved Museum Tissue Reveals a Shift in Their Generalist Diet Composition

Ecologies ◽

10.3390/ecologies2020011 ◽

2021 ◽

Vol 2 (2) ◽

pp. 187-202

Author(s):

Waylon Hiler ◽

Stanley E. Trauth ◽

Benjamin Wheeler ◽

Aimee Jimenez ◽

Milica Radanovic ◽

...

Keyword(s):

Stable Isotope ◽

Stable Isotope Analysis ◽

Diet Composition ◽

Isotope Analysis ◽

Population Declines ◽

Δ13c And Δ15n ◽

Cryptobranchus Alleganiensis ◽

N Isotopes ◽

Generalist Diet ◽

Stable Isotope Study

Ozark hellbenders (Cryptobranchus alleganiensis bishopi) have undergone marked population declines across their entire distribution. A variety of ecological life history research has been conducted to determine the cause(s) of the declines. Historically, hellbender diet studies used stomach content examination methods; however, alternative approaches such as less intrusive stable isotope analyses are now options for researchers. The goals of our study were to conduct stable isotope analysis on live and formalin-preserved museum specimen Ozark hellbender tissues to identify diet composition in the Eleven Point and Spring rivers, Arkansas. Also, we used stable isotope analysis to investigate if Spring River hellbender diets have changed over time. We sampled fish, live hellbenders (non-destructively), and formalin-preserved hellbender tissues from museum collections for stable isotope analysis. We sampled crayfish for assemblage composition and stable isotope analysis. The results of our stable isotope study revealed three main findings: (1) there were no statistically significant differences between hellbender δ13C and δ15N values among sites and hellbender stable C and N isotopes were correlated with body length; (2) traditional δ13C versus δ15N bi-plots and trophic discrimination values did not provide complete discernment in hellbender diets; however, Bayesian MixSIAR models revealed hellbenders to be generalists, and (3) the use of δ13C and δ15N values adjusted historic formalin-fixed and ethanol preserved hellbenders matched well with current crayfish and fish stable isotope values based on Bayesian MixSIAR models. These findings provide important diet information and a possible tool to examine dietary patterns from preserved specimens that may be used for hellbender conservation and management.

Download Full-text

Stable isotope analysis reveals partitioning in prey use by Kajikia audax (Istiophoridae), Thunnus albacares, Katsuwonus pelamis, and Auxis spp. (Scombridae) in the Eastern Tropical Pacific of Ecuador

Neotropical Ichthyology ◽

10.1590/1982-0224-2020-0015 ◽

2021 ◽

Vol 19 (4) ◽

Author(s):

Rigoberto Rosas-Luis ◽

Nancy Cabanillas-Terán ◽

Carmen A. Villegas-Sánchez

Keyword(s):

Stable Isotope ◽

Food Web ◽

Stable Isotope Analysis ◽

Trophic Ecology ◽

Isotope Analysis ◽

Middle Level ◽

Food Sources ◽

Thunnus Albacares ◽

Katsuwonus Pelamis ◽

Δ13c And Δ15n

Abstract Kajikia audax, Thunnus albacares, Katsuwonus pelamis, and Auxis spp. occupy high and middle-level trophic positions in the food web. They represent important sources for fisheries in Ecuador. Despite their ecological and economic importance, studies on pelagic species in Ecuador are scarce. This study uses stable isotope analysis to assess the trophic ecology of these species, and to determine the contribution of prey to the predator tissue. Isotope data was used to test the hypothesis that medium-sized pelagic fish species have higher δ15N values than those of the prey they consumed, and that there is no overlap between their δ13C and δ15N values. Results showed higher δ15N values for K. audax, followed by T. albacares, Auxis spp. and K. pelamis, which indicates that the highest position in this food web is occupied by K. audax. The stable isotope Bayesian ellipses demonstrated that on a long time-scale, these species do not compete for food sources. Moreover, δ15N values were different between species and they decreased with a decrease in predator size.

Download Full-text

Biodilution of heavy metals in a stream macroinvertebrate food web: Evidence from stable isotope analysis

The Science of The Total Environment ◽

10.1016/j.scitotenv.2008.01.006 ◽

2008 ◽

Vol 394 (1) ◽

pp. 57-67 ◽

Cited By ~ 44

Author(s):

Kozo Watanabe ◽

Michael T. Monaghan ◽

Yasuhiro Takemon ◽

Tatsuo Omura

Keyword(s):

Heavy Metals ◽

Stable Isotope ◽

Food Web ◽

Stable Isotope Analysis ◽

Isotope Analysis ◽

Stream Macroinvertebrate

Download Full-text

The Use of Carbon and Nitrogen Stable Isotope Analysis to Characterize Food Web Changes in Aquatic Systems for Reclamation of Oil Sands Process-Affected Materials

Water Quality Research Journal ◽

10.2166/wqrj.2009.032 ◽

2009 ◽

Vol 44 (4) ◽

pp. 313-322 ◽

Cited By ~ 4

Author(s):

Monalisa Elshayeb ◽

Michael D. MacKinnon ◽

D. George Dixon ◽

Michael Power

Keyword(s):

Food Web ◽

Oil Sands ◽

Isotope Analysis ◽

Naphthenic Acid ◽

Carbon Sources ◽

Nitrogen Isotope ◽

Isotopic Signatures ◽

Carbon And Nitrogen ◽

Aquatic Food ◽

Northern Alberta

Abstract One strategy for reclamation of oil sands leases in northern Alberta is the construction of lakes and wetlands by capping oil sands process-affected material (OSPM) with water. To assess this approach, experimental sites containing a range of OSPM have been constructed to monitor the evolution of the resulting aquatic habitats. Stable isotopes of carbon and nitrogen were used to assess the effects of OSPM on aquatic food webs. Carbon and nitrogen isotopic signatures of sediment, dissolved inorganic and organic carbon, particulate organic matter, periphyton, plants, plankton, aquatic invertebrates, and fish were used to assess differences related to the naphthenic acid (NA) concentration in OSPM and reference sites. NAs are a principal contaminant of concern in OSPM. Sites were grouped into low (0 to 4 mg/L), medium (4 to 15 mg/L), and high (>15 mg/L) NA concentrations. There were no significant differences in food web area or length among the three NA groupings. In most cases, carbon isotope analyses of samples from low, medium, and high NA concentration sites were not significantly different, suggesting that OSPM is not a significant contributor to food web carbon sources. Significant differences were found in nitrogen isotope signatures between low, medium, and high NA sites. Ammonia from OSPM is suggested as the main contributor to δ15N enrichment.

Download Full-text

Stable Isotope Analysis and Persistent Organic Pollutants in Crustacean Zooplankton: The Role of Size and Seasonality

Water ◽

10.3390/w11071490 ◽

2019 ◽

Vol 11 (7) ◽

pp. 1490 ◽

Cited By ~ 1

Author(s):

Roberta Piscia ◽

Michela Mazzoni ◽

Roberta Bettinetti ◽

Rossana Caroni ◽

Davide Cicala ◽

...

Keyword(s):

Stable Isotope ◽

Stable Isotope Analysis ◽

Isotope Analysis ◽

Standing Stock ◽

Fish Predation ◽

Crustacean Zooplankton ◽

Isotopic Signatures ◽

Carbon And Nitrogen ◽

Pollutant Concentrations ◽

Stock Biomass

Zooplankton is crucial for the transfer of matter, energy, and pollutants through aquatic food webs. Primary and secondary consumers contribute to the abundance and standing stock biomass, which both vary seasonally. By means of taxa- and size-specific carbon and nitrogen stable isotope analysis, the path of pollutants through zooplankton is traced and seasonal changes are addressed, in an effort to understand pollutant dynamics in the pelagic food web. We analyzed zooplankton plurennial changes in concentration of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane and its relatives (DDTs) and in taxa-specific δ15N signatures in two size fractions, ≥450 µm and ≥850 µm, representative of the major part of zooplankton standing stock biomass and of the fraction to which fish predation is mainly directed, respectively. Our work is aimed at verifying: (1) A link between nitrogen isotopic signatures and pollutant concentrations; (2) the predominance of size versus seasonality for concentration of pollutants; and (3) the contribution of secondary versus primary consumers to carbon and nitrogen isotopic signatures. We found a prevalence of seasonality versus size in pollutant concentrations and isotopic signatures. The taxa-specific δ15N results correlated to pollutant concentrations, by means of taxa contribution to standing stock biomass and δ15N isotopic signatures. This is a step forward to understanding the taxa-specific role in pollutant transfer to planktivores and of zooplankton enrichment in PCBs and DDTs.

Download Full-text