Sediment features, macrozoobenthic assemblages and trophic relationships (δ13C and δ15N analysis) following a dystrophic event with anoxia and sulphide development in the Santa Giusta lagoon (western Sardinia, Italy)

The unique Australian monotreme, the platypus (Ornithorhynchus anatinus) potentially exerts a strong top-down influence on riverine food webs in eastern Australia. However, despite considerable interest in the evolutionary history and physiology of the platypus, little is known of its trophic relationships. To address this lack of knowledge we used stable isotope analysis, in combination with the analysis of food items stored in cheek pouches, to determine its position in a typical riverine food web. This was the essential first step in the process of designing a larger study to investigate the relative importance of top-down and bottom-up effects in rivers where the platypus occurs. We found that platypuses were feeding on a wide range of benthic invertebrates, particularly insect larvae. The similarity of δ13C and δ15N values recorded for the platypus, a native fish (Galaxias sp.) and the exotic mosquitofish (Gambusia holbrooki) indicated dietary overlap and potential competition for the same resources. Although cheek pouch studies identify most of the major groups of prey organisms, the potential for contribution of the soft-bodied organisms such as larval dipterans, is suggested by stable isotope analysis, indicating that the use of both techniques will be important in future ecological investigations.

Download Full-text

Trophic relationships among animals associated with drifting wrack

Marine and Freshwater Research ◽

10.1071/mf17274 ◽

2018 ◽

Vol 69 (8) ◽

pp. 1248 ◽

Cited By ~ 2

Author(s):

Ryan J. Baring ◽

Rebecca E. Lester ◽

Peter G. Fairweather

Keyword(s):

Stable Isotope ◽

Food Webs ◽

Sandy Beach ◽

Sandy Beaches ◽

Trophic Levels ◽

Trophic Relationships ◽

Gut Contents ◽

Future Research ◽

Δ13c And Δ15n ◽

Trophic Pathways

Wrack accumulates commonly in surf zones of sandy beaches and can be a semipermanent feature. Very few studies have investigated the trophic pathways associated with wrack accumulations in sandy beach surf zones, despite their potential importance to nearshore food webs. In the present study, we were specifically interested in determining the fish–wrack trophic associations in the nearshore. Macrophytes, macroinvertebrates and fish were sampled from drifting wrack at two sites with different macrophyte compositions (i.e. algae v. an algae–seagrass mix) in South Australia. The gut contents of fish were sampled, and the δ13C and δ15N stable isotope signatures of fish, macroinvertebrates and macrophytes were analysed. Using both the stable isotope and diet data, we identified that fish are feeding among wrack accumulations, but some unexplained trophic pathways suggest that fish are also likely to be foraging over multiple habitats elsewhere for food. In contrast, there was more evidence that grazing macroinvertebrates may be feeding on and around macrophytes within the accumulations, as well as using them as habitat. Thus, the present study established some baseline trophic pathways associated with wrack accumulations in sandy beach surf zones. Given the modest evidence for use of wrack as a food source, the lower trophic levels of the food webs identified remain unknown and should be an area for future research.

Download Full-text

The ‘Near Threatened’ Bearded Screech-owl Megascops barbarus: diet pattern and trophic assessment using δ13C and δ15N stable-isotopes

Bird Conservation International ◽

10.1017/s095927090999013x ◽

2009 ◽

Vol 20 (1) ◽

pp. 25-33 ◽

Cited By ~ 3

Author(s):

PAULA L. ENRÍQUEZ ◽

KIMBERLY M. CHENG ◽

JOHN E. ELLIOTT

Keyword(s):

Stable Isotopes ◽

Trophic Relationships ◽

High Positive Correlation ◽

Δ13c And Δ15n ◽

Diet Patterns ◽

Diet Pattern ◽

Short And Long Term ◽

Rare Endemic ◽

Near Threatened

SummaryThe diet patterns and trophic relationships are poorly understood for most tropical owl species. We used stable isotopes of carbon (δ13C) and nitrogen (δ15N) in 24 feather samples of the rare, endemic, and ‘Near Threatened’ Bearded Screech-owl Megascops barbarus to determine the trophic level of their prey and evaluate whether diet patterns vary (1) among individuals, (2) spatially along the species's range in the highlands of Chiapas, Mexico, and (3) temporally during the short- and long-term. Our results indicated that there was diet variation among individuals during the period of feather growth and there was a high positive correlation between stable isotopes in body and rectrices. The stable isotopes showed significant temporal differences in δ15N signature values, but not in δ13C values, with no obviously interpretable temporal pattern. Spatially, values of δ13C and δ15N did not vary across all nine sampled locations. The observed lower δ13C values suggested that this owl lives in humid forests. More long-term studies and spatial dietary and prey analysis will be necessary to increase our understanding of how habitat conditions determine the distribution, abundance and quality of food for the Bearded Screech-owl.

Download Full-text

Characterization of Trophic Structure of Fish Assemblages in the East and South Seas of Korea Based on C and N Stable Isotope Ratios

Water ◽

10.3390/w14010058 ◽

2021 ◽

Vol 14 (1) ◽

pp. 58

Author(s):

Donghoon Shin ◽

Tae Hee Park ◽

Chung-Il Lee ◽

Kangseok Hwang ◽

Doo Nam Kim ◽

...

Keyword(s):

Food Web ◽

Fish Assemblages ◽

East Sea ◽

Trophic Relationships ◽

Food Sources ◽

Isotopic Niche ◽

The South ◽

Food Web Structure ◽

Δ13c And Δ15n ◽

South Sea

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.

Download Full-text

Determination of trophic relationships within a high Arctic marine food web using δ13C and δ15N analysis

Marine Ecology Progress Series ◽

10.3354/meps084009 ◽

1992 ◽

Vol 84 ◽

pp. 9-18 ◽

Cited By ~ 720

Author(s):

KA Hobson ◽

HE Welch

Keyword(s):

Food Web ◽

High Arctic ◽

Trophic Relationships ◽

Δ13c And Δ15n ◽

Marine Food Web ◽

Marine Food

Download Full-text

Analysis of δ13C and δ15N isotopic signatures to shed light on the hydrological cycle’s influence on the trophic behavior of fish in a Mediterranean reservoir

Biologia ◽

10.1515/biolog-2016-0160 ◽

2016 ◽

Vol 71 (12) ◽

Author(s):

Amedeo Fadda ◽

Francesco Palmas ◽

Federica Camin ◽

Luca Ziller ◽

Bachisio Mario Padedda ◽

...

Keyword(s):

Fish Species ◽

Hydrological Cycle ◽

Trophic Relationships ◽

Food Sources ◽

Water Level Fluctuations ◽

Gut Contents ◽

Fish Food ◽

Δ13c And Δ15n ◽

Mediterranean Reservoir ◽

C And N

AbstractStable isotope analysis (SIA) of carbon and nitrogen sheds light on the origin of the food resources exploited by the fish and provides basic information on the trophic relationships among taxa. In this study, SIA of C and N was used to investigate the trophic behavior of fish species in a small Mediterranean reservoir, Lake Sos Canales (SC) in Sardinia, Italy, during an annual hydrological cycle. Fish were caught approximately every two months, and baseline isotopic C and N levels in the pelagic and littoral area were analyzed to establish the origin of fish food sources, considering suspended particulate matter, planktonic crustaceans and littoral macroinvertebrates. To assess the relative contribution of the two different sources using SIA, a Dynamic Baseline Mixing Model (DBMM) was applied and the results were compared with the fish gut contents. Our aim was to chart the seasonal trophic behavior of the fish species inhabiting an anthropogenic aquatic environment under considerable stress due to water level fluctuations. Isotopic results showed a seasonal trend with

Download Full-text

Experimental Evaluation of δ2H, δ13C and δ15N Variability in Blood and Feathers of Wild and Captive Birds: Implications for Interspecific Food Web Studies

Diversity ◽

10.3390/d13100495 ◽

2021 ◽

Vol 13 (10) ◽

pp. 495

Author(s):

Robert G. Clark ◽

Russell D. Dawson ◽

Jennifer L. Greenwood ◽

David W. Johns ◽

Leonard I. Wassenaar ◽

...

Keyword(s):

Family Of Origin ◽

Prey Selection ◽

Isotope Composition ◽

Age Groups ◽

Trophic Relationships ◽

Ambient Conditions ◽

Natal Nest ◽

Δ13c And Δ15n ◽

Rearing Environment ◽

Nestling Development

Stable-hydrogen (δ2H), nitrogen (δ15N), and carbon (δ13C) isotopes are used to decipher broad movement patterns and trophic relationships among diverse species, and an improved understanding of factors controlling natural variation in tissue-isotope measurements will enhance these applications. To evaluate the rearing environment and family-related effects on the isotopic composition of tissues, we cross-fostered nestling tree swallows (Tachycineta bicolor, Vieillot 1808) and American kestrels (Falco sparverius, Linnaeus 1758) by swapping recently hatched birds (<4 days old) among nest boxes and collecting blood and feathers prior to fledging. To assess developmental effects, we measured δ2H in blood and feathers of captive mallard (Anas platyrhynchos, Linnaeus 1758) ducklings challenged energetically during growth. Stable isotope composition was not strongly related to nest box type or natal nest (i.e., family of origin) effects in swallows and kestrels; tissue-isotope composition was related to rearing environment, indicative of differences in nest and parental quality or parental provisioning tactics. Blood and feather δ2H values in swallows were positively related to antecedent maximum ambient temperature, and unrelated to elevated energy expenditure in mallards. The average differences between δ2H in blood and feathers were similar for nestling swallows (27‰, 32‰; two sites) and mallards (26‰, 30‰; two age groups), and lower than in nestling kestrels (50‰). Strong species-specific patterns in blood-feather differences were not observed for δ15N and δ13C in swallows or kestrels; divergent δ2H results may be related to differences in nest ambient conditions, diet composition, or physiological processes affecting hydrogen assimilation during growth and feather synthesis. In swallows, tissue-isotope values reflected parental prey selection from spatially distinct food webs during nestling development with little effect(s) of family of origin, egg composition, or early growth.

Download Full-text

Environmental factors influencing δ13C and δ15N in three Chesapeake Bay fishes

ICES Journal of Marine Science ◽

10.1093/icesjms/fst143 ◽

2013 ◽

Vol 71 (3) ◽

pp. 689-702 ◽

Cited By ~ 6

Author(s):

Lori A. Davias ◽

Matthew S. Kornis ◽

Denise L. Breitburg

Keyword(s):

Land Use ◽

Stable Isotope ◽

Environmental Factors ◽

Chesapeake Bay ◽

Fundulus Heteroclitus ◽

White Perch ◽

Isotope Analysis ◽

Habitat Type ◽

Trophic Relationships ◽

Δ13c And Δ15n

Abstract Stable isotope analysis has become a common tool for mapping trophic relationships, describing foodweb changes, and assessing ecosystem health. Clear interpretation of stable isotopes is facilitated by understanding how environmental factors can affect isotopic values; in estuarine systems, these factors may include salinity, land use, and shoreline habitat. To evaluate these factors, fish were collected from shallow-water habitats next to hardened (bulkhead and riprap) and unhardened (beach and marsh) shorelines within five subestuaries of the Chesapeake Bay that differed in predominant land use and salinity. This study focused on three common mid-Atlantic fish species: mummichog, Fundulus heteroclitus, Atlantic silverside, Menidia menidia, and white perch, Morone americana. Multiple regression analyses pointed to standard length, salinity, % of watershed as developed or crop land, and shoreline habitat type as important predictors for δ15N in all three species and for δ13C in mummichog and white perch. Further analysis controlling for the effects of salinity, land use, and fish size demonstrated that δ13C and δ15N were lower in tissues of fish collected next to marsh compared with hardened or beach habitat. Habitat effects were strongest for mummichog. This study focused on overarching patterns driving stable isotope signatures in fish; however, it also indicated potentially important interactions between nearshore habitat type and land use or salinity that deserve further analysis. Results have implications for the scale of isotope inquiry and give justification for more detailed follow-up studies of foodweb structure along modified and natural shorelines.

Download Full-text