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1.
S. I. Kiyashko T. A. Velivetskaya A. V. Ignatiev 《Russian Journal of Marine Biology》2011,37(4):297-302
Stable isotope ratios of sulfur (34S/32S), carbon (13C/12C), and nitrogen (15N/14N) were analyzed in the soft tissues of 12 common species of fish from the near-shore waters of the Peter the Great Bay in
the Sea of Japan. The average δ13C values of individual species varied from −20.7‰ for planktivorous fish to −16.8‰ for benthivorous fish, reflecting the growing
relative contribution of benthic primary producers to fish nutrition. The majority of the various species representatives
studied can be assigned to one trophic level, as indicated by their narrow range of δ15N values (9.9 to 12.6‰). Large interspecific variations were found in the sulfur stable isotope ratios of fish (the mean δ34S values ranged from 11.2 to 19.5‰). This is the result of the different contributions to fish nutrition of infaunal invertebrates
that are depleted in 34S due to the microbial food chain of the bottom sediments. 相似文献
2.
Contributions of stable-isotope data to elucidating food webs of Mediterranean rocky littoral fishes 总被引:18,自引:0,他引:18
The food webs of rocky infra-littoral ecosystems in the Mediterranean have been little studied. In this investigation stable
isotopes and dietary data were compared in an attempt to describe features of the food webs concerned. δ13C and δ15N were determined for plants, invertebrates and fishes from the Bay of Calvi, Corsica. Dietary data were derived from the
literature. δ13C of plants ranged from –8.59‰ to –33.74‰, of benthic invertebrates from –17.0‰ to –20.52‰, of planktonic invertebrates from
–20.08‰ to –22.34‰ and of fishes from –16.27‰ to –19.59‰. δ15N was generally greater at higher trophic levels. δ15N of plants was 0.95–2.92‰, of benthic invertebrates 1.69–6.54‰, of planktonic invertebrates 3.51–6.82‰ and of fishes 4.63–9.77‰.
13C enrichment tended to be associated with benthic food chains and 13C depletion with planktonic chains. Stable-isotope data suggested more varied diets for many species than implied by gut-contents
data. Omnivory and trophic plasticity were widespread, and many consumers fed lower down the food chain than previous studies
had suggested. Both stable-isotope and gut-contents analysis resolved differences between fishes feeding on planktonic and
benthic prey and indicated that the herbivorous fish Sarpa salpa fed on a diet substantially different from that of other fishes. Zooplankton were important in the diets of several consumers
(both primary and secondary), as was plankton derived detritus. One species of fish previously identified as planktivorous
was shown to feed largely on benthic organisms, whilst several species of benthic invertebrates may feed on plankton-derived
detritus. Although herbivores seemed to obtain most of their C from macroalgae, δ15N data suggested that many of these animals supplemented their intake of N, although gut-contents analysis did not provide
evidence for such uptake. The isotopic data have elucidated several features of the food web which we would not otherwise
have detected.
Received: 26 April 1999 / Accepted: 24 September 1999 相似文献
3.
We evaluated the potential utility of stable isotope analysis of tissues commonly archived by aquatic biologists. Previous
studies with chemically preserved samples have shown contradictory results, which present an obstacle for the use of archived
sample materials. We tested the effects of ethanol and formalin preservation on zooplankton and of ethanol on benthic macroinvertebrate
δ13C and δ15N values. We found that neither formalin nor ethanol had a significant effect on δ13C and δ15N values of preserved zooplankton. Nor did ethanol significantly affect δ13C or δ15N values of macroinvertebrates. However, ethanol preservation slightly, but significantly decreased C:N ratios of both zooplankton
and macroinvertebrates, probably reflecting some extraction of lipids. Overall, the effects of preservatives on δ13C and δ15N values that we observed were minor. We also compared δ13C and δ15N values analysed from roach scales and perch operculum bones with those analysed from muscle tissue. Decalcification of scales
and operculum bones only slightly improved our comparison to muscle tissue δ13C and δ15N values. Decalcified scales had slightly higher δ13C and lower δ15N values. Similarly, decalcified operculum bones showed slightly increased δ13C and decreased δ15N values to those for fish muscle. Our results confirm that scales and operculum bones can provide a suitable proxy for fish
muscle in isotope studies with minor correction. We conclude that various archived sample materials can indeed be used with
confidence for historical reconstructions of freshwater food webs by stable isotope analysis.
Handling editor: K. Martens 相似文献
4.
Ann M. A. Harding Keith A. Hobson Wojciech Walkusz Kasia Dmoch Nina J. Karnovsky Thomas I. Van Pelt Jan T. Lifjeld 《Polar Biology》2008,31(6):725-733
The little auk (Alle alle), a small and abundant planktivorous seabird that breeds in the high Arctic, has the potential to be used as a monitor of
the composition and abundance of lower trophic-level zooplankton. We investigated age- and sex-related sources of variation
in diet and stable isotope (δ13C and δ15N) values of little auks breeding in Spitsbergen during the summer of 2002 to evaluate this possibility. Stable isotope profiles
of both adult and chick blood changed over the breeding season, with blood δ15N values increasing and δ13C values decreasing. This could represent a switch to higher trophic-level prey derived from more pelagic sources. However,
while chick blood δ13C values followed those values in their meals, this was not the case for blood δ15N values, suggesting additional physiological mechanisms influencing blood δ15N values in growing chicks. Chicks had consistently lower δ15N values than their parents, which may indicate they were being fed on lower trophic-level prey items or may alternatively
reflect complexities in chick blood δ15N values through the growth period. These results have several important implications for use of stable isotope analysis as
a tool to detect changes in seabird diet and availability of lower trophic-level prey in high-Arctic marine environments.
Until physiological aspects of stable isotope discrimination are well understood, we caution against using chicks of this
seabird as any form of isotopic monitor. 相似文献
5.
Uchii K Matsui K Yonekura R Tani K Kenzaka T Nasu M Kawabata Z 《Microbial ecology》2006,51(3):277-284
Bluegill (Lepomis macrochirus) in Lake Biwa, Japan, feed on benthic invertebrates (benthivorous type), aquatic plants (herbivorous type), and zooplankton (planktivorous type). To evaluate the effect of food on intestinal bacterial microbiota, we characterized and compared the intestinal microbiota of these three types of bluegill in terms of community-level physiological profile (CLPP) and genetic structure. The CLPP was analyzed using Biolog MicroPlates (Biolog, Inc., Hayward, CA, USA), and multivariate analysis of variance revealed that the CLPP of intestinal microbiota differed significantly between any pairs of the three types of bluegill. The genetic profiles were analyzed by temperature gradient gel electrophoresis of polymerase chain reaction (PCR)-amplified 16S rDNA fragments, and multidimensional scaling indicated the existence of specific intestinal bacterial structures for both the benthivorous and the planktivorous types. These results suggest that the host's feeding habit can be one factor controlling the intestinal microbiota of fish in the natural environment. 相似文献
6.
Craig E. Hebert D. V. Chip Weseloh Lewis T. Gauthier Michael T. Arts Robert J. Letcher 《Oecologia》2009,160(1):15-23
Food web structure regulates the pathways and flow rates of energy, nutrients, and contaminants to top predators. Ecologically
and physiologically meaningful biochemical tracers provide a means to characterize and quantify these transfers within food
webs. In this study, changes in the ratios of stable N isotopes (e.g., δ15N), fatty acids (FA), and persistent contaminants were used to trace food web pathways utilized by herring gulls (Larus argentatus) breeding along the shores of the St Lawrence River, Canada. Egg δ15N values varied significantly among years and were used as an indicator of gull trophic position. Temporal trends in egg δ15N values were related to egg FA profiles. In years when egg δ15N values were greater, egg FA patterns reflected the consumption of more aquatic prey. Egg δ15N values were also correlated with annual estimates of prey fish abundance. These results indicated that temporal changes
in aquatic prey availability were reflected in the gull diet (as inferred from ecological tracer profiles in gull eggs). Analysis
of individual eggs within years confirmed that birds consuming more aquatic prey occupied higher trophic positions. Furthermore,
increases in trophic position were associated with increased concentrations of most persistent organic contaminants in eggs.
However, levels of highly brominated polybrominated diphenyl ether congeners, e.g, 2,2′,3,3′,4,4′,5,5′,6,6′-decabromoDE (BDE-209),
showed a negative relationship with trophic position. These contrasting findings reflected differences among contaminant groups/homologs
in terms of their predominant routes of transfer, i.e., aquatic versus terrestrial food webs. High trophic level omnivores,
e.g., herring gulls, are common in food webs. By characterizing ecological tracer profiles in such species we can better understand
spatial, temporal, and individual differences in pathways of contaminant, energy, and nutrient flow. 相似文献
7.
Stable isotopes and trophic positions of littoral fishes from a Mediterranean marine protected area 总被引:1,自引:0,他引:1
Stable isotope analyses were employed to explore feeding and foraging habitats and trophic levels of littoral fishes in a
western Mediterranean Marine Protected Area (Egadi Islands, Sicily, Italy). Carbon and nitrogen stable isotope ratios were
measured in primary producers, invertebrates and fishes collected in December 2001 and January 2002. Fishes of the littoral
region of the Egadi Islands had isotopic signatures that fell into a wider range for δ
13C (about 6‰) than for δ
15N (about 3‰). Carbon isotope ratios were consistent with a food web based on mixed sources and two trophic pathways leading
to different fish species. Differences in the isotopic composition between islands were higher for benthivorous than for planktivorous
fishes. The overall picture gained from this study is of a isotopic distinction between planktivorous and benthivorous fishes,
resource partitioning facilitating the coexistence of similar species within the same ecosystem, and spatial variability in
the isotopic signatures and trophic level of fishes. Asymmetrical analysis of variance showed that estimated trophic levels
were lower in the area with the highest level of protection (Zone A) for only two out of the nine fishes analysed. As a consequence,
overall spatial differences do not seem to be a consequence of protection, since in most cases trophic levels did not change
significantly between zone A and zones C where professional fishing (trawling apart) is permitted, but of natural sources
of variation (e.g. variability in food availability and site-specific food preferences of fishes). However, the results of
this study suggest a different response at the species compared to the community level. 相似文献
8.
K. M. Gorbatenko S. I. Kiyashko A. Ye. Lazhentsev V. A. Nadtochii A. B. Savin 《Russian Journal of Marine Biology》2008,34(7):497-506
The composition, abundance, diet and trophic status of zooplankton, bottom invertebrates, fish and nekton were analyzed based
on the data collected by the staff of the TINRO-Center during complex bottom trawl catches on the Bering Sea shelf in the
fall of 2004. The stomach contents of mass fish species were analyzed and the nitrogen and carbon isotopic composition of
36 mass species of plankton, benthos, nekton and nektobenthos, which together make up the basis of pelagic and bottom communities,
was determined. It was found that zooplankton noticeably differ from benthic invertebrates in carbon isotopic composition:
δ13C values in zooplankton varied from −20.3‰ to −17.9‰; in benthos—from −17.5‰to −13.0‰; and in fish—from −19.2‰ (juvenile walleye
pollock) to −15.3‰ (saffron cod). The levels of 13C isotope in the tissues of fish depended mostly on the share of pelagic or benthic animals in their diet. δ15N values in the studied species ranged from 8.6‰ (in sea urchins) to 17.2‰ (in large Pacific cods), which corresponds to a
trophic level of 2.8. Obviously the δ15N values reflect the degree of predation and generally show the ratio of primary, secondary and tertiary consumers in a fish’s
diet. Trophic interactions manifest a high degree of interdependence between benthic and pelagic communities (even without
taking into account such lower components of the food web as phytoplankton, bacteria, and protozoa) occurring in most nektonic
species that depend on both bottom and pelagic food. 相似文献
9.
Trophic specialization in Arctic charr Salvelinus alpinus (Pisces; Salmonidae): morphological divergence and ontogenetic niche shifts 总被引:2,自引:0,他引:2
SIGURDUR S. SNORRASON SKÚLI SKÚLASON BROR JONSSON HILMAR J. MALMQUIST PÉTUR M. JÓNASSON ODD TERJE SANDLUND TORFINN LINDEM 《Biological journal of the Linnean Society. Linnean Society of London》1994,52(1):1-18
Lake Thingvallavatn supports four trophic morphs of Arctic charr, Salvelinus alpinus (L.); two of the morphs are benthic (small and large benthivorous charr) one exploits pelagic waters (planktivorous charr) and the fourth is found in both habitats (piscivorous charr). The morphological variation among these morphs was analysed by use of principal component analysis and canonical discriminant analysis. The benihic morphs have a short lower jaw and long pectoral fins. The benthic fish also have fewer gillrakers than the other morphs. Small and large benthivorous charrs attain sexual maturity from 2 and 6 years of age, and at fork lengths from 7 and 22 cm, respectively. Small benthivorous charr retain their juvenile parr marks as adults, have beige ventral colours, and are frequently melanized under the lower jaw. Planktivorous and piscivorous charr attain sexual maturity from 4 and 6 years of age, from fork lengths of 15 and 23 cm, respectively. This phenotypic polymorphism is associated with habitat utilization and diet of the fish, and has probably arisen within the lake system through diversification and niche specialization. The pelagic morphs apparently stem from a single population, and are possibly diversified through conditional niche shifts which affect ontogeny. Juveniles reaching a body length of 23 cm may change from zooplankton to fish feeding. Asymptotic length increases thereby from 20.5 cm in planktivorous charr to 30.2 cm in piscivorous charr. The benthic morphs appear to represent separate populations, although both feed chiefly on the gastropod Lymnaea peregra. Their co-existence seems to be facilitated by size dependent constraints on habitat use. The small morph (asymptotic length 13.3 cm) exploit the interstitial crevices in the lava block substratum, whereas the large morph (asymptotic length 55.4 cm) live epibenthically. 相似文献
10.
The functional significance of inherited differences in feeding morphology in a sympatric polymorphic population of Arctic charr 总被引:7,自引:0,他引:7
Artificially fertilised eggs from wild-caught Arctic charr parents of two sympatric morphs (benthivorous and planktivorous) from Loch Rannoch, Scotland were reared in the laboratory under identical conditions. During the subsequent 2 years, aspects of their trophic anatomy and feeding behaviour were compared. As previously described for wild-caught fish, charr derived from the benthivorous morph had an increasingly wider mouth gape for a given body length than those derived from the planktivorous morph. The functional significance of these differences in gape was tested by comparing the maximum size of prey that could be handled by each of the two morphs. In both forms, a larger gape enabled larger food particles to be eaten, but the elevation of the regression of maximum prey size on gape was higher in the benthivorous form, indicating the existence of additional morphological and/or behavioural differences influencing the size of prey consumed. When offered a choice between a typical benthic prey item and a typical pelagic food item, charr of benthivorous origin were more likely to feed on the former, whereas those of planktivorous origin were more likely to feed on the latter. Thus inherited differences in gape place constraints on foraging ability and are associated with inherited differences in dietary preference. We conclude that the functional significance of the foraging specialisations indicate a strong selection pressure for the evolution of the divergence and propose that heterochronic growth is the mechanism resulting in the divergence of tropic anatomy. 相似文献
11.
Carbon and nitrogen stable isotopes are frequently used to study energy sources and food web structure in ecosystems, and
more recently, to study the effects of anthropogenic stress on aquatic ecosystems. We investigated the effect of nutrient
enrichment on δ13C and δ15N in fine (FPOM), coarse (CPOM) particulate organic matter, periphyton, invertebrates and fish in nine boreal streams in south-central
Sweden. In addition, we analysed the diet of benthic consumers using stable isotope data. Increases in δ15N of periphyton (R
2 = 0.88), CPOM (0.78), invertebrates (0.92) and fish (0.89) were related to nutrient enrichment. In contrast, δ13C signatures did not change along the nutrient gradient. Our results show that δ15N has potential as a sensitive indicator of nutrient enrichment in boreal streams. Carbon and nitrogen isotopes failed to
elucidate putative diets of selected aquatic consumers. Indeed, comparison of low- and high-impact sites showed that δ13C of many consumers were found outside the ranges of basal resource δ13C. Moreover, ranges of basal resource δ13C and δ15N overlapped at both low and high sites, making discrimination between the importance of allochthonous and autochthonous production
difficult. Our findings show that a fractionation rate of 3.4‰ is not always be appropriate to assess trophic interactions,
suggesting that more studies are needed on fractionation rates along gradients of impairment.
Handling editor: M. Power 相似文献
12.
Feeding ecology of phocid seals and some walrus in the Alaskan and Canadian Arctic as determined by stomach contents and stable isotope analysis 总被引:1,自引:0,他引:1
Larissa-A. Dehn Gay G. Sheffield Erich H. Follmann Lawrence K. Duffy Dana L. Thomas Todd M. O’Hara 《Polar Biology》2007,30(2):167-181
Feeding habits of ringed (Phoca hispida), bearded (Erignathus barbatus), spotted (Phoca largha) and ribbon (Phoca fasciata) seals and walrus (Odobenus rosmarus) were studied using stomach contents and stable carbon and nitrogen isotopes. Bearded seals fed benthically, primarily crustaceans and mollusks. Both zooplankton and fish were significant prey for ringed seals, while fish was principal spotted seal prey. Few gastric contents were available from ribbon seals. δ15N was positively correlated with age in ribbon seals and δ13C was positively correlated with age in ringed and ribbon seals. δ15N was highest in spotted seals, in agreement with their fish-dominated diet. δ15N was not different between Alaskan-harvested ringed and bearded seals, while δ15N was lowest in ribbon seals and walrus. Carbon-13 was most enriched in bearded seals and walrus reflecting benthic ecosystem use. Canadian ringed seals were depleted in 13C compared to Alaskan pinnipeds, likely because of Beaufort Sea versus Chukchi and Bering seas influence. 相似文献
13.
Stable isotope signatures of freshwater snails and mussels have been established as a convenient baseline measurement at the
primary consumer level for food-web coupling studies. We measured δ15N and δ13C of primary consumers, including mussels (Anodonta woodiana, Cristaria plicata, and Unio douglasiae), snails (Bellamya aeruginosa and Hippeutis sp.), and zooplankton from the same habitat within a shallow eutrophic lake. Primary consumers showed positive relationship
between δ15N and δ13C, indicating a linkage between planktonic and benthic habitats in this system. The variation in isotope ratios was higher
in short-lived primary consumers (zooplankton) compared with the long-lived primary consumers (mussels and snails), suggesting
limited availability of short-lived primary consumers as isotopic baselines in aquatic food-web assessment. Significant differences
in isotope ratios were also found among three species of mussels, and when using these mussels separately as pelagic baselines
to calculate trophic position and contribution of planktonic and benthic sources of fishes, bias and even misestimates were
observed. This finding suggests that caution is needed when multiple primary consumers coexist in the same habitat, and it
is important to assess potential effects of different baselines used. 相似文献
14.
Jialing Qiao Jiaxin Hu Qin Xia Ren Zhu Kang Chen Jie Zhao Yunzhi Yan Ling Chu Dekui He 《Ecology and evolution》2020,10(14):7431-7444
15.
Yoshito Chikaraishi Nanako O. Ogawa Hideyuki Doi Naohiko Ohkouchi 《Ecological Research》2011,26(4):835-844
Compound-specific stable isotope analysis (CSIA) of amino acids is a new method that enables estimates of trophic position
for consumers in food webs. We examined the nitrogen isotopic composition (δ15N) of amino acids of Japanese social insects (three bee, three wasp, and four hornet species) to evaluate the potential of
CSIA of amino acids in studies of terrestrial food webs. For wasps, we also examined samples at different growth stages (ranging
from egg to adult) to assess the effect of metamorphosis on CSIA estimates of trophic position. The δ15N values of bulk tissues for Japanese social insects are only weakly correlated with the biologically expected trophic positions.
In contrast, the trophic positions estimated from the δ15N values of amino acids (yielding values of between 2.0 and 2.3 for bees, between 2.8 and 3.3 for wasps, and between 3.5 and
4.1 for hornets) are consistent with the biologically expected trophic positions for these insects (i.e., 2.0 for bees, 3.0
for wasps, and 3.0–4.0 for hornets). Although large variability is observed among the δ15N values of individual amino acids (e.g., ranging from 3.0 to 14.9‰ for phenylalanine), no significant change is observed
in the trophic position during wasp metamorphosis. Thus, the CSIA of amino acids is a powerful tool for investigating not
only aquatic food webs but also terrestrial food webs with predatory insects. 相似文献
16.
Matthew M. Guzzo G. Douglas Haffner Stuart Sorge Scott A. Rush Aaron T. Fisk 《Hydrobiologia》2011,675(1):41-53
Stable isotopes of carbon (δ13C) and nitrogen (δ15N) often have unique values among lake habitats (e.g. benthic, littoral, pelagic), providing a widely used tool for measuring
the structure and energy flow in aquatic food webs. However, there has been little recognition of the spatial and temporal
variabilities of these isotopes within habitats of aquatic ecosystems. To address this, δ13C and δ15N were measured in seston, zebra mussels (Dreissena polymorpha) and young-of-year (YOY) yellow (Perca flavescens), and white perch (Morone americana) collected from four sites across the offshore habitat of the western basin of Lake Erie during June–September 2009. Values
of δ13C and δ15N showed significant spatial and temporal variations, with month accounting for >50% of the variation, for both stable isotopes
and all the species except seston. Such variation in isotope values has the potential to significantly influence or confound
interpretation of stable isotopes in measures, such as trophic position (TP) which use lower trophic level organisms as their
baseline. For example, TP was found to vary up to 0.7 for yellow and white perch (TP = δ15Nfish − δ15Nzebra mussel/diet-tissue fractionation factor) depending on the zebra mussel data used (e.g., from a different location or a different
collection month). As the use of stable isotopes continues to move from qualitative to more quantitative measures of trophic
structure, food web research must recognize the importance of stable isotopes' variability in lower trophic level organisms,
especially in large lake systems. 相似文献
17.
Food web structure of a shallow eutrophic lake (Lake Taihu,China) assessed by stable isotope analysis 总被引:1,自引:0,他引:1
Lake Taihu is a large, shallow, and eutrophic lake in China. It has provided local communities with valuable fisheries for
centuries, but little is known of the trophodynamics, or of its faunal communities. Carbon and nitrogen isotopic composition
was used to assess its trophic pathways and the food web structure [food sources and trophic levels (TL)]. Basal food sources
were distinguishable based on their δ13C values, ranging from −27.2 to −15.2‰. Consumers were also well separated in δ13C (−26.9 to −17.9‰ for invertebrates and −25.7 to −18.1‰ for fishes), which allowed for an effective discrimination of carbon
sources between these fauna. An average trophic enrichment factor of 3.4‰ was used to calculate the TLs based on δ15N of zooplankton, with results indicating a food web having four TLs. Although δ15N values overlap and cover a large range within trophic compartments, the isotopic signatures of the species assessed revealed
a general trend of 15N enrichment with increasing TL. Stable isotope signatures were also used to establish a general food web scheme in which
five main trophic pathways were analyzed. 相似文献
18.
Trophic patterns of omnivorous freshwater shrimps, Exopalaemon modestus and Macrobrachium nipponensis, were investigated in two shallow eutrophic lakes by using stable isotope analysis. δ15N and δ13C of M. nipponensis and E. modestus increased with increasing body weight, which might be attributed to larger individuals ingesting organisms that feed higher
up the food chain and/or increased assimilation of benthic food items with enriched isotopic signatures. Of the freshwater
shrimps occurring in the studied lakes, those from Lake Taihu had significantly elevated δ15N and δ13C values (4.3‰ and 1.8‰, respectively) compared with those from the less eutrophic Lake Chaohu, indicating that the isotopic
signature might partially reflect the trophic states of their habitats. Mixing model results suggested that the benthic food
web provides the primary carbon source for both shrimp species, and that E. modestus assimilated relatively more pelagic food sources than M. nipponensis in these lakes.
Handling editor: S. Wellekens 相似文献
19.
Trophic ecology of Pacific salmon (<Emphasis Type="Italic">Oncorhynchus</Emphasis> spp.) in the ocean: a synthesis of stable isotope research 总被引:1,自引:0,他引:1
Increasing interest in the marine trophic dynamics of Pacific salmon has been motivated by the recognition of their sensitivity
to changing climate and to the competitive effects of hatchery fish on wild stocks. It has become more common to use stable
isotopes to supplement traditional diet studies of salmon in the ocean; however, there have been no integrated syntheses of
these data to determine whether stable isotope analyses support the existing conventional wisdom of feeding strategies of
the Pacific salmon. We performed a meta-analysis of stable isotope data to examine the extent of trophic partitioning among
five species of Pacific salmon during their marine lives. Pink, sockeye, and chum salmon showed very high overlap in resource
use and there was no consistent evidence for chum relying on alternative food webs dominated by gelatinous zooplankton. δ15N showed that Chinook and coho salmon fed at trophic levels higher than the other three species. In addition, these two species
were distinctly enriched in 13C, suggesting more extensive use of coastal food webs compared to the more depleted (pelagic) signatures of pink, sockeye,
and chum salmon. This paper presents the first synthesis of stable isotope work on Pacific salmon and provides δ15N and δ13C values applicable to research on the fate of the marine derived nutrients these organisms transport to freshwater and riparian
ecosystems. 相似文献
20.
The δ15N trophic enrichment in littoral food webs is not well known despite the importance of macroinvertebrates in lacustrine energy
fluxes. We wanted to assess the influence of functional feeding group (grazer, collector, shredder, predator, predator–hematophagous,
predator–sucker) and spatiotemporal variables (year, month, station of sampling) on littoral macroinvertebrate δ15N signatures. For 2 years, during the plant growth period phytophilous littoral macroinvertebrates were sampled in Lake St.
Pierre, a large fluvial lake of the St. Lawrence River, Québec, Canada. The δ15N analyses showed that station was the most important factor for explaining δ15N variation, followed by sampling month and functional feeding group. The organisms sampled in the stations of the south shore,
which experienced greater macrophyte abundance, slower currents, and stronger NO3 depletion exhibited higher δ15N values than those sampled on the north shore. Grazer-to-predator δ15N enrichment valued 1.6‰, which is inferior to the 3.4‰ generally admitted in food-web research. Shredders exhibited the lowest
δ15N values and predators–hematophagous the highest. δ15N signature of invertebrates increased 3‰ through the summer between May and September. Only samples collected within a short
period should be pooled to avoid an error value equivalent to one trophic level (1.6) enrichment. Furthermore, it is recommended
not to pool macroinvertebrate samples collected at stations with differing watershed land uses. 相似文献