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1.
Elaine S. Fileman Penelope K. Lindeque Rachel A. Harmer Claudia Halsband Angus Atkinson 《Marine Biology》2014,161(11):2479-2494
Meroplankton are seasonally important contributors to the zooplankton, particularly at inshore sites, yet their feeding ecology is poorly known relative to holoplankton. While several studies have measured feeding in decapod larvae, few studies have examined the feeding rates of decapod larvae on natural prey assemblages throughout the reproductive season. We conducted 8 feeding experiments with Necora puber, Liocarcinus spp. and Upogebia spp. zoea larvae collected from the L4 monitoring site off Plymouth (50°15.00′N, 4°13.02′W) during spring–summer 2009 and 2010. This period spanned moderate-to-high food availability (0.5–1.6 µg chl-a L?1), but a great range in food composition with small cells <20 µm dominating in 2010. Daily rations averaged 17, 60 and 22 % of body C for the 3 respective decapod species. Clearance rates differed according to prey type, and all 3 decapod genera showed evidence of selection of dinoflagellates. Importantly, small cells including nano- and pico-plankton were ingested, this being demonstrated independently by flow cytometric analysis of the feeding experiments and molecular analysis. PCR-based analysis of the haptophyte portion of the diet revealed ingestion of Isochrysis galbana by decapod larvae in the bottle incubations and Isochrysis galbana and Phaeocystis globosa by decapod larvae collected directly from the field. This study has shown that pico- and nano-sized plankton form an important supplement to the diverse and variable diet of decapod larvae. 相似文献
2.
J. E. Cartes 《Marine Biology》1993,117(3):449-457
This study examines the feeding habits of Paromola cuvieri (Risso, 1816) and Geryon longipes A. Milne Edwards, 1881, the only two common deep-sea brachyuran crabs inhabiting the bathyal mud assemblages in the Catalan Sea (Western Mediterranean). Samples were obtained by bottom trawls at depths between 360 and 1871 m during 1983 to 1992. Both species had highly diverse diets, but very low feeding activity, as reflected by the high proportion of empty stomachs. Both characteristics may be important factors enabling deepsea crabs to adapt to bathyal zones, where trophic resources are scarce. The most important food items found in P. cuvieri were fish remains (teleost, sharks) and benthic decapods (Monodaeus couchii, Munida tenuimana). Scavenging activity plays an important role in this species. The diet of G. longipes included a broad range of benthic invertebrates. In the upper middle slope, the bivalve Abra longicallus, decapods (Calocaris macandreae and Monodaeus couchii), echinoderms and polychaetes were the dominant prey, with epibenthic peracarids as a secondary resource. On the lower middle slope, the incidence of decapod crustaceans (C. macandreae, Pontiphilus norvegicus) and peracarids in the diet declined. Small macrobenthic prey (glycerids, cumaceans or amphipods) were rare in the diet of both species, in accordance with the large size of the crab specimens studied. The absence of preferred prey items and the lack of food items of an optimum size on the lower slope may contribute to the progressive decline in abundance of P. cuvieri and G. longipes with increasing depth. 相似文献
3.
Large predatory fishes are disproportionately targeted by reef fisheries, but little is known about their trophic ecology, which inhibits understanding of community dynamics and the potential effects of climate change. In this study, stable isotope analyses were used to infer trophic ecology of a guild of large predatory fishes that are targeted by fisheries on the Great Barrier Reef, Australia. Each of four focal predators (Plectropomus leopardus, Plectropomus maculatus, Lethrinus miniatus and Lutjanus carponotatus) was found to have a distinct isotopic signature in terms of δ13C and δ15N. A two-source mixing model (benthic reef-based versus pelagic) indicated that P. leopardus and L. miniatus derive the majority (72 and 62 %, respectively) of their production from planktonic sources, while P. maculatus and L. carponotatus derive the majority (89 and 74 %, respectively) of their production from benthic reef-based sources. This indicates that planktonic production is important for sustaining key species in reef fisheries and highlights the need for a whole-ecosystem approach to fisheries management. Unexpectedly, there was little isotopic niche overlap between three of four focal predators, suggesting that inter-specific competition for prey may be low or absent. δ15Nitrogen indicated that the closely related P. leopardus and P. maculatus are apex predators (trophic level > 4), while δ13C indicated that each species has a different diet and degree of trophic specialisation. In view of these divergent trophic ecologies, each of the four focal predators (and the associated fisheries) are anticipated to be differentially affected by climate-induced disturbances. Thus, the results presented herein provide a useful starting point for precautionary management of exploited predator populations in a changing climate. 相似文献
4.
5.
J. Freire 《Marine Biology》1996,126(2):297-311
The diet of the portunid crab Liocarcinus depurator (L.) in soft-bottom areas of the Ría de Arousa (Galicia, north-west Spain) was studied by analysis of stomach contents, and by comparison of habitats of contrasting abundance, composition and diversity of prey communities. Monthly samples were taken from July 1989 to June 1990 (N=3747) in mussel (Mytilus galloprovincialis) raft-culture areas and central channel zones. Ninety-two food items were identified: crustaceans, molluscs, polychaetes, ophiuroids and fishes were the dominant prey. The raft epifauna and the mussels constituted the dominant group of prey in the raft areas and inner channel station (the epifaunal crab Pisidia longicornis comprised 30 to 52% of the diet), whereas the benthic macroinfauna was the dominant food component in the mid-outer channel (polychaetes constituted 32% of the diet). In the epifaunal community, diet selection for P. longicornis was positive and for amphipods was negative, whereas within the infauna diet selection for bivalves and ophiuroids was positive and for polychaetes negative or neutral. The seasonal importance of P. longicornis and M. galloprovincialis varied in the diet of L. depurator parallel to seasonal activities connected with mussel culture (seeding, thinning, harvesting) that determine the availability of prey from the rafts. Major changes in the composition of the diet related to the life history of L. depurator occurred during ontogeny. In the raft zones, consumption of mussels and fishes increased with increasing body size, while the consumption of Natantia, non-decapod crustaceans, gastropods, polychaetes Pectinariidae and plants decreased with increasing crab size. Maximum consumption of P. longicornis was by L. depurator individuals of intermediate size (15 to 44 mm carapace width). Stomach fullness (measured as dry weight of food) increased with increasing body size, but with negative allometry. During the late pre-moult and early post-moult periods L. depurator did not consume any food; maximum stomach fullness was recorded for the late post-moult and intermoult stages. Female food consumption decreased during egg incubation. Food consumption was greater in autumn and winter than at other seasons; this appears to be related to seasonal changes in reproduction and moulting. 相似文献
6.
Rocío Mariano-Jelicich Florencia Botto Paulina Martinetto Oscar Iribarne Marco Favero 《Marine Biology》2008,155(4):443-450
The degree of individual or gender variation when exploiting food resources is an important aspect in the study of foraging
ecology within a population. Previous information on non-breeding skimmers obtained through conventional methodologies suggested
sex-related differences in prey species. In this study, stable isotope techniques were used to investigate the intraspecific
segregation in diet and foraging habits of the Black Skimmer (Rynchops niger intercedens) at Mar Chiquita Coastal Lagoon (37°40′S, 57°22′W), Argentina. These results were compared with contemporary data on the
trophic composition obtained by conventional methodologies. Blood samples were taken from birds captured with mist-nets during
their non-breeding season. The isotopic signatures of skimmers showed a diet mainly composed of marine prey with some degree
of estuarine fish intake. When comparing diet between sexes, males showed enrichment in 15N compared to females, while no differences were observed in 13C. The use of mixing models revealed differences in the relative composition of prey in the diet of male and female skimmers.
This study highlights stable isotope analysis as a valuable tool to test inter-individual differences and sexual segregation
in trophic ecology of Black Skimmers as compared to conventional methodologies. The results show a trophic segregation in
the Black Skimmer during the non-breeding season that can be explained by differences in prey species and larger prey sizes
of male skimmers. Our findings have significant implications for conservation since any environmental change occurring at
wintering areas might have profound effects on several avian life-history traits, and could be different for males and females
due to trophic segregation. 相似文献
7.
S. Jaquemet M. Potier Y. Cherel J. Kojadinovic P. Bustamante P. Richard T. Catry J. A. Ramos M. Le Corre 《Marine Biology》2008,155(5):505-520
Over 6-million pairs of sooty terns Sterna fuscata breed once a year in the southwest Indian Ocean, mostly on three islands of the Mozambique Channel (Europa, Juan de Nova
and Glorieuses) and in the Seychelles region. Seasonal reproduction in either winter or summer is the dominant strategy in
the area, but non-seasonal reproduction also occurred in some places like at Glorieuses Archipelago. The feeding ecology of
the sooty tern was investigated during the breeding seasons to determine whether terns showed significant differences in their
trophic ecology between locations. Regurgitations were analyzed to describe the diet of individuals when breeding, and stable
isotopes and mercury concentrations were used to temporally integrate over the medium-term of the trophic ecology of both
adults and chicks. Overall, the diet was composed of fish, flying squid and fish larvae in different proportions. At Europa
and Aride in the Seychelles, where winter reproduction occurs, large epipelagic prey like flying fish or squid dominated the
diet. At Juan de Nova, sooty terns reproduce in summer and rely mostly on fish larvae. At Glorieuses (non-seasonal breeding),
the diet was intermediate with fish larvae and flying squid being important prey items. The stable-carbon and nitrogen isotope
values in blood confirm the differences observed in dietary analysis, and demonstrate different feeding strategies between
colonies. δ13C values of feathers showed spatial segregation between birds from the Mozambique Channel and the Seychelles region. Terns
from the Seychelles had also higher δ15N values. Feather δ13C values also suggest a significant shift from summer to wintering habitat for birds from Juan de Nova. This study emphasizes
the high phenotypic plasticity of the species, which may explain its numerical dominance in all tropical waters of the World’s
Ocean. 相似文献
8.
Influence of nutrients in the feeding ecology of seagrass (Posidonia oceanica L.) consumers: a stable isotopes approach 总被引:1,自引:1,他引:0
Nitrogen inputs to coastal environments can considerably alter the abundance of primary producers. However, how herbivores
modify their trophic signatures and adjust to changes in food resource conditions remains controversial. Here, we assess the
effect of nutrient availability on the diet shifts of the two main Mediterranean herbivores, the Sparid fish Sarpa salpa L. and the sea urchin Paracentrotus lividus (Lmk.) that feed mostly on the seagrass Posidonia oceanica L. (Delile), epiphytes and benthic macroalgae. To do this, we (1) investigate the patterns of isotopic composition (δ13C and δ15N signatures) of the two herbivores and their potential food sources in three areas of contrasting nutrient conditions and,
(2) we assess the diet shift along this nutrient gradient by estimating the isotopic nutrient enrichment (i.e., the contribution
of δ13C and δ15N signatures in consumers’ tissues relative to potential food sources). Food web signatures of δ13C were similar among the three study sites, and no patterns of δ13C shift were observed in their diets. In contrast, there was a consistent increase in N contents and δ15N along the nutrient gradient for all primary producers and their consumers. The rate of δ15N enrichment was also clearly distinctive between the two herbivores: in P. lividus it increased by 61% along the nutrient gradient, while in S. salpa it remained constant. Our results suggest that sea urchins behave as facultative omnivores and feed on vegetable or mixed
diets depending on the trophic status of the system. It is unclear, however, if this modification is behavioral or the consequence
of mere changes in the availability of food items, as animal epiphytes (e.g., hydrozoans, bryozoans and ascidians) can also
became more abundant on seagrass leaves under increased nutrient conditions. In contrast, adult fish appear to feed on vegetal
material independent of nutrient availability in the ecosystem. 相似文献
9.
Effects of predation may cascade down the food web. By alleviating interspecific competition among prey, predators may promote biodiversity, but the precise mechanisms of how predators alter competition have remained elusive. Here we report on a predator-exclosure experiment carried out in a tropical intertidal ecosystem, providing evidence for a three-level trophic cascade induced by predation by molluscivore Red Knots (Calidris canutus) that affects pore water biogeochemistry. In the exclosures the knots' favorite prey (Dosinia isocardia) became dominant and reduced the individual growth rate in an alternative prey (Loripes lucinalis). Dosinia, a suspension feeder, consumes suspended particulate organic matter (POM), whereas Loripes is a facultative mixotroph, partly living on metabolites produced by sulfur-oxidizing chemoautotrophic bacteria, but also consuming suspended POM. Reduced sulfide concentrations in the exclosures suggest that, without predation on Dosinia, stronger competition for suspended POM forces Loripes to rely on energy produced by endosymbiotic bacteria, thus leading to an enhanced uptake of sulfide from the surrounding pore water. As sulfide is toxic to most organisms, this competition-induced diet shift by Loripes may detoxify the environment, which in turn may facilitate other species. The inference that predators affect the toxicity of their environment via a multi-level trophic cascade is novel, but we believe it may be a general phenomenon in detritus-based ecosystems. 相似文献
10.
Aaron N. Rice 《Marine Biology》2008,154(2):255-267
Fish feeding behavior results from successful coordination of the fins, jaws, and sensory systems, and the organization of
this behavior may affect the fish’s foraging abilities and trophic ecology. Using quantitative kinematic methods, movements
of the jaws, fins and eyes of Tautoga onitis (Teleostei: Labridae) were analyzed during feeding events. Tautog feeding events consisted of three phases: approach, strike,
and recovery, each defined by a combination of kinematic events. The approach was characterized by changes in fin movements
and in body position, with the eyes directed forward at the food item. The strike began with the onset of jaw opening and
protrusion, then cranial elevation, with the eyes no longer looking at the food item. The end of the strike and the beginning
of the recovery involved a braking maneuver with the pectoral fins; the fish turns and swims away from the original food location
item after prey capture. The coordination performance variables of tautog were quantitatively compared to published data from
closely related cheiline wrasses and parrotfishes, which represent different feeding ecologies within a monophyletic assemblage.
Fishes feeding on molluscs and benthic invertebrates (Cheilinus fasciatus and Tautoga onitis) represented an intermediate coordination condition, with herbivores (the parrotfishes, Scarus quoyi and Sparisoma radians) at one extreme, and fishes feeding on elusive prey (Epibulus insidiator and Oxycheilinus digrammus) at the other extreme. The analysis suggests that the biomechanical demands of coordination for feeding on benthic invertebrates
may represent a generalized, and perhaps ancestral behavior in the wrasses, whereas more specialized trophic niches have evolved
divergent, more specialized demands. Examining the movement and coordination of the jaws, fins, and eyes during fish feeding
provides a detailed mechanistic basis for behavior, and comparison of coordination patterns during feeding among different
taxa can measure how these trophic strategies differ. Understanding the evolution of feeding ecologies in these demersal fishes
may have implications for understanding their role within their shallow water reef community. 相似文献
11.
Within the tropical and subtropical oceans, tuna forage opportunistically on a wide variety of prey. However, little is known
about the trophic ecology of the smallest size classes which play an important role in stock assessments and fisheries management.
The foraging behavior of yellowfin tuna, Thunnus albacares (23.5–154.0 cm FL), collected from nearshore Fish Aggregating Devices (FADs) around Oahu was studied using stable isotope
and stomach contents analyses. Emphasis was placed on small juveniles. Yellowfin tuna changed their diets significantly between
45 and 50 cm forklength (ca. 1.5 kg). Smallest size classes fed on planktonic organisms inhabiting the shallow mixed layer,
primarily larval stomatopod and decapod crustaceans, whereas larger tuna fed on teleosts and adult Oplophorus gracilirostris, a vertically migrating mesopelagic species of shrimp. When interpreting the variation in prey δ
15N values, we considered both their relative trophic position and δ
15N values of the nitrogen at the base of the food web. Based on the distinct diet shift of the yellowfin tuna, demonstrated
by both isotope and stomach content analyses, we propose a critical mass threshold was reached at about 45 cm FL that enabled
sufficient endothermic capability to allow tuna to access prey dwelling in deeper, colder water. These ontogenetic changes
in foraging range and commensurate shift in diet of small tunas would affect their vulnerability to fishing pressure. 相似文献
12.
Victoria González Carman Florencia Botto Esteban Gaitán Diego Albareda Claudio Campagna Hermes Mianzan 《Marine Biology》2014,161(2):339-349
Feeding ecology of juvenile green turtles (Chelonia mydas) was studied from 2008 to 2011 at Samborombón Bay (35°30′–36°30′S, Argentina), combining data on digestive tract examination and stable isotope analysis through a Bayesian mixing model. We found that animal matter, in particular gelatinous plankton, was consumed in large proportions compared to herbivorous food items such as terrestrial plants and macroalgae. This diet is facilitated by the high abundance of gelatinous plankton in the region, thus confirming the adaptive foraging behaviour of the juveniles according to prey abundance in the SW Atlantic. To our knowledge, this is the first study to employ this combination of techniques and to conclusively demonstrate that animal matter, in particular gelatinous plankton, is important in the diet of the neritic green sea turtles. 相似文献
13.
Predation and competition are important biotic interactions influencing populations and communities in marine soft sediments. Sea stars are ubiquitous predators with diverse diets that play functionally important roles in the benthos. In this study, we examined the diet and the ecological roles of three sympatric species of the genus Astropecten (A. aranciacus, A. irregularis pentacanthus and A. platyacanthus). The study was performed between March 2010 and February 2011 on the Maresme coast (northwestern Mediterranean Sea). Results showed that their main diet consisted on gastropods and bivalves, such as Glycymeris glycymeris, Callista chione, Gibbula guttadauri and Cyclope neritea. Food competition between species was avoided by partition of prey resources. Intraspecific differences in the dietary compositions between seasons were found, but not between size classes. Ontogenetic patterns of prey size consumption were recognized in the three species. A large diet overlap was detected between A. aranciacus and A. platyacanthus in winter, due to changes in prey availability. Nevertheless, the analysis of the infaunal community composition and stomach contents indicated that food selection was not associated with prey availability. 相似文献
14.
In many vertebrate radiations, food partitioning among closely related taxa is a key factor in both the maintenance of species
diversity and the process of diversification. We compared diet composition and jaw morphology of 18 New Zealand triplefin
species (F. Tripterygiidae) to examine whether species have diversified along a trophic axis. These fishes predominantly utilised
small, mobile benthic invertebrates, and interspecific differences in diet composition appeared to be mainly attributable
to habitat- or size-dependent feeding behaviour. Although there were differences in the relative size of the bones comprising
the oral jaw apparatus between species, the majority showed an apparatus consistent with a relatively high velocity, low force
jaw movement indicative of a diet of evasive prey. Phylogenetic comparative analyses showed that the evolution of jaw lever
ratios and diet breadth was best explained by a non-directional model in which character changes have occurred randomly and
independent of phylogeny. The mode of diet breadth evolution was gradual and the tempo has not accelerated or slowed down
over time. The mode of evolution for the jaw lever ratios has been gradual for the opening but punctuated for the closing
levers, suggesting that evolutionary changes have occurred rapidly for the latter trait. The tempo of trait evolution for
the jaw opening levers has not accelerated or slowed down over time, while the tempo for the jaw closing levers has accelerated
towards the tips of the tree, which is suggestive of species level adaptation. The lack of phylogenetic signal in diet breadth
and jaw lever ratios appears most likely to be a correlated response to the marked habitat diversification in this group,
and is thus the passive outcome of prey availability in species-specific habitat types. Overall, the trophic ecology of New
Zealand’s triplefin fauna parallels the generalist strategy typical of the family worldwide, suggesting that trophic resource
partitioning has not been an important factor in the evolution of these fishes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
Iain C. Field Corey J. A. Bradshaw John van den Hoff Harry R. Burton Mark A. Hindell 《Marine Biology》2007,150(6):1441-1452
Southern elephant seals are important apex predators in a highly variable and unpredictable marine environment. In the presence
of resource limitation, foraging behaviours evolve to reduce intra-specific competition increasing a species’ overall probability
of successful foraging. We examined the diet of 141 (aged 1–3 years) juvenile southern elephant seals to test the hypotheses
that differences between ages, sexes and seasons in diet structure occur. We described prey species composition for common
squid and fish species and the mean size of cephalopod prey items for these age groups. Three cephalopod species dominated
the stomach samples, Alluroteuthis antarcticus, Histioteuthis eltaninae and Slosarczykovia circumantarcticus. We found age-related differences in both species composition and size of larger prey species that probably relate to ontogenetic
changes in diving ability and haul-out behaviour and prey availability. These changes in foraging behaviour and diet are hypothesised
to reduce intra-specific food competition concomitant with the increase in foraging niche of growing juveniles. 相似文献
16.
Joan Navarro Lourdes López Marta Coll Claudio Barría Raquel Sáez-Liante 《Marine Biology》2014,161(7):1697-1707
Knowing the trophic ecology of marine predators is essential to develop an understanding of their ecological role in ecosystems. Research conducted on deep-sea and threatened shark species is limited. Here, by combining analyses of individual stomach contents and stable isotope values, we examined the trophic ecology (dietary composition and trophic position) of the kitefin shark Dalatias licha, a deep-sea shark considered as near threatened globally and as data deficient in the Mediterranean Sea. Results revealed the importance of small sharks in the diet of the kitefin shark at short- and long-term scales, although fin-fish, crustaceans and cephalopods were also found. Predation on sharks reveals the high trophic position of the kitefin shark within the food web of the western Mediterranean Sea. Stable isotope values from liver and muscle tissues confirmed our results from stomach content analysis and the high trophic position. 相似文献
17.
Júlia Reisser Maíra Proietti Ivan Sazima Paul Kinas Paulo Horta Eduardo Secchi 《Marine Biology》2013,160(12):3169-3179
Feeding ecology of green turtles was investigated between January 2005 and April 2008 at Arvoredo Reserve, Brazil (27°17′S, 48°18′W). Data were obtained through the performance of observational sessions, geo-referenced counts, benthic surveys, capture and recapture of individuals, and oesophageal lavages. This protected area was identified as an important green turtle feeding ground, used year-round by juveniles (curved carapace length = 32–83 cm). Turtles fed close to the rocky shores of the area and selected grazing sites commonly at hard-to-reach, near-vertical portions of the rocks. They were less active in cold months, and more abundant at shallow areas of the reef (0–5 m), where their preferred food items occurred. Their diet was dominated by macroalgae species but invertebrates were also present. Their main food item was the red algae Pterocladiella capillacea, which seems to be eaten through periodical cropping of its tips. Observational methods such as the ones applied here could be incorporated to other research programs aiming to understand the relationships between Chelonia mydas feeding populations and their environment. 相似文献
18.
The feeding ecology of Merluccius hubbsi was investigated in 2 regions of SE Brazil. The major food sources for the hakes were fish, crustaceans, and squid. In the
upwelling system of Cabo Frio, the diet was very similar in the summers of 2001/2002 and spring 2002; fish were the most important
prey followed by crustaceans. In Ubatuba, euphausiids were an important prey during the winter 2001 (100 m), while in the
summer 2002, fish and amphipods predominated in the diet in the shallower site (40 m) and squid in the deeper site (100 m).
The hakes showed temporal differences in stable isotope signatures in both regions, while C:N ratios varied only in Cabo Frio.
δ15N and δ13C (bulk and corrected for lipid content) increased with fish length, which seems to be related to the increasing importance
of fish and decreasing importance of euphausiids and amphipods in the diet of larger hakes. The mean trophic level of 3.7
for M. hubbsi was estimated using δ15N of bivalves as baseline and the fractionation of 3.4‰ between trophic levels. 相似文献
19.
Cephalopod beaks retrieved from stomachs of dead emperor penguin chicks at Pointe Géologie, Terre Adélie, provide information
on taxonomic and size composition of the penguin’s squid diet, on the trophic range of the squid species preyed upon and on
the fractional trophic impact of the penguin on the whole food web. Emperor penguins prey upon four squid species (Psychroteuthis glacialis, Kondakovia longimana, Gonatus antarcticus, Alluroteuthis antarcticus) and do not take squid larger than 480 mm mantle length. Larger squid live either below the penguin’s diving range or are
beyond its handling capacity. Nitrogen stable isotope ratios indicate that squids cover a range of about two trophic levels
(2.5–8‰ δ15N). The impact of the emperor penguin, however, concentrates on the upper part of this range, about 68% of its squid prey
being >6‰ δ15N. The principal components of the emperor’s diet, fish, krill and squid, differ distinctly in average trophic level. Consequently
the trophic position of the emperor penguin changes accordingly with diet composition and may differ by almost one trophic
level between different emperor penguin colonies. 相似文献
20.
We studied the winter dietary characteristics of two sympatric mysid species, Mysis mixta and M. relicta, which exploit both benthic and pelagic habitats during diel vertical migrations. Samples collected before and after the
ice-covered period in the northern Baltic Sea were investigated using both stomach content analyses and stable isotope analyses
of carbon and nitrogen. Both of the mysid species were omnivorous during winter and utilised both benthic and pelagic food
sources. The main food source before the ice period was calanoid copepods (40 and 36% for M. mixta and M. relicta, respectively), and after ice-out calanoid copepods (23%) and zooplankton resting eggs (23%) for M. mixta and diatoms (44%) and calanoids (25%) for M. relicta. Their patterns of food utilisation broadly followed seasonal fluctuations in the abundance of the main prey groups. Although
pelagic food availability is low in winter both mysid species utilised pelagic prey widely. We also show that when combining
these different diet analysis methods it is important to take into account the time lag in isotopic signatures, otherwise
the obtained results do not correspond but instead show the feeding history at different times. 相似文献