Omnivorous Consumers Research Articles

The impact of plant-based product denomination on consumer expectations and sensory perception: A study with vegan chocolate dessert

In recent years, there has been a growing demand for plant-based products from omnivorous consumers seeking a healthier and more sustainable diet, but sensory issues can still impact the consumption experience. Since food denomination and labeling can play a crucial role in consumer expectation and perception, investigating these interactions is essential. Thus, this study investigated the influence of plant-based product denominations on consumer expectations and sensory perceptions. Using descriptive and affective sensory analysis methods, the response of 300 untrained consumers to three variations of product denomination for the same sample of vegan chocolate dessert was evaluated: Vegan Chocolate Mousse (VCM), Chocolate Mousse (CM), and Creamy Coconut Dessert with Cacao (CCDC). The results indicated that the attributes expected by consumers for each denomination did not always correspond to the actual perceptions, particularly in terms of taste and aroma. The attributes highlighted in the consumption expectation varied among the sales denominations, although the perceived attributes did not significantly differ between the names. Furthermore, the addition of the term “vegan” in the name contributed to a greater correspondence between expectation and consumption reality, although the acceptance score did not significantly differ between the denominations. It was also noted that the term “mousse” did not adequately reflect the texture of the products, prompting consumers to suggest replacing the term with “cream.” The study reinforces the importance of transparent and informative labeling strategies to promote the acceptance of plant-based foods, thereby encouraging increased consumption frequency of plant-based analogs by non-restricted diet consumers, resulting in a better consumption experience.

Increasing the appeal of plant-based foods through describing the consumption experience: A data-driven procedure

Global meat consumption is a significant contributor to greenhouse gases emissions and environmental degradation, therefore, shifting diets to plant-based products will help to protect planetary health. However, omnivorous consumers often perceive plant-based products as less tasty and appealing than their meat-based counterparts. Previous research has shown that presenting plant-based dishes in terms of the rewarding aspects of consumption (i.e., with consumption and reward descriptions) can make them more appealing. Here, we report three online studies (using the research platform Prolific) to illustrate and test a systematic, data-driven procedure for generating such consumption and reward descriptions. In Study 1 (N = 653), we asked participants to rate the extent to which various sensory, context, and hedonic features were viewed as positive or negative in relation to 20 savoury dishes. In Study 2 (N = 246), we selected the most positive features from Study 1 and asked participants to rate the fit of these features in relation to 12 novel plant-based dishes. In Study 3 (N = 1,204), we used the features with the highest “fit” scores from Study 2 to examine whether descriptions that incorporated them could increase the appeal and intention to order the same 12 plant-based dishes. As predicted, consumption and reward descriptions led to significantly higher dish appeal and order intentions compared to control descriptions. Consequently, consumption and reward descriptions may help to increase the consumption of plant-based foods, reducing the demand for animal-based products and the associated greenhouse gas emissions and other environmental impacts.

Perception, knowledge, and insights on the Brazilian consumers about nut beverages

ABSTRACT “Plant-based beverages,” “plant-based milk” and “milk alternatives” are terms commonly used to refer to drinks made from plants, such as legumes, cereals, pseudocereals, and nuts. This study aimed to evaluate the perception and consumption of nut-based beverages by Brazilian consumers. An online questionnaire was prepared with socioeconomic and consumption questions and disseminated in digital media following established ethical standards. The almond beverage was the drink most consumed by the respondents and the Brazil nut beverage was the one that most aroused the most interest among the respondents. Nut beverages were elected as the healthiest, most sustainable, and nutritionally best beverages in comparison with soy beverages and cow’s milk. Fruits such as strawberries and bananas were cited as alternatives for flavoring these beverages. Consumers considered the possibility of fully and partially replacing cow’s milk and soy drinks with nut beverages. Interest in these along with plant-based milk was not restricted to the vegan segment, and these products were indicated as having strong potential for inclusion in the diets of omnivorous consumers. More studies on buying, purchase intention, acceptance, knowledge, and neophobia among Brazilian consumers are necessary for the development of these beverages, especially with more representative samples of society.

Omnivorous cultural consumption and the co-creation of cultural products: Interactive versus participatory art

How do omnivorous consumers perceive co-creation in cultural consumption? In this article, we combine observation data on co-created cultural productions, focus groups and field interviews to investigate omnivorous consumers’ perceptions of artistic experiences characterized by different degrees of co-creation. We explored this topic in the context of co-creative theatre, an emergent theatrical genre that provides for the active involvement of omnivorous consumers in the staging of a theatrical performance. Our findings reveal new dimensions of what it means for omnivorous consumers to be culturally open by showing their perceptions of interactive and participatory art, two distinct co-creative artistic experiences. While interactive art encourages consumers to intervene in the artistic experience by following the precise direction of the professional artists on stage, participatory art entails an even more active and autonomous role of consumers in the design of the experience. Our findings indicate that there are differences between the way in which consumers perceive interactive art and participatory art and that two distinct dimensions of cultural consumption – novelty and authenticity – emerge from different co-creative dynamics. The observed co-creation experiences portray the transformation of the omnivorous consumers from spectators or visitors to co-authors of the experience and mark the dissolution of the existing boundaries between production and consumption.

Benthic Invertebrates Abundance and Trophic Links in the Coastal Zone during Cladophora Blooms

The green macroalga Cladophora glomerata, a species typical of brackish water, predominates in most coastal areas of estuarine ecosystems. The present study aimed to determine the current ecological conditions in the Neva estuary (Baltic Sea) when subjected to eutrophication and the summer Cladophora bloom. Macroalgae bloom can result in temporary unfavorable conditions (oxygen depletion and pollution) for invertebrates during macroalgae decomposition, and its contribution to the autochthonous benthic food web remains unclear. We evaluated the Cladophora biomass and the abundance and composition of macro- and meiobenthic invertebrates and traced trophic links in the coastal area of the Neva estuary during the Cladophora bloom. Some species of grazing or omnivorous consumers (nematodes, gastropods, amphipods, insect larvae) reached high abundance in the Cladophora-dominated coastal community. The tracing of food sources in a food chain of the Cladophora-dominated coastal community (macrophytes-grazers-omnivores) were elucidated using dual δ13C and δ15N stable isotope analysis. The results showed that autochthonous organic sources derived from Cladophora at various stages might contribute notably (up to 89%) to the coastal food web, supporting the production of benthic consumers.

Erratum to: Market Work and the Formation of the Omnivorous Consumer Subject

Erratum to: Market Work and the Formation of the Omnivorous Consumer Subject

Just a matter of taste? Understanding rationalizations for dairy consumption and their associations with sensory expectations of plant-based milk alternatives

Although knowledge surrounding the obstacles omnivorous consumers face when substituting meat products with plant-based alternatives has increased dramatically, less is known about their perspectives on plant-based alternatives to dairy products. Here, these perspectives are assessed in two survey-based studies. Study 1 (N = 175) adapts an existing scale (the 4Ns of meat consumption) to dairy products in an effort to identify similarities and differences between rationalizations for meat and dairy consumption. This 16-item scale quantifies four factors (Natural, Necessary, Normal, and Nice) describing common rationalizations for meat consumption. The results revealed that the 4Ns transfer well to the dairy category, and that endorsement of dairy products as Nice was the strongest predictor of dairy consumption, relative to the other 3Ns. This is further supported by evaluation of consumers’ own qualitative descriptions of why they do or do not consume meat/dairy products, where “taste” was the most frequently used word in both categories. Study 2 replicates the relationships between dairy 4Ns scores and reported dairy consumption found in Study 1 and builds upon these results by showing that 4N score could accurately categorize consumers as frequent (N = 192) or infrequent (N = 210) consumers of plant-based milk alternatives (PBMAs). Differences in consumers’ expectations for the sensory characteristics of cow’s milk and PBMAs are identified, and the impact of rationalization (total 4N score) on the likelihood of expected sensory attribute associations is described. The role of rationalization in shaping sensory expectations and impacting dietary choices, in particular resistance to adopting PBMAs, is discussed.

Coastal hypoxia reduces trophic resource coupling and alters niche characteristics of an ecologically dominant omnivore

Energy and biomass move through a variety of trophic pathways in coastal ecosystems, with pelagic and benthic pathways often dominating food web dynamics. Consumers that couple these pathways play important structuring roles in these food webs by integrating spatially disconnected or asynchronous production pathways. The objective of this study was to quantify benthic and pelagic trophic pathway contributions to the diet of the mysid Neomysis americana in the Choptank and Patuxent rivers (tributaries of Chesapeake Bay) and determine if the relative contribution of these two trophic pathways differs between ecosystems with different environmental, physical, and watershed features. This mysid species undergoes daily vertical migrations throughout the water column and it was hypothesized that hypoxia (< 2 mg/L) in deep-water habitats of the Patuxent River (but not the Choptank) could reduce the importance of the benthic pathway for mysids in the Patuxent River relative to the Choptank River. Mysids and trophic resources were collected in each river during the summers of 2018 and 2019 and analyzed for carbon and nitrogen stable isotope composition and tissue stoichiometry (C:N). Stable-isotope based estimates of benthic trophic pathway contribution, trophic position, and isotopic niche area (proxy for trophic niche) and C:N composition of N. americana were compared within and between tributaries. Overall, mysids in the Patuxent River assimilated less benthic material, realized lower trophic positions, and had lower C:N ratios (proxy for lipid content) than Choptank River mysids. No consistent pattern in trophic niche area was observed although niche area (and pelagic trophic pathway contribution) of Choptank River mysids increased during a high river discharge event. This study provides evidence that hypoxic conditions in the Patuxent reduced the strength of benthic-pelagic coupling by N. americana and, further, is associated with lower trophic position and a reduced stoichiometric marker of lipid storage. In addition to their role as omnivorous consumers, N. americana are a dominant prey taxon for many predators, underscoring the importance of this species to local food webs and the potential for bottom-up effects on the dynamics of coastal ecosystems in response to changes in their trophic ecology.

Market Work and the Formation of the Omnivorous Consumer Subject

Abstract Omnivorousness is the tendency of culturally and economically privileged individuals to consume both highbrow and lowbrow products. Prior research explores omnivorousness as a manifestation of status distinction in which consumers deploy the aesthetic disposition—a generic and transposable ability to appreciate cultural products through a formal gaze—to lowbrow options. Existing work emphasizes the acquisition of the aesthetic disposition, but it does not explain how consumers transpose their generic disposition to specific cultural contexts and develop omnivorous tastes. Therefore, we study the formation of omnivorous consumer subjects and highlight its enabling conditions. Building on a 7-year ethnography of coffee consumption in France, we find that omnivorous subjects develop a dual and flexible cultural competence. First, they acquire a common appreciation of coffee during their primary socialization and enjoy the energizing and socializing functions of lowbrow coffee. Then, they develop a formal appreciation of coffee later in life as a result of market work conducted by market professionals. Specifically, market professionals do three types of market work: qualification, captation, and activation. Consumers respond to market work by transposing their aesthetic disposition to highbrow coffee and, therefore, enjoy its formal characteristics. We extend prior research on taste, omnivorousness, and consumer subject formation.

The cost of healthier and more sustainable food choices: Do plant-based consumers spend more on food?

Plant-based diets are often promoted as healthier and more sustainable and thus as a mechanism to achieve the targets proposed to mitigate climate change and noncommunicable diseases. However, plant-based diets can be perceived as more expensive than the common omnivorous diets, when considering the expensive novel meat substitutes and also the higher costs of fruits and vegetables, whose consumption is perceived to increase. Therefore, the present study assesses the question: Do plant-based consumers spend more on food compared to omnivorous consumers? Based on primary data (n = 1040) collected through an online survey, representative of the Portuguese population, through logistic regressions, it was possible to conclude that plant-based consumers, particularly vegan, are associated with lower food expenditures compared to omnivorous consumers. In fact, plant-based consumers are shown to spend less than all other consumers assessed. Food policies aligning healthiness and sustainability with affordability can deliver a major boost for the promotion of plant-based diets and help achieve the mitigation targets proposed.

Meat replacer? No thanks! The clash between naturalness and processing: An explorative study of the perception of plant-based foods

A shift towards a plant-based diet is desired to promote sustainability, improve health, and minimize animal suffering. However, many consumers are not willing to make such a transition, because of attachment to meat and unwillingness to change habits. The present work explored the perception of Norwegian and French consumers' attitudes, barriers and opportunities to increase the likelihood of a shift in diet. Three creative focus groups (CFGs), using interactive tasks such as photo-collage, projective mapping, story completion and third person technique, were run with omnivorous adult consumers in each country. CFGs gathers undirected feedback, providing less biased responses than other exploration methods, related to e.g. social norms. In both countries, results were in general lines comparable. Nutritional knowledge was low regarding vegetable proteins; familiar sources of protein were mostly animal. There is a strong gap between respondents’ desired behaviour (balancing nutrition, eating less meat) and their actual behaviour: meat is very important, and the menu is often organized around it. Consumers are curious about vegetable sources of protein, but major constraints were hedonics in France, and convenience in Norway. The main barrier to a shift in diet is the lack of knowledge on how to prepare plant-based meals. Many participants find a conflict between health & sustainability in industrial products, perceiving them as highly processed and suggesting that meat replacers might not be a straightforward way to drive omnivorous consumers to shift to a more plant-based diet.

基于高通量测序的象山港海域黑鲷(Acanthopagrus schlegelii)食性分析

PDF HTML阅读 XML下载 导出引用 引用提醒 基于高通量测序的象山港海域黑鲷(Acanthopagrus schlegelii)食性分析 DOI: 10.5846/stxb201911022308 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中国水产科学研究院基本科研业务费（2019ZD1102）；国家公益性行业（农业）科研专项经费项目（201303047）；上海市自然科学基金项目（17ZR1439500） Diet composition and feeding habits of black sea bream (Acanthopagrus schlegelii) in Xiangshan Bay based on high-throughput sequencing Author: Affiliation: Fund Project: the Special Scientifi c Research Funds for Central Non-profi t Institutes, Chinese Academy of Fishery Sciences (project no.2019ZD1102)；National Special Research Fund for Non-Profit Sector (Agriculture)(project no.201303047)；the Natural Science Foundation of Shanghai City (project no. 17ZR1439500) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:选取象山港黑鲷个体为研究对象，以18S rDNA为靶标，利用Illumina Miseq高通量测序方法研究黑鲷饵料生物组成特征，分析不同龄组黑鲷的食性异同。通过序列比对，共在黑鲷胃含物中鉴定出41个属中的62种饵料生物，分属9个门，其中节肢动物门（Arthropoda）、绿藻门（Chlorophyta）和软体动物门（Mollusca）是黑鲷饵料生物的优势组成门类。从饵料生物相对丰度和出现频率上分析，石莼（Ulva lactuca）、熊本牡蛎（Crassostrea sikamea）、胸刺水蚤（Centropages hamatus）、日本蟳（Charybdis japonica）、毛蚶（Scapharca subcrenata）和褐菖鲉（Sebastiscus marmoratus）是黑鲷的优势饵料物种，所占饵料生物总相对丰度的比重达60.90%。相似性分析检验（ANOSIM）结果显示：1至4龄黑鲷个体的饵料生物组成不存在显著性差异。与传统食性分析方法相比，高通量测序法在黑鲷饵料生物检测灵敏性上显现了较为明显的优势，保障黑鲷等重要物种的种群稳定对于该海域具有重要的生态和经济意义。 Abstract:Xiangshan Bay is a semi-closed bay in the central coast of Zhejiang Province, China. It is also a centralized distribution area of various fishery resources, and many economic fish species breeding there every year. However, due to long-term overfishing, ocean development and environmental pollution, deterioration of ecological environment was found in this sea area, which also caused the increasingly recession of local fishery resources. In recent years, after fishery resources conservation, fishery resources in this water have been restored. It also provides a good habitat for reef-loving species such as the black sea bream Acanthopagrus schlegelii. A. schlegelii is an important fish species targeted by recreational and commercial fisheries in Xiangshan Bay. Maintaining population stability of this species is economically and ecologically important for the embayment. Knowledge of the feeding ecology is of great value for conservation strategies, as it is thoroughly linked to subjects such as resource partitioning, habitat preferences, prey selection, predation, competition and energy transfer within and between ecosystems. However, relatively little work has been done on this aspect in A. schlegelii. In this study, 21 individuals of A. schlegelii were collected in Xiangshan Bay, and diet composition and feeding habits were analyzed by high-throughput sequencing methods targeting 18S rDNA gene. By Illumina high-throughput sequencing, 913,254 target fragments with length of about 420 bp were obtained. The minimum sequence number of samples was 30,826, while the maximum one was 52,374. A total of 554 OTU (operational taxonomic units) were obtained from 21 samples after clustering. And 62 species in 9 categories were identified in the stomach contents of this species after sequence alignment, in which Mollusca, Arthropoda and Chlorophyta exhibited the highest abundance, followed by Chordata, Platyhelminthes, Bacillariophyta and Annelida. Ulva lactuca, Crassostrea sikamea, Centropages hamatus, Charybdis japonica, Scapharca subcrenata and Sebastiscus marmoratus were dominant prey items for A. schlegelii in Xiangshan Bay. The above prey items accounted for 60.90% of the total abundance of gastric contents. In addition, a number of species, including Caprella scaura, Oithona sp., Melosira sp., Cyclotella sp., Chlorella stigmatophora, Picochlorum sp., Torodinium robustum, and Chromadorina sp., with quite low abundance were also detected. These prey items were distributed in different ecological communities, including macroalgae, shellfish, zooplankton, phytoplankton, macrozoobenthos, fish, and crab. These data suggests that A. schlegelii is a relatively large omnivorous consumer. Result from the analysis of similarities (ANOSIM) showed no significant difference in diet composition for fish among different age groups. This indicates that A. schlegelii did not alter feeding habits after 1 year old. Considering the limited sample size, however, further studies are still needed to address this conclusion. Compared with the traditional analysis methods, high-throughput sequencing has the characteristics of less sample demand, less workload, and more species detection. Meanwhile, due to its sensitivity, some species with low abundance that could not be found by traditional methods can also be detected. Hence, high-throughput sequencing technology has obvious advantages in fish diet studies and can provide strong support for marine organisms feeding and ecological studies. 参考文献 相似文献 引证文献

The diet of Macrogenioglottus alipioi Carvalho, 1946 (Anura: Odontophrynidae) tadpoles in Atlantic Forest of southern Bahia, Brazil

ABSTRACT Understanding the diet of tadpoles is fundamental to explain their ecological roles in aquatic food webs, as well as to allow more effective amphibian conservation and management programs. Studies on trophic ecology of tadpoles are scarce compared to other vertebrate groups, a gap that is even more accentuated in the Neotropical region, which harbors the greatest diversity of anuran species worldwide. The objective of this study was to describe the diet of the tadpole of Macrogenioglottus alipioi, from a population in southern Bahia, Brazil. Gut contents of 30 tadpoles were analyzed under light microscope. Additionally, the intestinal contents of 15 tadpoles were analyzed under a stereoscopic microscope to verify the presence of larger food items such as macroinvertebrates. Algae were the most important microscopic food item in the diet of M. alipioi tadpoles. Mites occurred in 80% of the analyzed specimens and represented the most important macroscopic food source, followed by insect fragments from dipterans, lepidopterans and spiders. The tadpoles of M. alipioi can be considered omnivorous consumers. As in benthic tadpoles from other species, diatoms, protozoans and small metazoans are considered important food sources in the diet of tadpoles. Additionally, the analysis of gut contents under a stereoscopic microscope identified several food items that were not recorded by analyses performed under light microscope.

Feeding Ecology of Sicydium bustamantei (Greeff 1884, Gobiidae) Post-Larvae: The “Little Fish” of São Tomé Island

The rivers of São Tomé Island are colonized by Sicydium bustamantei (Greeff 1882), an amphidromous fish that spawns in those areas. After hatching, larvae drift to the ocean with the river flow. In the marine realm, the planktonic larvae develop and migrate to freshwater as post-larvae. The migrations of post-larvae support important local fisheries at the mouth of rivers in tropical volcanic islands. Amphidromous post-larvae rely on plankton as their main source of organic matter. However, the biology and ecology of S. bustamantei in the West African islands are understudied, despite its importance for local fisheries. Thus, this study aimed to start bridging this gap by studying its feeding ecology. Our objectives were to identify the main prey of S. bustamantei post-larvae, combining gut content with stable isotope analyses. The gut contents included zooplankton (Chaetognatha, Ostracoda, and unidentified crustaceans), debris from plant and/or macroalgae-derived material, and microplastics (including microfibers). The stable isotopes analysis indicated that zooplankton and macroalgae detritus were the main sources of organic matter assimilated by this species. We also demonstrated that S. bustamantei post-larvae are omnivorous and secondary consumers. These data provide pioneering information that can be used in management plans that still need to be developed.

Comparing methods for predicting the impacts of invasive species

With the accelerating spread of invasive species around the globe, there is an urgent need to predict where invaders are likely to have the largest impacts and what those impacts will be. Predicting the impacts of individual invasive species a priori has proven to be a problematic endeavor, and several possible methods for doing this have been proposed. In this study we use a model system to compare the different predictive methods that have been proposed to determine which provides the most accurate predictions. Community composition in this system was measured at two separate sites in the Gulf of Maine 20 years ago, just before the arrival of the invasive Asian shore crab Hemigrapsus sanguineus. We repeated the community assessment at each site and determined the overall impacts of this invader over the last two decades. We then predicted the likely impacts based on the historical community composition using 3 methods: the invasion history of this species at sites further south along the mid-Atlantic, scaling up per capita consumption rates that have been measured on individual species in the recipient community, and using mesocosm experiments that used a range of experimental approaches. We show that the invader has had clear, but moderate impacts on the invaded sites since its arrival. We further show that for this omnivorous consumer, predictions based on invasion history and on long term field mesocosm experiments performed much better than predictions based on scaling up from consumption on individual species or based on short term mesocosm experiments conducted in the lab or field. These results highlight potential biases that can be produced by some mesocosm approaches and by scaling up from per capita consumption on individual prey species measured in isolation to predict consumer impacts under more natural conditions.

Experimentally derived incorporation rates and diet-to-tissue discrimination values for carbon and nitrogen stable isotopes in gray wolves (Canis lupus) fed a marine diet

Recent studies have noted the differential effects of marine versus terrestrial diets on the carbon and nitrogen stable isotope (13C and 15N, respectively) diet-to-tissue discrimination values and incorporation rates for omnivorous and carnivorous mammals. Inaccurate estimates of these parameters may result in misrepresentation of diet composition or in the timing of diet shifts. Here, we present the results of a diet-switch experiment designed to estimate diet-to-tissue discrimination values and incorporation rates for tissues of gray wolves (Canis lupus Linnaeus, 1758) fed a diet of Pacific salmon (genus Oncorhynchus Suckley, 1861). Our results demonstrate substantial differences in both parameters between wolves maintained on a marine (salmon) diet and wolves maintained on terrestrially sourced prey (beef, Bos taurus Linnaeus, 1758). Increased awareness of the significance of marine resources to omnivorous and carnivorous consumers, like wolves, highlights the importance of phenomenological and mechanistic understandings of the effects of fish and other marine prey on dietary investigations based on stable isotopes.

Calanoid copepod grazing affects plankton size structure and composition in a deep, large lake

Abstract Cultural oligotrophication is expected to shift lake zooplankton to become dominated by calanoid copepods. Hence, understanding the influence of calanoids on the taxonomic and size structure of the lower plankton food web is crucial for predicting the effects of oligotrophication on energy fluxes in these systems. We studied the effect of an omnivorous calanoid, Eudiaptomus gracilis, on the lower planktonic food web using an in situ incubation approach in large and deep Lake Constance. We show that E. gracilis significantly reduced ciliate, phytoplankton, rotifer, but increased bacteria biovolume. Highest clearance rates were observed for ciliates whose biovolume declines may have caused a release of predation pressure on bacteria. E. gracilis grazing shifted the size structure of the phytoplankton community by reducing mean phytoplankton cell size (directional selection) and simultaneously increasing cell size variance (disruptive selection). Ciliate cell sizes experienced a similar selective regime in one of the experiments, whereas in the other two experiments, no change of size structure was detected. Results suggest strong influences of E. gracilis grazing on the lower plankton food web and a significant shift in phytoplankton size structure. For evaluating detailed effects of omnivorous consumers on plankton size structure, cascading interactions need to be considered.

Environmental constraint of intraguild predation: Inorganic turbidity modulates omnivory in fairy shrimps

Abstract Omnivory is widespread in food webs, with an important stabilising effect. The strength of omnivorous trophic interactions may change considerably with changes in the local environment. Shallow temporary waters are often characterised by high levels of inorganic turbidity that may directly limit the food uptake of filter‐feeding organisms, but there is little evidence on how it might affect omnivorous species. Anostracans are key species of temporary waters and recent evidence suggests that these organisms are omnivorous consumers of both phyto‐ and zooplankton. Using Branchinecta orientalis as a model species, our aim was to test how turbidity affects the feeding of an omnivorous anostracan. To do this, we used short‐term feeding experiments and stable isotope analyses, with animals collected from soda pans in eastern Austria. In the feeding experiments, algae and zooplankton were offered as food either separately or in combination. The prey type treatments were crossed with turbidity levels in a factorial design. There was a pronounced decrease in the ingested algal biomass with increasing turbidity. Conversely, ingestion rates on zooplankton were less affected by turbidity. Stable isotope analyses from field material supported our experimental results by showing a positive relationship of the trophic position of anostracans and the trophic niche of the communities with turbidity. Our results show that turbidity modulates the intraguild trophic relationship between anostracans and their prey by shifting the diet of anostracans from more herbivorous in transparent to more carnivorous in turbid waters. Thus, inorganic turbidity might also have a community‐shaping role in plankton communities of temporary waters through altering trophic relationships.

Increased sea ice cover alters food web structure in East Antarctica

In recent years, sea ice cover along coasts of East Antarctica has tended to increase. To understand ecological implications of these environmental changes, we studied benthic food web structure on the coasts of Adélie Land during an event of unusually high sea ice cover (i.e. two successive austral summers without seasonal breakup). We used integrative trophic markers (stable isotope ratios of carbon, nitrogen and sulfur) to build ecological models and explored feeding habits of macroinvertebrates. In total, 28 taxa spanning most present animal groups and functional guilds were investigated. Our results indicate that the absence of seasonal sea ice breakup deeply influenced benthic food webs. Sympagic algae dominated the diet of many key consumers, and the trophic levels of invertebrates were low, suggesting omnivore consumers did not rely much on predation and/or scavenging. Our results provide insights about how Antarctic benthic consumers, which typically live in an extremely stable environment, might adapt their feeding habits in response to sudden changes in environmental conditions and trophic resource availability. They also show that local and/or global trends of sea ice increase in Antarctica have the potential to cause drastic changes in food web structure, and therefore to impact benthic communities.

Aquatic omnivores shift their trophic position towards increased plant consumption as plant stoichiometry becomes more similar to their body stoichiometry.

Human induced eutrophication has strongly altered aquatic ecosystems. With increasing eutrophication, plant nutrient concentrations increase, making them more attractive as food for herbivores. However, most aquatic consumers are omnivorous. Ecological stoichiometry theory predicts that animals prefer to consume food which has a similar nutrient (N and P) composition or C:nutrient ratio compared to their own bodies, hence omnivorous animals may prefer to eat animal prey instead of plants. We asked whether aquatic omnivores would shift their diet towards more plant consumption when plants are more nutritious and their stoichiometry becomes more similar to the stoichiometry of the omnivore. We hypothesized that: (1) the omnivore increases plant consumption as the plant C:nutrient ratio decreases when there is only plant material available; (2) the omnivore generally prefers animal food over plant material; (3) the omnivore will increase its relative plant consumption as the plant C:nutrient ratio decreases, in the presence of animal food. As a model system, we used the pond snail Lymnaea stagnalis (omnivorous consumer), the aquatic plant Potamogeton lucens (plant food to the consumer, cultured at different nutrient regimes to obtain different plant C:nutrient ratios), and the crustacean Gammarus pulex (animal food to the consumer, using freshly dead individuals). When there was only plant material available, the consumers increased their relative consumption rate with decreasing plant C:nutrient ratio from no measurable amount to about 102 mg g-1 day-1. When plant material was offered simultaneously with animal food, even though the omnivores always preferred animal food over plant material, the omnivores still increased their relative intake of plant material as plant C:nutrient ratio decreased, from virtually nothing at the highest to on average 16% of their diet at the lowest plant C:nutrient ratio, with a maximum of 28%. Therefore, we conclude that as nutrient loading increases in aquatic ecosystems, plant-eating omnivorous animals may shift their trophic position towards increased plant consumption and alter the food web structure. As a result, we may observe increased top-down control on aquatic plants.