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1.
BMC Res Notes ; 14(1): 347, 2021 Sep 06.
Artículo en Inglés | MEDLINE | ID: mdl-34488867

RESUMEN

OBJECTIVES: Existing information on Arctic marine food web structure is fragmented. Integrating data across research programs is an important strategy for building a baseline understanding of food web structure and function in many Arctic regions. Naturally-occurring stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) measured directly in the tissues of organisms are a commonly-employed method for estimating food web structure. The objective of the current dataset was to synthesize disparate δ15N, and secondarily δ13C, data in the Canadian Beaufort continental shelf region relevant to trophic and ecological studies at the local and pan-Arctic scales. DATA DESCRIPTION: The dataset presented here contains nitrogen and carbon stable isotope ratios (δ15N, δ13C) measured in marine organisms from the Canadian Beaufort continental shelf region between 1983 and 2013, gathered from 27 published and unpublished sources with associated sampling metadata. A total of 1077 entries were collected, summarizing 8859 individual organisms/samples representing 333 taxa across the Arctic food web, from top marine mammal predators to primary producers.


Asunto(s)
Organismos Acuáticos , Nitrógeno , Animales , Regiones Árticas , Canadá , Ecosistema , Cadena Alimentaria , Isótopos de Nitrógeno/análisis
2.
Math Biosci Eng ; 18(5): 5221-5235, 2021 06 11.
Artículo en Inglés | MEDLINE | ID: mdl-34517485

RESUMEN

This paper proposed a fractional-order Holling type-II food chain model. First, we verified the existence, uniqueness, nonnegativity and boundedness of the solution of the model, and some conditions for equilibrium existence and local stability were studied. Second, a controller was proposed, and the Lyapunov method was used to study the global stability of the positive equilibrium point. Finally, numerical simulations were performed to verify the theoretical results.


Asunto(s)
Cadena Alimentaria , Conducta Predatoria , Animales , Alimentos , Modelos Biológicos , Dinámica Poblacional
3.
Nat Commun ; 12(1): 5432, 2021 09 14.
Artículo en Inglés | MEDLINE | ID: mdl-34521825

RESUMEN

The relative importance of evolutionary history and ecology for traits that drive ecosystem processes is poorly understood. Consumers are essential drivers of nutrient cycling on coral reefs, and thus ecosystem productivity. We use nine consumer "chemical traits" associated with nutrient cycling, collected from 1,572 individual coral reef fishes (178 species spanning 41 families) in two biogeographic regions, the Caribbean and Polynesia, to quantify the relative importance of phylogenetic history and ecological context as drivers of chemical trait variation on coral reefs. We find: (1) phylogenetic relatedness is the best predictor of all chemical traits, substantially outweighing the importance of ecological factors thought to be key drivers of these traits, (2) phylogenetic conservatism in chemical traits is greater in the Caribbean than Polynesia, where our data suggests that ecological forces have a greater influence on chemical trait variation, and (3) differences in chemical traits between regions can be explained by differences in nutrient limitation associated with the geologic context of our study locations. Our study provides multiple lines of evidence that phylogeny is a critical determinant of contemporary nutrient dynamics on coral reefs. More broadly our findings highlight the utility of evolutionary history to improve prediction in ecosystem ecology.


Asunto(s)
Antozoos/fisiología , Peces/fisiología , Cadena Alimentaria , Nutrientes/metabolismo , Filogenia , Animales , Evolución Biológica , Ciclo del Carbono/fisiología , Región del Caribe , Arrecifes de Coral , Peces/clasificación , Humanos , Ciclo del Nitrógeno/fisiología , Nutrientes/química , Filogeografía , Polinesia
4.
Math Biosci Eng ; 18(5): 5478-5504, 2021 06 21.
Artículo en Inglés | MEDLINE | ID: mdl-34517497

RESUMEN

In this paper, we propose both deterministic and stochastic predator-prey models with digestion delay, incorporating fear factor and self-defence. For the deterministic model, the existence and stability of the equilibrium are investigated and the occurrence of Hopf bifurcation is studied. For the stochastic model, we investigate the existence of a unique global positive solution of the model and analyze the asymptotic behavior of the global solution around the equilibriums of the deterministic model. Finally, numerical simulations are carried out to verify our analytical results, which indicate that the intensity of white noise, fear factor and self-defence have a significant relationship with the dynamics of the predator-prey model and expand the theoretical analyses.


Asunto(s)
Modelos Biológicos , Conducta Predatoria , Animales , Digestión , Cadena Alimentaria , Dinámica Poblacional
5.
Nat Commun ; 12(1): 5226, 2021 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-34471105

RESUMEN

Marine phytoplankton and zooplankton form the basis of the ocean's food-web, yet the impacts of climate change on their biodiversity are poorly understood. Here, we use an ensemble of species distribution models for a total of 336 phytoplankton and 524 zooplankton species to determine their present and future habitat suitability patterns. For the end of this century, under a high emission scenario, we find an overall increase in plankton species richness driven by ocean warming, and a poleward shift of the species' distributions at a median speed of 35 km/decade. Phytoplankton species richness is projected to increase by more than 16% over most regions except for the Arctic Ocean. In contrast, zooplankton richness is projected to slightly decline in the tropics, but to increase strongly in temperate to subpolar latitudes. In these latitudes, nearly 40% of the phytoplankton and zooplankton assemblages are replaced by poleward shifting species. This implies that climate change threatens the contribution of plankton communities to plankton-mediated ecosystem services such as biological carbon sequestration.


Asunto(s)
Biodiversidad , Calentamiento Global , Biología Marina , Plancton/clasificación , Animales , Regiones Árticas , Cambio Climático , Ecosistema , Cadena Alimentaria , Fitoplancton , Temperatura , Zooplancton
6.
Environ Sci Technol ; 55(18): 12372-12382, 2021 09 21.
Artículo en Inglés | MEDLINE | ID: mdl-34499472

RESUMEN

The presence of microplastics within the gut of animals is well documented. Whether microplastics bioaccumulate in organisms and biomagnify in food webs remains unclear and relies on the ability of microplastics to translocate to other tissues. Here, we demonstrate the widespread presence of microplastics and other anthropogenic microparticles in the gastrointestinal tract, fillet, and livers of seven species of sportfish from Lake Simcoe, Ontario, Canada. Larger fish had a higher microplastic load compared to smaller fish, but the opposite trend was observed with translocated microplastics standardized by fish mass (i.e., smaller fish contained more translocated particles per gram wet weight than larger fish). Moreover, we observed no evidence of biomagnification as there was no significant relationship between the trophic level and total or translocated microplastics per individual. Overall, this suggests that microplastics are translocating, but that excretion of translocated particles or growth dilution may be occurring rather than bioaccumulation and biomagnification. Moreover, the assemblages of shapes and material types varied among tissues, suggesting that particle characteristics may predict biological fate. Our findings highlight the need for further work to understand the mechanisms of microplastic translocation and excretion and the implications for the dynamics of microplastics accumulation in food webs and human exposure.


Asunto(s)
Microplásticos , Contaminantes Químicos del Agua , Animales , Monitoreo del Ambiente , Cadena Alimentaria , Humanos , Ontario , Plásticos , Contaminantes Químicos del Agua/análisis
7.
Oecologia ; 197(2): 485-500, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34480229

RESUMEN

Historically, anthropogenic fixed nitrogen has been purposely increased to benefit food production and global development. One consequence of this increase has been to raise concentrations of nitrogen in aquatic ecosystems. To evaluate whether nitrogen pollution promotes changes in the estimates of niche space of fish communities, we examined 16 sites along a Brazilian river basin highly impacted by anthropogenic activities, especially discharge of domestic and industrial sewage from a region with more than 5 million inhabitants. We analysed the carbon (δ13C) and nitrogen (δ15N) isotope ratios of fish species and both autochthonous (periphyton) and allochthonous (course and fine particulate organic matter) basal food resources. To estimate the magnitude of nitrogen pollution, we measured the nitrate and ammonium concentrations at each site. Sampling was conducted in the dry and wet seasons to evaluate the influence of seasonality. Nitrogen pollution generally increased estimates of niche space, and seasonality influenced only the niche estimates of fish communities from polluted sites. In addition, isotopic analyses of nitrogen polluted sites yielded unrealistic estimates of trophic positioning (detritivores at the top of the food web). We conclude that changes in niche space estimates reflect both alterations in baseline isotopic values and differential trophic behaviour among fishes. Our study suggests that under conditions of high pollution, other factors appear to influence isotopic estimates of niche, such as isotopically distinct sources that have not been sampled, and/or differences in δ15N turnover rates between fish tissue and basal resources, creating isotopic baselines that are challenging to interpret.


Asunto(s)
Ecosistema , Nitrógeno , Animales , Isótopos de Carbono/análisis , Peces , Cadena Alimentaria , Isótopos de Nitrógeno/análisis , Ríos
8.
J Environ Manage ; 300: 113737, 2021 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-34536739

RESUMEN

Persistent Organic Pollutants (POPs) have become a very serious issue for the environment because of their toxicity, resistance to conventional degradation mechanisms, and capacity to bioconcentrate, bioaccumulate and biomagnify. In this review article, the safety, regulatory, and remediation aspects of POPs including aromatic, chlorinated, pesticides, brominated, and fluorinated compounds, are discussed. Industrial and agricultural activities are identified as the main sources of these harmful chemicals, which are released to air, soil and water, impacting on social and economic development of society at a global scale. The main types of POPs are presented, illustrating their effects on wildlife and human beings, as well as the ways in which they contaminate the food chain. Some of the most promising and innovative technologies developed for the removal of POPs from water are discussed, contrasting their advantages and disadvantages with those of more conventional treatment processes. The promising methods presented in this work include bioremediation, advanced oxidation, ionizing radiation, and nanotechnology. Finally, some alternatives to define more efficient approaches to overcome the impacts that POPs cause in the hydric sources are pointed out. These alternatives include the formulation of policies, regulations and custom-made legislation for controlling the use of these pollutants.


Asunto(s)
Contaminantes Ambientales , Plaguicidas , Cadena Alimentaria , Humanos , Contaminantes Orgánicos Persistentes , Plaguicidas/análisis , Suelo
9.
Oecologia ; 197(2): 437-446, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34550444

RESUMEN

Stochasticity in food availability influences vital rates such as survival and fertility. Life-history theory predicts that in long-lived organisms, survival should be buffered against environmental stochasticity showing little temporal variability. Furthermore, to optimize survival prospects, many animal species perform migrations to wintering areas where food availability is larger. Species with large latitudinal distribution ranges may show populations that migrate and others that are resident, and they may co-occur in winter. One example of these species is the predatory raptor buzzard Buteo buteo. Here, we test whether temporal variability in the density of five small mammal species of prey inhabiting different habitats (shrubland and forests) influences local annual survival of buzzards in a wintering area depending on their age and residency status (residents versus wintering individuals). We found that prey density explained a considerable amount of annual changes in local survival, which was higher for older and resident birds. This difference in local survival likely corresponded to philopatry to the wintering area, which was larger for residents and increased when prey density was larger. The total density of prey inhabiting open shrublands was the variable explaining more variance in temporal variability of local survival, even though the study area is mostly occupied by woodlands. Temporal population dynamics of the different small mammals inhabiting shrublands were not synchronous, which suggests that buzzards preyed opportunistically on the most abundant prey each winter. Generalist predation may buffer the impact of resource unpredictability for pulsed and asynchronous prey dynamics, typical of small mammals in winter.


Asunto(s)
Conducta Predatoria , Rapaces , Animales , Aves , Cadena Alimentaria , Dinámica Poblacional , Estaciones del Año
10.
Proc Natl Acad Sci U S A ; 118(39)2021 09 28.
Artículo en Inglés | MEDLINE | ID: mdl-34544855

RESUMEN

Ecological interactions uphold ecosystem structure and functioning. However, as species richness increases, the number of possible interactions rises exponentially. More than 6,000 species of coral reef fishes exist across the world's tropical oceans, resulting in an almost innumerable array of possible trophic interactions. Distilling general patterns in these interactions across different bioregions stands to improve our understanding of the processes that govern coral reef functioning. Here, we show that across bioregions, tropical coral reef food webs exhibit a remarkable congruence in their trophic interactions. Specifically, by compiling and investigating the structure of six coral reef food webs across distinct bioregions, we show that when accounting for consumer size and resource availability, these food webs share more trophic interactions than expected by chance. In addition, coral reef food webs are dominated by dietary specialists, which makes trophic pathways vulnerable to biodiversity loss. Prey partitioning among these specialists is geographically consistent, and this pattern intensifies when weak interactions are disregarded. Our results suggest that energy flows through coral reef communities along broadly comparable trophic pathways. Yet, these critical pathways are maintained by species with narrow, specialized diets, which threatens the existence of coral reef functioning in the face of biodiversity loss.


Asunto(s)
Biodiversidad , Arrecifes de Coral , Dieta , Ecosistema , Peces/fisiología , Cadena Alimentaria , Conducta Predatoria/fisiología , Animales , Biomasa , Peces/clasificación
11.
Nat Commun ; 12(1): 5481, 2021 09 16.
Artículo en Inglés | MEDLINE | ID: mdl-34531395

RESUMEN

A fundamental question in community ecology is the role of predator-prey interactions in food-web stability and species coexistence. Although microbial microcosms offer powerful systems to investigate it, interrogating the environment is much more arduous. Here, we show in a 1-year survey that the obligate predators Bdellovibrio and like organisms (BALOs) can regulate prey populations, possibly in a density-dependent manner, in the naturally complex, species-rich environments of wastewater treatment plants. Abundant as well as rarer prey populations are affected, leading to an oscillating predatory landscape shifting at various temporal scales in which the total population remains stable. Shifts, along with differential prey range, explain co-existence of the numerous predators through niche partitioning. We validate these sequence-based findings using single-cell sorting combined with fluorescent hybridization and community sequencing. Our approach should be applicable for deciphering community interactions in other systems.


Asunto(s)
Bdellovibrio/genética , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN/métodos , Aguas del Alcantarillado/microbiología , Bacterias/clasificación , Bacterias/genética , Bacterias/crecimiento & desarrollo , Bdellovibrio/clasificación , Bdellovibrio/fisiología , Ecosistema , Cadena Alimentaria , Variación Genética , Filogenia , Dinámica Poblacional , Análisis de la Célula Individual/métodos
12.
An Acad Bras Cienc ; 93(suppl 3): e20200778, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34431864

RESUMEN

Studies considering the functional traits of organisms, populations, and communities functional indices increase the understanding of many factors on ecosystem functioning. Here, we analyze the predation effect (by fish) on zooplankton functional diversity and the effects of biomass and density of periphytic algae on zooplankton feeding type trait and body size. We expect that intense predation by fish on zooplankton leads to higher values of zooplankton functional diversity and that food resource will be positively related to the abundance of zooplankton trait and body size. For that, microcosms were established (T1- fish-absence, and T2- fish-presence, both with periphytic algae as food). We observed that fish presence decreased zooplankton functional diversity through modifications in the availability of nutrients and algae, through the middle-out effect. We also observed that body size had a negative relationship with the food resource, reaffirming that high food availability in subtropical lakes is linked to small-bodied zooplankton. The raptorial copepods covariate positively with the periphytic algae, which was an alternative food resource and, in this case, the main form of carbon input into the system. In this study, omnivorous fish reduced zooplankton functional traits, which can alter the energy stock and energy flow in aquatic ecosystems.


Asunto(s)
Conducta Predatoria , Zooplancton , Animales , Ecosistema , Cadena Alimentaria , Fitoplancton
13.
Mar Environ Res ; 170: 105439, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34365122

RESUMEN

Kelps are ecosystem engineers, which collectively form forests that provide a variety of important ecosystem services for humans and other organisms. Kelp forests are threatened by multiple local and global stressors, one of the most notable is herbivory. Overabundant sea; urchins can consume kelp, leading to a phase shift from productive forests to unproductive; rocky barrens. Reducing sea urchin densities by directly removing them can reverse this; phase shift. However, maintaining low densities of sea urchins, is logistically and financially; challenging. Following a review of herbivore exclusion methods to date, we tested the efficacy of three different methods for excluding sea urchins from kelp in the laboratory: flexible fences; electricity; and copper anti-fouling paint. The results from the laboratory; experiment showed that flexible fencing was the most successful method for excluding sea urchins. To test the efficacy of this method in the field, sea urchins were removed from 1m2 patches in barrens and intact kelp beds, and the effectiveness of flexible fences of two different heights (30 cm and 60 cm) at excluding sea urchins were tested. The results from the field study demonstrated that flexible fences of both heights were effective at maintaining low sea urchin densities in barrens but not in intact kelp beds, relative to unmanipulated; rocky barrens. These findings suggest that flexible fencing could be an important tool in restoring kelp in barrens, however the costs of fencing are likely to place limits on the scale at which this management strategy can be implemented.


Asunto(s)
Kelp , Animales , Ecosistema , Cadena Alimentaria , Bosques , Humanos , Erizos de Mar
14.
Mar Environ Res ; 170: 105446, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34418733

RESUMEN

Mercury (Hg) and methylmercury (CH3Hg) are found at trace levels in most marine waters. These species, particularly CH3Hg, then ominously bioaccumulate through marine food chains eventually reaching potentially harmful levels in top oceanic wildlife. Accordingly, it is important to measure and evaluate uptake at environmentally relevant concentrations where trophic transfer initiates; during uptake in primary producers, and consumption by plankton grazers. Experiments using cultured copepods (Acartia tonsa) and field zooplankton assemblages were performed with two different sized diatom species labeled with stable isotopes of inorganic Hg (200Hg) and CH3Hg (CH3199Hg) at different concentrations. We observed size-specific effects on algal uptake and transfer to copepods, in addition to effects of Hg species concentration. Prey size effects were likewise observed on copepod assimilation efficiencies (AE). Average AE of 200Hg for copepods feeding on smaller diatoms was 50%, and 39% for larger diatoms. The AEs were much greater for CH3199Hg, yielding 71% for the smaller and 88% for the larger diatoms. These experiments add evidence demonstrating a significant relationship between Hg and CH3Hg exposure concentration and subsequent algal uptake and transfer to zooplankton. Furthermore, results imply that facilitated uptake of CH3Hg into algae occurs at low (~pM) concentrations, which has been suggested but not confirmed in previous research.


Asunto(s)
Copépodos , Diatomeas , Mercurio , Compuestos de Metilmercurio , Contaminantes Químicos del Agua , Animales , Cadena Alimentaria , Mercurio/análisis , Contaminantes Químicos del Agua/análisis , Zooplancton
15.
Nat Commun ; 12(1): 4716, 2021 08 05.
Artículo en Inglés | MEDLINE | ID: mdl-34354058

RESUMEN

Habitat fragmentation and eutrophication have strong impacts on biodiversity. Metacommunity research demonstrated that reduction in landscape connectivity may cause biodiversity loss in fragmented landscapes. Food-web research addressed how eutrophication can cause local biodiversity declines. However, there is very limited understanding of their cumulative impacts as they could amplify or cancel each other. Our simulations of meta-food-webs show that dispersal and trophic processes interact through two complementary mechanisms. First, the 'rescue effect' maintains local biodiversity by rapid recolonization after a local crash in population densities. Second, the 'drainage effect' stabilizes biodiversity by preventing overshooting of population densities on eutrophic patches. In complex food webs on large spatial networks of habitat patches, these effects yield systematically higher biodiversity in heterogeneous than in homogeneous landscapes. Our meta-food-web approach reveals a strong interaction between habitat fragmentation and eutrophication and provides a mechanistic explanation of how landscape heterogeneity promotes biodiversity.


Asunto(s)
Biodiversidad , Ecosistema , Cadena Alimentaria , Modelos Biológicos , Migración Animal , Animales , Simulación por Computador , Eutrofización , Herbivoria , Recursos Naturales , Plantas , Densidad de Población , Conducta Predatoria
16.
Sci Total Environ ; 790: 148234, 2021 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-34380278

RESUMEN

Designating and managing marine protected areas (MPAs) can mitigate many ocean threats. Banning fishing activities within MPAs enhances the robustness of food-web dynamics and thus increases trophic resilience. Ecosystem function indicators, such as mean trophic level, are increasingly applied in conservation management. Stable isotope analysis is a common tool in trophodynamic studies as it provides information about food sources and trophic level within food webs. In contrast to the traditional top-down approaches in conservation management (mainly for fisheries), this study focuses on bottom-up responses to protection according to the target species in regional small-scale fisheries. The present study aimed to examine how MPA status affects trophodynamics in the rocky reefs of the Illas Atlánticas Marine-Terrestrial National Park (Galicia, NW Spain). Results showed no differences between inside and outside the MPA in species stable isotopic signatures or trophic level. However, these results should be considered with caution due to some limitations in the study design (small number of sites per location, biogeographic differences associated with the island nature of the MPA, or seasonal variability). Nevertheless, the lax fishing management, the lack of proper implementation (the MPA was established in 2002 without a management plan until 2019), and the small size of the studied MPA may result in ineffective conservation outcomes that could have been reflected in the stable isotopic content of the food web. The large number of "paper park" MPAs existing worldwide are not only detrimental to the perception of marine protection, but also provide poor protection of marine ecosystems. Subject to further studies accounting for both environmental and management factors on stable isotope signatures, trophic interactions can form a cost-effective tool for monitoring MPA effectiveness.


Asunto(s)
Conservación de los Recursos Naturales , Ecosistema , Animales , Explotaciones Pesqueras , Peces , Cadena Alimentaria , Isótopos
17.
Chaos ; 31(7): 073124, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-34340359

RESUMEN

The most important issue of concern in a food chain is the stability of species and their nature of persistence against system parameter changes. For understanding the stable dynamics and their response against parameter perturbation, the local stability analysis is an insufficient tool. A global stability analysis by the conventional techniques seems to supplement some of the shortcomings, however, it becomes more challenging for multistable ecosystems. Either of the techniques fails to provide a complete description of the complexity in dynamics that may evolve in the system, especially, when there is any transition between the stable states. A tri-trophic resource-consumer-predator food chain model has been revisited here that shows bistability and transition to monostability via a border collision that leads to a state of predator extinction. Although earlier studies have partially revealed the dynamics of such transitions, we would like to present additional and precise information by analyzing the system from the perspective of basin stability. By drawing different bifurcation diagrams against three important parameters, using different initial conditions, we identify the range of parameter values within which the stability of the states persists and changes to various complex dynamics. We emphasize the changes in the geometry of the basins of attraction and get a quantitative estimate of the nature of relative changes in the area of the basins (basin stability) during the transitions. Furthermore, we demonstrate the presence of a down-up control, in addition to the conventional bottom-up and top-down control phenomena in the food chain. The application of basin stability in food networks will go a long way for accurate analysis of their dynamics.


Asunto(s)
Ecosistema , Cadena Alimentaria , Animales , Modelos Biológicos , Dinámica Poblacional , Conducta Predatoria
18.
Chaos ; 31(7): 073141, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-34340363

RESUMEN

In this article, we derive and analyze a novel predator-prey model with account for maturation delay in predators, ratio dependence, and Holling type III functional response. The analysis of the system's steady states reveals conditions on predation rate, predator growth rate, and maturation time that can result in a prey-only equilibrium or facilitate simultaneous survival of prey and predators in the form of a stable coexistence steady state, or sustain periodic oscillations around this state. Demographic stochasticity in the model is explored by means of deriving a delayed chemical master equation. Using system size expansion, we study the structure of stochastic oscillations around the deterministically stable coexistence state by analyzing the dependence of variance and coherence of stochastic oscillations on system parameters. Numerical simulations of the stochastic model are performed to illustrate stochastic amplification, where individual stochastic realizations can exhibit sustained oscillations in the case, where deterministically the system approaches a stable steady state. These results provide a framework for studying realistic predator-prey systems with Holling type III functional response in the presence of stochasticity, where an important role is played by non-negligible predator maturation delay.


Asunto(s)
Cadena Alimentaria , Modelos Biológicos , Animales , Ecosistema , Dinámica Poblacional , Conducta Predatoria
19.
Nutrients ; 13(7)2021 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-34371918

RESUMEN

Effective actions for the fishery and aquaculture sectors to contribute toward improving nutrition rely on an understanding of the factors influencing fish intake, particularly amongst vulnerable populations. This scoping review synthesises evidence from 33 studies in the African Great Lakes Region to examine the influence of food environments on fish acquisition and consumption. We identified only two studies that explicitly applied a food environment framework and none that linked policy conditions with the contribution of fish to diets. Economic access to fish was represented in the largest number of included studies (21 studies), followed by preferences, acceptability and desirability of fish (17 studies) and availability and physical access (14 studies). Positive perceptions of taste and low cost, relative to other animal-source foods, were drivers of fish purchases in many settings; however, limited physical and economic access were frequently identified as preventing optimal intake. In lakeside communities, fish were increasingly directed toward external markets which reduced the availability and affordability of fish for local households. Few studies considered intra-household variations in fish access according to age, gender or physiological status, which represents an important knowledge gap. There is also scope for future research on seasonal influences on fish access and the design and rigorous evaluation of programmes and policies that address one or more constraints of availability, cost, convenience and preferences.


Asunto(s)
Conducta Alimentaria , Explotaciones Pesqueras , Peces , Abastecimiento de Alimentos , Alimentos Marinos , África del Sur del Sahara , Animales , Explotaciones Pesqueras/economía , Cadena Alimentaria , Abastecimiento de Alimentos/economía , Humanos , Lagos , Valor Nutritivo , Ingesta Diaria Recomendada , Alimentos Marinos/economía , Factores Socioeconómicos
20.
Chemosphere ; 277: 130371, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34384195

RESUMEN

Little is known about the bioaccumulation and trophic transfer of total mercury (THg) and methylmercury (MeHg) via food webs in terrestrial ecosystems, especially in subtropical forest ecosystems. In the present study, THg and MeHg were determined as well as the carbon (δ13C) and nitrogen (δ15N) isotope composition in samples of soils, plants, invertebrates, and songbird feathers to construct food webs in a remote subtropical montane forest in Mt. Ailao, southwest China and assess the bioaccumulation, biomagnification, and trophic transfer of Hg. Results showed that the trophic levels (TLs) of all consumers ranged from 0.8 to 3.3 and followed the order of songbirds > spiders > omnivorous insects > herbivorous insects > plants, and THg and MeHg exhibited a clear biomagnification up the food chain from plants-herbivorous/omnivorous insects-spiders-songbirds. The lowest MeHg concentration was observed in pine needles ranged from 0.104 to 0.949 ng g-1 with only a 1.6% ratio of MeHg to THg (MeHg%), while the highest MeHg concentrations ranged from 425 to 5272 ng g-1 in songbirds with MeHg% values of up to 96%. High values of trophic magnification slope (TMS) for THg (0.22) and MeHg (0.38) were observed in plant-invertebrate-songbird food chain, verifying the significant bioaccumulation of Hg, particularly MeHg, in the remote subtropical forest ecosystem. This study confirmed the production and efficient biomagnification of MeHg in remote subtropical montane forest and the significant bioaccumulation of MeHg in terrestrial top predators.


Asunto(s)
Mercurio , Compuestos de Metilmercurio , Contaminantes Químicos del Agua , Animales , Bioacumulación , China , Ecosistema , Monitoreo del Ambiente , Peces , Cadena Alimentaria , Bosques , Mercurio/análisis , Contaminantes Químicos del Agua/análisis
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