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1.
Rev Environ Contam Toxicol ; 252: 51-96, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31286265

RESUMO

In the past two decades, increased production and usage of metallic nanoparticles (NPs) have inevitably increased their discharge into the different compartments of the environment, which ultimately paved the way for their uptake and accumulation in various trophic levels of the food chain. Due to these issues, several questions have been raised on the usage of NPs in everyday life and have become a matter of public health concern. Among the metallic NPs, Cu-based NPs have gained popularity due to their cost-effectiveness and multifarious promising uses. Several studies in the past represented the phytotoxicity of Cu-based NPs on plants. However, comprehensive knowledge is still lacking. Additionally, the impact of Cu-based NPs on soil organisms such as agriculturally important microbes, fungi, mycorrhiza, nematode, and earthworms is poorly studied. This review article critically analyses the literature data to achieve a more comprehensive knowledge on the toxicological profile of Cu-based NPs and increase our understanding of the effects of Cu-based NPs on aquatic and terrestrial plants as well as on soil microbial communities. The underlying mechanism of biotransformation of Cu-based NPs and the process of their penetration into plants have also been discussed herein. Overall, this review could provide valuable information to design rules and regulations for the safe disposal of Cu-based NPs into a sustainable environment.


Assuntos
Cobre , Poluentes Ambientais , Nanopartículas Metálicas , Animais , Cadeia Alimentar , Oligoquetos , Solo
2.
Adv Mar Biol ; 83: 61-114, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31606070

RESUMO

Feeding studies, since traditional stomach content analysis to stable isotopes analyses, provides insights into the trophic relationship among the apex predators and the ecosystems they inhabit. The Pacific Coast of Mexico (PCM) is inhabited by 62 known species (or 12%) of living sharks, which belong to 21 families and 34 genera. We divide the Pacific Coast of Mexico (PCM) into four regions for consideration: (1) the western coast of Baja California (WcBJ), (2) the Gulf of California (GC), (3) the Central Pacific Mexican (CPM), and (4) the Gulf of Tehuantepec (GT). Biodiversity is highest in the GC, with 48 shark species, followed by the WcBJ with 44 species, then the CPM with 28 species and the GT with 26 species. Few large species (>2m in total length) function as top predators in any region, with a greater number of smaller shark species (<1.5m total length). Information about the trophic ecology of different shark species is included to know the ecological role and position of each shark species within a food web to understand the dynamics of marine communities and the impact that each species has on trophic net, which is critical to effective resource conservation and responsible exploitation. The different shark species predate mainly on coastal or oceanic waters. The coastal sharks feed mainly on crustaceans and small fishes; whereas the oceanic species predate mainly on squids and fishes from mesopelagic to epipelagic habits. Also is included a summary of the IUCN Red List category assigned to all shark species from the Mexican Pacific. Thirty-one percent (19 species) of sharks in the Mexican Pacific are considered as threatened (Critically Endangered, Endangered or Vulnerable). Of these, 4.9% (3 species) are Endangered and 26.2% (15 species) are Vulnerable. In addition, since 2012 the fishing of shark and rays has been closed between 1 May and 31 July in the Mexican Pacific as a conservative management measure.


Assuntos
Conservação dos Recursos Naturais , Ecossistema , Cadeia Alimentar , Tubarões/fisiologia , Animais , México , Oceano Pacífico , Comportamento Predatório , Tubarões/classificação
3.
Oecologia ; 191(2): 411-420, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31501977

RESUMO

Free-living parasite infectious stages, such as the cercariae of trematodes (flatworms), can represent substantial biomass in aquatic ecosystems, yet their interactions with other planktonic fauna are poorly understood. Given that cercariae are consumed by various aquatic predators, sometimes even preferentially over zooplankton, their presence may decrease predation pressure on free-living organisms within similar trophic niches by serving as alternate prey. Here, we experimentally examined how the presence of cercariae (Plagiorchis sp.) affected the population dynamics of common freshwater zooplankton (Daphnia sp.) in the presence of a predator (the larval dragonfly, Leucorrhinia intacta) known to consume both. After seeding 48 mesocosms with starting populations of Daphnia, we used four treatments (12 replicates each) representing a factorial combination of the absence/presence of both cercariae and dragonfly larvae and tracked Daphnia populations over 4 weeks. We found a significant interaction between the presence of cercariae and predators on Daphnia population size. When faced with predation pressure, Daphnia reached ~ 50% higher numbers when accompanied by cercariae than without, suggesting a "protective" effect of the latter by acting as substitute prey. Within aquatic ecosystems, an abundance of trematodes may prove advantageous for zooplankton communities that share common predators, but further studies will be needed to determine how this varies depending on the predator, trematode, and zooplankton taxa involved.


Assuntos
Odonatos , Parasitos , Animais , Ecossistema , Cadeia Alimentar , Comportamento Predatório , Zooplâncton
4.
Ecol Lett ; 22(11): 1734-1745, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31389145

RESUMO

The foraging behaviour of species determines their diet and, therefore, also emergent food-web structure. Optimal foraging theory (OFT) has previously been applied to understand the emergence of food-web structure through a consumer-centric consideration of diet choice. However, the resource-centric viewpoint, where species adjust their behaviour to reduce the risk of predation, has not been considered. We develop a mechanistic model that merges metabolic theory with OFT to incorporate the effect of predation risk on diet choice to assemble food webs. This 'predation-risk-compromise' (PR) model better captures the nestedness and modularity of empirical food webs relative to the classical optimal foraging model. Specifically, compared with optimal foraging alone, risk-mitigated foraging leads to more-nested but less-modular webs by broadening the diet of consumers at intermediate trophic levels. Thus, predation risk significantly affects food-web structure by constraining species' ability to forage optimally, and needs to be considered in future work.


Assuntos
Cadeia Alimentar , Modelos Biológicos , Animais , Dieta , Comportamento Predatório
5.
Ecol Lett ; 22(11): 1828-1837, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31392829

RESUMO

Metacommunity theory suggests that dispersal is a key driver of diversity and ecosystem functioning in changing environments. The capacity of dispersal to mitigate effects of environmental change might vary among trophic groups, potentially resulting in changes in trophic interactions and food web structure. In a mesocosm experiment, we compared the compositional response of bacteria, phyto- and zooplankton to a factorial manipulation of acidification and dispersal. We found that the buffering capacity of dispersal varied among trophic groups: dispersal alleviated the negative effect of acidification on phytoplankton diversity mid-experiment, but had no effect on the diversity of zooplankton and bacteria. Likewise, trophic groups differed in whether dispersal facilitated compositional change. Dispersal accelerated changes in phytoplankton composition under acidification, possibly mediated by changes in trophic interactions, but had no effect on the composition of zooplankton and bacteria. Overall, our results suggest that the potential for spatial insurance can vary among trophic groups.


Assuntos
Ecossistema , Zooplâncton , Animais , Bactérias , Cadeia Alimentar , Fitoplâncton
6.
Ecol Lett ; 22(11): 1850-1859, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31412432

RESUMO

Most prominent theories of food web dynamics imply the simultaneous action of bottom-up and top-down forces. However, transient bottom-up effects resulting from resource pulses can lead to sequential shifts in the strength of top-down predator effects. We used a large-scale field experiment (32 small islands sampled over 5 years) to probe how the frequency and magnitude of pulsed seaweed inputs drives temporal variation in the top-down effects of lizard predators. Short-term weakening of lizard effects on spiders and plants (the latter via a trophic cascade) were associated with lizard diet shifts, and were more pronounced with larger seaweed inputs. Long-term strengthening of lizard effects was associated with lizard numerical responses and plant fertilisation. Increased pulse frequency reinforced the strengthening of lizard effects on spiders and plants. These results underscore the temporally variable nature of top-down effects and highlight the role of resource pulses in driving this variation.


Assuntos
Lagartos , Alga Marinha , Aranhas , Animais , Cadeia Alimentar , Ilhas , Comportamento Predatório
7.
Ying Yong Sheng Tai Xue Bao ; 30(7): 2415-2425, 2019 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-31418245

RESUMO

The coastal waters in Jiangsu Province have always been an important fishery base since ancient time. In recent years, with the development of the industry in coastal cities, heavy metal pollution is becoming serious in Jiangsu Province. However, the bioaccumulation of heavy metals in the coastal food web is still unclear. In this study, we collected samples (including macroalgae, bivalves, cephalopods, gastropods, crustaceans and fish) through fishery resources survey in the coastal waters of Jiangsu in May 2017 and quantified the main ways of the material circulation and energy flows by constructing the food web using stable carbon and nitrogen isotopes. In addition, the bioaccumulation patterns of eight elements (seven heavy metals and 1 metalloid) through the food chains were investigated. The results showed that there were two energy pathways in this offshore ecosystem: the planktonic food-chain and the benthic food-chain, with Scapharca subcrenata and Phalium strigatum as the primary consumers, respectively. The benthic food-chain was the dominant food chain in energy recycling. The mean concentration of heavy metals from high to low in orga-nisms were Zn, Cu, As, Cd, Cr, Pb, Ni and Hg. The highest concentrations of elements were found in bivalves and the lowest ones in fish. The concentration of As in most species, the levels of Cd in bivalves and Oratosquilla oratoria, the Cr in Coilia mystus and the Zn, Cu, Cr in Ostrea denselamellosa exceeded the proposed health advisory levels. Regarding the bioaccumulation, a decrease in the concentration levels of Zn, Cd and Ni were observed along the planktonic food-chain and a significant positive correlation between Hg and trophic position were found across the benthic food-chain. Other elements had no significant change.


Assuntos
Monitoramento Ambiental , Cadeia Alimentar , Metais Pesados/análise , Poluentes Químicos da Água/análise , Animais , China
8.
Sci Total Environ ; 691: 195-204, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31323568

RESUMO

Contamination of agricultural soils by trace elements is a recurrent hazard for human health because of the possibility of pollutants entering the food chain. Aim of this study was to assess the human health risk from consumption of the common leafy (Lactuca sativa L.) and fruit (Cucurbita pepo L.) crops, in an agricultural area of Southern Italy. Along with agricultural practices, a major pollutant source is recurrent flooding from the highly polluted Solofrana river. Soil samples and edible parts of crops from 14 sites (10 flooded and 4 not flooded) were analyzed for total amounts of As, Cd, Co, Cr, Cu, Ni, Pb, V, Zn. The bio-accumulation factor (BAF) and Health Risk Index (HRI) were calculated for each element, crop and site and as average values of all sites (BAFmean and HRImean). Moreover, the Hazard Index (HI) was determined for each site, as the sum of HRI for all elements. Cr and Cu, mostly derived from river flooding and agricultural practices, respectively, were the only elements whose levels exceeded law thresholds and/or the natural background of the study area. Of the two considered crops, L. sativa accumulated more Cd, Cr and Ni, whereas C. pepo was a more effective bioaccumulator of Zn. Both HRImean (for As, Cd, Cr and Ni) and HI were higher for L. sativa than for C. pepo. A low health risk was associated to major soil pollutants (Cr and Cu) found in the study area; in contrast, combined data on soil pollution and plant bio-accumulation points to accumulation of Cd and As, mainly in lettuce, as a potential risk for human health. The results suggest that soil pollution data alone is not sufficient to assess health risk.


Assuntos
Produtos Agrícolas/química , Exposição Dietética/estatística & dados numéricos , Cadeia Alimentar , Metais Pesados/análise , Poluentes do Solo/análise , Monitoramento Ambiental , Humanos , Itália , Medição de Risco , Solo
9.
Environ Pollut ; 252(Pt B): 1582-1592, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31279252

RESUMO

Localised sites in Antarctica are contaminated with mixtures of metals, yet the risk this contamination poses to the marine ecosystem is not well characterised. Recent research showed that two Antarctic marine microalgae have antagonistic responses to a mixture of five common metals (Koppel et al., 2018a). However, the metal accumulating potential and risk to secondary consumers through dietary exposure are still unknown. This study investigates cellular accumulation following exposure to a mixture of cadmium, copper, nickel, lead, and zinc for the Antarctic marine microalgae, Phaeocystis antarctica and Cryothecomonas armigera. In both microalgae, cellular cadmium, copper, and lead concentrations increased with increasing exposures while cellular nickel and zinc did not. For both microalgae, copper in the metal mixture drives inhibition of growth rate with R2 values > -0.84 for all cellular fractions in both species and the observed antagonism was likely caused by zinc competition, having significantly positive partial regressions. Metal accumulation to P. antarctica and C. armigera is likely to be toxic to consumer organisms, with low exposure concentrations resulting in cellular concentrations of 500 and 1400 × 10-18 mol Zn cell-1 and 160 and 320 × 10-18 mol Cu cell-1, respectively.


Assuntos
Haptófitas/química , Metais Pesados/análise , Microalgas/química , Poluentes Químicos da Água/análise , Animais , Regiões Antárticas , Exposição Dietética/análise , Cadeia Alimentar , Haptófitas/crescimento & desenvolvimento , Metais Pesados/toxicidade , Microalgas/crescimento & desenvolvimento , Modelos Teóricos , Risco , Poluentes Químicos da Água/toxicidade
10.
Glob Chang Biol ; 25(10): 3549-3561, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31301198

RESUMO

Theory suggests that more complex food webs promote stability and can buffer the effects of perturbations, such as drought, on soil organisms and ecosystem functions. Here, we tested experimentally how soil food web trophic complexity modulates the response to drought of soil functions related to carbon cycling and the capture and transfer below-ground of recent photosynthate by plants. We constructed experimental systems comprising soil communities with one, two or three trophic levels (microorganisms, detritivores and predators) and subjected them to drought. We investigated how food web trophic complexity in interaction with drought influenced litter decomposition, soil CO2 efflux, mycorrhizal colonization, fungal production, microbial communities and soil fauna biomass. Plants were pulse-labelled after the drought with 13 C-CO2 to quantify the capture of recent photosynthate and its transfer below-ground. Overall, our results show that drought and soil food web trophic complexity do not interact to affect soil functions and microbial community composition, but act independently, with an overall stronger effect of drought. After drought, the net uptake of 13 C by plants was reduced and its retention in plant biomass was greater, leading to a strong decrease in carbon transfer below-ground. Although food web trophic complexity influenced the biomass of Collembola and fungal hyphal length, 13 C enrichment and the net transfer of carbon from plant shoots to microbes and soil CO2 efflux were not affected significantly by varying the number of trophic groups. Our results indicate that drought has a strong effect on above-ground-below-ground linkages by reducing the flow of recent photosynthate. Our results emphasize the sensitivity of the critical pathway of recent photosynthate transfer from plants to soil organisms to a drought perturbation, and show that these effects may not be mitigated by the trophic complexity of soil communities, at least at the level manipulated in this experiment.


Assuntos
Cadeia Alimentar , Solo , Secas , Ecossistema , Microbiologia do Solo
11.
Ecotoxicol Environ Saf ; 182: 109440, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31336228

RESUMO

Mercury, and particularly its organic form, methylmercury (MeHg), is a ubiquitous environmental contaminant with documented dosage-dependent adverse effects on endpoints spanning many levels of biological organization. However, relatively little is known about the sublethal impacts of environmentally-relevant exposures on behavioral characteristics that may impact predator-prey relationships, and thus the potential for Hg bioaccumulation within food webs due to behavioral impairments. This study investigated the potential for dietary mercury exposure to impair two behavioral outcomes in the highly invasive rusty crayfish, Faxonius rusticus, which are expected to influence interactions with their fish predators: the tail-flip escape response and chelae pinch strength. Field-caught animals were randomly assigned to four dietary treatments with mean (±1 SE) dry-weight total Hg (THg) concentrations of 3.52 ±â€¯0.57, 114.01 ±â€¯4.05, 274.10 ±â€¯0.38, and 565.79 ±â€¯1.33 ng/g in the control, low, moderate and high exposure treatments, respectively, for 16 weeks. After initial observations, exposures began and mass and behavior were measured every two weeks. At the end of the experiment, THg concentrations in tail muscle tissue were significantly higher in the high exposure treatment than in the control and low exposure treatments (Tukey's HSD, family-wise α = 0.05). Exposure-dependent declines in survival, mass, pinch strength, or tail-flip escape response velocity were not detected within the 12- to 16-week experimental exposure period, which represents one season of the crayfish's 3-4 year lifespan. This suggests that crayfish may be relatively tolerant of dietary exposure to sublethal concentrations of mercury within a single season. Further investigation of the physiological underpinnings of this tolerance is warranted.


Assuntos
Astacoidea/fisiologia , Comportamento Animal/efeitos dos fármacos , Mercúrio/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Cyprinidae , Dieta , Exposição Dietética , Exposição Ambiental , Peixes , Cadeia Alimentar , Mercúrio/análise , Compostos de Metilmercúrio , Músculos/química , Alimentos Marinhos
12.
Sci Total Environ ; 691: 908-918, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31326814

RESUMO

Energy (photosynthetically active [PAR] and ultraviolet [UVR] radiation) and matter (organic and inorganic nutrients) fluxes regulate the ecosystem's stability. However, the mechanisms underpinning the potential interplay between resistance and resilience to shifts in nutrient inputs and UVR are poorly understood. To assess how the UVR × nutrients interaction alters ecosystem stability, we exposed in situ a microbial food web from an oligotrophic ecosystem to: (1) two light (UVR + PAR and PAR), and (2) four nutrient (ambient concentrations, phosphorus [P], carbon [C] and C × P addition) treatments for three weeks. During this period, we quantified the community composition and biomass, sestonic P and C:P ratio, primary [PP] and bacterial [BP] production, community [CR] and bacterial [BR] respiration, excreted organic carbon [EOC], as well as the commensalistic phytoplankton-bacteria interaction (i.e. bacterial carbon demand [BCD]:EOC ratio) and the metabolic balance of the ecosystem (i.e. [PP:R] ratio). The stability of all response variables under the four environmental scenarios tested (i.e. UVR, UVR × C, UVR × P, and UVR × C × P) was quantified by means of the resistance and resilience indexes. The microbial community was dominated by phototrophs during the experimental period regardless of the treatment considered. The most complex scenario, i.e. UVR × C × P, decreased the resistance for all variables, except for BR and the PP:R ratio. Despite that PP:R ratio showed the highest resistance under such scenario, it was >1 in all environmental scenarios (i.e. net autotrophic), except under the UVR × C interaction, where, concomitant with increased resilience, the balance shifted towards net heterotrophy (PP:R < 1). Under the UVR × C × P scenario, the metabolic balance of the ecosystem proved strongly resistant due mainly to high resistance of bacterial respiration and a firm stability of the commensalistic interaction. Our results evidence that the high resilience of phototrophs (favoring their predominance over mixo- and heterotrophs) may lead to the maintenance of the autotrophic nature and carbon (C) sink capacity of the ecosystem.


Assuntos
Cadeia Alimentar , Água Doce/microbiologia , Biomassa , Carbono/metabolismo , Ecossistema , Nitrogênio/metabolismo , Fósforo/metabolismo , Fitoplâncton
13.
Environ Pollut ; 252(Pt B): 1483-1490, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31265959

RESUMO

Biodiversity in running water ecosystems such as streams and rivers is threatened by chemical pollution derived from anthropogenic activities. Zooplankton are ecologically indicative in aquatic ecosystems, owing to their position of linking the top-down and bottom-up regulators in aquatic food webs, and thus of great potential to assess ecological effects of human-induced pollution. Here we investigated the influence of water pollution on zooplankton communities characterized by metabarcoding in Songhua River Basin in northeast China. Our results clearly showed that varied levels of anthropogenic disturbance significantly influenced water quality, leading to distinct environmental pollution gradients (p < 0.001), particularly derived from total nitrogen, nitrate nitrogen and pH. Redundancy analysis showed that such environmental gradients significantly influenced the geographical distribution of zooplankton biodiversity (R = 0.283, p = 0.001). In addition, along with the trend of increasing environmental pollution, habitat-related indicator taxa were shifted in constituents, altering from large-sized species (e.g. arthropods) in lightly disturbed areas to small-sized organisms (e.g. rotifers and ciliates) in highly disturbed areas. All these findings clearly showed that anthropogenic activity-derived water pollution significantly influenced biological communities. Thus, biotic consequences of human-induced environmental pollution in running water ecosystems should be deeply investigated. More importantly, the findings of biotic consequences should be well integrated into existing monitoring programs to further assess impacts of anthropogenic disturbance, as well as to advance the management of running water ecosystems for conservation and ecological restoration.


Assuntos
Biodiversidade , Monitoramento Ambiental , Rios/química , Poluentes Químicos da Água/análise , Poluição da Água/análise , Zooplâncton/crescimento & desenvolvimento , Animais , China , Ecossistema , Cadeia Alimentar , Humanos , Nitratos/análise , Nitrogênio/análise , Qualidade da Água , Zooplâncton/classificação
14.
Sci Total Environ ; 690: 821-830, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31302547

RESUMO

Microplastics were determined in pink Bombay-duck (Harpadon nehereus), white Bombay-duck (H. translucens) and gold-stripe sardine (Sardinella gibbosa) collected from the Northern Bay of Bengal at Bangladesh. Gastrointestinal tracts of fishes (n = 25 per species) were examined for microplastics following alkali digestion protocol, microscopic observations and chemical analysis by micro-Fourier Transformed Infrared Spectroscope (µ-FTIR). A total of 443 microplastic items were found in the intestines of H. nehereus, H. translucens and S. gibbosa, averaging in the range of 3.20-8.72 items per species. Among various shapes, colours and types of microplastics, irregular (37-43%), white/transparent (26-68%) and fiber (50-55%) were dominant. The size fraction of microplastics ranging between 1 µm and 5 mm was 68-84 items/kg biomass, and µ-FTIR analysis identified 13 particles of polyethylene terephthalate and 66 particles of polyamide. The study findings raised concern that microplastics in marine fish could be a threat to public health via the food chain.


Assuntos
Monitoramento Ambiental , Peixes/metabolismo , Plásticos/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Bangladesh , Cadeia Alimentar , Plásticos/análise , Poluentes Químicos da Água/análise
15.
Sci Total Environ ; 690: 831-840, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31302548

RESUMO

The Water Framework Directive was widely welcomed because it sought to integrate chemical and biological elements of aquatic ecosystems to achieve 'good ecological status', reflecting at most slight anthropogenic impact. However, implementation has been criticised because of the failure to adequately integrate these elements and assess status of the whole ecosystem. In this study, a suite of environmental and biotic variables was measured to assess their relative importance as predictors of lake status for 50 lakes in the north of the island of Ireland. Total Phosphorus (TP) had a strong effect on taxon biomasses and ecological quality ratios (EQR) for most taxa, as expected, but other environmental variables, such as pH, water colour and spatial location, were also important. Most variance in mean EQR, the average of the taxon values, was predicted by five environmental variables (chlorophyll a, TP, population density, water colour and elevation) and whether (alien) cyprinid fish were present. Oligotrophic lakes with cyprinid fish had lower mean EQRs than cyprinid-free lakes, indicating the importance of recording species introductions when assessing lake status. Strong evidence for bottom-up effects was also detected, and cyprinids probably influenced trophic structure by increasing nutrient release from the sediment rather than by top-down effects. Phytoplankton biomass, fish biomasses, and the percentage of predatory fish, increased with TP. Our results further emphasize the need to adopt a more integrated approach when assessing lake status.


Assuntos
Monitoramento Ambiental/métodos , Lagos/química , Animais , Biomassa , Clorofila A , Ecossistema , Peixes , Cadeia Alimentar , Irlanda , Fósforo/análise , Fitoplâncton
16.
Ecol Lett ; 22(10): 1638-1649, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31359570

RESUMO

The top-down and indirect effects of insects on plant communities depend on patterns of host use, which are often poorly documented, particularly in species-rich tropical forests. At Barro Colorado Island, Panama, we compiled the first food web quantifying trophic interactions between the majority of co-occurring woody plant species and their internally feeding insect seed predators. Our study is based on more than 200 000 fruits representing 478 plant species, associated with 369 insect species. Insect host-specificity was remarkably high: only 20% of seed predator species were associated with more than one plant species, while each tree species experienced seed predation from a median of two insect species. Phylogeny, but not plant traits, explained patterns of seed predator attack. These data suggest that seed predators are unlikely to mediate indirect interactions such as apparent competition between plant species, but are consistent with their proposed contribution to maintaining plant diversity via the Janzen-Connell mechanism.


Assuntos
Cadeia Alimentar , Florestas , Insetos , Clima Tropical , Animais , Biodiversidade , Panamá , Filogenia , Sementes
17.
Sci Total Environ ; 685: 1276-1283, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31272787

RESUMO

Antarctica is still considered one of the few pristine areas in the globe. Despite this, several studies have shown phased out organic pollutants are present in several environmental abiotic and biological compartments. This study, based on blubber and fecal samples collected from five species of Antarctic pinnipeds, assessed the relationship between organochlorine pesticide (OCs) levels and trophic characterization using stable isotope analysis (δ13C and δ15N). The prevailing pollutants found in blubber were hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB), Heptachlor and Aldrin (0.84-564.11 ng g-1 l.w.). We also report a high presence of HCHs, Endrin, Dichlorodiphenyltrichloroethane (DDTs) and Methoxychlor (4.50-363.86 ng g-1 d.w.) in feces suggesting a detoxification mechanism. All the species tend towards high trophic positions (3.4-4.9), but with considerable variation in trophic niche and organochlorine pesticide concentrations per sampling site. This finding suggests that differences in pesticide levels in individuals are associated to foraging ecology.


Assuntos
Caniformia/metabolismo , Monitoramento Ambiental , Hidrocarbonetos Clorados/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Regiões Antárticas , Cadeia Alimentar
18.
Oecologia ; 190(4): 955-967, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31327076

RESUMO

Marine intertidal systems have long served as focal environments for ecological research, yet these environments are changing due to the entry of human-produced carbon dioxide into seawater, which causes 'ocean acidification' (OA). One component of OA is a decline in seawater pH, an alteration known to disrupt organism behaviors underlying predator-prey interactions. To date, however, studies examining OA's effects on feeding relationships consider predominantly simple direct interactions between consumers and their food sources. Here, we extended these established approaches to test how decreased seawater pH might alter cascading effects that span tiered linkages in trophic networks. We employed a model shoreline food web incorporating a sea star predator (Leptasterias hexactis), an herbivorous snail prey (Tegula funebralis), and a common macroalgal resource for the prey (Mazzaella flaccida). Results demonstrate direct negative effects of low pH on anti-predator behavior of snails, but also weakened indirect interactions, driven by increased snail consumption of macroalgae even as sea stars ate more snails. This latter outcome arose because low pH induced 'foolhardy' behaviors in snails, whereby their flight responses were supplanted by other activities that allowed for foraging. These findings highlight the potential for human-induced changes in seawater chemistry to perturb prey behaviors and trophic dynamics with accompanying community-level consequences.


Assuntos
Cadeia Alimentar , Água do Mar , Animais , Concentração de Íons de Hidrogênio , Comportamento Predatório , Estrelas-do-Mar
19.
Ambio ; 48(11): 1337-1349, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31350721

RESUMO

We developed numerical simulations of potential future ecological states of the Baltic Sea ecosystem at the end of century under five scenarios. We used a spatial food web (Ecospace) model, forced by a physical-biogeochemical model. The scenarios are built on consistent storylines that describe plausible developments of climatic and socioeconomic factors in the Baltic Sea region. Modelled species diversity and fish catches are driven by climate- and nutrient load-related changes in habitat quality and by fisheries management strategies. Our results suggest that a scenario including low greenhouse gas concentrations and nutrient pollution and ecologically focused fisheries management results in high biodiversity and catch value. On the other hand, scenarios envisioning increasing societal inequality or economic growth based on fossil fuels, high greenhouse gas emissions and high nutrient loads result in decreased habitat quality and diminished biodiversity. Under the latter scenarios catches are high but they predominantly consist of lower-valued fish.


Assuntos
Pesqueiros , Cadeia Alimentar , Animais , Países Bálticos , Mudança Climática , Ecossistema
20.
Nat Ecol Evol ; 3(8): 1153-1161, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31358950

RESUMO

The productivity of marine ecosystems and the services they provide to humans are largely dependent on complex interactions between prey and predators. These are embedded in a diverse network of trophic interactions, resulting in a cascade of events following perturbations such as species extinction. The sheer scale of oceans, however, precludes the characterization of marine feeding networks through de novo sampling. This effort ought instead to rely on a combination of extensive data and inference. Here we investigate how the distribution of trophic interactions at the global scale shapes the marine fish food web structure. We hypothesize that the heterogeneous distribution of species ranges in biogeographic regions should concentrate interactions in the warmest areas and within species groups. We find that the inferred global metaweb of marine fish-that is, all possible potential feeding links between co-occurring species-is highly connected geographically with a low degree of spatial modularity. Metrics of network structure correlate with sea surface temperature and tend to peak towards the tropics. In contrast to open-water communities, coastal food webs have greater interaction redundancy, which may confer robustness to species extinction. Our results suggest that marine ecosystems are connected yet display some resistance to perturbations because of high robustness at most locations.


Assuntos
Ecossistema , Cadeia Alimentar , Animais , Extinção Biológica , Peixes , Humanos , Oceanos e Mares
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