Marine litter is an emerging pollution all over the world. In addition to the macro sized plastics, ongoing scientific efforts revealed risks of micro and nano sized plastic particles in marine ...environment. In the past decades, an increasing number of studies have been carried out to understand the dynamics of this pollution. The aim of the present study was to investigate the microplastic (MPs) ingestion in commercially important fish species and to evaluate biological and environmental factors influencing the ingestion status. Gastrointestinal tract content of a total of 2222 individuals belonging to 17 species were examined for MPs existence. Out of 17 species evaluated, 13 of them was detected to ingest MPs. Our results showed that 18.1% of investigated fishes ingested MPs and the average length of the detected particles was 1.26 ± 1.38 (±SD) mm. The most dominant MP type was fiber (90.1%), while the most common particle colours were black (46.9%) and blue (29.4%). Polypropylene (85%) was the most common polymer type detected. Our evaluations indicated that the exposure of fish distributed in coastal areas to microplastic pollution is corelated to physical (precipitation and distance to nearest shore) and biological (functional trophic group, habitat of the species) factors. In order to design a more effective control mechanism, these impacts should be included in the assessments in future practices to reveal the effects of microplastic pollution on biota.
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•Microplastic exposure rate of the fish species was detected to be between 3.8 and 35.5%.•The average abundance of microplastics in the digestive systems was 1.3 microplastic. individual−1.•Most dominant microplastic type was fiber particle (90.1%).•Functional trophic groups and habitat preferences were the biological factors influencing microplastic ingestion.•Distance of sampling area to coastline was the physical factor influencing microplastic ingestion.
In a comprehensive study of microplastic contamination in southern Germany, 1167 individual fish of 22 different species were sampled from 11 rivers and 6 lakes across the state. The microplastic ...burden of investigated fish was analyzed on the basis of habitat type, location, and a number of abiotic and biotic factors. A particle size distribution analysis of the detected microplastics was carried out. The results showed a relatively low plastic prevalence of 18.8%, with significant differences between rivers (20.6%) and lakes (16.5%). The number of ingested plastic particles ranged between 1 and 4 particles per fish. The majority of abiotic and biotic factors seem to play little or no role in the ingestion of microplastics, suggesting that in most cases uptake is passive or accidental. It is notable that piscivorous fish appeared significantly less burdened, suggesting a low transfer rate and no accumulation in the food web. However, size distribution analysis identified a power law growth fit in particle numbers at the smallest end of the distribution. This carries a worrying implication, that >95% of particles are likely to be smaller than 40 μm and thereby beyond the detection range of this and most other microplastic surveys conducted so far. When the frequency development of small particles is taken into account, the likely microplastic prevalence in the present study increases to 100%, with an average intensity of around 23 predominantly small particles per fish. A striking 70% of those particles would be smaller than 5 μm and therefore eligible for translocation into tissues, with critical implications for fish health and consumer exposure. This raises a question as to whether current estimates of microplastic burden in fishes generally might be overlooking a majority of potential contamination within the critical smaller particle size classes.
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•A comprehensive study to examine microplastic burden in fishes was carried out•Ingested microplastics were detected in around one fifth of examined fishes•Piscivorous fish were significantly less burdened, indicating a excretory effect•Models indicate a hyperbolic increase of particle number with decreasing size•95% of particles are <40 μm and thus not detectable by current methods.
1. The role of interspecific competition for generating patterns in species' distribution is hotly debated and studies taking into account processes occurring at both large and small spatial scales ...are almost missing. Theoretically, competition between species with overlapping niches should result in divergence of their niches in sympatry to reduce the costs of competition. Many species show a mosaic distribution within sympatric zones, with the syntopic sites occupied by both species, and allotopic sites where only one species occurs. It is unclear whether such mosaics arise as a consequence of competition-driven niche segregation or due to the decline of their abundances towards range edges driven by environmental gradients. 2. If the interspecific competition matters, we should observe (1) a shift in habitat tween allopatry and (2) between allopatry and allotopy. Moreover, (3) species should show greater divergence in their habitat preferences in allotopy than in allopatry where (4) no differences in habitat preferences may occur. Finally, (5) shifts should be generally greater in the competitively subordinate species than in the dominant species. 3. We used a unique dataset on abundance of two closely related passerine species, the Common Nightingale (Lusdnia megarhynchos) and the Thrush Nightingale (Lusdnia lusdnia), collected across their syntopy, allotopy and allopatry. The predictions were tested within a generalized mixed-effects modelling framework. 4. After accounting for environmental gradients perpendicular to the species' contact zone, we found a strong support for all but one prediction. Habitat preferences of both species shifted markedly between syntopy and allotopy, as well as between allopatry and allotopy. Whereas the species preferred the same habitats in allopatry, their preferences became strikingly different in allotopy where the abundance of the Common Nightingale increased towards dry and warm sites with low coverage of pastures, while the abundance of the Thrush Nightingale showed exactly opposite trends. Fifth prediction was not supported. 5. Our results indicate that the competition between closely related species can result in considerable changes in habitat use across their geographic ranges accompanied with divergence in their habitat preferences in sympatry. Here, the species "escape" from competition to allotopic sites covered by habitats avoided by the competitor. Therefore, we argue that the interspecific competition is an important driver of species' distribution at both large and small spatial scales.
Parrotfishes may affect the structure of benthic communities and reef ecosystem functioning. Despite extensive studies worldwide, parrotfishes in the southwestern Atlantic are relatively ...understudied, limiting our ability to propose effective management strategies. We assessed abundance, biomass and size class distribution of parrotfish assemblages in northeastern Brazil and identified habitat preferences based on reef attributes. Outer-shelf reefs sustained larger individuals and higher biomasses for all species (except Sparisoma radians). In contrast, inner-shelf reefs supported higher abundances of small individuals. Even though most species occurred across all areas, their abundances, biomass and size-class distributions were variable and related to their respective feeding modes and reef attributes. Benthic cover, reef structural complexity, depth and distance from the coast affected the composition of parrotfish assemblages, but had different effects on each species. The endemic greenbeak parrotfish Scarus trispinosus was more abundant on calcareous substrates and higher-complexity reefs. Sc. zelindae and Sp. amplum were more common in deeper biogenic reefs further from the coast, which were characterized by high abundances of sponges, stony corals and cyanobacterial mats. Sp. axillare and Sp. radians were more abundant on reefs that had high cover of large-bladed macroalgae, while Sp. frondosum was ubiquitous across all studied reefs. Such heterogeneity in habitat use is suggestive of functional complementarity rather than functional redundancy among parrotfish assemblages. Conservation of Brazilian endemic parrotfishes requires protecting reefs with diverse attributes and a better understanding of habitat connectivity and the role of different habitats in parrotfish reproduction and life cycle.
Despite the potential emissions of heavy metal pollution in Lake Caizi due to extensive agriculture, urban growth and fishing activities, the risk posed by metal concentrations to aquatic ...environments and human populations has not yet been studied. In this study we compared the concentrations of Hg, As, Pb, Cd, Cr, Cu and Zn in water, sediment, and economic fish species with different habitat preferences and trophic guilds across important fishery areas in Lake Caizi, located on the northern shore of the Yangtze River, Southeast China. The concentrations of Cr in water were found approximately 6 times higher than the safety thresholds established by international legislation. Cr, Zn, As and Cd concentrations in sediments surpassed the background values for Yangtze River basin in Anhui Province. However, all the studied fish species in Lake Caizi had metal concentrations lower than legislation thresholds established by China and international organizations. Heavy metal concentrations were found to be significantly higher in demersal (inhabiting near the sediments) and piscivorous (possessing higher trophic level) fishes than in pelagic/benthopelagic (inhabiting the upper and lower water column) and herbivorous/planktivorous (possessing lower trophic level) fishes. Our finding demonstrated that the metal concentrations in fishes are simultaneously influenced by the habitat and bio-accumulation through the food chain. According to target hazard quotient (THQ) calculations for heavy metal contents in the muscles of fish species, all the determined heavy metals gave THQ values lower than 1, suggesting the inexistence of health risks from the intake of fishes from Lake Caizi.
•Cr content in the water of Lake Caizi exceeded international safety thresholds.•High levels of Cr, Zn, As and Cd were found in sediments from Lake Caizi.•Fishes located in higher trophic level showed higher accumulation of heavy metals.•Demersal fishes accumulate more heavy metals than pelagic and benthopelagic fishes.
Urban areas represent a spectrum that goes from being safe habitats for biodiversity (i.e., habitats more or equally preferred, without costs to fitness) to being ecological traps (i.e., habitats ...more or equally preferred, but with costs to fitness). Given the imminent urban expansion, it is valuable to assess how biodiversity is responding to urbanization and thus generate timely conservation strategies. We systematically review the urban ecology literature to analyze how much do we know about the role of urban areas as ecological traps. Using a formal meta-analytical approach, we test whether urban areas are functioning as ecological traps or as safe habitats for different taxonomic groups. We generated a data set of 646 effect sizes of different measures of habitat preferences and fitness from 38 papers published between 1985 and 2020. The data set covered 15 countries and 47 urban areas from four continents, including 29 animal species. Studies from North America and Europe were best represented, and birds were the most studied taxa. Overall, the meta-analysis suggests that urbanized habitats are functioning more as safe sites than as ecological traps, mainly for certain species with characteristics that have allowed them to adapt well to urban areas. That is, many of the studied species prefer more urbanized habitats over other less urbanized sites, and their fitness is not modified, or it is even increased. However, there was high heterogeneity among studies. We also performed meta-regressions to identify variables accounting for this heterogeneity across studies and we demonstrate that outcomes may depend on methodological aspects of studies, such as study design or the approach used to measure habitat preference and fitness. More research is needed for poorly studied regions and on a wider range of species before generalizations can be made on the role of urban areas for biodiversity conservation.
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•Urban habitats can be representing ecological traps and/or safe habitats for urban species•A meta-analysis indicates that urban zones are not ecological traps for many species•However, outcomes are affected by the type of approach used to measure habitat preference and fitness•Birds are the most studied group, thus more studies with other groups are imperative•Studies in more biodiverse and less studied countries are also necessary
Juveniles of three cyprinids with various diets and habitat preferences were collected from the Szamos River (Hungary) during a period of pollution in November 2013: the herbivorous, benthic nase ...(Chondrostoma nasus), the benthivorous, benthic barbel (Barbus barbus), and the omnivorous, pelagic chub (Squalius cephalus). Our study aimed to assess the accumulation of these elements across species with varying diets and habitat preferences, as well as their potential role in biomonitoring efforts. The Ca, K, Mg, Na, Cd, Cr, Cu, Fe, Mn, Pb, Sr, and Zn concentration was analyzed in muscle, gills, and liver using MP-AES. The muscle and gill concentrations of Cr, Cu, Fe, and Zn increased with trophic level. At the same time, several differences were found among the trace element patterns related to habitat preferences. The trace elements, including Cd, Pb, and Zn, which exceeded threshold concentrations in the water, exhibited higher accumulations mainly in the muscle and gills of the pelagic chub. Furthermore, the elevated concentrations of trace elements in sediments (Cr, Cu, Mn) demonstrated higher accumulation in the benthic nase and barbel. Our findings show habitat preference as a key factor in juvenile bioindicator capability, advocating for the simultaneous use of pelagic and benthic juveniles to assess water and sediment pollution status.
Aim
Habitat loss and alteration are widely considered one of the main drivers of current pollinator diversity loss. Yet little is known about habitat importance and preferences for major groups of ...pollinators, although this information is crucial to anticipate and mitigate the current decline of their populations. We aim to rank and assess the importance of different habitats for bees, to determine the preference for and avoidance of particular habitat types by different bees and to quantify the diversity of bees within and among habitats.
Location
North‐eastern USA.
Time period
The sampling was done over 15 years (2001–2015).
Major taxa studied
Apoidea.
Methods
We used an unprecedented extensive dataset of >15,000 bee specimens, comprising more than 400 species collected across north‐east USA. We extracted habitat information from the sample points and used network analyses, null models comparisons and beta‐diversity analysis to assess habitat importance, habitat preference, use and diversity.
Results
We found that natural habitats sustain higher bee diversity and a different set of species than agricultural and urban areas. Although many bee species used human‐altered habitats, most species exhibited strong preferences for forested habitats and only a few preferred altered habitats over more natural habitats. In contrast to previous studies, landscape composition only had moderate buffer effects on diversity loss. The loss of biodiversity in human‐altered environments could have been higher but it was partially compensated by the presence of human commensals and exotic species.
Main conclusions
Although human‐altered environments may harbour a substantial number of species, our work suggests that preserving natural areas is still essential to guarantee the conservation of bee biodiversity.
Fisheries scientists and managers must track rapid shifts in fish spatial distribution to mitigate stakeholder conflict and optimize survey designs, and these spatial shifts result in part from ...animal movement. Information regarding animal movement can be obtained from selection experiments, tagging studies, flux through movement gates (e.g. acoustic arrays), fishery catch‐per‐unit effort (CPUE), resource surveys and genetic/chemical markers. However, there are few accessible approaches to combine these data types while accounting for spatially correlated residual patterns. We therefore discuss a movement model involving diffusion (random movement), taxis (movement towards preferred habitat) and advection (passive drift following ocean currents). We specifically outline how these movement processes can be fitted to data while discretizing space and time and estimating non‐linear habitat preferences using environmental layers as well as spatial process errors. Finally, we introduce an R package, ATM, by fitting the model to bottom trawl survey, longline fishery and tagging data for Pacific cod (Gadus macrocephalus, Gadidae) in the Bering Sea during winter/summer seasons from 1982 to 2019. Combining data types predicts an increasing proportion of cod residing in the northern Bering Sea from 2013 to 2019, and estimates are informative in a recent stock assessment model. We fit sensitivity analyses by dropping tag, survey or fishery data, and this analysis shows that tagging data are necessary to identify diffusion rates, while survey data are informative about movement among biogeographic strata. This “hybrid” species distribution model can help explain poleward movement, project distributions under future climate conditions and evaluate alternative tag‐deployment scenarios to optimize tagging designs.
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