Large-sized Species Research Articles

COMPOSITION CAPACITY OF SIDEWALK AFFORESTATION USING THREE DIFFERENT SIZED TREES

Planning the sidewalk afforestation composition is critical to understanding tree development over time, as well as enabling trees to deliver their many quality benefits. The objective of this work was to evaluate the number of small, medium and large-sized tree species during eight growth projection moments on the streets of Irati city– PR. Different streets with and without power grids and streets with sidewalks larger and smaller than three meters were evaluated by counting the number of suitable trees in the appropriate spaces and the average increase in crown area of Lagerstroemia indica, Handroanthus albus and Paraptadenia rigida, over 5, 10, 15, 20, 25, 30, 35 and 40 years of growth projection. Data was transformed to attend the normality criteria and compared by the Tukey test at 5% probability, using an experimental design in subdivided plots. There was a significant difference and interaction between species size and projection time. The large-sized species presented higher increase in crown area throughout the years, despite the smaller number of trees that could be planted. This kind of species is advised for planting as long as proper maintenance is considered for trees to provide maximum benefits.

Minimal stories in Southeast Buenos Aires grasslands: carabid beetle biodiversity throughout an urban-rural gradient

Urbanization modifies the original habitat and the biodiversity. Research throughout urban-rural gradients allows the monitoring of human activities on the biodiversity of native environments. Our aims were to a) record the diversity of edaphic coleopteran families and carabid species in native grassland remnants of urban, suburban and rural areas; b) identify potential taxa exclusively associated with urban and rural sites, respectively, or indifferent to such categorization; and c) compare the body sizes, wing morphology and trophic groups of carabid beetles in the three levels of urbanization. Our results showed that carabid species richness is higher in urban areas, but we found no difference in the number of families of edaphic coleopterans. One species, the eurytopic Argutoridius bonariensis, dominated in all areas; but in the suburban and rural areas it shared the dominance with stenotopic Argutoridius sp. N° 2. Carabid species assemblages did not exactly reflect the urban-rural gradient selected a priori. Regarding size variation, we found that large size species were more abundant in two urban sites; wing-dimorphic and apterous species were more abundant in urban areas. In reference to trophic groups, we recorded larger number of omnivores in the urban areas. We showed that some species can develop and survive in cities while others cannot, creating and sustaining a “new” urban ecosystem, with its own history, rules, dynamics and internal ecological memory.

New Light on Parasorex Depereti (Erinaceomorpha: Erinaceidae: Galericini) from the Late Messinian (MN 13) of the Monticino Quarry (Brisighella, Faenza, Italy)

Abstract A large-sized species of Parasorex is common in the MN 13 mammal assemblages from the uppermost Messinian sandy-marly fissure fillings within the Gessoso Solfifera Formation at Brisighella (Northern Apennine). This erinaceid has been classified as Galerix sp. in the first papers on the Brisighella fauna. Later, it was described in detail in an unpublished Ph.D. dissertation by Fanfani (1999), who referred it to Galerix depereti. Van den Hoek Ostende (2001) included G. depereti in the genus Parasorex, Parasorex depereti has been described by Crochet (1986) on scarce material from a few Early Pliocene (MN 14–15) localities of southern France and Spain. Parasorex cf. depereti has been reported from the Early Pliocene fauna of Capo Mannu (Mandriola, Sardinia; Furió and Angelone 2010). The species seems actually distributed in south-western Europe, where it represents the youngest occurrence of the genus Parasorex. The very abundant sample of P. depereti from fissure filling BRS 25 enables a more accurate and comprehensive description of the species. It also permits inspection of the mesial elements of the dentition, which were lacking in the material examined by Crochet (1986). The systematic position of the species has been revisited and compared with those of other Galericini of the Parasorex group.

Differential Leaf Age-Dependent Thermal Plasticity in the Keystone Seagrass Posidonia oceanica.

Introduction: Gene-expression patterns and their upstream regulatory mechanisms (e.g. epigenetic) are known to modulate plant acclimatability and thus tolerance to heat stress. Within species, thermal plasticity (i.e. temperature-sensitive phenotypic plasticity) and differential thermo-tolerance are recognized among different genotypes, development stages, organs or tissues. Leaf age and lifespan have been demonstrated to strongly affect photosynthetic thermo-tolerance in terrestrial species, whereas there is no information available for marine plants. Materials and Methods: Here, we investigated how an intense warming event affects molecular and photo-physiological functions in the large-sized seagrass Posidonia oceanica, at fine spatial resolution. Plants were exposed for one week at 34°C in a controlled-mesocosm system. Subsequent variations in the expression of 12 target genes and global DNA methylation level were evaluated in three leaf-age sections (i.e. basal, medium and high) established along the longitudinal axis of youngest, young and fully mature leaves of the shoot. Targeted genes were involved in photosynthesis, chlorophyll biosynthesis, energy dissipation mechanisms, stress response and programmed cell death. Molecular analyses paralleled the assessment of pigment content and photosynthetic performance of the same leaf segments, as well as of plant growth inhibition under acute warming. Results: Our data revealed, for the first time, the presence of variable leaf age-dependent stress-induced epigenetic and gene-expression changes in seagrasses, underlying photo-physiological and growth responses to heat stress. An investment in protective responses and growth arrest was observed in immature tissues; while mature leaf sections displayed a higher ability to offset gene down-regulation, possibly through the involvement of DNA methylation changes, although heat-induced damages were visible at photo-physiological level. Discussion: Overall, mature and young leaf tissues exhibited different strategies to withstand heat stress and thus a variable thermal plasticity. This should be taken in consideration when addressing seagrass response to warming and other stressors, especially in large-sized species, where sharp age differences are present within and among leaves, and other gradients of environmental factors (e.g. light) could be at play. Molecular and physiological evaluations conducted only on adult leaf tissues, as common practice in seagrass research, could give inadequate estimates of the overall plant state, and should not be considered as a proxy for the whole shoot.

Can demand-side management replicate a size limit in a small-scale fishery?

We tested whether it is possible to replicate the effects of a size limit with a voluntary mechanism – a price premium for larger fish. We randomly offered fishers in Indonesia a bonus for catching certain species of fish above certain sizes. We observe clear differences in catch as a result. Instead of inducing fishers to catch more fish of every size, the premium caused a shift in the size distribution of catch towards larger fish. The price premium worked well for a large-sized species but had no effect on the catch of a small-sized species. In particular, we find that the length of Aprion virescens increased by 15% and the average length of all fish caught increased by 8% when fishers were offered the price premium. It does not appear that fishers respond to the premium by high-grading their catch, which would only affect supply and not extraction. The changes appear to be driven by fishers going to different locations and fishing at different depths. Our experiment is the first ever proof-of-concept of Payment for Ecosystem Services in a developing country fishery. Our results also suggest that prices can alter length–frequency distributions, confirming a possible source of bias in length-based stock assessment models.

Species composition and frequency of habitat use by medium and large-sized mammals in the Brazilian Cerrado Biome, State of Tocantins

The Cerrado biome is the second largest natural vegetation type existing in Brazil after the Amazon, covering 91% of the State of Tocantins, with 30% of the territory changed as a result of the expansion of economic development areas. The substitution of natural vegetation means habitat loss on species, and may put the survival of medium and large-sized mammal species under extinction risk. These species represent significant energy demands and high requirements of area within the habitat. This study aims to assess the species composition and the frequency of use of physiognomic types of vegetation by medium and large-sized mammals. The study was conducted from 2001 to 2011 using a set of complementary and alternative techniques in fragments of seven different physiognomic types of vegetation. Fourth-seven medium and large-sized mammals were registered. This record corresponds to 92% of species already described within the biome, and five additional species to those registered in the data base of the State of Tocantins. Fourteen of these species are at certain degree of threat of extinction. The most used physiognomic types of vegetation in terms of canopy cover were Cerradao, Typical Cerrado, Riparian Forest and Dense Cerrado, and the less used were Gallery Forest, Campo Sujo and Vereda.

Carabidae assemblages in pine forests with different recreation regimes within and outside a megalopolis

The expansion of cities highlights the need for studies of the biodiversity on urban territories and factors affecting the structure and functioning of communities. In 2010–2011, we compared the abundance and diversity of carabid beetles in pine forests of natural origin within the Russian megalopolis Yekaterinburg and outside. To estimate the effects of recreation (R+: trampling, soil compaction, eutrophication) and other urbanization factors (U+: pollution, habitat fragmentation, adventive species), we selected 12 urban and non-urban forest sites with contrasting recreation regimes (U + R+, U + R−, U − R+, U − R−; three sites in each combination). We hypothesized that both urbanization and recreation decrease the abundance and diversity of carabids; the combination of two factors enhances negative effects. The total activity density of carabids and the abundances of all ecological groups increased in urban forests compared to non-urban ones. In urban forests, the Simpson dominance decreased, while Shannon diversity, total species richness, and mean number of species per site increased. The most abundant species in all forests were Pterostichus oblongopunctatus, P. mannerheimii, and P. magus, while Carabus nemoralis was abundant in urban forests only. Proportion (by the number of individuals) of forest species was lower and that of generalists and large-sized species higher in urban forests. High recreation load resulted in lower total abundance and diversity of ground beetles. Negative effect of recreation load on carabids leveled positive effect of urbanization: both abundance and diversity of ground beetles were lower at urban sites with intense recreational use compared to forest sites closed for townspeople.

Medium- and large-sized mammal composition in the Chapada dos Veadeiros National Park and adjacent areas, state of Goiás, Brazil

The Cerrado is the second largest Brazilian biome and only 2.8% is represented by protected areas. Considering the relevance of the Cerrado and Conservation Units in preserving the mammalian diversity, we provided the first assessment of the diversity of medium- and large-sized mammal species in the Chapada dos Veadeiros National Park (CVNP) and surroundings. We tested the effectiveness of the CVNP by assessing the difference in species composition within the park and its surroundings. We sampled CVNP in the rainy (October-December 2013) and dry seasons (March-June 2014) in order to characterize the seasonality within the community. We selected 36 sampling sites to evaluate the composition of the medium and large mammals in the CVNP and its surroundings, 18 in the CVNP and 18 in the park surroundings. We ordered mammalian composition and frequency of individuals data by using a Non-metric Multidimensional Scaling analysis (NMDS). We assessed the effect of season (dry and rainy seasons) and locality (within the CVNP and surroundings) on mammalian species richness with a two-way analysis of variance (Two-way ANOVA). We recorded 23 species, 13 within the CVNP and 17 species in its surroundings. Composition and frequency of records differed between dry and rainy seasons, with higher richness in the rainy season. Species’ composition and the frequency of records were also different between within the CVNP and its surroundings, with higher richness in the surroundings. These results provide information for the increase of the knowledge of mammalian ecology but also is useful as a tool for future strategies to the conservation of these species. More attention should be given to the monitoring of these species in the long term because this area still harbor some viable populations.

Adaptive morphologies of the brachiopod fauna from Danian coral mounds at Faxe, Denmark

Only few of the brachiopod species that lived in the Late Cretaceous Chalk Sea of northern Europe survived the mass extinction at the Cretaceous–Paleogene boundary. However, a rich brachiopod fauna rapidly evolved from the survivors and most of the vacant niches were filled in by the middle Danian when a large cool-water, subphotic coral-bryozoan mound complex was developed at Faxe in the eastern part of the Danish Basin. The brachiopod fauna of the complex comprises 17 species dominated by micromorphic species of similar types as those known from the Upper Cretaceous, Maastrichtian chalk from the same region. All species are found in the coral mound facies and six of the species are restricted to this facies. Large-sized species are rare both in terms of species numbers and abundance. One species is adapted to a life between the branches of the cool-water hexacorals Dendrophyllia candelabrum and Oculina becki. Secondarily free-living species are close to absent. This is in contrast to the Maastrichtian chalk fauna where this group includes 10 species (~24% of the total brachiopod fauna). The otherwise great similarity in morphological adaptations in the brachiopods from the Maastrichtian chalk and the Danian coral mounds is remarkable and somewhat surprising as the latter almost lacks soft substrates. The Danian brachiopod fauna essentially represents a continuation of the Maastrichtian fauna, but in a very different habitat. The similarity between the two faunas is explained by the abundance of small, hard substrates, notably bryozoans in both environments. The brachiopods from Faxe are one of the very few ancient examples of a rich brachiopod fauna from a coral mound environment.

Leg bones of a new penguin species from the Waipara Greensand add to the diversity of very large-sized Sphenisciformes in the Paleocene of New Zealand

Mayr, G., De Pietri, V.L., Love, L., Mannering, A. & Scofield, R.P., 9 August 2019. Leg bones of a new penguin species from the Waipara Greensand add to the diversity of very large-sized Sphenisciformes in the Paleocene of New Zealand. Alcheringa 44, 194–201. ISSN 0311-5518 We describe a new large-sized species of the Sphenisciformes (penguins) from Paleocene strata of the Waipara Greensand in New Zealand. ?Crossvallia waiparensis, sp. nov. is represented by leg bones of a single individual as well as two tentatively referred proximal humeri and resembles Crossvallia unienwillia from the late Paleocene of Antarctica in size and morphology. The new species is the fifth published species of stem group Sphenisciformes from the Waipara Greensand and the fourth one, which has been formally named. It is distinguished from a recently reported tarsometatarsus of an unnamed large-sized penguin species from the Waipara Greensand and is the oldest well-represented giant penguin. ?C. waiparensis approaches the size of the Eocene taxa Anthropornis and Palaeeudyptes and provides further evidence that penguins attained a very large size early in their evolutionary history. Gerald Mayr [gerald.mayr@senckenberg.de], Senckenberg Research Institute and Natural History Museum Frankfurt, Ornithological Section, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany; Vanesa L. De Pietri [vdepietri@canterburymuseum.com], Al Mannering [alman@slingshot.co.nz], R. Paul Scofield [pscofield@canterburymuseum.com], Canterbury Museum, Rolleston Avenue, Christchurch 8050, New Zealand; Leigh Love [lvlove@xtra.co.nz], PO Box 49, Waipara 7483, New Zealand.

Alien war: ectoparasite load, diet and temporal niche partitioning in a multi-species assembly of small rodents

Interspecific interactions shape the structure of animal communities, and they rely on a number of multifactorial mechanisms, including e.g. activity rhythms, ectoparasite prevalence, predation pressure and food habits. Despite this, no study has analysed multispecies interactions by combining such a high number of aspects, mostly because the experimental manipulation of studied populations is rarely possible. In our work, we assessed several aspects of interspecific interactions in a rodent assembly composed by three species, by examining diet and temporal- niche partitioning, as well as relevant ectoparasite load and predation pressure, in a natural environment. We analysed stomach contents and ectoparasite load of 78 individuals belonging to all the species, whereas activity rhythms were measured with camera trapping (2200 night-traps, throughout 1 year). Our findings showed that the largest-sized species, i.e. the brown rat Rattus norvegicus was the strongest competitor and may affect diet, temporal behaviour and susceptibility to parasites of smaller-sized ones, i.e. the black rat Rattus rattus and the house mouse Mus domesticus. Larger-sized species showed a broader trophic niche with respect to smaller-sized ones, whereas the smallest species seemed to avoid the largest ones by shifting its temporal activity when the latter was mostly inactive. Larger-sized species may also act as potential predators towards smaller ones, which are also more vulnerable to ectoparasite infestation and to the predation by the only raptor bird present in the study area, the barn owl Tyto alba. We therefore highlight the importance to carry out community-wide studies, to understand interspecific intraguild relationships.

Biological consequences of environmental pollution in running water ecosystems: A case study in zooplankton

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.

New and Reassessed Species of Griffinia (Amaryllidaceae) from the Brazilian Atlantic Forest

Abstract—In the context of the revision of Amaryllidaceae tribe Griffinieae that we are preparing, we describe and illustrate a new species, Griffinia albolineata, known from a single fragment of the Atlantic Forest in the Brazilian State of Minas Gerais. It is distinguished by the foliar blade with a whitish longitudinal stripe and long-acuminate apex, unique features among the large-sized species of the genus. Additionally, we present a taxonomic reassessment of G. intermedia, described two centuries ago and historically of very uncertain identity. We provide a description and detailed distribution data, previously unpublished records, and photographs of the species in its natural habitat. We also compare the foliar anatomy and surface micromorphology of the two species. The conservation status of the two species is informally evaluated, and both are tentatively considered endangered. An identification key to the large-sized species of the genus is presented.

Assessing the Most Irreplaceable Protected Areas for the Conservation of Mammals in the Atlantic Forest: Lessons for the Governance of Mosaics

We have gathered 21,353 records of 40 different medium- and large-sized species of mammals existing in the Atlantic Forest conservation units of Brazil, including full protection and sustainable use types of management. We have classified the conservation units by their irreplaceability in terms of their role in the protection of mammalian species. Most irreplaceable conservation units are concentrated in the southern and southeastern regions of Brazil, mainly in the states of Rio de Janeiro, São Paulo and Paraná. Our data show that over and above the area of the conservation unit or its type of use, protection of its surroundings appears to be of most consequence. Therefore, it is essential to develop effective mosaic governance mechanisms that include protected areas and different types of land use. However, it is also necessary to establish common ground that allows the coexistence of human economic demands and wildlife preservation.

Medium- and large-sized mammals in forest remnants of the southern Cerrado: diversity and ecology

Here we present a complete data set on the richness of medium- and large- sized mammals from a fragmented area of the southern Brazilian savanna (Cerrado). We described the frequency, occurrence status and activity period of the most common species. In each remnant, the community of medium- and large-sized mammals was inventoried across the following methods: tracks/prints, vocalizations, sightings, burrows, and camera trap images between August 2016 and January 2017. We recorded 23 species of medium- and large-sized mammals, of which seven are threatened. The study area presented a great potential, where we recorded 45.1% of all medium- and large-sized mammal species occurring in the Cerrado. Myrmecophaga tridactyla, Dasypus novemcinctus, Tapirus terrestris, Cerdocyon thous and Cuniculus paca were classified as common, which was expected since they have large habitat range, and therefore, can be recorded more frequently. Species with large body size, such as T. terrestris, M. tridactyla and C. thous, were also the ones with the greatest variation in time period of activity, occurring both in nocturnal and diurnal time periods. Therefore, our study underscores that this transition area, although fragmented, still maintains an expressive fauna of medium- and large-sized mammals, including endangered species.

First record of Propagurus haigae (McLaughlin, 1997) (Decapoda, Anomura, Paguridae) from Japan

Abstract Propagurus haigae (McLaughlin, 1997), a relatively large-sized species of Paguridae, is reported for the first time from Japanese waters based on a single specimen collected from a depth of 620 m off Ie Island, central Ryukyu Islands, southwestern Japan. It is the third species of the genus Propagurus McLaughlin &amp; de Saint Laurent, 1998 known from Japanese waters. The present specimen greatly extends the distribution range of P. haigae, because the previous northernmost record was the Molucca Sea in Indonesia.

Reductions in body size of benthic macroinvertebrates as a precursor of the early Toarcian (Early Jurassic) extinction event in the Lusitanian Basin, Portugal

AbstractReduction of body size is a common response of organisms to environmental stress. Studying the early Toarcian succession in the Lusitanian Basin of Portugal, we tested whether the shell size of benthic marine communities of bivalves and brachiopods changed at and before the global, warming–related Toarcian oceanic anoxic event (T-OAE). Statistical analyses of shell size over time show that the mean shell size of communities decreased significantly before the T-OAE. This trend is distinct in brachiopods and is caused by larger-sized species becoming less abundant over time, whereas it is not significant in bivalves, suggesting a decoupled response to environmental stress. Reductions in shell size precede the decline in standardized sample-level species richness associated with the early Toarcian extinction event. Such decreases in the shell size of marine invertebrates, well before the onset of biodiversity change, suggest that reductions in body size more generally may be a precursor of a subsequent loss of species and turnover at the community level caused by climate change. Sedimentological evidence is against hypoxia as a driver of extinction and the preceding size decrease in the brachiopod fauna in the studied succession, although low oxygen levels are widely held responsible for elevated early Toarcian extinction rates globally. Reduction of mean shell size in brachiopods but stasis in bivalves is difficult to explain with ocean acidification, because experimental work shows that brachiopods can be resilient to lowered pH, albeit long-term metabolic costs and potential evolutionary adaptations are unknown. Rising early Toarcian temperatures in the Lusitanian Basin seem to be a plausible factor in both diversity decline associated with the T-OAE and the preceding reductions in mean shell size, because thermal tolerances in modern bivalves are among the highest within marine invertebrates.

Insights into Body Size Evolution: A Comparative Transcriptome Study on Three Species of Asian Sisoridae Catfish.

Body size is one of the most important attributes of a species, but the basic question of why and how each species reaches a different “right size” is still largely unknown. Herein, three phylogenetically closely related catfishes from Sisoridae, including one extraordinarily large-sized Bagarius yarrelli and two average-sized Glyptothorax macromaculatus and Oreoglanis setiger, were comparatively studied using RNA-Seq. Approximately 17,000 protein-coding genes were annotated for each of the three fishes, and 9509 genes were identified as high-confidence orthologous gene pairs. Comparative expressions uncovered a similar functional cluster about ribosome biogenesis was enriched in different tissues of the upregulated genes of Bagarius yarrelli. Moreover, differentially expressed genes and positively selected genes revealed that the glycolysis/pyruvate metabolism and cell cycle pathways have also greatly enhanced in this large-sized species. In total, 20 size-related candidate genes (including two growth modulators: the serine/threonine-protein kinases 3 (AKT3) and adaptor protein 1 (SH2B1), and a crucial pyruvate kinase (PKM2A)) were identified by multiplying comparative analyses along with gene functional screening, which would play major roles in enabling the large body size associated with Bagarius yarrelli and provide new insights into body size evolution. In conjunction with field observations and morphological comparisons, we hypothesize that habitat preferences promote size divergence of sisorids.

Intra-annual variation of zooplankton community structure and dynamics in response to the changing strength of bio-manipulation with two planktivorous fishes

Zooplankton is widely used in indicating environmental changes and energy flow efficiency in aquatic ecosystems. Species composition and body size spectrum of zooplankton assemblage are sensitive to the changes of physico-chemical variability and fish feeding stress, and thus have in turn a prime bearing on water quality and cultured fishes. To study the response of zooplankton community to the introduction of planktivorous carps, monthly surveys were conducted in 2015 at six traditionally monitored locations in Miyun Reservoir, the unique surface drinking water of Beijing. There was a decrease in species richness, diversity, density and biomass, suggesting simplification of the community structure. Species diversity, density, and biomass declined significantly through the growth season, illustrating the great pressure imposed on the zooplankton. Regression and canonical correspondence analysis (CCA) showed low relationships between community traits and environmental variables. Zooplankton biomass had a significantly negative relationship with the stocking intensity of the filter-feeding carp. The different responses of the subgroups of Protozoa, Rotifera, Cladocera and Copepoda indicated that they responded differently to environmental stress. Seasonal variations in the density and biomass of the four subgroups and biomass size spectrum (BSS) indicated that planktons with medium and large body sizes were more sensitive and suffered more stress from the filter-feeding carp. The filter feeding by the silver and bighead carp disrupted the natural equilibrium of the zooplankton community, decreased diversity and stocks, altered the seasonal dynamics of all quantitative traits and suppressed the dominance of medium- and large-sized species or functional groups. The impacts of the fishery mode and the responses of different functional groups of zooplankton must be considered in ecological assessments and biomanipulation studies based on the zooplankton community structure and dynamics.

Aquatic food webs will need to stand on giants’ shoulders

Abstract Aquatic food webs have been especially impacted in the last thirty years. This is particularly true for trophic webs with Mobile Generalist Species (MGS), which are species with high mobility (movement and dispersal) and flexibility in both foraging and habitat use. In general, MGS are large-sized species with the ability to move long distances, and they may be top predators (Large Generalist Predator; LGP) or feed lower in the food web than predicted from their size (Giant Secondary Consumers; GSCs). These species groups will play a fundamental role in connecting and rewiring human-impacted food webs, however this may be challenging because the stream network connectivity in most of the world’s largest river basins has been severely fragmented by dams.