Urban river wall habitat and vegetation: observations from the River Thames through central London

Bryophyte Communities along a Tropical Urban River Respond to Heavy Metal and Arsenic Pollution

Aquatic and rheophilous bryophytes can indicate water pollution as they bioaccumulate toxic water elements. We evaluated (1) bioaccumulation of eight heavy metals and arsenic by Marchantia polymorpha L., and (2) changes in bryophyte community structure, as responses to urban pollution in southern Ecuador. To this end, we registered presence/absence and coverage of submerged bryophytes in 120 quadrats across three zones of the Zamora river inside Loja city, and a control zone in a nearby forest. We found that the concentrations of five (Al, Cd, Cu, Fe, and Zn) of the eight chemical elements and arsenic were highest in urban M. polymorpha. Moreover, bryophyte species richness decreased in urban zones. Bryophyte community structure also differed between control and city zones, but no differences were found among city zones. The control zone was composed by a more distinct set of bryophyte species, e.g., an indicator species analysis showed that 16 species had high and significant indicator values for control zone, but only 11 species were indicators of at least one of the three urban zones. We concluded that bryophytes, in general, and M. polymorpha, in particular, can be suitable biomonitors of water quality in tropical urban rivers.

Circle of life: the common hamster (Cricetus cricetus) adaptations to the urban environment

Traditionally, urbanization has been seen as a negative phenomenon for biota. However, changes in the environmental parameters induced by urbanization might be favorable for some species. Over the past half-century, the common hamster has actively populated cities, establishing populations in some European, Russian and Kazakhstan cities. Based on integrative methods, we investigated free-range common hamsters inhabiting Simferopol from 2015 to 2018 to reveal possible adaptations to the urbanized environment across several parameters, including lifespan, hibernation period, reproductive activity and body mass. Results show that in urban areas, the common hamster demonstrates an extremely short hibernation period compared to other localities, possibly due to enhanced food resources from urban forestry (walnuts, locus and hazelnut), allowing the species to start breeding very early (February) and finish as late as October. We present the first evidence of polyandry for this species: mating of receptive females with several males and subsequent confirmation of multiple paternity. Despite high reproductive potential, the lifespan of the common hamster in urban conditions is generally very short (less than 1 year). We speculate that in the process of synurbization, the common hamster's innate plasticity across many life history traits permits it to successfully colonize throughout a wide range of habitats, with the ability to form novel adaptations to urban environments.

Tracing the scientific trajectory of riparian vegetation studies: Main topics, approaches and needs in a globally changing world

Riparian vegetation is a crucial component of fluvial systems and serves multiple socio-ecological functions. The objective of this review is to follow the scientific trajectory of studies of riparian vegetation throughout history and across regions and fields of knowledge. Such a synthesis is challenging because riparian vegetation is an open co-constructed socio-ecological system at the crossroads of the biosphere, hydrosphere, lithosphere, atmosphere and anthroposphere; thus, it exhibits a wide range of ecological patterns and functioning depending on climatic, morphological and land-use contexts. To address this, we used qualitative and quantitative approaches in our review of the scientific literature. From the scientific perspective, how riparian vegetation is studied has changed over time (e.g. development of modeling and geomatic approaches) and varies among fluvial systems and geographic areas (e.g. its relation to groundwater is usually studied more in Oceania and Asia than on other continents). This review revealed the lack of a single and well-identified scientific community that focuses on riparian vegetation. This is probably due to the nature of the subject, which includes diverse fields of knowledge and several applied issues: biodiversity, forestry, water quality, hydromorphology, restoration, ecology, etc. Some topics are actively regenerated (e.g. biogeomorphological approaches) and others are emerging, which reflects general trends in ecology (e.g. functional approaches). The literature review indicates that a substantial amount of knowledge already exists; therefore, a major priority of our study is to produce a clear and integrative understanding of riparian zone functioning to address the inherent complexity of these zones and remain valid across a wide diversity of geographical contexts. It is also essential to develop detailed analysis of the sociocultural dimension of riparian vegetation to understand the ecology of riparian zones and to improve riparian vegetation management according to local recommendations in order to maintain and improve its functions and services in the face of global changes.

Biodiversity in intertidal rock pools: informing engineering criteria for artificial habitat enhancement in the built environment

Coastal defence structures are proliferating to counter rising and stormier seas. With increasing concern about the ecological value of built environments, efforts are being made to create novel habitat to increase biodiversity. Rock pools are infrequent on artificial structures. We compared biodiversity patterns between rock pools and emergent rock and assessed the role of pool depth and substratum incline in determining patterns of biodiversity. Rock pools were more taxon rich than emergent substrata. Patterns varied with depth and incline with algal groups being more positively associated with shallow than deeper habitats. Substratum incline had little influence on colonising epibiota, with the exception of canopy algae in deeper habitats where vertical surfaces supported greater taxon richness than horizontal surfaces. The creation of artificial rock pools in built environments will have a positive effect on biodiversity. Building pools of varying depths and inclines and shore heights will provide a range of habitats, increase environmental heterogeneity, therefore creating more possible ecological niches, promoting local biodiversity.

Urban reconciliation ecology: the potential of living roofs and walls

Reconciling human and non-human use of urban regions to support biological conservation represents a major challenge for the 21st century. The concept of reconciliation ecology, by which the anthropogenic environment may be modified to encourage non-human use and biodiversity preservation without compromising societal utilization, potentially represents an appropriate paradigm for urban conservation given the generally poor opportunities that exist for reserve establishment and ecological restoration in urban areas. Two habitat improvement techniques with great potential for reconciliation ecology in urban areas are the installation of living roofs and walls, which have been shown to support a range of taxa at local scales. This paper evaluates the reconciliation potential of living roofs and walls, in particular highlighting both ecological and societal limitations that need to be overcome for application at the landscape scale. We further consider that successful utilization of living roofs and walls for urban reconciliation ecology will rely heavily on the participation of urban citizens, and that a 'citizen science' model is needed to facilitate public participation and support and to create an evidence base to determine their effectiveness. Living roofs and walls are just one aspect of urban reconciliation ecology, but are particularly important 'bottom-up' techniques for improving urban biodiversity that can be performed directly by the citizenry.