Wetlands serve as natural sources for improvement of stream ecosystem health in regions affected by acid deposition

For over 40 years, acid deposition has been recognized as a serious international environmental problem, but efforts to restore acidified streams and biota have had limited success. The need to better understand the effects of different sources of acidity on streams has become more pressing with the recent increases in surface water organic acids, or ‘brownification,’ associated with climate change and decreased inorganic acid deposition. Here, we carried out a large scale multi‐seasonal investigation in the Adirondacks, one of the most acid‐impacted regions in the United States, to assess how acid stream producers respond to local and watershed influences and whether these influences can be used in acidification remediation. We explored the pathways of wetland control on aluminum chemistry and diatom taxonomic and functional composition. We demonstrate that streams with larger watershed wetlands have higher organic content, lower concentrations of acidic anions, and lower ratios of inorganic to organic monomeric aluminum, all beneficial for diatom biodiversity and guilds producing high biomass. Although brownification has been viewed as a form of pollution, our results indicate that it may be a stimulating force for biofilm producers with potentially positive consequences for higher trophic levels. Our research also reveals that the mechanism of watershed control of local stream diatom biodiversity through wetland export of organic matter is universal in running waters, operating not only in hard streams, as previously reported, but also in acid streams. Our findings that the negative impacts of acid deposition on Adirondack stream chemistry and biota can be mitigated by wetlands have important implications for biodiversity conservation and stream ecosystem management. Future acidification research should focus on the potential for wetlands to improve stream ecosystem health in acid‐impacted regions and their direct use in stream restoration, for example, through stream rechanneling or wetland construction in appropriate hydrologic settings.     

Environmental and socio‐economic factors related to urban bird communities

Urban fauna communities may be strongly influenced by environmental and socio‐economic factors, but the relative importance of these factors is poorly known. Most research on urban fauna has been conducted in large cities and it is unclear if the patterns found in these locations coincide with those from smaller human settlements. We examined the relative importance of environmental and socio‐economic factors in explaining variation in urban bird communities across 72 neighbourhoods in 18 regional towns in south‐eastern Australia. Native bird species richness varied from 6 to 32 across neighbourhoods and was higher in neighbourhoods with more nectar‐rich plants. Variation in bird species diversity across neighbourhoods was also strongly positively related to the density of nectar‐rich plants, but was higher also in neighbourhoods with higher socio‐economic status (reflecting higher levels of disposal income, education and home ownership). The density of native birds across neighbourhoods per season varied from 1 to 15 birds per hectare and was lower in neighbourhoods with a greater cover of impervious surfaces. The density of exotic birds (introduced to Australia) per season also varied across neighbourhoods (0–13 birds per hectare) and was lower in neighbourhoods with more nectar‐rich plants and higher in neighbourhoods with greater impervious surface cover. Our results demonstrated that the vegetation characteristics of household gardens, along streetscapes and in urban parklands had a strong influence on the richness and diversity of urban bird communities. The density of native and exotic birds varied primarily in response to changes in the built environment (measured through impervious surface cover). Socio‐economic factors had relatively little direct influence on urban birds, but neighbourhood socio‐economics may influence bird communities indirectly through the positive relationship between socio‐economic status and vegetation cover recorded in our study area.     

THE BENTHIC MACROINVERTEBRATE FAUNA OF A SOUTH AFRICAN MOUNTAIN STREAM AND ITS RESPONSE TO FIRE

Summary

The effects of a late-summer prescribed burn on the temperature and benthic macroinvertebrate fauna of a south-western Cape mountain stream were investigated over a period of 12 months. Temperature and discharge regimes appear well-defined and relatively predictable from year to year. As in other mediterranean-type ecosystems, seasonal changes in the structure of the invertebrate community and the relative abundance of different feeding groups appear to be associated primarily with changes in the physical environment. Distinctive summer and winter communities were identified, with chironomids dominating the fauna in summer and simuliids dominant in winter. Although the riparian vegetation was only slightly damaged by the fire, a heavy, aseasonal leaf-fall occurred shortly afterwards. The canopy remained sparse for approximately four months. Stream temperature in the post-burn year was not demonstrably affected by increased exposure to solar radiation, however, probably because the canopy remained open during the winter months. The fire appeared to have little effect on the invertebrate fauna. Apart from five rare elements of the biota, all species recorded in the pre-burn year were present in the post-burn year and in similar densities. It is concluded that the riparian vegetation is of major importance in maintaining the integrity of the stream environment.     

Spatial covariation of fish population vital rates in a stream network

Animal populations are spatially structured in heterogeneous landscapes, in which local patches with differing vital rates are connected by dispersal of individuals to varying degrees. Although there is evidence that vital rates differ among local populations, much less is understood about how vital rates covary among local patches in spatially heterogeneous landscapes. In this study, we conducted a nine-year annual mark–recapture survey to characterize spatial covariation of survival and growth for two Japanese native salmonids, white-spotted charr Salvelinus leucomaenis japonicus and red-spotted masu salmon Oncorhynchus masou ishikawae, in a headwater stream network composed of distinctly different tributary and mainstem habitats. Spatial structure of survival and growth differed by species and age class, but results provided support for negative covariation between vital rates, where survival was higher in the tributary habitat but growth was higher in the mainstem habitat. Thus, neither habitat was apparently more important than the other, and local habitats with complementary vital rates may make this spatially structured population less vulnerable to environmental change (i.e. portfolio effect). Despite the spatial structure of vital rates and possibilities that fish can exploit spatially distributed resources, movement of fish was limited due partly to a series of low-head dams that prevented upstream movement of fish in the study area. This study shows that spatial structure of vital rates can be complex and depend on species and age class, and this knowledge is likely paramount to elucidating dynamics of spatially structured populations.     

Urban exploiters have broader dietary niches than urban avoiders

Urbanization is currently one of the most pervasive threats to biodiversity worldwide, yet traits permitting birds to exploit urban environments are not fully understood. I used bird traits related to diet (dietary item and foraging stratum), accounting for latitude, body size, development mode and phylogeny, to compare diet breadths of urban exploiters and urban avoiders, using a global dataset (463 bird species). Urban exploiters (urban species) were larger, consumed more vertebrates and carrion, and fed more frequently on the ground or aerially, and also had broader diets than urban avoiders (non-urban species). In contrast, urban species had narrower foraging strata ranges than non-urban species. These results not only support the hypothesis that urban species share dietary traits allowing them to cope with urban environments but also highlight the importance of considering multiple dietary traits to properly quantify species niches when assessing a species’ response to environmental change.     

Where the Wild Things Are Now: Domestication Reconsidered

ABSTRACT

Although the occurrence of cat-caretaking of free-roaming cats is widespread, particularly so in countries with a climate suitable for cats to reproduce year-round, our knowledge of this relationship is still incomplete. People who engage in daily activities of feeding and caring for groups of free-roaming cats (cat caretakers) are known to be devoted to their cats and invest considerable resources in their care, including neutering and veterinary care. These caretakers often encounter difficulties, such as resentment by neighbors and lack of cooperation or financing by the municipal veterinary services. Despite the fundamental understanding of these caretakers' high daily commitment, and sometimes strong bond with the cats, detailed knowledge is still lacking regarding the nature of this bond, the difficulties that ensue from this daily occupation, and the relationship between the two. The purpose of this study was thus to acquire a deeper understanding, by means of an in-depth interview with cat caretakers. The study has identified, for the first time, two distinct emotional approaches that accompany extensive caretaking for free-roaming cats: emotional attachment and emotional detachment. We show how these two different responses affect both social and financial aspects in the caretakers' lives, and report on the ways in which these individuals experience cat caretaking. Our findings provide a first systematic understanding of the relationship between the level of technical caretaking (feeding, medical care, etc.) and the level of emotional involvement, and reveal the ambivalence often inherent in human–animal relations in general and the caretaker–cat bond in particular. The understanding acquired here can be put into practice to reduce the emotional and technical difficulties experienced by cat caretakers, as well as to improve free-roaming cat management efforts and cat welfare. By increasing public and municipal awareness of the possible contribution of cat caretakers to cat management, and of the emotional and technical difficulties they experience, both the caretakers and other community members can benefit.     

Migrant economies: opportunity structures and potential in different city types

In this paper we wish to appraise how opportunities for migrant economies and their role in urban development may differ among various city types. The article contributes to the debate about the relationship of migrant economies and urban development and takes up two perspectives: it examines local opportunity structures for migrant entrepreneurs and sheds light on migrant economies’ potential for urban development. To address the many interrelated historical and contemporary processes in cities that influence migrant economies, we adopt the rescaling and the mixed embeddedness approaches. Studies on the role of migrant economies in urban development have predominantly focused on metropolises. Based on mixed-methods case studies in two medium-sized German cities, we ask how different city types influence the opportunities and potential of migrant economies for urban development.     

A New Neotropical Species of Spercheus Kugelann,and its Larval Stages (Coleoptera,Hydrophiloidea: Spercheidae)

Spercheus halophilus n. sp. is described together with its egg case and larval stages. This is the second Neotropical species for the genus. Comparative notes with adults of related species are included: S. halophilus seems closely related to S. fimbriicollis Bruch, 1915 and S. spangleri Hebauer, 1990. Larvae of S. halophilus show several important differences when compared with those of S. emarginatus (Schaller, 1783) and S. cerisyi Guérin-Meneville, 1842, most of them related to the mouthparts. This species lives in temporary pools of water gathered along the margins of roads running through a large salt flat in Central Argentina. Notes on the biology of this species are also included.