Effects of Urbanization on Stream Ecosystems

2005 ◽  
Keyword(s):  
Land Cover ◽  
Valley Floor ◽  
Benthic Macroinvertebrate ◽  
Urban Habitat ◽  
Habitat Assessment ◽  
Santa Clara Valley ◽  
Anthropogenic Habitat ◽  
Channel Slope ◽  
Highly Correlated ◽  
Habitat Variables

<em>Abstract.</em>—We evaluated several approaches for measuring natural and anthropogenic habitat characteristics to predict benthic macroinvertebrate assemblages over a range of urban intensity at 85 stream sites in the Santa Clara Valley, California. Land cover was summarized as percentage urban land cover and impervious area within upstream buffers and the upstream subwatersheds. Field measurements characterized water chemistry, channel slope, sediment, and riparian canopy. In addition to applying the visual-based habitat assessment in U.S. Environmental Protection Agency’s rapid bioassessment protocol, we developed a simplified urban habitat assessment index based on turbidity, fine sediment deposition, riparian condition, and channel modification. Natural and anthropogenic habitat variables covaried along longitudinal stream gradients and were highly correlated with elevation. At the scale of the entire watershed, benthic macroinvertebrate measures were equally correlated with variables expressing natural gradients and urbanization effects. When natural gradients were reduced by partitioning sites into ecoregion subsection groupings, habitat variables most highly correlated with macroinvertebrate measures differed between upland and valley floor site groups. Among the valley floor sites, channel slope and physical modification of channel and riparian habitats appeared more important than upstream land cover or water quality in determining macroinvertebrate richness and ordination scores. Among upland sites, effects of upstream reservoir releases on habitat quality appeared important. Rapid habitat evaluation methods appeared to be an effective method for describing habitat features important to benthic macroinvertebrates when adapted for the region and the disturbance of interest.

scholarly journals Estimation of Ecological Connectivity in a City Based on Land Cover and Urban Habitat Maps

2020 ◽  
Vol 12 (22) ◽  
pp. 9529
Author(s):  
Dohee Kim ◽  
Wonhyeop Shin ◽  
Heejoon Choi ◽  
Jihwan Kim ◽  
Youngkeun Song
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Green Infrastructure ◽  
Urban Areas ◽  
Landscape Connectivity ◽  
Urban Habitat ◽  
Ecological Data ◽  
Ecological Connectivity ◽  
Future Work ◽  
The City

Anthropogenic land use has led to the loss and fragmentation of native habitats and disruption to ecosystem processes, resulting in a decline in landscape connectivity and biodiversity. Here, in order to find the potentials of improvements in ecological connectivity, we provide a spatial analysis to present differences in ecological connectivity based on land cover maps and urban habitat maps in Suwon city, Republic of Korea. We generated two permeability maps for use in a network analysis, one being land cover and the other urban habitat, including a 5-km buffer area from the city boundary. We then determined the current-flow betweenness centrality (CFBC) for each map. Our results indicate that forests are typically the most highly connected areas in both maps. However, in the land cover map results, nearly all high-priority areas were in the mountainous region (CFBC value: 0.0100 ± 0.0028), but the urban habitat indicated that grasslands and rivers within the city also significantly contribute to connectivity (CFBC value: 0.0071 ± 0.0022). The CFBC maps developed here could be used as a reference when introducing green infrastructure in cities. Before establishing ecological networks for urban areas, future work should integrate the land use and ecological data of different administrative districts with continuous ecological connection.

scholarly journals Estimating watershed degradation over the last century and its impact on water-treatment costs for the world’s large cities

2016 ◽  
Vol 113 (32) ◽  
pp. 9117-9122 ◽  
Author(s):  
Robert I. McDonald ◽  
Katherine F. Weber ◽  
Julie Padowski ◽  
Tim Boucher ◽  
Daniel Shemie
Keyword(s):  
Land Use ◽  
Water Treatment ◽  
Land Cover ◽  
Treatment Costs ◽  
Anthropogenic Activity ◽  
Urban Water ◽  
Large Cities ◽  
Capital Costs ◽  
Highly Correlated ◽  
Watershed Degradation

Urban water systems are impacted by land use within their source watersheds, as it affects raw water quality and thus the costs of water treatment. However, global estimates of the effect of land cover change on urban water-treatment costs have been hampered by a lack of global information on urban source watersheds. Here, we use a unique map of the urban source watersheds for 309 large cities (population > 750,000), combined with long-term data on anthropogenic land-use change in their source watersheds and data on water-treatment costs. We show that anthropogenic activity is highly correlated with sediment and nutrient pollution levels, which is in turn highly correlated with treatment costs. Over our study period (1900–2005), median population density has increased by a factor of 5.4 in urban source watersheds, whereas ranching and cropland use have increased by a factor of 3.4 and 2.0, respectively. Nearly all (90%) of urban source watersheds have had some level of watershed degradation, with the average pollutant yield of urban source watersheds increasing by 40% for sediment, 47% for phosphorus, and 119% for nitrogen. We estimate the degradation of watersheds over our study period has impacted treatment costs for 29% of cities globally, with operation and maintenance costs for impacted cities increasing on average by 53 ± 5% and replacement capital costs increasing by 44 ± 14%. We discuss why this widespread degradation might be occurring, and strategies cities have used to slow natural land cover loss.

scholarly journals Estimating densities of larval Salmonflies (Pteronarcys californica) through multiple pass removal of post-emergent exuvia in Colorado rivers

2019 ◽  
Author(s):  
Brian D. Heinold ◽  
Dan A. Kowalski ◽  
R. Barry Nehring
Keyword(s):  
Larval Density ◽  
Benthic Macroinvertebrate ◽  
Low Density ◽  
Ecological Studies ◽  
Density Estimates ◽  
Multiple Pass ◽  
Efficient Alternative ◽  
Highly Correlated ◽  
Removal Technique ◽  
Benthic Sampling

AbstractTraditional methods of collecting and sorting benthic macroinvertebrate samples are useful for stream biomonitoring and ecological studies; however, these methods are time consuming, expensive, and require taxonomic expertise. Estimating larval densities through collection of post-emergent exuvia can be a practical and time efficient alternative. We evaluated the use of multiple pass depletion techniques of the post-emergent exuvia of Pteronarcys californica to estimate larval densities at ten sites in three Colorado rivers. Exuvia density was highly correlated with both final-instar larval density (R2 = 0.90) and total larval density (R2 = 0.88) and the multiple pass removal technique performed well. Exuvia surveys found P. californica at three low density sites where benthic sampling failed to detect it. At moderate and high density sites the exuvia surveys always produced lower density estimates than benthic surveys. Multiple pass depletion estimates of exuvia proved to be an accurate and efficient technique at estimating larval densities and provided an effective alternative for traditional benthic sampling when objectives are monitoring P. californica and detecting populations, especially at low density sites.

Monitoring Biodiversity Using Remote Sensing and Field Surveys

2011 ◽  
pp. 78-102 ◽  
Author(s):  
C. A. Mücher
Keyword(s):  
Remote Sensing ◽  
Land Cover ◽  
Satellite Imagery ◽  
Spatial Modelling ◽  
Spatial Extent ◽  
Data Sets ◽  
Field Surveys ◽  
Distribution Maps ◽  
Plant Life Forms ◽  
Highly Correlated

This chapter concludes that, in combination with additional environmental data sets, it is now possible to model quantitatively the spatial extent of widespread habitats and landscapes on the basis of land cover information derived from satellite imagery. Although it is now possible to model the spatial extent of widespread European habitats, these patterns cannot be directly translated into area estimates. The retrieval of accurate land cover information is not only crucial for the spatial modelling of European landscapes and habitats, but also for their monitoring. Operational remote sensing enables land cover characterization at various scales but the classification accuracies are still insufficient at continental and global scales for monitoring purposes. Instead, the use of continuous thematic fraction layers, as derived from linear unmixing, provides a good basis for monitoring land cover changes of Europe’s complex landscapes. However, gradual and small changes in habitats and their quality are not easily detected from space by satellite imagery, and therefore, additional information from field surveys is needed. Protocols for rapid field surveying of habitats have been developed that can provide a European baseline based on a sampling design across European landscapes. The information from the field samples (e.g. square kilometres) can be used for the validation and calibration of the obtained distribution maps of European habitats. The field surveying method is amongst others based on the estimation of the main plant life forms, which are highly correlated with vegetation structure. The latter has been shown to have a good relationship with satellite imagery. Field surveys are always limited to relatively small areas in Europe, and therefore, the spatial modelling of habitats and landscapes with the help of remotely sensed information remains important for providing a synoptic overview.

Effects of Urbanization on Stream Ecosystems

2005 ◽  
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Geographical Information Systems ◽  
Reference Conditions ◽  
Ordinary Least Squares ◽  
Urban Land ◽  
Limiting Factor ◽  
Physical Habitat ◽  
Santa Clara Valley ◽  
Biological Responses

<em>Abstract.</em>—Lotic habitats in urban settings are often more modified than in other anthropogenically influenced areas. The extent, degree, and permanency of these modifications compromise the use of traditional reference-based study designs to evaluate the level of lotic impairment and establish restoration goals. Directly relating biological responses to the combined effects of urbanization is further complicated by the nonlinear response often observed in common metrics (e.g., Ephemeroptera, Plecoptera, and Trichoptera [EPT] species richness) to measures of human influence (e.g., percentage urban land cover). A characteristic polygonal biological response often arises from the presence of a generalized limiting factor (i.e., urban land use) plus the influence of multiple additional stressors that are nonuniformly distributed throughout the urban environment. Benthic macroinvertebrates, on-site physical habitat and chemistry, and geographical information systems– derived land cover data for 85 sites were collected within the 1,600-km2 Santa Clara Valley (SCV), California urban area. A biological indicator value was derived from EPT richness and percentage EPT. Partitioned regression was used to define reference conditions and estimate the degree of site impairment. We propose that an upper-boundary condition (factor-ceiling) modeled by partitioned regression using ordinary least squares represents an attainable upper limit for biological condition in the SCV area. Indicator values greater than the factor-ceiling, which is monotonically related to existing land use, are considered representative of reference conditions under the current habitat conditions imposed by existing land cover and land use.

Characterizing Variability of the Urban Physical Environment for a Suite of Cities in Rondônia, Brazil

2008 ◽  
Vol 12 (13) ◽  
pp. 1-32 ◽  
Author(s):  
Rebecca L. Powell ◽  
Dar A. Roberts
Keyword(s):  
Land Cover ◽  
Urban Environments ◽  
Model Complexity ◽  
Economic Activities ◽  
Urban Centers ◽  
Aerial Videography ◽  
Urban Sample ◽  
Moderate Resolution ◽  
Region Model ◽  
Highly Correlated

Abstract Urban environments are characterized by high spectral and spatial heterogeneity and, as a consequence, most urban pixels in moderate-resolution imagery contain multiple land-cover materials. Despite these complexities, virtually all urban land cover can be generalized as a combination of vegetation, impervious surfaces, and soil (V–I–S components), in addition to water. Previous work has demonstrated the potential of multiple endmember spectral mixture analysis (MESMA) to model the subpixel abundance of V–I–S components. Here, the authors test whether the technique is sufficiently robust to map V–I–S components for a diverse set of cities, selecting 10 urban centers in the state of Rondônia, Brazil, to represent a range of populations, development histories, and economic activities. For each urban sample, a 20 km × 20 km region centered over the built-up area was subset from Landsat Enhanced Thematic Mapper Plus (ETM+) imagery. MESMA was applied to all subscenes using the same spectral library, model constraints, and selection rules. Accuracy of the modeled V–I–S fractions was assessed using high-resolution images mosaicked from digital aerial videography. Modeled fractions and reference fractions were highly correlated, with R2 values exceeding 0.75 for all materials in multiple cities across a region. Model complexity, or the number of endmembers required to accurately model each pixel, was correlated with the degree of human impact on the landscape. Built-up areas, as delineated by model complexity, exhibited a strong fit to the well-established relationship between the built-up area of a settlement and its population. Finally, this work demonstrates that the V–I–S components as modeled by MESMA can capture both inter- and intraurban variability, suggesting that these data products could contribute to comparative studies of urbanizing areas through time and across regions.

Distribution, habitat, and conservation status of the Giant Barred Frog Mixophyes iteratus in the Bungawalbin catchment, northeastern New South Wales

2005 ◽  
Vol 11 (3) ◽  
pp. 189 ◽  
Author(s):  
B. D. Lewis ◽  
D. A. Rohweder
Keyword(s):  
New South ◽  
Conservation Status ◽  
New South Wales ◽  
Habitat Assessment ◽  
Isolated Populations ◽  
South Wales ◽  
Habitat Analysis ◽  
Stream Bank ◽  
Components Analysis ◽  
Habitat Variables

A distribution and habitat assessment was used to determine the conservation status of the Giant Barred Frog Mixophyes iteratus in the Bungawalbin catchment in northeastern New South Wales. Repeated surveys were used to collect presence absence data at 70 sites between January 1997 and March 1999. Giant Barred Frogs were found at 23 sites (33%) comprising five isolated populations which may have contracted from a single remnant population. Habitat analysis revealed frogs showed a significant preference for sites with pool riffle sequences and the presence of undercuts and overhanging vegetation on the primary stream bank. Principal Components Analysis identified five habitat variables that accounted for 73% of the variability in our bi-variate data. We found the level of disturbance to riparian and instream habitats significantly influenced frog distribution, but this trend was not apparent when adjacent habitats outside the riparian zone were analysed. We propose that sedimentation of waterways may have facilitated this decline due to a reduction in the permanency of surface water flows resulting in reduced recruitment opportunities.

scholarly journals Characteristics of Microbial Communities of Pachygrontha antennata (Hemiptera: Pachygronthidae) in Relation to Habitat Variables

2019 ◽  
Vol 16 (23) ◽  
pp. 4668
Author(s):  
Jae-Yeon Kang ◽  
Yong-Su Kwon ◽  
Gilsang Jeong ◽  
Injung An ◽  
Soyeon Park
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Urban Areas ◽  
Environmental Variables ◽  
Environmental Heterogeneity ◽  
Community Diversity ◽  
Microbial Community Diversity ◽  
Highly Correlated ◽  
Agricultural Areas ◽  
Habitat Variables

The microbial community interacts with the environment and the health and immune function of its host both directly and indirectly. However, very few studies about microbial communities have considered habitat and external environmental variables. This study examined environmental influences on the microbial community of Pachygrontha antennata, which is found in various habitats (e.g., urban, forested, and agricultural areas). The results demonstrated that the composition of the microbial community differed according to land use, while the bacterial diversity did not. In urban areas with high environmental heterogeneity, microbial community diversity tended to be high. Furthermore, bacteria in forests and agricultural areas (e.g., Paraburkholderia, Burkholderia) have been found to be highly correlated with habitat variables. Therefore, we suggest that habitat variables should be considered in future symbiotic studies.

scholarly journals The selection of anthropogenic habitat by wildlife as an ecological consequence of rural exodus: empirical examples from Spain

2021 ◽  
pp. 195-203
Author(s):  
A. Martínez-Abraín ◽  
X. Ferrer ◽  
J. Jiménez ◽  
I. C. Fernández-Calvo
Keyword(s):  
Urban Areas ◽  
Second Step ◽  
Urban Habitat ◽  
Mesopredator Release ◽  
Ecological Processes ◽  
Anthropogenic Habitats ◽  
Anthropogenic Habitat ◽  
Rural Exodus ◽  
Under Construction ◽  
Selection Of

The increasing urbanization of the landscape is a major component of global change worldwide. However, it is puzzling that wildlife is selecting anthropogenic habitats despite the availability of apparently high–quality semi–natural (i.e. less intensively modified) habitats. Definitive explanations for this process are still lacking. We have previously suggested that colonization of the urban habitat is initially triggered by ecological processes that take place outside urban areas as a consequence of past rural exodus. Here we present a diverse array of examples of selection of several types of anthropogenic habitat by wildlife in Spain (including transportation infrastructure, human–exclusion areas, urban areas under construction, cities, reservoirs, quarries and landfills) in support of this idea. Wildlife is moving out of its historical ecological refuges and losing fear of harmless urban humans. Mesopredators are rebounding by mesopredator release, due to ceased human persecution, and shrubs and trees are claiming former agricultural habitats. Together, these factors force many species to move to urbanized areas where they find open habitats, food associated with these habitats, and protection against predation. Hence, the classical balance of costs and benefits that takes place once inside urban areas, would actually be a second step of the process of colonization of urban areas. A better understanding of the initial triggers of urban colonization could help us increase the biological value of human–made habitats for wildlife in the future.

scholarly journals Gut microbiome shifts with urbanization and potentially facilitates a zoonotic pathogen in a wading bird

2019 ◽  
Author(s):  
Maureen H. Murray ◽  
Emily W. Lankau ◽  
Anjelika D. Kidd ◽  
Catharine N. Welch ◽  
Taylor Ellison ◽  
...  
Keyword(s):  
Land Cover ◽  
Habitat Use ◽  
Community Composition ◽  
Urban Land ◽  
South Florida ◽  
Urban Habitat ◽  
Microbial Composition ◽  
Negatively Associated ◽  
Microbiome Composition ◽  
Urban Land Cover

AbstractMicrobial communities in the gastrointestinal tract influence many aspects of host health, including metabolism and susceptibility to pathogen colonization. These relationships and the environmental and individual factors that drive them are relatively unexplored for free-living wildlife. We quantified the relationships between urban habitat use, diet, and age with microbiome composition and diversity for 82 American white ibises (Eudocimus albus) captured along an urban gradient in south Florida and tested whether gut microbial diversity was associated withSalmonella entericaprevalence. Shifts in community composition were significantly associated with urban land cover and, to a lesser extent, diets higher in provisioned food. The diversity of genera was negatively associated with community composition associated with urban land cover, positively associated with age class, and negatively associated withSalmonellashedding. Our results suggest that shifts in both habitat use and diet for urban birds significantly alter gut microbial composition and diversity in ways that may influence health and pathogen susceptibility as species adapt to urban habitats.

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