scholarly journals Landscape heterogeneity and the biodiversity of Arctic stream communities: a habitat template analysis

2005 ◽  
Vol 62 (8) ◽  
pp. 1905-1919 ◽  
Author(s):  
Alexander D Huryn ◽  
Karie A Slavik ◽  
Rex L Lowe ◽  
Stephanie M Parker ◽  
Dennis S Anderson ◽  
...  
Keyword(s):  
Landscape Heterogeneity ◽  
Detrended Correspondence Analysis ◽  
Functional Feeding Groups ◽  
Mountain Glacier ◽  
Stream Communities ◽  
Stream Community ◽  
Arctic Alaska ◽  
Template Analysis ◽  
Habitat Template ◽  
And Function

We predicted that substratum freezing and instability are major determinants of the variability of stream community structure in Arctic Alaska. Their effects were conceptualized as a two-dimensional habitat template that was assessed using a natural experiment based on five stream types (mountain-spring, tundra-spring, tundra, mountain, glacier). Detrended correspondence analysis (DCA) indicated distinct macroinvertebrate assemblages for each stream type. The contribution of functional feeding groups to assemblage biomass varied systematically among stream types, indicating that structure and function are linked. Assemblage position within a DCA biplot was used to assess factors controlling its structure. Springs separated from other stream types along a gradient of nutrient concentration and freezing probability. Glacier and mountain streams separated from springs and tundra streams along a gradient of substratum instability and freezing probability. Owing to differences in sources of discharge to streams, the effects of nutrients and substratum stability could not be separated from freezing. Although many factors likely contribute to the variability of Arctic stream communities, the major determinants may be conceptualized as a template structured by gradients in (i) nutrient supply and substratum freezing and (ii) substratum instability and substratum freezing. This template provides a basis for predicting the response of Arctic stream communities to climate change.

Effects of natural disturbance on stream communities: a habitat template analysis of arctic headwater streams

2011 ◽  
Vol 56 (7) ◽  
pp. 1342-1357 ◽  
Author(s):  
STEPHANIE M. PARKER ◽  
ALEXANDER D. HURYN
Keyword(s):  
Headwater Streams ◽  
Natural Disturbance ◽  
Stream Communities ◽  
Template Analysis ◽  
Habitat Template

scholarly journals Regional hydrology controls stream microbial biofilms: evidence from a glacial catchment

2004 ◽  
Vol 1 (1) ◽  
pp. 497-531 ◽  
Author(s):  
T. J. Battin ◽  
A. Wille ◽  
R. Psenner ◽  
A. Richter
Keyword(s):  
Landscape Heterogeneity ◽  
Low Flow ◽  
Detection Rates ◽  
Stream Communities ◽  
Stream Discharge ◽  
Carbon Production ◽  
Microbial Biofilms ◽  
Short Period ◽  
Alpine Stream

Abstract. Glaciers are highly responsive to global warming and important agents of landscape heterogeneity. While it is well established that glacial ablation and snowmelt regulate stream discharge, linkage among streams and streamwater hydrogeochemistry, the controls of these factors on stream microbial biofilms remain insufficiently understood. We investigated glacial (metakryal, hypokryal), groundwater-fed (krenal) and snow-fed (rhithral) streams – all of them representative for alpine stream networks – and present evidence that these hydrologic and hydrogeochemical factors differentially affect sediment microbial biofilms. Average microbial biomass and bacterial carbon production were low in the glacial streams, whereas bacterial cell size, biomass, and carbon production were higher in the tributaries, most notably in the krenal stream. Whole-cell in situ fluorescence hybridization revealed reduced detection rates of the Eubacteria and higher abundance of α-Proteobacteria in the glacial stream, a pattern that most probably reflects the trophic status of this ecosystem. Our data suggest low flow during the onset of snowmelt and autumn as a short period (hot moment) of favorable environmental conditions with pulsed inputs of allochthonous nitrate and dissolved organic carbon, and with disproportional high microbial growth. Krenal and rhithral streams with more constant and favorable environments serve as possible sources of microbes and organic matter to the main glacial channel during periods (e.g. snowmelt) of elevated hydrologic linkage among streams. Ice and snow dynamics have a crucial impact on microbial biofilms, and we thus need better understanding of the microbial ecology and enhanced consideration of critical hydrological episodes in future models predicting alpine stream communities.

scholarly journals Water sources aggregate parasites with increasing effects in more arid conditions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Georgia Titcomb ◽  
John Naisikie Mantas ◽  
Jenna Hulke ◽  
Ivan Rodriguez ◽  
Douglas Branch ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Animal Movement ◽  
Landscape Heterogeneity ◽  
Water Sources ◽  
East African ◽  
Small Areas ◽  
Arid Conditions ◽  
Animal Activity ◽  
Herbivore Species ◽  
And Function

AbstractShifts in landscape heterogeneity and climate can influence animal movement in ways that profoundly alter disease transmission. Water sources that are foci of animal activity have great potential to promote disease transmission, but it is unknown how this varies across a range of hosts and climatic contexts. For fecal-oral parasites, water resources can aggregate many different hosts in small areas, concentrate infectious material, and function as disease hotspots. This may be exacerbated where water is scarce and for species requiring frequent water access. Working in an East African savanna, we show via experimental and observational methods that water sources increase the density of wild and domestic herbivore feces and thus, the concentration of fecal-oral parasites in the environment, by up to two orders of magnitude. We show that this effect is amplified in drier areas and drier periods, creating dynamic and heterogeneous disease landscapes across space and time. We also show that herbivore grazing behaviors that expose them to fecal-oral parasites often increase at water sources relative to background sites, increasing potential parasite transmission at these hotspots. Critically, this effect varies by herbivore species, with strongest effects for two animals of concern for conservation and development: elephants and cattle.

Macroinvertebrate Communities and Environment in a Southern African Mountain Stream

1988 ◽  
Vol 45 (12) ◽  
pp. 2168-2181 ◽  
Author(s):  
J. M. King ◽  
J. A. Day ◽  
P. R. Hurly ◽  
M-P. Henshall-Howard ◽  
B. R. Davies
Keyword(s):  
Community Structure ◽  
Environmental Variables ◽  
Mediterranean Ecosystems ◽  
Mountain Stream ◽  
Functional Feeding Groups ◽  
Stepwise Discriminant Analysis ◽  
Macroinvertebrate Communities ◽  
Strong Correlations ◽  
Stream Community ◽  
Community Changes

In a study of a second-order southern African stream, complementary classification and multidimensional scaling (MDS) techniques revealed longitudinal changes in macroinvertebrate community structure, but no temporal changes. Stepwise discriminant analysis and multiple linear regression were used to identify environmental variables correlated with the community changes but produced conflicting results depending on the information used, possibly because of strong correlations between some of the variables. The MDS plot of biotic samples illustrated that potassium levels correlated most strongly with community distribution. Because of the large number of variables now shown worldwide to correlate with faunal distributions, we suggest ways to choose the variables to suit the kind of study to be undertaken. Attempts to assign the invertebrates to functional feeding groups (FFGs) were unsatisfactory as the relevant categories are poorly defined and often inadequate for classifying the fauna. We suggest that until these categories are more clearly defined, and more uniformly applied, concepts relating to FFGs cannot be tested satisfactorily. The stream community in Langrivier is more similar to communities found in two other mediterranean ecosystems than to those in other southern African rivers, probably because of the greater predictability of flow in the former.

scholarly journals Exploring the Meaning of Organizational Purpose at a New Dawn: The Development of a Conceptual Model Through Expert Interviews

2021 ◽  
Vol 12 ◽  
Author(s):  
Ramon van Ingen ◽  
Pascale Peters ◽  
Melanie De Ruiter ◽  
Henry Robben
Keyword(s):  
Conceptual Model ◽  
Empirical Research ◽  
Theory Development ◽  
Conservation Of Resources ◽  
Academic Knowledge ◽  
Professional Management ◽  
Template Analysis ◽  
Organizational Purpose ◽  
Person Organization Fit ◽  
And Function

Organizational purpose has flourished in the professional management literature, yet despite increased scholarly interest, academic knowledge and empirical research on the topic remain scarce. Moreover, studies that have been conducted contain important oversights including the lack of a clear conceptualization and misinterpretations that hinder the further development and understanding of organizational purpose. In view of these shortcomings, our interview study aimed to contribute to academic and societal conversations on the contemporary meaning and function of organizational purpose considering the voices and perspectives of 44 global experts. Employing template analysis, we defined organizational purpose as “an organization’s reason for being characterized by significance, aspiration, direction, unification, and motivation.” Moreover, we proposed an explanatory conceptual model, including drivers and outcomes of purpose, important boundary conditions, and explanatory mechanisms. Drawing on self-determination theory, person–organization fit theory, job characteristics theory, and conservation of resources theory, we were able to explain how and under what conditions these concepts are related to organizational purpose. In doing so, our research contributes to advancing the knowledge and understanding of organizational purpose and its effects on human lives within and outside organizations. Our study thereby enhances the understanding of the role of organizations in society and helps in evaluating whether organizations take responsibility by living their purpose in the society they are part of. As such, our study provides important insights for theory development, scale development, and further empirical research on organizational purpose and its effects in different streams such as OB, HRM, marketing, leadership, and strategy.

Landscape Effects on Ecosystem Structure and Function

2019 ◽  
pp. 512-546
Author(s):  
Kimberly A. With
Keyword(s):  
Nutrient Dynamics ◽  
Landscape Heterogeneity ◽  
Landscape Management ◽  
Structure And Function ◽  
Landscape Context ◽  
Ecological Resilience ◽  
Ecosystem Structure ◽  
The Face ◽  
And Function ◽  
Ecosystem Structure And Function

Landscape ecosystem ecology is concerned with the study of how landscape structure affects ecosystem structure and function, and how landscape heterogeneity in turn is generated or sustained by the redistribution of nutrients or organisms within and among ecosystems. This chapter begins with an overview of how landscape context influences ecosystem processes, including the effects of land management and land-cover change on nutrient dynamics and productivity. Next, the chapter considers the linkages among systems (metaecosystems) and how spatial subsidies are important for understanding ecosystem function in a landscape context. The chapter then explores under what conditions landscape function becomes disrupted, possibly precipitating irreversible system state changes, before concluding with a clarion call for landscape sustainability; that is, landscape management that preserves the productivity, multifunctionality, and ecological resilience of landscapes in the face of future societal demands, intensifying land use, and rapid climate change.

Colonization by Lotic Macroinvertebrates: A Review of Processes and Patterns

1992 ◽  
Vol 49 (3) ◽  
pp. 617-628 ◽  
Author(s):  
Rosemary J. Mackay
Keyword(s):  
Large Scale ◽  
Trophic Ecology ◽  
Experimental Studies ◽  
Life Cycles ◽  
Small Scale ◽  
Stream Communities ◽  
Stream Community ◽  
Lotic Habitats ◽  
Ecological Patterns ◽  
Filter Feeders

Ways in which invertebrates colonize lotic habitats are reviewed, tracing patterns in behaviour, trophic ecology, and life history that could lead to predictions concerning resilience of stream communities after disturbance. Patterns are described for small-scale experimental studies using introduced or natural substrates, for large-scale observations of new or rewatered channels, for rivers recovering from pollution, and for unstable rivers with fluctuating discharge. Colonization depends on invertebrate mobility (drift, swimming, crawling, and flight), substrate texture and associated food supplies, competition, and predation. Epilithon-browsers and filter feeders can use the resources of smooth stones; gatherers colonize as fine detritus accumulates; grazers increase as periphyton becomes established; shredders and predators tend to be late arrivals. Propagules for colonization are made more available by asynchronous and aseasonal life cycles, long oviposition periods, and refuges in the streambed or neighbouring waterbodies. Species in frequently disturbed streams benefit from these characteristics. Although disturbance may be due to stochastic factors, recovery is not due to chance. Recurring ecological patterns among early colonizers suggest that knowledge of the hydrologic regime, food resources, and dominant taxa can be used to predict the overall resilience of a stream community.

Consequences of acid mine drainage for the structure and function of benthic stream communities: a review

2012 ◽  
Vol 31 (1) ◽  
pp. 108-120 ◽  
Author(s):  
Kristy L. Hogsden ◽  
Jon S. Harding
Keyword(s):  
Acid Mine Drainage ◽  
Mine Drainage ◽  
Structure And Function ◽  
Stream Communities ◽  
Acid Mine ◽  
Benthic Stream ◽  
And Function

Structure and function of a benthic invertebrate stream community as influenced by beaver (Castor canadensis)

Oecologia ◽  
1986 ◽  
Vol 68 (4) ◽  
pp. 481-489 ◽  
Author(s):  
Donald M. McDowell ◽  
Robert J. Naiman
Keyword(s):  
Castor Canadensis ◽  
Benthic Invertebrate ◽  
Structure And Function ◽  
Stream Community ◽  
And Function
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