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<div><font face="Geneva" size="-1" color="#000000">Ryan S. King,
Matthew E. Baker, Paul F. Kazyak, and Donald E. Weller 2011. How novel
is too novel? Stream community thresholds at exceptionally low levels
of catchment urbanization. Ecological Applications
21:1659-1678.</font><font face="Geneva" size="-1" color="#0040C2"><u>
http://dx.doi.org/10.1890/10-1357.1</u></font></div>
<div><font face="Geneva" size="-1" color="#000000"><br></font></div>
<div><font face="Geneva" size="-1" color="#000000"><b>How novel is too
novel? Stream community thresholds at exceptionally low levels of
catchment urbanization</b><br>
Ryan S. King,</font><font face="Geneva" size="-1"
color="#000076">1,5</font><font face="Geneva" size="-1"
color="#000000"> Matthew E. Baker,</font><font face="Geneva"
size="-1" color="#000076">2</font><font face="Geneva" size="-1"
color="#000000"> Paul F. Kazyak,</font><font face="Geneva" size="-1"
color="#000076">3</font><font face="Geneva" size="-1" color="#000000">
and Donald E. Weller</font><font face="Geneva" size="-1"
color="#000076">4</font><font face="Geneva" size="-1"
color="#000000"><br>
<br>
1-Center for Reservoir and Aquatic Systems Research, Department of
Biology, Baylor University, One Bear Place #97388, Waco, Texas 76798
USA<br>
2-Department of Geography and Environmental Systems, University of
Maryland-Baltimore County, Baltimore, Maryland 21250 USA<br>
3-Maryland Department of Natural Resources, Annapolis, Maryland 21401
USA<br>
4-Smithsonian Environmental Research Center, Box 28, Edgewater,
Maryland 21037 USA</font><br>
<font face="Arial" size="-1" color="#1A1A1A"></font></div>
<div><font face="Geneva" size="-1" color="#000000">Key
words:</font><font face="Geneva" size="-1"> aquatic biodiversity
conservation, bioassessment, ecological thresholds, indicator species,
no-analog ecosystems, novel environmental gradients, species
sensitivity distribution, watershed classification</font><font
face="Arial" size="-1" color="#1A1A1A"><br>
</font><font face="Geneva" size="-1" color="#000000"><br>
Abstract</font><font face="Arial" size="-1" color="#1A1A1A"><br>
</font><font face="Geneva" size="-1"
color="#0040C2"><u
>http://www.esajournals.org/doi/abs/10.1890/10-1357.1</u></font><font
face="Arial" size="-1" color="#1A1A1A"><br>
</font><font face="Geneva" size="-1" color="#000000">Novel physical
and chemical conditions of many modern ecosystems increasingly diverge
from the environments known to have existed at any time in the history
of Earth. The loss of natural land to urbanization is one of the most
prevalent drivers of novel environments in freshwaters. However,
current understanding of aquatic community response to urbanization is
based heavily upon aggregate indicators of community structure and
linear or wedge-shaped community response models that challenge
ecological community theory. We applied a new analytical method,
threshold indicator taxa analysis (TITAN), to a stream biomonitoring
data set from Maryland to explicitly evaluate linear community
response models to urbanization that implicitly assume individual taxa
decline or increase at incrementally different levels of urbanization.
We used TITAN (1) to identify the location and magnitude of greatest
change in the frequency and abundance of individual taxa and (2) to
assess synchrony in the location of change points as evidence for
stream community thresholds in response to percent impervious cover in
catchments. We documented clear and synchronous threshold declines of
110 of 238 macroinvertebrate taxa in response to low levels of
impervious cover. Approximately 80% of the declining taxa did so
between 0.5% and 2% impervious cover, whereas the last 20% declined
sporadically from 2% to 25% impervious cover. Synchrony of individual
responses resulted in distinct community-level thresholds ranging from
?0.68% (mountains), 1.28% (piedmont), and 0.96% (coastal plain)
impervious cover. Upper limits (95% confidence intervals) of community
thresholds were <2% cover in all regions. Within distinct
physiographic classes, higher-gradient, smaller catchments required
less impervious cover than lower gradient, larger catchments to elicit
community thresholds. Relatively few taxa showed positive responses to
increasing impervious cover, and those that did gradually increased in
frequency and abundance, approximating a linear cumulative
distribution. The sharp, synchronous declines of numerous taxa
established a consistent threshold response at exceptionally low
levels of catchment urbanization, and uncertainty regarding the
estimation of impervious cover from satellite data was mitigated by
several corroborating lines of evidence. We suggest that threshold
responses of communities to urban and other novel environmental
gradients may be more prevalent than currently
recognized.</font><font face="Arial" size="-1" color="#1A1A1A"><br>
</font><font face="Arial" size="-3" color="#000000"></font></div>
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>********************************************************************<span
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"The death knell for the grizzly in the Southwest was tolled not by
a church bell but by a train whistle."<br>
<br>
"Changing economic conditions, new homesteading laws, and cheap rail
travel resulted in an ever-increasing influx of settlers, who
eventually penetrated to the remotest corners of the
region."</font></div>
<div><font face="Cambria" color="#000000"><br>
David E. Brown. <i> The grizzly in the southwest</i>. University
of Oklahoma Press. 1985. p. 97<br>
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