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Status assessment in acid-sensitive and non-acid-sensitive
Maryland coastal plain streams using an integrated biological,
chemical, physical, and land-use approach
Lenwood W. Hall, Jr., Steven A. Fischer,
William D. Killen, Jr., Mark C. Scott, Michael C. Ziegenfuss
& Ronald D. Anderson
University of Maryland System, Agricultural Experiment
Station, Wye Research and Education Center; Box 169 Queenstown,
Maryland 21658, USA
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Abstract
This study was designed to: (1) evaluate the ecological
status of acid-sensitive and non acid-sensitive Maryland coastal
plain streams using biological (Index of biotic Integrity [IBI]
for fish), chemical and physical habitat conditions; (2) determine
if a low IBI for coastal plain stream fish can be related to stream
sensitivity from acidic inputs and (3) correlate land use activities
and watershed size in the coastal plain streams with biological,
chemical and physical conditions. IBI values obtained using 12 community
metrics for Maryland coastal plain stream fish demonstrated that
there were no significant differences in these values when acid-sensitive
and non-acid-sensitive streams were compared. However, other complementary
data in acid-sensitive streams such as absence of the acid- sensitive
species, blacknose dace and higher numbers and biomass of tolerant
species suggested that these streams may be impacted, IBI values
were also found to be negatively correlated with various trace metals
in acid-sensitive streams but not in non-acid-sensitive areas. Chemical
conditions such as trace metals and nutrients were associated with
land use activities. Highest concentrations of trace metals (chromium,
nickel, and cadmium) were found in streams with the highest percentage
of low residential housing. Nitrate concentrations were significantly
higher in streams found in agricultural areas than in forested areas.
Agriculturally dominated streams with highest nitrate concentrations
(> 10mg 1-1) also contained
the highest percentage of livestock feeding operations. The mean
IBI score for streams draining agricultural land was higher than
the mean value for forested streams when all streams were compared.
However, when several streams that were only marginally forested
(<50%) were removed from the analysis, the IBI scores did not
differ significantly by land use. Two physical habitat indices exhibited
a strong associated with each other. Each habitat index also correlated
with IBI values.
Keywords: acidification, Index of Biotic Integrity, physical
habitat, fish
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