viii
Contents
5.4
Conduct Exploratory Analyses
144
5.4.1 Analysis of Water Quality Status
144
5.4.2 Graphing and Qualitative Analysis
144
5.4.3 Recommended Data Analyses
146
5.4.3.1 Creating Data Subsets
147
5.4.3.2 Determine Whether One Lake or Stream,
or a Group of Lakes or Streams, Is N Limited for
Algal Growth
148
5.4.3.3 Quantify Episodic Excursions from Base Flow
Conditions in Surface Water Chemistry during
Hydrologic Events
149
5.4.3.4 Determine the Distribution of Lake or Stream
Water Chemistry across a Particular Study Area 152
5.4.3.5 Quantify Long-Term Changes in Lake or Stream
Chemistry over Time
155
5.4.3.6 Determine to What Extent Air Pollution Is
Currently Affecting the Water Resources in a
Study Area
158
5.4.3.7 Evaluate Whether the Current Condition of Acidor Nutrient-Sensitive Waters Warrants Mitigation 163
5.5
Conduct, If Needed, Statistical Analyses
163
5.5.1 Statistical Tests for Difference
163
5.5.2 Trend Detection
165
5.5.3 Statistical Power
169
5.6
Summary and Conclusions
170
References
171
6 Field Sampling for Aquatic Biota
175
6.1
Background
175
6.1.1 Lake Zooplankton
175
6.1.2 Stream Macroinvertebrates
176
6.2
Aquatic Invertebrate Study Design
177
6.3
Site Selection
179
6.3.1 Laying Out the Support Reach for Stream
Macroinvertebrate Sampling
180
6.3.2 Lake Selection for Zooplankton Sampling
182
6.4
Pretrip Preparation
184
6.4.1 Equipment and Supplies
184
6.4.2 Equipment-Cleaning Protocols
186
6.5
Collection Procedures
186
6.5.1 Stream Benthic Macroinvertebrates
186
6.5.2 Lake Zooplankton
193