Predicting the Presence of Filamentous Algae from Cottager Perceptions and Lake Characteristics: an Exploratory Study.

48 Pages·1991·1 MB·English

by  Vandermeulen, H.

ie.V6
PREDICTING THE PRESENCE
OF
FILAMENTOUS ALGAE
FROM
COTTAGER PERCEPTIONS
AND
LAKE CHARACTERISTICS:
SEPTEMBER 1991
Environment
Environnement
Ontario

ISBN 0-1119-%^H-l
PREDICTING THE PRESENCE OF FILAMENTOUS ALGAE
FROM COTTAGER PERCEPTIONS AND LAKE CHARACTERISTICS:
AN EXPLORATORY STUDY
Report prepared by:
H. Vandermeulen and M. Jackson
Limnology Section
Water Resources Branch
Ontario Ministry ofthe Environment
SEPTEMBER 1991
u
Cette publication technique
n'est disponible qu'en anglais.
Copyright: Queen's Printer for Ontario, 1991
This publication may be reproduced for non-commercial purposes
with appropriate attribution.
PIBS 1683

ASTRACT
In 1986, over five thousand cottagers on 214 Central Ontario lakes were surveyed via
questionnaire onthe extent ofthe shorehne oftheir respective lake affectedbyfilamentous
green algae (primarily metaphytic growths ofmembers ofthe Zygnematales). Accuracy of
cottager perceptions were determined by comparison to field survey data of algal growths
at 32 ofthe lakes. A predictive model based upon cottager perceptionswas able to classify
lakes according to algal abundance with over 90% accuracy. Cottager perceptions were
concluded tobeuseful as alow costmethodforsurveying the extent ofalgalgrowthinmany
lakes over a wide geographic range in a small time frame.
Water chemistry data for 191 of the 1986 survey lakes was compared to the cottager algal
abundance estimates to determine if water chemistry could be used to predict algal
abundance. Discriminant analyses results indicated that coarse scale algal abundance could
beaccuratelypredicted inover60%ofthe lakesonthebasisofwaterchemistryparameters.
Thediscriminantanalysismodelswerethenappliedtowaterchemistrydatafromlargerlake
data bases (735 and 5,276 lakes). A 1988 field survey of algal abundance in 44 lakes
determined that over 60% of the lakes in each of the three databases were correctly
classified according to algal abundance by the water chemistry models.

TABLE OF CONTENTS
Page
ABSTRACT
i
LIST OF TABLES iii
LIST OF FIGURES iv
INTRODUCTION
1
MATERIALS AND METHODS 2
1985 Cottager Survey 2
1986 Cottager Survey 3
Water Chemistr\' Databases 4
Water Chemistr\' Database I 4
Water Chemistr\' Database II 4
Water Chemistry Database III 5
Summary of Databases and Statistical Tests 5
1988 Field Survey 5
RESULTS 6
1985 Cottager Survey 6
1986 Cottager Survey 6
Database I 7
Database II 8
Database III 8
1988 Field Survey 8
DISCUSSION 9
REFERENCES 14

LIST OF TABLES
Table 1. Characteristics of the randomly selected subset of 178 lakes surveyed in
1986 for cottager perceptions of FGA growths across two stratification
dimensions, acid sensitivity and completeness ofwater chemistry data.
Table 2. Known filamentous algae status of the 32 reference lakes (1986 survey)
organized according to lake acid sensitivity.
Table 3. Variables (long list) used for discriminant analyses of Database I lakes.
Table 4. Overview of discriminant analysis models tested on Database L
Table.5. Results of discriminant analysis models tested on Database I. Percentage
of lakes correctly classified according to the original cottager classifications.
Table 6. Standardized canonical discriminant function coefficients (Axis or
Eigenvector compositions) for Model 3 and Model 7 as developed with
Database L
Table 7. Predicted incidence of FGA by watershed for the lakes in Database IL
Table 8. Predicted incidence of FGA by watershed for lakes in Database IIL
FGA
Table 9. 1988 field survey. Percentage of shoreline affected by versus
predicted by the Model 7 discriminant analysis.
HI
LIST OF FIGURES
Fig. 1. Primary watershed divisions of Ontario (adapted from Cox, 1978).
Fig. 2. Flow chart of Surveys, Databases and statistical analyses.
Fig. 3. Discriminant analysis results for Database I, coarse scale grouping (S =
SOME, N = NIL, see text). (A) Model 3 (B) Model 7.
Fig. 4. Estimated incidence (Model 3 predictions) of FGA for lakes in Database II
displayed by latitude and longitude quadrants. Percentage of lakes
classified as having SOME or CONSIDERABLE algal growths, by
quadrant (GB, Georgian Bay; LN, Lake Nipissing; LS, Lake Simcoe; NA,
no data base lakes in this quadrant; **, less than five Database II lakes in
this quadrant).
Fig. 5. Estimated incidence (Model 7 predictions) of FGA for lakes in Database
III displayed by latitude and longitude quadrants. Percentage oflakes
classified as having SOME or CONSIDERABLE algal growths, by
quadrant (GB, Georgian Bay; JB, James Bay; LH, Lake Huron; LM Lake
Michigan; LS, Lake Superior; *, less than five Database III lakes in this
quadrant; blank quadrants refer to areas outside of provincial boundaries,
or no lakes in data base; arrow marks longitude 90° 00', see text).