LIMNOLOGICAL STUDIES OF

DYSTROPHIC WATERS

by

Lee Clifford Bowling, B.Sc. ( Hons)

in the Department of Botany

Submitted in fulfilment of the

requirements for the degree of

Doctor of Philosophy

University of Tasmania

January, 1988

DECLARATION

This thesis contains no material which has been

accep ted for the award of any other h igher degree

or graduate d iploma in any tertiary institution

and that , to the best of the candidate ' s knowledge

and bel ief , this thesis contains no material

prev iously published or written by another person ,

except when due reference is made in the text of

the the s i s .

Lee C . Bowling

ABSTRACT

A number o f asp ects o f the l imnology o f dystrophic lent ic

freshwaters are covered in this thes is . Initially , studies covering

a wide range of heterogeneous lakes and reservoirs from several

different areas are reported , to give an overall perspective of many

o f the roles d i s solved humic substances play in v arious l imnological

processes . More detailed case s tudies of a number o f dystrophic lakes

and reservo irs are then outlined , to demonstrate how dissolved humic

substances actively influence the limnology of these individual waters .

Inves t igations o f the underwater l igh t cl imates of f ifty lakes

and reservoir s f r om Tasmania , thirty-seven from north-east New South

Wales , and o f twenty- s ix coastal dune lakes in south-east Queensland

showed that dissolved humic substances were the maj or attenuators o f

l ight i n all three areas . Increasing gilvin concentrat ions led to

the rap id ext inction o f l ight at shallow dep th s , and to changes in

its underwater spectral distribut ion from green-yellow in the

clearest water s , to red in the most humic . Turbidity and phytopl ankton

were important c ont r ibutors to attenuation in only a few of the waters

studied . Resul t s from Tasmania allowed the cons truction of a

predict ive model for use in estimating the underwater l ight climates

of the many remote l akes of the island where in s itu measurements are

impossible , from s imple laboratory measurement s o f small water samples .

The rap id attenuation o f l ight in humic waters also strongly affects

thermal strat i f ication , leading to strong thermal gradients , shallow

thermoclines , and l engthy periods of stratification .

Chemical aspects were also examined. S trong negative correlations

were found between the concentration of dis solved humic substances and

pH in coastal dune l ake waters from south-east Queensland , King and

Flinders Island s , and western and south-west Tasmania . In contrast ,

there was no correlation between these two parameters in north-east

New South Wales waters , probably due to lower humic concentrat ions

and buf fering by higher bicarbonate levels . Calcium and bicarbonate

l evel s were al s o sometimes low in acidic , dystrophic lakes .

A wide range o f photosynthetic organisms were present in the s ites

investigated from New South Wales , Queensland , and coastal l akes of

south-west Tasmania . Phytoplankton came both from the Chlorophyceae

and from o ther algal d ivisions , and desmids and d ino flagellates were

e specially common . Proportions of green algae decreased relative

t o those with acces sory pho tosynthetic pigments , as humic concentr at ion

increased , in the h ighly humic western and south-west Tasmanian lagoons ,

but this was no t app arent in the less dystrophic waters of the o th er

two areas . However , high humic concentrations reduced the number of

phytopl ankton g enera present from all group s . Chrysophytes dominated

the phytoplankton communities of polyhumic Lake Chisholm .

S tudies o f Lake Chisholm , the reservoirs o f the Pieman River

Power Development , and the meronictic lakes of the lower Gordon Riv er ,

all in Tasmania , showed humic materials played an important role in

their l imnology . The rapid attenuation of l ight , and sub sequent

s trong thermal s trat ification for much of the year lead to sluggish

c irculation , all owing near-mero�ict ic conditions in Lake Chisholm ,

and the protect ion and resultant slowing of the demise o f ectogenic

meromixis in the Gordon River l akes . The se features, along with

enhancing the sol��9ility of iron and manganese in the reduc ing ,

sulphide l aden bottom waters of the Pieman River reservoirs , enabled

their chemical s tratification . However , other factors , such as basin

morphometry and shel ter , are also of importance in the l imnology o f

these l akes and reservo irs .

ACKNOWLEDGEMENTS

I wish to thank my supervisor , Dr P A Tyler , for his valuable

as sistance and encouragement throughout the proj ect . I also thank

Dr M A Brock for her encouragement during the final stages of this

work , and for her construct ive c omments on the initial drafts of

this thesis .

I am grateful al so for the interest and assistance o f the staf f

and postgraduate studentsof the Dep artment o f Botany , Univer s ity o f

Tasmania during the earl ier stages o f this project . In the same v e in ,

I acknowledge the encouragement and assistance of the staff and

po stgraduate students o f the Department o f Botany , University of New

England , during the l ater period of the work , and for allowing me t o

continue with the proj ect after my move there .

I thank the Internal Resear ch Grants Committee , University of

New England , for research money whi ch allowed the collection of

data from nortfreast New South Wales and south-east Queensland , and

the Tasmanian National Parks and Wildlife Service for a research

grant and logist i cal support to enable sampling of remote coastal

lagoons in western and s outh-wes t Tasmania . The remainder o f the

work reported in this thesis was carried out using various research

grants made to my superv isor .

I am particularly indebted to the many people who freely made

time avail able to assist with f ield work . O f part icular note are

J M Ferris , who al so advised on use of the LIMNO computer program ,

0 Bourke for her assistance on Fraser Island , and R L Croome , with

whom data from the Gordon River has been j ointly collected and shared .

R. D. King also made his original field note-books avail able so I

could use data from 1 9 77 and 1 9 7 8 f or the computation o f stabilities ,

heat budgets , and other similar p arameters.

The cheerful help of Mrs Rosemaree Wickham throughout the proj ect

is al so acknowledged . Mrs J Hanlan is thanked for her t yp ing . I

thank R J Ban�ns for assistance with the nutrient analyses o f waters

from north-east New South Wales , south-east Queensland , and western

and south-west Tasmania .

Finally , I wish to thank my wife , Regie , and children for their

support and forbearance during the course of the proj ect , especially

during my many absences from home ; and my p arents for their

encouragement , and for funding the production costs o f this thesis .

I therefore dedicate this thesis to my family , without whose help

it would never have eventuated .

TABLE OF C ONTENTS

CHAPTER 1 : INTRODUCTION TO THE STUDY

1 . 1 Aims and Signif icance 1 . 2 The S cope of this Thesis

CHAPTER 2 : A REVIEW OF LITERATURE RELEVANT TO THI S STUDY

P ar t One : Descrip tion of S tudy Areas

2 . 1

2 . 2

2 . 3

A Limnological Background to Tasmania

2 . 1 . 1 2 . 1 . 2 2 . 1 . 3 2 . 1 . 4

The Western Limnological Province The Eastern Limnological Province The Coast al Limnological Province Additional Limnological Studies in Tasmania

A Limnological Background to North-east New South Wales

A Limnological Background to Studies on Coa s t al Lakes

2 . 3 . 1 2 . 3 . 2

The Nature of Australian Coast al Dune Lakes Studies of Coa s t al Lakes of the Australian

Mainland

Part Two : A Theoretical Background to the S tudies

2 . 4

2 . 5

2 . 6

The Nature of Humic Substances in Aquat ic Sys t ems

2 . 4 . 1

2 . 4 . 2 2 . 4 . 3 2 . 4 . 4 2 . 4 . 5

2 . 4 . 6

The Chemistry , Origin , and Distribution of Dis solved Humic Substances

Humic Sub s t ances and Colour Humic Sub s tances and pH Humic Sub s t ances and Metal Ions The Ecological Significance of Humic

Sub s t ances Limnological Features of Humic Lakes -

Examples from Finland

Factors Determining the Underwater Light Climates of Lakes

2 . 5 . 1 2 . 5 . 2

2 . 5 . 3 2 . 5 . 4 2 . 5 . 5

The Fate of Light in Water Components of the Aquatic Medium Caus ing

Ab sorption and Scattering The Op tical Properties of the Water Column The Attenuation of P . A . R . with Dep th Studies of Light At tenuat ion in Aus tralian

and New Zealand Inland Waters

A Background to Chemical Stratificat ion and Meromixis

2 . 6 . 1 2 . 6 . 2 2 . 6 . 3

The Nature of Chemical S tr atificat ion Meromixis in Impoundments Causes of Biogenic Meromixis in

Impoundments

1

1 2

5

5

5

5 8 9

10

10

1 1

1 1

13

18

18

18 19 20 20

2 1

23

27

27

27 29 3 1

3 1

34

34 35

36

CHAPTER 3 : STUDIES OF THE u�ERWATER LIGHT CLIMATES OF LENTIC FRESHWATERS FROM TASMANIA , NORTH-EAST NEW SOUTH WALES , AND SOUTH-EAST QUEENSLAND 3 7

3 . 1 Introduct ion 3 7

3 . 2

3 . 3

3 . 1 . 1 3 . 1 . 2

Methods

3 . 2 . 1 3 . 2 . 2

Resul t s

The Aims and S cope o f the Study The S tudy Sites

Sources of Data Collection and Analysis of Samples , and

Computation of the Data

P art A : Tasmania

3 . 3 . 1 3 . 3 . 2 3.3 . 3 3 . 3 . 4 3 . 3 . 5 3 . 3 . 6

Colour , Turbidity , and Chlorophyll a Attenuation of Total P . A . R . Reflectance and S cattering Coefficients Spectr al D is tr ibution of Underwater P . A . R . Secchi Disc Transparency Regres sion Analysis

P art B: North-east New South Wales

3 . 3 . 7 3 . 3 . 8 3 . 3 . 9 3 . 3 . 1 0 3 . 3 . 1 1

3. . 3 . 1 2

Surface Temperature , pH , and Conductivity Total Nitrogen and Total Phosphorus Turbidity , Colour , and Chlorophyll a The Attenuation of P.A . R . Reflectance and the Scattering

Coefficient The Sp ectral Dis tribution of Underwater

P . A . R . 3 . 3 . 1 3 Secchi Disc Tran sparency 3 . 3 . 1 4 Regres sion and Correlation Analyses 3 . 3 . 1 5 Phytopl ankton

Part C : South- east Queensl and

3 . 4

3 . 5

3 . 3 . 1 6 Temper ature , p H , and Conductivity at 1 8°C (K1 8 )

3 . 3 . 1 7 Total Nitrogen and Tot al Phosphorus 3 . 3.1 8 Turbidity , Colour , and Chlorophyll a 3 . 3 . 1 9 The At tenuation , Reflectance , and

S cattering of P .A . R . 3 . 3 . 20 Secchi Disc Transparency 3 . 3 . 2 1 Regression and Correlations 3 . 3 . 2 2 Phytoplankton

Discussion

3 . 4 . 1

3 . 4 . 2

3 . 4 . 3 3 . 4 . 4

3 . 4 . 5

Factor s Influencing the Underwater Light Climates of the Three S tudy Areas

Upwelling Irradiance , Reflectance , and Scattering

Humics , Turbidity , and Chlorophyll a Op tical Clas sifications of the Lakes

of the S tudy Areas Phytoplankton Diversity and Distribut ion

Conclusions

37 38

4 1

4 1

46

46

46 46 49 52 6 1 6 1

64

64 64 64 66

68

68 74 74 7 6

7 9

7 9 7 9 8 1

8 1 85 85 87

8 7

8 7

9 5 9 7

9 7 1 04

1 06

CHAPTER 4: PHYSICO-CHEMICAL STUDIES OF FRESHWATER COASTAL LAGOONS FROM WESTERN AND SOUTH-WEST TASMANIA , AND FROM KING AND FLINDERS ISLAND , BASS STRAIT 108

4 . 1 Introduction 108

4 . 2

4 . 3

4 . 4

4 . 1 . 1 The Aims and S cope of This S tudy

Methods

4 . 2 . 1 Collection and Analyses of Samples

Results

4 . 3 . 1 4 . 3 . 2 4 . 3 . 3 4 . 3.4 4 . 3 . 5 4 . 3 . 6 4 . 3 . 7 4 . 3 . 8 4 . 3 . 9

4 . 3 . 10

Thermal and Oxygen Profiles Turbidity and Colour Secchi Disc Dep th pH , Conduct ivity , and Salinity Maj or Ions Present Dis solved Iron and S ilica Nutrient Analyses Pearson Correlation Analysis Princip le Co-ordinates Analysis of the

Lagoons from the Bass S trait Islands Phytoplankton Present in the Coastal

Lagoons of Western and South-wes t Tasmania

Discussion

4 . 4 . 1 The Physicochemical Properties of the Coastal Lagoons

4 . 4 . 2 The Phytoplankton o f the Lakes of Western and South-wes t Tasmania

4 . 5 Conclusions

CHAPTER 5: DETAILED LIMNOLOGICAL STUDIES OF DYSTROPHIC LAKES AND RESERVOIRS FROM WESTERN TASMANIA

5 . 1 Introduct ion

5 . 2

5 . 3

5 . 1 . 1 5 . 1 . 2

Methods

The Aims and S cope of these S tudies The Study Areas

5 . 2 . 1 Dat a Collection and Analysis

Results

P ar t A : Lake Chisholm

5 . 3 . 1 5 . 3 . 2

5 . 3 . 3

Physicochemical Features of Lake Chisholm Thermal Stabilities and Birgean Wind Work

for Lake Chisholm Biological Features of Lake Chisho lm

Part B : The Reservoirs o f the Pieman River and Lake Barrington

5 . 3 . 4 5 . 3 . 5 5.3 . 6

Physico chemical Features of Lake Mackintosh Phys icochemical Features of Lake Nurchison Physicochemical Features of Lake Roseb ery

108

109

109

113

113 113 117 117 120 120 122 123

126

126

13 1

13 1

135

136

138

138

138 139

144

146

146

146

157 160

163

163 166 180

5 . 3 . 7 5 . 3 . 8 5 . 3 . 9

Physicochemical Features o f Lake Pieman 1 80 Physicochemical Features of Lake Barrington 1 83 Volume Weighed Average Temperature and

Oxygen ; Heat C ont ent s , Thermal Stabilities and Birgean Wind Work in the Five Reservoirs 1 85

P art C: The Lakes of the Lower Gordon River Area 1 9 0

5 . 3 . 1 0 Physicochemical Features o f Lake Fidler 1 90 5 . 3 . 1 1 Physicochemical Featur es o f Sulphide Pool 1 93 5 . 3 . 1 2 Physicochemical Featur es of Lake Norrison 1 99 5 . 3 . 1 3 Cal culations o f Meromictic S t ability 1 99

5 . 4

5 . 3 . 1 4 Thermal Stabilit ies , Birgean Wind Hark , Heat Content, and Volume Weighed Average Temperatures

D iscussion

5 . 4 . 1

5 . 4 . 2

5 . 4 . 3 5 . 4 . 4

5 . 4 . 5

The Role of Humics in the Limnology of these Lakes

The Inf luence o f Basin Morphometry , Alignment, and Shelter from Wind Action

Heating and Mixing Dynamics Meromictic Tendancies in the Lakes and

Reservoirs The Future of Meromixis in Lake Hurchison ,

Lake Barrington , and the Gordon River Lakes

5 . 4 . 6 Signif icance of the Gordon River Lakes to the World Heritage Area of South-west Tasmania

5 . 4 . 7 The Ecology of Phytoplankton in Lake Chisholm

5 . 5 Conclus ions

CHAPTER 6 : THE LIMNOLOGY OF DYSTROPHIC WATERS

6 . 1 Conclus ions from the Study

REFERENCES CITED

APP ENDIX 1: Papers Resul ting from this thesis

20 1

2 1 0

2 1 0

2 1 5 2 1 8

220

223

226

227

228

231

23 1

234

253