Limnology of Parakrama Samudra — Sri Lanka: A case study of an ancient man-made lake in the tropics

234 Pages·1983·7.655 MB·English

by  F. Schiemer (auth.), F. Schiemer (eds.)

Limnology of Parakrama Samudra - Sri Lanka
Developments in Hydrobiology 12
Series editor
H. J. Dumont
DR W. JUNK PUBLISHERS THE HAGUE-BaSTON-LONDON 1983
Limnology of Parakrama Samudra - Sri Lanka
A case study of an ancient man-made lake in the tropics
Edited by
F. Schiemer
DR W. JUNK PUBLISHERS THE HAGUE-BOSTON-LONDON 1983
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Library of Congress CatalogjJlg in Publication Data
Main entry under title:
L:im<lology of Parakrama Samudra, Sri Lanka.
(Developments in hydrobiology ; 12)
1. Limnology--Sri Lanka--Parakrama Sa.mudra
ReserVQ:Ilr. 2. Parakrama Sa.mudra Reservoir (Sri Lanka)
I. Schiemer, F. II. Series.
QHl83.5.L55 1983 574.92'9'5491 82-18645
ISBN-13: 978-94-009-7283-4 e-ISBN-13: 978-94-009-7281-0
DOl: 10.10071978-94-009-7281-0
Copyright © 1983, Dr W. Junk Publishers, The Hague
Softcover reprint of the hardcover I st edition 1983
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system. or transmit/ed in anyform ofb y any means,
mechanical, photocopying, recording, or otherwise, without the prior writ/en permission of the publishers.
'Let not even a drop of rain water go to the sea, without benefitting man'
Parakrama Bahu The Great
(in M ahavansa, the old
historical chronicle of Sri Lanka)
Colossal statue at Polonnaruwa, considered to represent King Parakrama Bahu I (1153-1186 A D), thefounder
of important irrigation systems.
Contents
1. The Parakrama Samudra Project - scope and objectives,
by F. Schiemer .. . . . . . . . . . . . . . . . . . .. . ................... .
2. Energy and water budget of a tropical man-made lake,
by H. Dobesch ........................................... 19
3. Thermal stratification, mixis and advective currents in the Parakrama Samudra Reservoir,
Sri Lanka,
by K. Bauer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 27
4. Phosphorus and phosphatase dynamics in Parakrama Samudra based on diurnal observations,
by A. Gunatilaka . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 35
5. An assessment of the phytoplankton biomass and primary productivity of Parakrama Samudra,
a shallow man-made lake in Sri Lanka,
by M. Dokulil, K. Bauer & 1. Silva . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 49
6. Some remarks on long-term and seasonal changes in the zooplankton of Parakrama Samudra,
by C. H. Fernando & R. Rajapaksa . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
7. The composition, density and distribution of the zooplankton in Parakrama Samudra,
by A. Duncan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
8. A diurnal study of the planktonic rotifer populations in Parakrama Samudra Reservoir, Sri Lanka,
by A. Duncan & R. D. Gulati ................................... 95
9. The influence of temperature upon the duration of embryonic development of tropical Brachionus
species (Rotifera),
by A. Duncan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 107
10. Feeding studies with natural food particles on tropical species of planktonic rotifers,
by A. Duncan & R. D. Gulati ................................... 117
II. Sediment characteristics and benthic community oxygen uptake rates in Parakrama Samudra, an
ancient man-made lake in Sri Lanka,
by P. Newrkla . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 127
12. A contribution to the ecology of the fish fauna of the Parakrama Samudra Reservoir
by F. Schiemer & R. Hofer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 135
13. Feeding ecology, assimilation efficiencies and energetics of two herbivorous fish: Sarotherodon
(Tilapia) mossambicus (Peters) and Puntiusfilamentosus (Cuv. et Val.),
by R. Hofer & F. Schiemer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 155
14. Aspects of gut passage of algal cells in Sarotherodon mossambicus (Peters), (Pisces, Cichlidae),
by M. Dokulil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 165
15. Contributions to the functional anatomy of the feeding apparatus of five cyprinids of Parakrama
Samudra (Sri Lanka),
by P. Adamicka . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 171
16. Changes in body condition and proximate composition with maturation in Puntius saran a and
Sarotherodon mossambicus,
by S. S. De Silva, C. D. De Silva & W. M. K. Perera ...................... . 177
17. Reproductive strategies of some major fish species in Parakrama Samudra Reservoir and their
possible impact on the ecosystem - a theoretical consideration,
by S. S. De Silva ......................................... . 185
18. The ecology of cormorants (genus Phalacrocoraxj,
by H. Winkler ................... . 193
19. Parakrama Samudra Project - a summary of main results,
by F. Schiemer & A. Duncan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Floristic and faunistic surveys
20. A contribution to the phytoplankton species composition of Parakrama Samudra, an ancient
man-made lake in Sri Lanka,
by E. Rott . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 209
21. Caddisflies (Trichoptera) from Parakrama Samudra, an ancient man-made lake in Sri Lanka,
by H. Malicky .......................................... 227
SUbject index 229
Species index 233
1. The Parakrama Samudra Project: scope and objectives
F. Schiemer
Keywords: tropics, limnology, training, hydrography
Abstract
The demand for environmental control and aquatic resource management necessitates the promotion of
limnological training and research in many tropical countries. Sri Lanka has high potential for the develop
ment of fisheries in its several thousand of irrigation reservoirs. On the other hand, intensification ofland use
in the 'dry zone' of the country is creating new problems connected with environmental deterioration. The
Parakrama Samudra Project was planned as a cooperative venture of European and Sri Lankan scientists
with the object of analyzing the main components and interrelationships of a reservoir ecosystem. The
project combined training and research interests: in the course of the two field-research phases (August/ Sep
tember 1979 and March/ April 1980), a number of post-graduates from Sri Lankan universities joined the
project and received training within the specific research programmes.
Parakrama Samudra is a large (25.5 km2), shallow (zmax = 12.7 m), man-made irrigation reservoir situated
within the dry zone of Sri Lanka. Due to the seasonal cycle in rainfall and the management of water for
irrigational purposes, it exhibits strong fluctuations in water level, volume and water exchange rates during
the course of the year. Research concentrated on topics of particular relevance to fish production: availability
of nutrients, primary productivity, the characteristics of the fish fauna and trophic interactions between
phytoplankton, zooplankton, fish and fish-eating birds.
1. Limnological training and research in tropical Ie these problems and many organizations have
countries repeatedly emphasized the urgent need for better
training and education within this sphere in devel
The demand for proper management of inland oping nations (see e.g. Mori & Ikusima 1981).
water resources in tropical countries is increasing as The successful application of limnological tech
a result of acute population growth and gradual niques and the value of environmental recommen
industrialization. The urgent need for drinking wa dations come only from a good background in basic
ter, food and recreational areas on one hand, and limnological and ecological theory. It is facile to
the dangers of increasing eutrophication and pollu suppose that a general ecological 'know-how' of
tion on the other, are problems well known in the temperate lakes can solve the complex problems
temperate zone. Although not yet as serious as in arising in tropical waters. Most of our limnological
many industrial, temperate countries, the latter knowledge at present comes from temperate-zone
problems may develop quickly and may - for var research and is not directly applicable to tropical
ious reasons - become more serious in the tropics. aquatic ecosystems. The structure and annual cy
In most tropical countries, there is a dearth of cles of the tropical aquatic biota, the thermal condi
qualified limnologists and fishery biologists to tack- tions and nutrient situation are too different for any
Schiemer, F. (ed.), Limnology of Parakrama Samudra -Sri Lanka
© 1983, Dr W. Junk Publishers. The Hague. ISBN 90 6193 763 9
2
immediate transfer of knowledge obtained in the organized since 1975 in Austria with the coopera
temperate zone. Many well-known failures of re tion of Unesco. A workshop to promote the study
commendations put forward in tropical resource of limnology in developing countries was held in
management, which have been based upon insuffi 1980 at the SIL Congress in Kyoto and further
cient knowledge of the functioning of tropical eco- workshops and training courses are planned for the
. systems, are clear warnings in this respect. next few years to be held in the tropical regions. The
The scope is very wide for developing new tech ultimate goal ofthese efforts is to establish self-sus
nologies in aquaculture and for management of taining research and training centres in the tropics.
water bodies for their economic exploitation. The Stimulation of and participation in such endea
possibilities range from increasing fish production, vours offer a challenging opportunity to ecologists
establishing new fisheries and exploiting macro from developed countries.
phyte crops for animal husbandry to the develop
ment of integrated land-water systems (such as the
Chinese 'mulberry-fish pond system' or an intensi
2. The Sri Lankan example
fied use of exposed littoral areas of shallow tanks
for live-stock and water-fowl) (see Loffler, in press).
Various attempts have been made recently to Sri Lanka is an island situated 6°_10° N of the
promote training and research in tropical limnol equator, and covers an area of 66000 km2. The
ogy. An annual post-graduate course in limnology morphological structure is characterized by a flat
for students from developing countries has been coastal area and a central highland (Fig. 1a ). The
o
0-300 m
[J
300-1200
dry zone --;..;..---~, .
\ ,...
wet zone ',.
\./ ::
.. .
' ,
...
\
)
~
N
I ,.--""
<'::'
{~/.
I',':':'
\.'
100km
Fig. J. (a) Contour map of Sri Lanka and main river systems. (b) Reservoirs in Sri Lanka according to Fernando (1970).
3
latter form a climatic barrier dividing the island Landings of inland fisheries increased enormous
into a 'wet zone' with continuously high precipita ly following the introduction of Sarotherodon ('Ti
tion, and a 'dry zone' with high rainfall only during lapia') mossambicus in 1952. The reasons for the
the NE monsoon (October-January) (Dobesch spectacular success of this species in some of the
1983). About 100 major river systems drain the reservoirs (lack of lacustrine competitors among
island radially to the sea (Fig. la). the indigenous fauna) and the low yield of indigen
Although Sri Lanka has no natural lakes, its dry ous species have been aptly discussed (C. H. Fer
zone possesses a sophisticated irrigation system of nando & Indrasena 1969; C. H. Fernando 1971,
reservoirs and canals (Fig. I b), built mainly for rice 1973,1977,1982; De Silva & C. H. Fernando 1980).
cultivation. The origins of this system reach back The varying success of S. mossambicus in different
approximately 4000 years (Brohier 1934). These reservoir types has led to a subsequent search for
reservoirs have been maintained and enlarged to a other exotic species that would allow the yields
varying extent throughout the history of Sri Lanka. from inland fisheries to be further increased. This
At present, there are approximately 3 500 reser search has not been successful (C. H. Fernando
voirs in existence, representing a surface area of 1973) and inland fisheries yields have been stagnant
1250 km2• for some years, despite a considerable investment of
A maj or enlargement of the irrigation system will funds (Oglesby 1979). The main reason for this
be achieved by the Mahaweli River Diversion failure is the lack of knowledge about the biological
Scheme. This programme aims to improve and ex structure and functioning of the reservoir ecosys
pand rice cultivation in the dry zone as well as tems, their carrying capacity for different trophic
increase hydro-electric power and control flooding. forms, the effects ofthe hydrological regime impos':
The scheme will make available an additional ed by irrigational management and the impact of
200 km2 of reservoir area (Wijeyaratne & Costa the very large populations of fish-eating birds so
1981) and change the hydrological regime of some characteristic of these water bodies.
of the major existing reservoirs, e.g. Parakrama In order to master the forthcoming problems of
Samudra. The environmental impact of the planned eutrophication and pollution and to allow a suc
changes upon the aquatic biota will be profound. cessful integration of the mUltiple uses of the reser
Due to the increase in the number of settlements voirs(irrigation, fisheries, recreation, washingfacil
and intensified land cultivation, a significant in ities, pastures for live-stock etc.), a profound insight
crease in nutrient and pesticide accumulation and into how they are functioning is indispensable. The
in water-borne diseases (malaria) as well as a silta aim of the project was to gain knowledge of the
tion of reservoirs by land erosion can be envisaged. structure and functioning of Parakrama Samudra,
The change in flow regimes could result in a reduc as an example reservoir, in order to provide a basis
tion of existing fisheries output in some of the lakes. for effective management along these lines.
On the other hand, availability of aquatic habitats
for fish production will be increased, as will be the
local demand for fishery products (see TAMS re 3. Objectives of the Parakrama Samudra project
port 1980).
Attention has been focussed recently on reser The project is investigating ecosystem properties
voirs as a protein resource. For various reasons, the that are especially relevant to fisheries manage
development of freshwater fisheries in Sri Lanka is ment. The Parakrama Samudra reservoir was se
now receiving high priority: lected as an example of a large shallow impound
ment in the dry zone with high fish production
I) inland fisheries have a high potential for devel (c. H. Fernando & Indrasena 1969; C. H. Fernan
opment, do 1979; De Silva & C. H. Fernando 1980). By
2) the development of inland fisheries is less costly carrying out a detailed investigation of one charac
than marine fisheries, and teristic reservoir type - including basic limnological
3) inland fisheries are of great socio-economic im parameters, productivity, nutrient flow and major
portance within the dry zone, in regard to food trophic interactions - it was hoped to provide a
supply and employment opportunities. model for further limnological studies of man-