Ecosystems and Living Resources of the Baltic Sea: Their assessment and management

300 Pages·2017·11.94 MB·English

by  Evald Ojaveer (auth.)

Evald Ojaveer
Ecosystems
and Living
Resources of
the Baltic Sea
Their assessment and management
Ecosystems and Living Resources of the Baltic Sea
Evald Ojaveer
Ecosystems and Living
Resources of the Baltic Sea
Their assessment and management
Evald Ojaveer
Estonian Marine Institute
University of Tartu
Tallinn, Estonia
ISBN 978-3-319-53009-3 ISBN 978-3-319-53010-9 (eBook)
DOI 10.1007/978-3-319-53010-9
Library of Congress Control Number: 2017933477
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Preface
Over many millennia, the systems of the Baltic Sea have developed under very vari-
able climate conditions in fresh, marine, and brackish waters into present-day eco-
systems and stocks. Today, the basic environmental conditions vary dramatically
throughout the Baltic Sea. The most substantial ecophysiological parameter for
aquatic organisms – salinity – ranges from 35 psu in the Kattegat to 1–2 psu in the
northernmost Bothnian Bay. Therefore, compared to a number of other (“normal”)
seas with a constant salinity of 33–37 psu, in the Baltic Sea, ecosystems and envi-
ronment are very different.
In recent decades, the state of the biota in the Baltic Sea has modifed. Since the
last deglaciation, the organisms which have found their home in the brackish Baltic
Sea and adapted to its environmental conditions have become increasingly affected
by humans – by their intemperate exploitation, pollution of the marine environment,
and facilitation of invasion of alien species. The management usages have fre-
quently not taken into account the differences between the natural areas of the Baltic
Sea. As a result, a number of important protection measures have become useless.
Therefore, the ecosystems and resources of the Baltic Sea have deviated from their
ordinary state, and their services and goods are no longer available in the quality and
quantity they were before.
Differentiation and separate assessment of Baltic Sea natural systems are neces-
sary for correct management of the ecosystems and living resources of this sea. It is
essential that a clear understanding of the structure of the Baltic Sea ecosystems and
the diversity of the brackish Baltic Sea from the eumarine areas of the World Ocean
is fully accounted for. This would allow ecosystem- and population-based consider-
ation of living resources. The ecosystem-based treatment assumes that we have to
deal with living alliances of vegetation, microorganisms, animals, and their abiotic
environment behaving together as a functional unit. Such an approach to the envi-
ronmental units related to the natural regions and population-based treatment of
exploited living resources as presented below is the realistic possibility that can lead
to the responsible management of ecosystems and resources in the Baltic Sea.
This monograph consists of six chapters. An overview of the evolution of the
Baltic Sea and its living organisms after the last Ice Age is given in Chap. 1. Abiotic
v
vi Preface
characters of the contemporary Baltic Sea, the natural regional system based on cur-
rents, and other hydrological and environmental features are discussed in Chap. 2.
Vegetation and primary production, heterotrophic bacteria, zooplankton, zooben-
thos, fsh (the most important populations of the marine pelagic, marine demersal,
diadromous, freshwater, and relict fshes), marine birds, and marine mammals are
considered in Chap. 3.
In addition to the fsh species of marine origin (cod, herring, and sprat) which
presently provide over 90% of the exploitable fsh resources of the Baltic Sea,
migratory, freshwater, and relict fsh species constituting the remaining exploitable
resources in the Baltic ecosystems should be studied to a certain level to develop the
possibility of their assessment and management in the future. Recent dynamics of
ecosystems and biological resources are analyzed in Chap. 4, with the salinity- and
climate-related driving forces and anthropogenic infuences differentiated. In Chap.
5, the basic principles of routine assessment and management of existing fsh
resources are addressed. Also, the possibility of composition of the long-term (10–
20 plus years in advance) qualitative forecasts on ecosystems and fsh resources is
discussed. An overview of the international collaboration in the assessment and
management of ecosystems and living resources in the Baltic and corresponding
organizations is given in Chap. 6.
The bulk of the information presented in this monograph is taken from a book
written in Estonian (Läänemeri by Evald Ojaveer, Tallinn: Teaduste Akadeemia
Kirjastus, 2014). The material was thoroughly reviewed and condensed. The con-
sideration of the management of the living resources in the Baltic Sea was notably
extended.
The overview is based on the information published in various languages since
the nineteenth century. This information was substantially complemented with new
data collected during the long-term series of detailed hydrographic and biological
complex investigations carried out in the Baltic Proper and the gulfs of Finland and
Riga from 1957 to 1997 by the Tallinn and Riga marine laboratories. Thanks to the
participation of Dr. Margers Kalejs (†) in this work, a very strong effort was devoted
and rich material collected during 420 specifc scientifc cruises (on monthly to
quarterly bases, the total count of stations visited numbering 10, 300, Fig. 1).
Therefore, the most complicated marine ecological problems involving multiple
sophisticated interrelations are treated below on the basis of the results of these
original complex studies avoiding simplifcations involved in model calculations.
Assessment and management of ecosystems and natural resources are closely
related to the application of the results of scientifc studies in practice. Applicability
of the means and solutions discussed below has been the touchstone for deciding
upon their value, as the author has devoted over half century to studies of the eco-
systems and fsh resources of the Baltic Sea. Also, one of the most outstanding
experts in the assessment and management of the Baltic Sea ecosystems and fsh
stocks, Dr. Hans Lassen, strongly supported the monograph in the form of many and
lengthy discussions of the material and the fundamental theses presented in this
book. He read the manuscript at different stages and made critical comments with
Preface vii
Fig. 1 The area of observations and collection of materials by the Tallinn and Riga marine labo-
ratories in 1957–1997 (author’s data)
constructive proposals on how to improve the text, especially that of Chaps. 5 and
6. I am very grateful to him.
The book is intended for graduate students, researchers, and managers involved
with the Baltic Sea ecosystems and living resources.
Tallinn, Estonia Evald Ojaveer
January 2016
Contents
1 E volution of the Baltic Sea ....................................................................... 1
1.1 D evelopment of the Baltic Sea After the Last Ice Age .................... 1
1.2 F ormation of Biota in the Baltic Sea ............................................... 6
References ................................................................................................... 9
2 A biotic Conditions in the Contemporary Baltic Sea ............................. 11
2.1 W ater Balance .................................................................................. 15
2.2 W ater Salinity .................................................................................. 16
2.2.1 T he Role of Currents ............................................................ 25
2.2.2 Vertical Mixing of Water Layers .......................................... 26
2.3 W ater Temperature ........................................................................... 30
2.4 O xygen Conditions .......................................................................... 36
2.5 L ight Conditions .............................................................................. 37
2.6 N atural Regional System of the Baltic Sea ...................................... 38
2.6.1 M acro-regions ...................................................................... 41
2.6.2 R egions and Subregions ....................................................... 42
References ................................................................................................... 47
3 L ife in the Baltic Sea ................................................................................. 49
3.1 S alinity-Induced Ecophysiological Problems of Organisms
in the Baltic Sea ............................................................................... 50
3.2 M ultitude of Ecosystems ................................................................. 52
3.3 L iving Organisms............................................................................. 54
3.4 V egetation and Primary Production ................................................. 55
3.5 B ottom Vegetation ........................................................................... 61
3.6 H eterotrophic Microorganisms ........................................................ 67
3.7 Z ooplankton ..................................................................................... 74
3.8 Z oobenthos ...................................................................................... 88
3.9 F ish .................................................................................................. 101
3.9.1 M arine Pelagic Fish.............................................................. 103
3.9.2 M arine Demersal Fish .......................................................... 139
3.9.3 D iadromous Fish .................................................................. 162
ix
x Contents
3.9.4 F reshwater Fish .................................................................... 178
3.9.5 R elict Fish Species ............................................................... 183
3.10 M arine Birds .................................................................................... 192
3.11 M arine Mammals ............................................................................. 197
References ................................................................................................... 201
4 R ecent Dynamics of the Environment and Biota ................................... 209
4.1 C hanges in the Environment and Biota Induced
by Natural Conditions ...................................................................... 210
4.1.1 S alinity ................................................................................. 210
4.1.2 T emperature .......................................................................... 213
4.1.3 I nteractions of Fish Species ................................................. 216
4.2 C hanges Caused by Anthropogenic Impacts ................................... 219
4.2.1 E utrophication ...................................................................... 219
4.2.2 T oxic Pollution ..................................................................... 224
4.2.3 I nfuences Related to the Storage
of Dangerous Substances ..................................................... 228
4.2.4 O ther Impacts of Human Activity ........................................ 231
4.3 I mmigration into the Contemporary Baltic Sea ............................... 232
References ................................................................................................... 235
5 A ssessment and Management of Ecosystems
and Living Resources in the Baltic Sea ................................................... 237
5.1 C omposition and Exploitation of Living Resources
in the Baltic Sea ............................................................................... 238
5.2 M ain Goals of the Management of Ecosystems
and Living Resources ....................................................................... 240
5.3 B asic Principles in the Assessment and Management
of Ecosystems and Living Resources .............................................. 243
5.3.1 A ssessments and Management Recommendations .............. 244
5.4 A ssessment of Existing Fish Resources of the Baltic Sea ............... 245
5.5 A ssessment and Management of Ecosystems in the Baltic Sea ...... 252
5.6 L ong-Term Assessments and Forecasts on Ecosystems
and Fish Resources .......................................................................... 256
5.7 O verexploitation of Living Resources ............................................. 261
5.8 M arine Spatial Planning and Protected Areas ................................. 265
References ................................................................................................... 267
6 I nternational Collaboration in the Assessment and Management
of Baltic Ecosystems and Living Resources ............................................ 269
6.1 U NCLOS and the Fisheries Agreement ........................................... 270
6.2 S cientifc Cooperation ..................................................................... 271
6.2.1 I nternational Council for the Exploration
of the Sea (ICES) ................................................................. 272
6.2.2 Baltic Marine Biologists (BMB) .......................................... 274
6.2.3 Conference of Baltic Oceanographers (CBO)
and Baltic Marine Geologists (BMG) .................................. 275
Contents xi
6.3 C ollaboration in the Management of Ecosystems ........................... 276
6.3.1 Baltic Marine Environment Protection Commission
(Helsinki Commission) ........................................................ 276
6.3.2 A SCOBANS ......................................................................... 280
6.4 F ishery Organizations ...................................................................... 280
References ................................................................................................... 283
Index ................................................................................................................. 285