Hermann Remmert Arctic Animal Ecology With 156 Figures Springer-Verlag Berlin Heidelberg New York 1980 Professor Dr. HERMANN REMMERT Fachbereich Biologie der Universitat Lahnberge, Karl-von-Frisch-StraBe 3550 Marburg/Lahn, FRG Translated by: JOY WIESER Madleinweg 19 6064 Rum/Austria ISBN-l3: 978-3-540-10169-7 e-ISBN-l3: 978-3-642-67710-6 DOl: 10.1007/978-3-642-67710-6 Library of Congress Cataloging in Publication Data. Remmert, Hermann, Arctic animal ecology. Bibliography: p. Includes index. 1. Animal ecology-Arctic regions. I. Title. QL105.R4513 591.5'2621 80-18707. This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machine or similar means, and storage in data banks. Under § 54 of the German Copyright Law where copies are made for other than private use, a fee is payable to the publisher, the amount of the fee to be determined by agreement with the publisher. © by Springer-Verlag Berlin Heidelberg 1980 The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names arc exempt from the relevant protective laws and regulations and therefore free for general use. Cover design: W. Eisenschink, Heidelberg. 2131/3130-543210 Preface A large number of comprehensive publications has been devoted to the Antarctic, to its plant and animal life. It is therefore relatively easy to familiarize oneself with the current state of Antarctic research. Nothing comparable is available for the Arctic. The heterogeneity and richness of the northern polar regions seem to have discouraged any attempt at a synthethic approach. This book has evolved from an attempt to summarize the results of 15 years of ecological and physiological research work in the Arctic - mostly on Spitsbergen. The necessity of comparing our results and the ecological conditions of Spitsbergen with other arctic regions grew into a full-sized book on arctic animal ecology. It is not meant as an exhaustive survey ofthe relevant literature. Instead I have tried to show how closely the various fields of research are interwoven, how many questions can be solved if only notice is taken of fellow scientists and their results, and how much arctic animals have in common. This book would not have been possible without the helpfulness of many colleagues. Above all I should like to mention Professor Ronning and Professor Solem of Trondheim University (Norway), Professor Arnthor Gardasson of Reykjavik University (Iceland), Dr. NettIeship, Dr. Oliver and Dr. Ryder of Canada and Professor West of Fairbanks University (Alaska, USA). The first two drafts of the manuscript were typed by Dagmar Weidinger-Messner, who also drew the new figures. Mrs. Kohler and Mrs. Riediger gave valuable assistance in the further prepara tion of the manuscript, which Mrs. Joy Wieser has translated into English. Dr. Konrad F. Springer and Dr. D. Czeschlik encouraged me throughout. My warm thanks to all of them! Marburg, July 1980 Hermann Remmert Contents I. Introduction: Delimitation of the Arctic II. Ecological Factors in the Arctic . . . . . . . . . . 7 1. The Diurnal Rhythm of Organisms and Its Relationship to Environmental Parameters . . . . . . . ... 7 2. Temperature Conditions in the Arctic . . . . . . . 24 3. Ecological Factors Other Than Temperature and Light 58 4. The Combination of Factors in the Arctic 65 III. (Almost) Common Characteristics of Arctic Animals 70 1. Population Cycles . . . . . . . . . . . . 70 2. Seasonal Migrations of Birds and Mammals 82 3. Entrainment of Animals to the Yearly Cycle 93 4. The Importance of the Proximity of the Ocean: Marine Birds and Mammals . . . . . . . . . . . 103 5. The Ratio of Productivity to Biomass in the Arctic 107 6. Species Problems . . . . . . . . . . . . . 109 IV. Peculiarities of the Systems 122 1. General Principles .. ......... 122 2. Stability and Constancy of Arctic Ecosystems 129 3. The Animals in Terrestrial Ecosystems 131 4. The Animals in Limnic Ecosystems . 137 5. The Animals in Marine Ecosystems 141 V. Types of Arctic Climates 155 VI. Case Studies 161 1. "Warm" Arctic: A Section Through Northern Scandinavia from Troms0 (Norway) to Kevo (Finland) 161 2. Arctic Alaska: Comparison Between Prudhoe Bay and Point Barrow ............... 176 3. High-Arctic Continental: the Canadian Archipelago 183 4. High-Arctic Oceanic: Svalbard or Spitsbergen 190 VIII Contents 5. Arctic Lakes ........ . .203 6. The Arctic Seas of the Old World · 214 7. Antarctica: a Comparison · 225 References · 235 Subject Index .247 I. Introduction: Delimitation of the Arctic Whereas the antarctic continent itself is identical with the antarctic terrestrial ecosystem, it is a far more difficult matter to define the limits of the Arctic. Indeed, it often seems that mere naive impressions or the special field of research of the investigators concerned have been responsible for the variety of definitions found in the literature. Botanists and physical geographers have frequently taken the forest limit as representing the boundary of the Arctic, whereas others have preferred to make use of the length of the growing season. Climatologists have employed annual mean temperatures, as expressed for example by the 0 °C annual isotherm or by the 10 °C isotherm for July. Social geographers have claimed that the Arctic begins at the northernmost limit of agriculture, thus associating it with special forms of human culture. Soil scientists and engineers have defined the Arctic on the basis of the distribution of permanently frozen ground, with all of its attendant problems (structured soils, pingos, construction problems). Zoologists and botanists have postulated connections between the distribution of characteristic plant and animal species and the limits of the Arctic. Depending upon their personal preference oceanographers have defined the High Arctic or the Arctic as the region consistently covered with ice in summer or in winter (Figs. 1, 2). Although the boundaries often run parallel with one another, or are even congruent, they may equally well show considerable divergence, and discrepancies of a thousand kilometres are not uncommon. In practice not one of these lines provides a truly satisfactory delimitation of the Arctic. The circumpolar forest limit is made up in some places of birch (Betula), in others of spruce (Pice a) and pine (Pinus) and in some places of larch (Larix). The determining factors differ considerably from region to region. Along the coasts, for example, the forest limits are displaced far to the south, not as a result of the temperature conditions, but on account of the strong winds prevalent. Man himself has assisted in the process by clear-felling: since the large quantities of water in very rainy regions cannot be utilized by the few remaining trees, moors develop which in turn prevent recolonization by tree species. Examples of this can be seen on the west coasts of Scotland and Ireland. Both of these regions were included in the "Tundra" project of the IBP programme and comparisons were made with the "Tundra" regions of Norway, Sweden, and the Canadian Archipelago. Warm oceanic cur rents push the ice limits far to the north along the coasts of Norway and Iceland, so that the harbour Longyearbyen on the west coast of Spitsbergen remains free of ice in some winters despite its latitude of 78 ON. On the other hand, polar oceanic currents moving in a southerly direction push the ice limits far south in some places, such as on the east coast of Greenland. The length of the growing season is highly dependent upon winter temperatures, i.e., whether the winter is warm and oceanic or cold and continental, but the vegetation in continental regions is often much 2 Introduction: Delimitation of the Arctic Fig. 1. Limits of the arctic. Forest limit --; limit of cultivation TTm7; Arctic limit according to Nordenskiold ... southern limit of the High Arctic - - - -; Arctic Circle- richer than in oceanic regions with equally short growing seasons. In fact, melons can be cultivated successfully in continental regions almost up to the permafrost, whereas in oceanic regions like Europe the limit of melon cultivation is several thousand kilometres further south. Not all of the permafrost nowadays in existence is the product oftoday's climate. Relics of permanently frozen ground from glacial times exist in Switzerland and can be localized by the retarded growth of the trees above them. As to the use of temperature in defining the Arctic, it obviously has its drawbacks. The 0 °C annual mean isotherm or the 10°C July isotherm, for example, both run through tropical mountains as well as the Arctic and give no indication of the vast differences between the two regions. And as to the northernmost limit at which agriculture is practised, this is displaced far to the south along the coasts. At the same time we know of primitive communities on the equator that support themselves by hunting and fishing and practise no form of agriculture, although the reasons are very different from those applying in the Arctic. Quite clearly, the criteria discussed in the foregoing are not merely naive, subjective and dependent upon the particular field of interest of the investigator concerned: not one of them can be employed universally, and not one of them has been strictly worked out. Where the incongruencies between the postulated limits and the true Arctic become too apparent, help is sought in constructions such as the Nordenski61d line (Fig. 1). Nevertheless, there is a clear mathematical boundary to the Arctic and this is the Arctic Circle, which girdles the regions where in summer the sun does not set for at Introduction: Delimitation of the Arctic 3 ----" -----I Fig. 2. Limits of the Arctic. "-" -"... ,, ," , Continuous permafrost --; .. \ . -: ., southern limits of the dis \ ••••• I , continuous permafrost - - - -, o °C annual isotherm·····; Arctic Circle - - - least 24 h, and where in winter complete darkness prevails for at least 24 h. Although it has often been included as an additional piece of mathematical information in the literature it has never been employed as a definition of the Arctic. At first sight it might appear that a definition of this kind has neither geographical nor ecological significance. Nevertheless, the midnight sun has always held a remarkable fascination for Man, and the question which we shall now try to answer is whether this mathematical boundary is as irrelevant as a cursory glance would suggest. This is quite definitely not the case. Troll long ago drew attention to the fact that the arctic climate is a purely seasonal one and undergoes no daily fluctations, i.e., a situation exactly the opposite of that prevailing in tropical mountain regions where the climate is purely diurnal (Troll, 1955; Figs. 3-6). On Kilimanjaro, Mount Kenya or in the tropical Andes the same temperature can be measured at anyone time of day all the year round, although from one time of day to another it differs considerably. In the Arctic, on the other hand, summer and winter are quite different, but the temperatures typical of each of these seasons, the summer with its perpetual daylight and the winter with perpetual darkness, remain constant throughout. Now the activity of poikilothermic organisms, such as the bacteria and fungi which play an essential role in soil formation, is exponentially dependent 4 HutPOint Feb. 1902-Jon, 1904 (Hut Point Cape EVMS of Cape Royds) Cape floyds.-M. y 1908--Feb, 1909 Me. Murdo-Sound (",- 77'42' S. 1.=165'35' 0) H_Om C.pe Evans: Jan. 1911-Dec 1912 ;~~---''-rT~~nn~1~ar~Tn--rr-~~~mM~~~n-~-~-:'>~7Tr-~-!-7n--' 9 ,~ -~, ~ ____ :H!_ - ___q B_ -.:z{J- - 8 ~ -iF -zF . -Zt J " ¥-I --'._- - ~t~ -ltJ -~J -zp -tp --z~iJr -z, --1J,p,3 -ZJ . if1 13 2J9uly~ A~ug~. S~ep~t. ~O~ct~. ~~~~-L~LU~~~~~~~~~~~~ Fig. 3. Thermoisopleth diagram of a station with an antarctic coastal climate. (The space between the dot-dash lines indicates the length of the polar days and nights), Ordinate: time of day. (Troll, 1955) upon temperature. It is therefore of enormous significance whether temperatures are relatively constant, especially in the lower ranges of the usual optimum for biochemical processes, or whether they fluctuate about a mean value and are thus sufficient to accelerate the biological processes in poikilotherms for a few hours daily. This explains why mean temperatures, even those of the growing season, as indicated by the 10°C isotherm for example, convey little information of any value. Exactly the same applies to solar radiation per day and unit area. The vital point is whether this radiation is fairly evenly distributed over the 24 h, as it is in the Arctic, or whether it is confined to about half of the day, in which case the hourly values would have to be twice as high. Consequently, daily or monthly mean values for incoming radiation convey very little biological information. Another factor is the internal clock in plants and animals which, as we now know, is indispensable to the organism. This clock completes a revolution once in approximately 24 h. However, it has to be "reset" regularly by external factors, its zeitgeber usually being the alternation of light and darkness. What happens in the uninterrupted darkness of the arctic winter or in the continuous daylight of its summer? And lastly there is the fact that the ratio of the length of daylight to length of darkness, or the "photoperiod", changes over the course of the year and is the factor responsible for the ability of plants and animals to coordinate their activities with the annual march of seasons. Is this mechanism still effective north of the Arctic Circle? Evidently the biological implications of a mathematical delimitation of the Arctic are greater than at first sight apparent. We shall therefore make use of the