ACTA PHYTOGEOGRAPHICA SUECICA EDIDIT SVENSKA VA.XTGEOGRAFISKA SA.LLSKAPET 42 NAHUEL HUAPI PLANKTON OF SOME LAKES IN AN ARGENTINE NATIONAL PARK WITH NOTES ON TERRESTRIAL VEGETATION BY KUNO THOMASSON UPPSALA 1959 ALMQVIST & WIKSELLS BOKTRYCKERI AB SVENSKA VAXTGEOGRAFISKA ·sA.LLSKA.PET (SOCIETAS PHYTOGEOGRAPHICA SUECANA) Adress: Uppaala UniversitetB Vaxtbiologiaka Inatitution, Villaviigen 14, Uppsala 8, Sverige ( Styrelse: Ordf. Prof. G. EINAR Du RIETZ, v. ordf. Prof. HuGo OsvALD, sekr. Fil. kand. BENGT M. P. LARSSON, skattm. Fil. mag. SvANTE PEXKARI, red. Doe. MATS JERN,W klubbm. Fil. lie·. ELIEL STEEN, avr. .� Prof. Emo HULTEN, Prof. BERTIL LINDQUIST, Prof. JOHN AxEL NANNFELDT, Doe. Nrr..s QUENNERSTEDT, Doe. RoLF SANTEssoN, Prof. SVEN THUNMARK. 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Die Acta Phytogeographica Suecica konnen Les publications peuvent aussi etre obtenues nach Obereinkommen mit dem ,Bibliotekarien, en echange par convention avec << Bibliotekarien, Uppsala Universitets Vaxtbiologiska Institu­ Uppsala Universitets Vaxtbiologiska Institu­ tion, Uppsala" auch im · Austauschswege er­ tion, Uppsala>>. halten werden. ACTA PHYTOGEOGRAPHICA SUECICA 42 NAHUEL HUAPI PLANKTON OF SOME LAKES IN AN ARGENTINE NATIONAL PARK, WITH NOTES ON TERRES TRIAL VE GETATION BY KUNO THOMASSON UPPSALA 1959 Almqvist & Wiksells Boktryckeri AB The present paper constitutes no. 4 of the Studies on South American Fresh-Water Plankton by the author, and no. 2 of the Reports of the Swedish Limnological Expedition to South America in 1953-54. CONTENTS I. Preface 5 VIII. Tarns, ponds, and temporary waters . 51 II. Introduction 6' , 1. Strand-pool 51 III. Climate 7 2. Pond near military camp 52 IV. Geology 9 3. Inundation pool 53 V. Flora and vegetation 10 4. Tarn in Paso V uriloche 55 1. Eastern zone . 13 5. Alpine tarns 56 2. Central zone . 15 IX. Running waters 56 3. Western zone 24 1. Brook at Lake Gutierrez 56 4. Alpine belt 28 2. Brook at Lake Mascardi 56 VI. Hydrography 34 3. Riv.er between L. Gutierrez and L. VII. Lakes 36 N ahuel Huapi 57 1. Nahuel Huapi 36 X. Benthos 58 a. Morphometry 36 XI. Retrospective survey 59 b. Thermal relations 37 XII. Taxonomical comments 64 c. Plankton 42 1. Microphyta 64 2. Gutierrez 44 2. Microzoa 76 3. Mascardi 45 XIII. Fishes and waterfowl 79 4. Guillelmo 46 Acknowledgements 80 5. Frias 48 6. Hess 49 References . 81 Acta Phytogeogr. Suec. 42 .. .. Jnternational boundary ;· ....... .·. Divortium ·213o Acta Phytogeogr. Suec. 42 I. PREFACE The National Park of Nahuel Huapi, situated January 19 until February 1, 1954. During our stay between 71 o and 72° west longitude and 40°20' and we studied the lakes in the southern half of the 41 °35' south latitude, is the largest of Argentine National Park. Naturally it was quite out of the national parks, its area being 785,000 ha. It lies question to carry out any thorough investigations along the eastern slope of the Andean chain and in the too. short time at our disposal. Hence our encircles the large Lake Nahuel Huapi and a number studies were restricted to obtaining a general view of smaller lakes. Some of the lakes within the Na­ of physical conditions and to collecting random tional Park were the object of a short visit by the samples from lakes in order to enable us to get some Swedish Limnological South-America Expedition comparative data for our investigations on the lakes 1953-54. west of the Andean range, in the Valdivian area. Our thanks are due to the Argentine Ministry of Samples of plankton and bottom fauna were col­ Defence for their generous support making it lected, in addition sporadic observations were made possible for us to obtain the maximum benefit. on the terrestrial flora and fauna along our excur­ from our short 10-days visit. The representative sion routes. of Ministry of Defence Captain CARLOS HoFFM.ANN The following notes are of a sketchy character, from Buenos Aires did all in his power to facilitate in spite of which we hope to contribute something our studies on the natural features of the National to the knowledge of plankters in South American Park of Nahuel Huapi. We are also indebted to lakes. The few words on the natural features of the him for his good fellowship during the often rather National Park of Nahuel Huapi are also frag­ arduous excursions in the National Park. mentary but give an indication of the nature of Our sojourn in the National Park lasted from the terrain. Fig. 1. Map of the Nahuel Huapi National Park and its situation in South America. The lakes surveyed by the present author are N ahuel Huapi, Gutierrez, Mascardi, Guillelmo, Frias, and Hess. Acta Phytogeogr. Suec. 42 II. INTRODUCTI ON The discovery of the Nahuel Huapi area can be inclined to make a comparison with the Swiss traced back to the legend about "Ciudad de los scenery; on the other hand the number of rock­ Cesares" which plays an important role in all stages bound lakes hidden in the interior of the Cordillera, of earlier exploration history of South America. gleaming between the precipitous rock-faces has The conquerors were followed by Jesuits, some of very often duplicated the nature of Norwegian whom are perpetuated in the names of lakes, e.g. fjords. The lakes are surrounded by the greenery of Mascardi and Guillelmo. luxuriant forests, dominated by Nothofagus. On the Dr. FRANCISCO P. MoRENO was the first to record slope of the Chilean watershed the forest is at its the natural history of the Nahuel Huapi area� Dur� best; here we meet the exuberant temperate rain­ ing his many exploratory expeditions and finally forest, known as the Valdivian forest. The extra­ as leader of the Argentinean-Chilean frontier-com­ ordinary overgrowth of trees and shrubs the impos­ mission he was seized by the extraordinary charm ing intert·wining of lianas artistically twisting round of the scenery around Lake Nahuel Huapi. He fully the trunks and branches of the massive Nothofagus appreciated the value of this area· as a significant dombeyi and the Lomatia obligua recall impressions natural region and proposed in 1903 that the Nahuel of the cloudforests of the Urubamba-valley in Peru. Huapi area should be proclaimed a national park. The western boundary of the park is formed by According to a decree of February 1, 1909 the the immense barrier of the snow-capped Cordillera. Nahuel Huapi National Park was founded. Its Above the serried lines of haughty peaks towers the territory was later extended from about 9 square white massive cupola of Mt. Tronador (3554 m miles to 3030 square miles. a. s.-1.), of volcanic origin, the highest mountain The principal centre for Nahuel Huapi National in Northern Patagonia. From this giant of the Park is the town San Carlos de Bariloche, the well Cordillera there issues enormous glaciers whose known startingpoint · of the ride of the Swedish formidable bulks hanging from its steep walls emit . Patagonian and Tierra del Fuego Expedition (1907- hoarse growls and thunderous roars when the sun 09) in 1908, down to the Straits of Magellan. The melts the snow and ice. These glaciers terminate in settlement was then made up of a few primitive the magnificent belt of green woods below. Mt. ramshackle houses only few years old.