Magellanic Region Research Articles

First record of a ceramiaceous red algal species, Ceramium stichidiosum, from magellanic region, chile

La alga roja Ceramium stichidiosum fue encontrada por primera vez en aguas del Estrecho de Magallanes, Chile. Los talos son frecuentemente encontrados epifitando otras macroalgas como Mazzaella laminarioides (Bory) Fredericq y Sarcothalia crispata (Bory) Leister. Se caracteriza por presentar ejes completamente corticados y ramificaciones alternadas a dicotomas, apices rectos y seis celulas periaxiales por cada celula central. Este reporte extiende el limite de distribucion sur de C. stichidiosum desde la X Region de los Lagos (42o 58'S; 74o 19'W) hasta la XII Region de Magallanes (53°37'S; 70°59'W).

Southern elephant seals north of the Antarctic Polar Front

This paper reports on sightings and dispersion of individual southern elephant seals (Mirounga leonina) along the Atlantic and Pacific coasts of South America based on reports of tagged/marked seals from Patagonia and of animals of unknown origin. From 154 sightings, encompassing at least 354 individuals, we found that individuals dispersed to subequatorial latitudes on both sides of the continent, and to more temperate sites, in the Magellanic region of Tierra del Fuego. Nineteen sites were visited by tagged seals from the established colony of Península Valdés (PV, Argentina). PV and the smaller seal population of the Falklands/Malvinas were regularly connected by adults of both sexes. There were more sightings of males than females. No incipient new breeding colonies were found along the Atlantic coast of South America. Some observations coincided with places where elephant seals had been recorded or exploited in the seventeenth and eighteenth centuries. A shortage of suitable habitat for expansion and proximity to predictable food could act as a stabilizing process preventing colonization of new areas from PV. Dispersion data, coherent with population genetics, support a Patagonian elephant seal stock.

Community structure and zonation patterns of rocky shores at high latitudes: an interocean comparison

AbstractAim To compare the structure of communities of sheltered rocky shores at high latitudes in widely separated regions in order to search for similarities and dissimilarities.Locations Three regions with similar physical environments were investigated: south‐western Iceland, southern Alaska, and the Magellanic region.Methods Cover of algae and sessile animals was estimated and animals were counted in quadrats laid along a number of transects in each of the three regions. Transects were divided into 10 height intervals with reference to tidal levels, and comparisons made on the basis of average distributions of species within each of 11 defined guilds.Results Icelandic and Alaskan shores had a number of species in common, although these were in the minority. No species was common to southern and northern regions, with the possible exception of Mytilus edulis. Most defined guilds were present in all regions, but their taxonomic composition was often radically different. The molluscan filtering guild was the guild showing greatest similarity in the three regions, while canopy‐forming algae were absent from the Magellanic region and balanid filterers were virtually absent from Iceland. Crustacean grazers were only prominent in Iceland, and molluscan grazers were more common there than in the other regions. Zonation of species was recognizable and species diversity increased seawards in all regions.Main conclusions Few, if any, assembly rules could be detected when comparing regions, except for the universal increase in species diversity seawards. The absence of ‘key’ species in one region may affect the distribution of other species. All major opportunities for resource exploitation are not utilized in all regions. In some instances it is possible to recognize ecological equivalents in different regions. No recurrent distinct zones are apparent when regions are compared. A universal descriptive system of zonation, such as developed by Stephenson & Stephenson (1949) and Lewis (1964), was found to be not applicable.

Postembryonic development of Apseudes heroae and Allotanais hirsutus (Tanaidacea, Crustacea) in Magellanic and sub-Antarctic waters

Apseudes heroae Sieg, 1986 (Family Apseudidae) and Allotanais hirsutus (Beddard, 1886) (Family Tanaidae) are common Tanaidacea of the southern Magellanic region. The aim of the investigation is to elucidate the postmarsupial development of these tanaid species that differ in their biogeography. Population structures are analysed from size frequency data and from different postembryonic stages of specimens collected in the Atlantic entrance of the Beagle Channel and from the Atlantic continental slope to the south-east. The population of Apseudes heroae shows three age groups, the one of Allotanais hirsutus probably at least three. Some large specimens indicate that the latter sub-Antarctic species might reach an age of several years. Both species are probably gonochoristic, and protandric hermaphroditism was not observed. The fecundity of Apseudes heroae and Allotanais hirsutus was analysed. No significant correlation could be found between cephalothorax width and egg number or number of larvae. For both species hypothetical life cycles are reconstructed. As sub-Antarctic temperatures are low and seasonality is strong in the Magellanic region, it is possible that these species are reasonably adapted in reproduction as shown in some polar species of Isopoda and Cumacea.

Revision of the nudibranch genus Cadlina (Gastropoda: Opisthobranchia) from the Southern Ocean

The taxonomy of Magellanic and Antarctic cadlinids has been for many years in extreme disorder, and the species were not reliably identifiable. Recent collections in Chile and Argentina, mainly by SCUBA, and re-examination of type material provided data for a comprehensive revision. The present study gives new morphological information on all southern species, both by scanning electron microscope examinations of cuticular structures and detailed microanatomical investigation of the genitalia. The high Antarctic Cadlina affinis does not possess an aberrant androdiaulic genital system but, as all other doridoidean nudibranchs, a triaulic system with a separate vagina and nidamental duct. The vaginal duct is short and leaves the vagina distally, distinguishing this species from other known cadlinids. The genitalia of the holotype of C. kerguelensis from Kerguelen Island have been re-examined. In contrast to previous assumptions, it is not conspecific with cadlinids from South Georgia and the Magellanic region because of clear differences in the genital system. The south-western Atlantic C. magellanica is redescribed and considered to be conspecific with the holotype of C. falklandica from the Falklands. A specimen previously assigned to C. falklandica from South Georgia, however, differs from other southern cadlinids due to genital features and is redescribed as C. georgiensis sp. nov. The Argentinian species C. laevigata and C. berghi, cannot be clearly distinguished from C. sparsa, of which a lectotype has been designated and, therefore, are regarded as junior synonyms. Five Cadlina species from the Southern Ocean are regarded to be valid, and their biogeography is briefly discussed.

Non-seasonality of births in Tierra del Fuego (Chile)

Tierra del Fuego is situated at the southern tip of the American continent, which conditions its environmental and climatic characteristics. The colonizing population arrived, at the end of the 19th century, from other Chilean regions (particularly from Chiloe) and diverse European countries, especially Britain and Croatia, but also Germany, Spain and Italy. In the present study, the existence of a seasonal pattern in 5430 births registered in the Chilean population of Tierra del Fuego from 1890 to 1995 was analysed. The analysis showed no seasonal distribution of births in the periods 1890-1920 and from 1946 to the present day, a phenomenon rarely reported in the literature. The absence of seasonality in birth distribution could be related to the great diversity in the origins of the population's families, the constant renovation of this and the declining importance of the administrative capital of the province of Tierra del Fuego, Porvenir, in favour of Punta Arenas, capital of the Magellanic region. In the period of maximum development of the capital of the province, a seasonal pattern was detected with a peak in April and a trough in October, which corresponds with a maximum of conceptions in July and, in general, during the early southern winter and a decline in births from late spring to mid-summer, with a trough in January. This birth distribution is interpreted as a subordination of activity and social life to the annual sheep cycle. In addition to temporal trends, the influence on the observed patterns of environmental parameters, father's occupation, seasonality of marriage and the origin of the parents were analysed.

Morpho-ecological study on the South American species of the genus Nothofagus

The morphology of the 11 taxa of South American Nothofagus are compared. Thirty eight characteristics were taken into account: 12 from leaves, 3 from stipules, 3 from buds, 6 from cupules, 7 from fruits, 4 from petioles and 3 from male flowers. The data matrix, with average values of 100 measurements per taxon, was analyzed with multivariate statistical methods of classification and polar and spatial ordination. Five groups were established: The first one (Nothofagus obliqua, N. obliqua var. macrocarpa, N. leoni and N. alessandrii), with deciduous leaves, is adapted to mediterranean climatic conditions. The second groups (N. dombeyi, N. nitida and N. antarctica), with small leaves which are evergreen for the first two species and deciduous for the last, develops under temperate humid conditions typical of the Valdivian region. The three remaining groups correspond to isolated species with different requirements: N. glauca, has large deciduous leaves and colonizes the most xerophytic biotope that a Nothofagus in central Chile can tolerate. N. pumilio, with mid-sized deciduous leaves, is adapted to the cold and dry zones of the southern Andes. Finally, N. betuloides, with small evergreen leaves, grows in the cold/humid somewhat boggy conditions of the Magellanic region.

Magellanic Bryozoa: Some ecological and zoogeographical aspects

This study summarizes observations made on more than 140 species obtained in Southern Chile and on many others collected from the Juan Fernandez Islands to the Antarctic Peninsula from 1962 to 1980. The total number of the Magellanic Bryozoa including the author's records and those of the literature reaches 195. These species are: 15 Ctenostomata (7.69%), 46 Cyclostomata (23.59%) and 134 Cheilostomata (68.72%). Seven species are described as new: Arachnopusia admiranda sp. nov., Celleporella chiloensis sp. nov., Electra pilosissima sp. nov., Hippoporina chilota sp. nov., Parasmittina pluriavicularis sp. nov., Smittina ectoproctolitica sp. nov. and Smittina molarifera sp. nov. Typical characteristics of the Magellanic bryozoan fauna are: the Cyclostomata amount to 50% of all the subantarctic and antarctic species, with two endemic families Calvetiidae and Pseudidmoneidae; the Cheilostomata show a low endemism at the generic level compared to the antarctic group; the hippothoan fauna is very diversified with four species having tatiform ancestrulae. The zoarial diversity and the polymorphism of the Magellanic Bryozoa are qualitatively and quantitatively different from that of the Antarctic. Thus the encrusting species make up the main bulk of this bryozoan fauna with at least 110 spp. From a bryozoogeographical point of view the Magellanic Region comprises the following parts that could be considered as provinces: (a) Magellanic: including the southern tip of South America south to Lat. 40°S, plus the Patagonian Shelf and the Falkland Islands. (b) Tristan da Cunha and Gough Island. (c) Kerguelen and the nearby archipelagos in the Indian Sector of the Austral Ocean.

Breeding of the Band-Tailed Gull (Larus belcheri) on the Atlantic Coast of Argentina

The Band-tailed Gull (also called Belcher's Gull and Sime6n Gull) has long been known to breed on the arid Pacific coast and adjacent islands of Perui and northern Chile (Murphy, 1936:1053-1056; Goodall, Johnson, and Philippi, 1951: 283). Earlier authors (Saunders, 1896:226; Dwight, 1925:158; Alexander, 1928: 129) included in the range the coast of Argentina, the Magellanic region, and the Falkland Islands, but Hellmayr (1932:409), Peters (1934:314), and Murphy (1936) rejected such reports, regarding Larus belcheri as endemic species of the Humboldt Current littoral. The collection of specimens on the Atlantic coast of Argentina (Daguerre, 1933:214; MacDonagh, 1934:312; Steullet and Deautier, 1938:2; 1946:654), with the publication of morphological data, satisfied Hellmayr and Conover (1948:257) that this species did in fact occur on the Atlantic. The question still remained whether it bred on that coast. Daguerre (1933:215) had reported finding on an island in Bahia San Blas, in the southern part of the province of Buenos Aires, deserted gull nests with some dead chicks, which he attributed to this species. During the probable breeding season there had been sight observations of Larus belcheri at Puerto Ingeniero White and Puerto Belgrano, a little to the north of the Bahia San Blas (Casares, 1939:286; Olrog, 1958a:31). Sight reports and specimen records indicated that the species ranged in Argentina at least from Puerto Deseado on the Patagonian coast to Mar del Plata in Buenos Aires, and even to Uruguay during the Southern Hemisphere winter (Olrog, 1948:492 and 1958b:8; Cuello and Gerzenstein, 1962:84). Field experience and examination of specimens convinced me that there was a distinct Atlantic population, which I described as Larus belcheri atlanticus (Olrog, 1958b:8), because it differed from the nominate Peruvian population in longer culmen and wing. With assistance from the Mae P. Smith Gull Fund of the American Museum of Natural

Biological research by the British Antarctic Survey

The Antarctic Peninsula, the islands rising from the Scotia Ridge, and the Falkland Islands are a key area for biologists interested in the origin, relationships, and adaptations of the Antarctic flora and fauna. Of all Antarctic regions, furthermore, this has perhaps been the most intensively studied. The pioneer observations of J. R. and J. G. Forster during Cook's circumnavigation in 1772–75, and of James Eights in 1833 (Caiman, 1937), supplemented by the less systematic accounts of those engaged in early nineteenth-century sealing and whaling voyages (Weddell, 1825; Allen, 1899) paved the way for the thorough scientific programmes of more modern expeditions. The first of these, theBelgicaexpedition under de Gerlache, 1897–99, yielded much general information and brought back an apterous fly{Belgica antarctica),the first higher insect to be discovered in the true Antarctic. Soon afterwards, the Swedish South Polar Expedition led by Nordenskjold, 1901–04, brought to the Antarctic an outstanding botanist, the late C. J. F. Skottsberg, whose botanical researches on Antarctic and sub-Antarctic themes were to last for over half a century (Skottsberg, 1963). During the following decade the two French expeditions led by Charcot, 1903–05 and 1908–10, contributed important microbiological and ornithological information, and in 1902–04 the Scottish National Antarctic Expedition under Bruce made the first study of the South Orkney Islands and provided a general evaluation of botanical and biogeographical problems (Rudmose Brown, 1912). All these expeditions made general collections of flora and fauna which revealed that the Antarctic Peninsula and its adjacent islands were the richest area, biologically speaking, of the whole Antarctic region. Farther north, the Swedish Magellanic Expedition, led by Skottsberg in 1907–09, provided what is still the only published account of the vegetation of the Falkland Islands and information vital to the evaluation of biogeographical relationships between the Scotia Ridge, the Antarctic Peninsula, and the Magellanic region of South America. Skottsberg (1912) also described the vegetation of South Georgia, where pioneer work had been done by Will during the German International Polar Year expedition, 1882–83. The botanical work on this island, up to 1964, has recently been comprehensively reviewed by Greene (1964a).

Notes on the Behavior of the Flying Steamer Duck

THE steamer ducks of the genus Tachyeres are a small group of three closely related species of diving ducks, confined to the colder southern part of the neotropical region. They are all dull grayish or brownish birds, very massive and heavy, with short wings and heavy bills; superficially similar to the large eiders of the northern hemisphere in general proportions and ecological adaptations. Their common name derives from their practice of steaming along the surface of the water, using their wings as paddles and churning up the water like the oldfashioned side-wheel steamers. Two of the species are so heavy and short-winged that they are essentially flightless. They can raise the body partly out of the water during steaming; but they cannot leave the surface completely. The third species is lighter and capable of real sustained flight in the air for short periods. One of the flightless species, brachypterus, is confined to the Falkland Islands; while the other, pteneres, is found in the magellanic region of continental South America, Tierra del Fuego, and some of the adjacent islands. The Flying Steamer Duck, patachonicus, is more widely distributed, and is found throughout the ranges of both the flightless forms. Some of the habits of the steamer ducks have been described in previous publications (see Murphy, 1936); but very little has been recorded about their special social signal behavior patterns. It may be of interest, therefore, to describe and analyze some of the hostile and sexual reactions of Flying Steamer Ducks which I observed during November and December of 1956, along the east coast of Tierra del Fuego, near Viamonte, Argentina, and the north coast of the same island, near Porvenir and Gente Grande, Chile. This may help to reveal or explain some of the basic factors regulating such behavior, and may also clarify the systematic position of the group. It has been found that some hostile, sexual, and associated patterns, especially the ritualized patterns or displays, i.e. those behavior patterns which have become specialized (standardized and/or exaggerated in physical form) in order to subserve a social signal function, may provide reliable indications of phylogenetic relationships (see Lorenz, 1951-53). (Those patterns apparently ritualized, I indicate with capitalized names.) Most of my observations of the Flying Steamer Duck were made in the open, without cover; but it was sometimes possible to use an empty building or some natural obstruction as a blind. I was able to watch