Wind Transport of Electrostatically Charged Particles and Minute Organisms in Antarctica

Airborne dispersal of antarctic terrestrial algae and cyanobacteria

“…The appearance of algae in culture from rotorod stnps exposed dunng January 1994 but not in January 1993 at Jane Col is cunous (Fig 3) Davey (1991a) found similar inconsistencies in the lnterannual occurrence of filamentous chlorophytes m soils between years This may also be the case for P crtspa at Jane Col (Fig 2a) Throughout the winter positive cultures were obtained from the Factory Bluffs rotorods more regularly than from the other sites This may be a consequence of the thinner snow cover at Factory Bluffs with more frequent melting due to black body absorption of solar radiation by the substratum A similar but more pronounced effect was noted m the release of lichen soredia (vegetative propagules) at the three sites (Marshall 1996a) On other occasions algae were found at all sites August andNovember 1993 (andMay andJune 1993 at Factory Bluffs and Jane Col) The cultures developing from the May and June samples could be due to frequent thaws providing disp>ersal opportumties at these times The greater number of cultures obtained from deposition samples, dunng this early part of winter (Apnl-July mcltisive), could be due to the continuous sampling, all thaws would be intercepted by the samphng programme…”

“…Susceptibility to desiccation and the effects of high lrradiances are the most likely causes for the declining growth of filamentous chlorophytes as summer progresses (Davey 1991a), desiccation will also increase the ability of soil algae to become airbome Dunng the early stunmer of 1993/94, snow cleared from Factory BlufTs by the second week of November and had gone from all three sites by the beginning of December Tioga Hill and Factory BlufTs sites are on hill tops, whereas Jane Col IS flanked on two sides by higher ground It is therefore likely that the soil at Jane Col retains a high water content for a longer penod than at the other two sites Should desiccation be the major factor promoting the lofting of filamentous chlorophytes, this situation would explain the delay seen between the appearance of these orgamsms m the air at Jane Col relative to Factory Bluffs and Tioga Hill Filamentous cyanobactena were collected on rotorods at Jane Col and Factory Bluffs dunng late summer in 1993, dechnes in the soil populations of these orgamsms have been recorded dunng this penod m 1987, 1988and 1990(Davey 1991a, Davey and Rothery 1992 The growth rates (Davey 1991b) and percentage soil cover of filamentous cyanobactena throughout the year (Davey 1991a) demonstrate a typically annual growth pattem and suggest that only small mocuia are required to initiate spnng growth. The (Hawes 1991) Such a scenario may be expected if large aggregates of entangled filaments, glued together with mucilage, with only a few viable cells, are dispersed This seems likely given that these groups are rapid colonizers and that there is little difference in the distnbution of small particles with height above the ground (between 0 15 m and 1 m) (Marshall 1996a) Snow algae (Chlamydomonas nwalts and Chlorosphaera antarctica) occur on most areas of permanent snow on Signy Island and heavy red coloration develops dunng snow melts (Fogg 1967) The site at Tioga Hill IS surrounded by permanent snow and ice yet, despite heavy coloration of the surrounding snow durmg summer, no snow algae aplanospores were trapped heie In contrast, snow algae were trapped on Factory Bluffs, although this site has only small f)ermanent snow patches within 1 km of the site, with the main areas of red snow on the Island's ice cap 1 6 km distant Thus snow algae, despite the size of their spores, and of clumps of spores, are able to disperse over reasonably long distances The lack of snow algae aplanospores at Tioga Hill IS most likely a consequence of the site being upwind (in the prevailing westerly winds) of the largest areas where snow algae are abtmdant, and that, unlike contmental Antarctica regions, melt dominates over ablation This would mean that instead of being lofted, following the sublimation of surrounding snow (Bennmghoff and Benninghoff 1985), the snow algae cysts would remain m the snow/water until earned away by melt water At Jane Col water flows from the ice cap onto the site where cysts could become desiccated and lofted into the air.…”

“…Algae have been collected from Antarctic air by a ntimber of workers using sedimentation methods Rudolph (1970) trapped 148 algal propagules (0 63 algal propagules m"-h"') on sticky shdes at Cape Hallett in Victona Land, where the frequency of occurrence in the air was proportional to their local vegetation cover Rudolph (1970) also sampled air in Mane Byrd Land at a site seven miles from the nearest vegetation and collected only a few algal cells Broady (1979a) collected samples on agar plates at Signy Island, South Orkney Islands on a number of occasions throughout the year and found up to 369 algal propagules m"^ h~' dunng early summer He related the ntimber of airborne algae to the extent of lowland snow cover and concluded that, given such large numbers, each algal taxon will be dispersed to, and have the opportunity to colonize, all available habitats Harmata and Olech (1991) collected algae from the deck of a ship in the South Shetland Islands at the start of a transect of the Atlantic Ocean Active samphng methods have also been used, the first mstance bemg the use of an Andersen cascade impactor, at intervals throughout the year, in 1964year, in -1965 (Meyer et al 1967) similar organisms were found in the air to those occumng in the soil at this locality More recently, Burkard jet spore traps have been used alongside Tauber traps on the McMurdo Ice Shelf and in the Taylor Valley, McMurdo Dry Valleys region (Hawes 1991) The work conducted on the Ice Shelf was to investigate the dispersal of algal propagules between ponds and lakes in an area of undulating ice No propagules capable of germinating on any of the media used were detected in 54 000 m^ of air sampled on the Ice Shelf or in 8000 m' air sampled in Taylor Valley using the jet spore trap (with the mtake 0 8m above the ground) On the Ice shelf, two sets of three Tauber traps (with intakes ca 0 1 m above the ground) were used with media for fresh, brackish and salt water One set was sited on Bratina Island and one on the shelf Itself Tauber traps from both sites collected a wide vanety of algae in all three types of media, with those from the Bratina Island traps charactenstic of soil, and those in the Ice Shelf traps resembhng algae found in the ponds on the Ice Shelf It was concluded that locally denved matenal travelling close to the ground was being caught The jet trap was assumed not to have collected any algae because its onfice was 0 8m above the ground whilst that of the Tauber trap was only 0 1 m above the ground A Burkard jet spore trap was also operated in 1990-91 as part of an investigation into the introduction of algae mto Antarctica by htiman activity (Broady and Smith 1994) The sampler was deployed at Scott Base, were it sampled 1800 m-* of air, and, for companson, at two other pnstme sites Lake Vida in Victona Valley (77°23'S, 161°26'E) and a site on the Ross Ice Shelf (78''01'S, 169°42'E) where, respectively 4140 m^ and 1800 m' of air were sampled Nothing was collected at either of the pnstine sites and only 0 006 propagules m"-* were foimd at Scott Base Work has been conducted in the McMurdo region to look at the effects of electrostatic charges on the dispersal and deposition of airborne particles using a vanety of air sampling devices (Benninghoff and BenninghofT 1980…”

Ciliate biogeography in Antarctic and Arctic freshwater ecosystems: endemism or global distribution of species?

“…Although transport by wind is widely assumed to be a dispersal mechanism for protists (e.g. Broady, 1996), ciliates (in durable resting cysts) are rare or often absent in aerosol collections (Schlichting, 1961; Sudzuki, 1972; Benninghoff & Benninghoff, 1985; Marshall, 1996; Marshall & Chalmers, 1997; Rogerson & Detwiler, 1999). Likewise, ciliates were not found on Antarctic flying birds, which may act as dispersal agents for algae and other protists (Schlichting et al , 1978).…”

Organic carbon cycling in Taylor Valley, Antarctica: quantifying soil reservoirs and soil respiration

“…Furthermore, it was assumed that displaced organic material from these sites was the primary source of organic carbon found in arid soils (Horowitz et al 1972;Friedmann 1982;Vincent 1988). This concept of the dry valley soil environment being a passive receptor of organic carbon from other environments seemed the best explanation for the ecosystem, being based on observations of (i) little to no soil primary productivity due to low moisture and cold temperatures (Horowitz et al 1972) and (ii) particulate organic material from lacustrine mats and cryptoendoliths carried by strong Antarctic winds (Benninghoff & Benninghoff 1985;Nienow & Friedmann 1993).…”