Short distance wind transport of microfauna in maritime Antarctic [King George Island, South Shetland Islands]

Traps to catch microfauna transported by wind were installed on already col­ onised by plants area, in the vicinity of the glacier. After 6-week-exposition 859 individuals of microfauna were caught, of which Nematoda constituted 71 %, Tardigrada 22% and Rotifcra 7%. Number of microfauna individuals caught depended on distance from the already col­ onised areas and presence of plant parts, together with which animals can be transported more easily. Microfauna connected with vegetation, which is transferred together with plant parts, was transported in higher numbers. Probably these taxa (i.e. Diphascon within tardigrades and Dorylaimidae within nematodes) colonise new habitats at first, but other species dominate later in freshwater bodies. K e y w o r d s : Antarctic, wind transport, colonisation, microfauna. Introduction Global warming processes have gained recently a lot of notification in scien­ tific publications. The recession of the glaciers creates new bare areas, where the process of colonisation can be observed from its beginning. This is probably the reason why, the process of colonisation in the Antarctic have become recently a subject of increasing scientific interest (Smith 1982, Walton 1990, Ellis-Evans and Walton 1990, Kappen and Straka 1990). According to Ellis-Evans and Walton (1990) for successful colonisation the propagules, alive and able to survive in new environment, as well as suitable mechanism of their transport are necessary. Propagules are generally transported by wind, birds and, especially now, by humans. Smaller propagules are mainly transported by wind, while bigger by birds and humans (Cameron et al. 1977). Smith (1982) suggested that skuas and dominican gulls in Antarctic are responsible for spreading of a plant Deschamps ia anta rctica. 204 Katarzyna Janiec Fig. 1. The study area. Invertebrate microfauna can be transported as adult individuals, sometimes in a state of desiccation, or as eggs. Microfauna itself can be also a vector for bacteria or protozoans (Ellis-Evans and Walton 1990). According to Walton (1990) most successful for transport are such mixed propagules, i.e. protozoan cyst glued to the algae cells. Short distance wind transport of microfauna 205 In our experiment we tried to find out whether, and in what amount, microfauna is transported for short distance by wind to colonise new areas. Materials and methods The experiment lasted for 6 weeks, between 10th January and 21st February 1991, in the vicinity of Polish Antarctic Station Henryk Arctowski, on the western shores of Admiralty Bay on King George Island, South Shetland Islands. The study area were two rows of moraine hills, colonised intensively in its northern part by mosses and lichens (Olech 1993), and only in a small degree in its southern part (having lichens on the top of the hills and mosses between the hills, Olech, pers. commun.) (Fig. 1). This area is bordered to the East by the sea, and to the South west by Ecology Glacier. Eleven identical plastic bowls (30 cm in diameter) served as traps and were placed in the study area, on two directions: from the glacier toward the moraine hills and from the sea up the moraine hills. (Fig. 1). The bowls were filled with filtered fresh water with the addition of 40% formaldehyde to attain 4% for­ maline solution. Every week all water from the bowls was taken to the laboratory and filtered through the plankton net of 30 urn mesh size. All the samples were Jan 10 Jan 17 Jan 24 Jan 31 Feb 7 Feb 14 Feb 21 Date Fig. 2. Numbers of individuals per site during the experiment. 206 Katarzyna Janiec 35 30 25 20 15 10 5 0 JanlO Jan 17 Jan 24 Jan 31 Feb 7 Feb 14 Feb 21 50