The ecology and physiology of Antarctic invertebrates at Cape Bird

The effect of temperature on the terrestrial arthropod fauna at Cape Bird was investigated. The work was carried out over three field season and the site was visited for three periods during each field season (October, December and February). Samples were collected of both mites and springtails from Keble Valley (Caughley Beach, SSSI No.10, Cape Bird) and frozen and returned to New Zealand for analysis of ployol cryoprotectants and thermal hysteresis (antifreeze proteins) and microscopic analysis of age, sex and gut contents. An HPLC system to examine sugar alcohol cryoprotectants and the splat freezing technique were used to screen for ice active proteins. The supercooling point (the temperature at which their bodies freeze) of both springtails and mites was determined for different periods during the season. Invertebrate samples were removed to measure water content of invertebrates bodies to investigate the effects of surface water on cold tolerance of this species. A cloche (small greenhouses) experiments was installed and the invertebrate population within was monitored over the three seasons to study responses to temperature changes expected from global warming. Micro arthropods populations were removed from the soil and from the ground surface and rocks, sorted, counted and measured. A map was made of the pattern and longevity of snow banks and the whole study site was mapped (450m2 to c10cm resolution). The habitat requirements and the factors affecting invertebrate distribution were investigated at two scales: a transect across a stream in November (before snowmelt) and January (after snowmelt) and a broadscale survey to cover a representation of ice free areas. The ability of springtails to live in dry or salty habitats was determined The wider icefree area was surveyed (rock undersides and soil samples) with a sampling trip in the area near Harrison Bluff, South of Cape Bird southern rookery and Shell Glacier. The hameolymph concentrations (an indication of the quantity of carbohydrate cryoprotectants and other solutes in the animals blood) and the thermal hysteresis (indicative of the presence of antifreeze proteins) in mites and springtails was investigated. The distribution of invertebrates was studied by setting out sticky traps to intercept windborne animals, placing a drift net across a stream to capture water dispersed animals and checking the feet of penguins in the area for micro invertebrates. A data logger was installed to measure air temperatures and soil temperatures (at five different depths) throughout the year to determine relationships with the temperatures that the mites and springtails experience.