The Ecology of Nematodes in Antarctic Dry Valleys

线虫是一种微小的无脊椎动物，存在于所有生态系统中。它们在土壤中尤其丰富，它们生活在土壤颗粒周围的水膜中。它们以微小的动植物以及细菌和其他分解者为食，在土壤食物网的养分循环中发挥着重要作用。这项研究将继续对南极洲干谷生态系统中线虫的首次密集生态调查。在1990年和1991年的南半球夏季，在各种土壤性质(水分、盐分、氮和碳含量)的干旱河谷土壤中发现了线虫。这项拟议的研究将通过从维多利亚州南部干旱河谷地区不同的土壤结构、海拔和地点的不同生境(土壤特性和微生物活动)中采集线虫样本，增加我们对线虫丰度和营养作用的了解。作为对恶劣条件的反应，线虫可以呈现一种隐生物状态，在这种状态下，它们的新陈代谢变得不可检测，动物的生理和形态都发生了变化。野外和实验室对隐生生物的研究将确定线虫在这片寒冷沙漠中活动的潜在持续时间，并将补充线虫种群动态的研究。将进行田间试验，以考察线虫和土壤总微生物活性对土壤温度、水分和能量有效性的响应。土壤的总反应将通过二氧化碳外流和底物诱导的呼吸来确定，这是一种与土壤微生物生物量有关的衡量标准。将利用分子生物学技术对干旱河谷优势线虫种群的遗传多样性进行评估。据推测，如果线虫很容易被风吹散，这种多样性将在很大范围内与之相媲美。

Nematodes are microscopic invertebrates found in all ecosystems. They are particularly abundant in soils, where they live in water films surrounding soil particles. They play an important role in nutrient cycling in soil food webs by feeding on microscopic plants and animals as well as bacteria and other decomposers. This study will continue the first intensive ecological investigation of nematodes in the Dry Valley ecosystems in Antarctica. During the 1990 and 1991 austral summers, Nematodes were found to occur in Dry Valley soils over a wide range of soil properties (moisture, salinity, nitrogen and carbon contents). The proposed research will increase our understanding of the abundance and trophic role of nematodes by sampling them in various habitats (soil properties and microbial activity) from a wide range of soil formations, elevations and locales in the Dry Valley region of southern Victoria Land. In response to harsh conditions nematodes can assume a cryptobiotic state in which their metabolism becomes undetectable and there are both physiological and morphological changes to the animals. Studies of cryptobiosis in the field and laboratory will determine the potential duration of nematode activity in this cold desert and will complement research on nematode population dynamics. A field experiment will be conducted to examine the response of nematodes and total soil microbial activity to temperature, moisture and energy availability in the soil. Total soil response will be determined as carbon dioxide efflux and substrate-induced respiration, a measure related to soil microbial biomass. The genetic diversity of populations of the dominant nematode in the Dry Valleys will be evaluated using molecular biology techniques. It is hypothesized that if nematodes are easily dispersed by wind, this diversity will be comparable over a wide area.